image: oldsmobility.com
(first posted 11/17/2011)
It may seem like during the late sixties Detroit’s power train engineers were all just focused on ever higher maximum performance and had given up any interest in fuel economy. There was a little pocket of engineers at Oldsmobile who seemed to think that efficiency still might be of some possible utility, even then. Their efforts resulted in the interesting (and obscure) Turnpike Cruiser package the Olds engineers came up with in 1967. I’d almost forgotten about it, but CC reader MarcKyle64 sent me a link to a 1967 Car Life test that explains it in great detail.
I’ll give you the Cliff’s Notes version here, but before I do, let’s jump ahead and explain why I’d forgotten about it and you may have too. It obviously didn’t click (as in sell); folks just weren’t interested in what was actually a simple but effective engineering solution to tailoring existing technology for the conditions American cars were commonly used. Buyers would rather spend the couple hundred dollars it cost on vinyl roofs or the 442 package; gas was cheap; image was more important.
The essence of the Turnpike Cruiser was the acknowledgement that a detuned large engine can power a car more efficiently than a higher-revving smaller engine. In German, this was called the drosselmotor, or throttled engine, which in actually is a misnomer. It does involve a relatively modest carburetor, but most of all, a camshaft with an extremely modest duration, yet fairly high lift. The goal is to create a very low and rich torque curve, which combined with a very low (numerical) axle ratio assured that the engine would run at low rpm, but at relatively greater throttle openings, lowering both engine friction losses as well as pumping losses.
Frankly, the classic VW air-cooled boxer motor operated on this principle, as well as other in Europe. The most extreme example was BMW’s eta motor, which made a mere 128 hp from the 2.8 l six, at a diesel-like 4800 rpm.
The Olds engineers started with a 442 400 cubic inch engine, specifically for the large valves, which help compensate for the short valve opening duration. The cam had a 250/264 (intake/exhaust duration degrees) grind, and a relatively large but two-barrel carb. But the real key was in reducing effective gearing. The result was 300 hp (290 in 1968) at a relatively low 4600 rpm. Torque was a very healthy 440 lb ft at 2400 rpm.
The really critical component was the new three-speed Turbo Hydramatic transmissions. Not that it had an overdrive ratio, but by combining it with a super low 2.41 to 1 rear axle ratio, the THM in effect became a two speed with an overdrive third. Top speed in first was 60 mph, second top at 100 mph. The big 400 ran at 1850 rpm at 60 mph, very close to its torque peak, which corresponds to an engine’s most efficient speed.
The result were steady state speed fuel economy readings of 21.04 mpg @ 50 mph; 19.26 @ 60 mph; 17.22 mpg @ 70 mph, and 15.26 @ 80 mph. Yet 0 to 60 came in a very respectable 8.2 seconds (all in first gear, presumably).
And there’s more: the Turnpike Cruiser only came with the excellent 4-4-2 suspension package, with heavy duty springs and shocks, and a rear anti-roll bar. Radials were optional. What’s Detroit coming to? Stuttgart?
It appears the TC package became available as an option in the spring of 1967, and shows up in the 1968 brochures, but no more thereafter. Of course, it was a preview of things to come in the mid seventies, when detuned engines, lazy axle ratios, and overdrive transmissions enforced a similar regime. The only problem was that they often didn’t perform as well as the TC. Weight and emissions controls were doing their part to assure that. We could call the Cutlass TC a prophet, which are usually never appreciated in their time.
Never knew this existed why didnt this carry on when the gas crisis kicked in high torque is where its at for both performance and fuel economy of course the supersizeme body engineers fought against real fuel efficiency and still do.
Those low horsepower engines in the 70’s had tons of torque, just like the Turnpike Cruiser. Fuel economy suffered due to emissions requirements.
Worked for an Olds dealer in the ’60s. Service many TCs. My favorite. Suspected that the gains in emissions on paper were canceled by the losses in MPGs. Sticking a hose into the exhaust pipe cannot predict emissions if it takes 100 gallons of gas to get across the street. I’m no engineer, but the last time I looked, I had a brain. Something is wrong with the way they think.
It did carry on full force through the 70’s, as 2.73 and similar gear ratios became the norm as did low duration cams.
Your making me think of the Ford 400 that was used at the close of the 70s. That is one of the most undersquare, longstroke engine ever produced. I’ve always wondered what fuel economy would have been like on a fuel injected version. (Of course Oldsmobile’s 403 was similiarly longstroke.)
The Ford 400 is “square” with a 4 inch bore and 4 inch stroke.
The 403 was the opposite of the ‘late 400’, it had a huge bore & short stroke. The late 400 wasn’t much of a performance engine, it came out when the 455 did. It shared the long stroke crank with the 455.
The early olds 400 had a nearly square bore/stroke, it was a great performance engine, the 425 was even better.
Same could held for ANY large displacement engines of that era. Two barrel 10.5 429 in a full size mercury with a 2.75 rear gives outstanding highway miles. Not too bad around town, either.
That’s a fascinating lesson in engine and drivetrain design. This owner now reports 22 mpg: http://history.gmheritagecenter.com/wiki/index.php/1967_Oldsmobile_Cutlass_Supreme
Is this how the current 6.2L Corvette gets 26 mpg highway?
Corvette: yes, essentially. Modern engines with variable valve timing (and lift) can emulate the full range of capabilities of what used to be limited by the camshaft. That, and other tricks with fuel injection, and variable cylinder de-activation; all stuff of dreams back then.
C6 Corvettes have 2.56 gears with auto transmissions, but they also have 6 speeds so that there is a nice ratio spread. Aerodynamics and light weight help the Corvette. A family member has a 2012 C6 convertible auto and he has been able to squeeze 29 MPG on the highway out of the 6.2 and these cars don’t have direct injection or the cylinder deactivation like the C7.
But either the steering wheel will fall off or the ignition switch will cut off, resulting in exactly what GM wants. Dead people.
Right, right, we all know the ignition recall goes back to 1967! Ugh, get a new line…
Döuchẹbagiin
Except Corvette isn’t one of the cars affected. The media is doing a terrible job on this story. Car and Driver actually looked into the deaths these ignition switches caused and the results are quite interesting, ie most of the driver’s who died had other aggravating factors like impairment. Further, they also tested a Saturn Ion under worst case scenario conditions, and guess what – nobody died.
But seriously, when that scandal broke I was surprised to learn GM *hadn’t* been using the same ignition assembly since column switches came in in the late ’60s.
What a superb write-up!
Thanks for another great read, Paul
I didn’t go to the external link, but this is the way many modern cars work, including the C6 Corvette.
Our G6 runs in a similar fashion, but with six speeds in the ‘box, I can cruise at 80 MPH and still get 27 MPG.
EDIT: Man, that black Cutty looks GOOD!
I believe the picture is from “Sons of Anarchy”. That’s the doc’s (Jax’s ol lady) car, or at least it was the first couple of seasons. It disappeared this season.
Thanks for that info. I’ve never watched the show, but now at least if I did, I’d have something to look forward to…
Even though the Car Life Link above, is now dead. For those still interested, this link is active. http://www.oldsmobility.com/old/carlife_apr67.htm
I always wondered why my Hyundai with the 1.6 liter four gets worse mileage than the Cobalt with the 2.2 four I used to have. Now I know.
I bet I could make a 67 Mustang with the 200 inch Six get mileage in the high 20s by installing a 240 or 300 Six while keeping the carb from the 200, installing an appropriate cam and putting a very low ratio rear-end on it.
You would be better to stick with the 250 in. Version of the Falcon motor available in the Mustang since 1969. The 340/300 is a big car/truck motor which weighs as much as a small block v8. The 250 weighs in at approx. 400lbs. Ford made a similar effort for economy with the 69/70 250 in the Mustang. The torque peak is 240 lbs.at only 1600 rpm. Horsepower is rated at 155 hp.at 4000 rpm. This would put the motor into it’s most efficient power range at legal speeds. I noticed that it takes a greater amount of throttle opening than I’m used to using to cruise at 65-70mph. I would imagine this was to reduce pumping losses. The c/r was still 9.0-1 so it hadn’t been lowered yet but still runs fine on 87 octane. Interestingly enough the 200 reaches it’s torque peak of 190 lbs. at 2400 rpm. and it’s hp peak at 4400 rpm. It would seem that the 250 would match the 200s economy with better performance. Since my car came with a good running 250/auto combo I’m concentrating on getting it running right and getting some mileage readings. I plan on doing some improvements: a cold air intake, electronic ignition, lower restriction exhaust, maybe a header. Got a turbo muffler on it now. I’ve put radials on it now and will add a Mach One chin spoiler to the front end later. My goal is to make gradual changes and measure the possible improvements to mileage and performance with G Tech meter. I’ve read lots of good things about the 250 on the I6 forums so we’ll see. My first impressions are that it’s pretty responsive off the line and really likes to pull long hills at 45-50 mph. I’ve had it up to 80 mph. And it seems that performance flattens out after that. You know my 96 GT is set as a turnpike cruiser also. HP is low 215, but torque is high 285 ft.lbs. The AOD tranny keeps the rpms real low on the highway, about 2000 ish at 70 mph. I routinely get 25 mpg. at 70 mph. I like good fuel economy on regular gas.
I had the privilege of driving two 1968 Mustangs when I was in HS. Both were HT coupes equipped with 3-speed C-4 A/T and A/C. My car was a 200 straight six with the 1 or 2 bbl carb, basically the base Mustang. My mother purchased a used Mustang which had the 289 2-bbl motor. I had been driving my 6 for about two years by that time and was used to its leisurely acceleration but steady drone when it got to speed.
The first time I drove the 289, I punched the gas like I did in my six and almost blew out of the driveway at our house. The 289 was a much smoother running car with plenty of acceleration. You could barely hear the 289 running when stopped at a light. As I recall, both cars got about the same mileage, but the 289 was a lot more fun to drive.
I’d vote for one of these being the Best Cutlass Ever, even over a 1961-63 model. This would put the joy in the cross country classic American Road Trip: Quick (8.2 0-60 wasn’t anything to sneeze at in 1967 and would be competitive through the mid 1990s) Nimble(ish, as good as it got from the A bodies during the 1960s) and (relatively) efficient, as that mileage would best most family sized SUVs up until recently.
All with OIdsmobile style, build quality and personality (that distinct Olds V8 sound). Make mine A Supreme Holiday Hardtop Sedan please.
You’re out of luck; two door coupes and convertibles only; since they were basically a 4-4-2 in many respects.The THM wasn’t installed in the sedans; only 4-4-2s and the TC, at least for ’67.
fine, twist my arm into a convertible whydontcha…….
I do recall reading that there was one available for the 455 in 70-72, with similar tweeks and a larger gas tank for extended crusing range.
Maybe for the Cutlass SX only?
The good looking trip-black Cutlass was driven by Tara(the good looking girl in the car) on the FX show Sons of Anarchy for a couple of seasons, though I have not seen it in recent episodes.
CC effect,I’ve just been watching SOA and watching the Cutlass being driven by Tig the scary Sergeant at Arms.
The reduced pumping losses of the throttle opening is key here – I spoke to a man years ago who had installed a centrifugal supercharger on his 5.4 32v FPV, taking the engine power from 390hp to over 500hp, yet he gained highway fuel economy thanks to the pound or two boost easing the air’s passage past the throttle plate.
As a corollary, is there any info on how badly the tall gearing affected fuel economy around town? Also I would expect that a manual trans would give a decent mileage gain over a 1960’s slushbox, as well as the wider gearing range available with an extra gear ratio.
Another point, even without any special economy features conventional wisdom has it that the Holden 308 V8 will usually give better economy than the 253ci V8 in normal driving, and if the vehicle is loaded or towing, better than the 202ci 6cyl as well. Personally I think that is a reflection on the 202…
It’s worth noting, though, that four-speed gearboxes were quite rare on Detroit cars of this era, and not generally offered except with performance engines or on pony or muscle cars. Compared to a three-speed gearbox, I don’t think the Turbo Hydramatic did that badly — some fluid losses, inevitably, but better off-the-line multiplication. Through 1967, Oldsmobile (and Cadillac and Buick) also used a variable-pitch stator for the torque converter, which provided a bit of intermediate multiplication without a downshift. I recall that Car Life found that particularly helpful with the TC’s tall axle.
That is a fair point & applied to the American based cars in Australia too of course. I imagine the THM (400?) for the TC package could be set up pretty tight in the converter too, to minimize the fluid losses.
It is interesting to compare the gearing, the 2004 BA Falcon I drove would do almost 60 mph in first gear of its 4sp auto, and sit on ~1700 rpm at 60 mph in 4th overdrive, so similarly not a rocket off the line. Kickdown acceleration on the highway (4th-2nd) was pretty good though!
Bryce that is not bad – obviously open road miles. Dare I ask if you saw the same mileage?
My first 202 a Belmont was a dairy board car huge milage regular servicing and driven sensibly by one guy its fuel records showed 29 mpg for many years. The 308 returns better towing fuel economy over the 253 or 202 simply as it doesnt need to work as hard to achieve the same result but a 265 Valiant hemi6 is a better tow car than any Holden.
I had a 76 Chevy Malibu Classic sedan that had a TH350 and a box stock 305 with a 2bbl carb, and a 3.08 rear axle. It could get 15mpg in town pretty easy even with the A/C running.
I now have a 77 Malibu Classic sedan now, that is equipped almost exactly the same way save for a 2.56 rear axle ratio, it gets 12 in town with the A/C running. It has gotten a high of 22mpg on the road, but 20mpg at 65-70mph is my goal.
My 76 struggled a bit to get over 18mpg at 70mph. It did get better once I put new heads on the tired old 200,000 mile short block that had bigger valves and higher compression but it only gained one MPG.
The 77 has had nothing done to the 305 save for tuneup and decarboning and new timing chain and tin gaskets. It has somewhere around 200,000 miles as well and still sports the original crap tiny valve heads.
The 76 was noticeably faster to 60 (about 9 seconds before the head swap) and the 77 takes about 11, the 77 will walk the 76 above 70mph though since it gets into the meat of the 245lbft of torque at 2400rpm and stays there longer.
A 2bbl 350 might beat the 305 for economy though. But putting a 4bbl on the 305 doesn’t make it much more powerful due to the low-lift cam.
Tommy T, I’d say you’ve have great luck with your 76 & 77 Malibu.
I wish I know FOR SURE what the axle ratio was on our 3-spd auto, 260 V8 75 Pontiac Ventura.
I think I recall seeing that a 75 Nova had a 2.71 ratio.
No matter, our car typically got 15 mpg according to my dad. When I started driving, I really couldn’t afford to top off the tank regularly and check. I got between 14 and 17, and I may have gotten 19 mpg on the “highway” (80 mile round trip, not accurate).
Consumer Reports used to test cars for mpg at 40, 50, and 60 mph. I think your car getting 18 mpg at 70 is excellent for that era–with 200k miles, even more so!
I recall that Olds engineers were very keen on the Turnpike Cruiser package for their own personal cars. I suppose you could fairly call it a package designed by engineers for engineers…
Perhaps that’s why it is sort of “German” in it’s thinking? BTW I WANT!
Is this another case of one car company picking up an unprotected name previously used by another?
http://en.wikipedia.org/wiki/Mercury_Turnpike_Cruiser
https://www.curbsideclassic.com/blog/from-the-cc-cohort-1981-ford-durango-shoulda-coulda-did/
I guess I had no idea these guys were appropriating each others names so much. With the Mercury Turnpike Cruiser being such a flop I am surprised someone at GM thought it was a good name to use, and so soon after the Mercury.
I guess I don’t know how to embed a link. Sorry.
Actually in practice the Quadrajet usually gets better MPG due to it’s small primaries that result in higher velocity for better fuel mixing and distribution. GM even used the Q-Jet on V6 cars in the 70’s & 80’s that returned excellent MPG for the vehicles in which they were installed.
Reducing pumping losses certainly does improve an engines efficiency. However the size of the carb doesn’t really make that much difference. At any given load an engine will require a certain amount of air/fuel mixture. So to produce a given amount of power the vacuum reading will be the same no matter what the size of the throttle. A smaller throttle will be farther open to achieve the same air flow. Sure at WOT you can have too small of a throttle to realize the full power potential of an engine. At part throttle cruising though and engine will always produce the same amount of vacuum at a given RPM and power output. Where a smaller carb does help is in the fact that with the fuel induced above the throttle low throttle openings tend to make a certain amount of fuel fall out of suspension as it hits that throttle plate and makes a hard turn. The throttle being straight up and down reduces the surface area that the fuel can do that on. Again that results in better fuel distribution.
So the key to this equation is to reduce engine rpm so that a lower amount of vacuum will be required to supply the engine with enough air and fuel to make the needed power. It all comes down to VE or volumetric efficiency. You may have a 50cu in cylinder with a given static compression ratio but you almost never put a 50 cu in charge in the cyl and never reach the full compression ratio.
The reason the 2bbl was likely chosen is the better cyl to cyl fuel distribution. With any intake that doesn’t result in an equal distance from the point of fuel induction to the valve will result in different fuel mixtures in different cyls. With the centrally located 2bbl you end up with more even distribution.
As you can see now a lot of this is concerning distribution of fuel. Because running too lean can damage an engine, with poor fuel distribution and mixing you need to have a number of cyls running too rich to prevent some running too lean. Improve distribution and you can run a leaner mixture and thus improve MPG and emissions too. That is why the EPA and CAFE almost killed the straight 6 and why you hear reports of old carb’ed V8s often returned as good or better MPG as a smaller carb’ed straight 6s of the same vintage.
Another good trick in reducing pumping losses is the often lamented (and disconnected) EGR. Putting some inert gas into the mix decreases the vacuum reducing the pumping losses. That also means the cyl is fuller giving a greater actual compression ratio.
It is interesting to note that a 2bbl 396 was available on ’69 full size Chevrolets
I had a 67 Galaxie 500 with a 2bbl 390 that was coupled to 2:70 gears. Although 10-12 mpg was normal around the city (and I was 17) I could hold 18 on the highway pretty easily, and once got over 19.
Wife’s 64 Marauder had the same power train with similar results. Very heavy car.
As was a 2 bbl. 429 on full size ’69 Fords and Mercs. Also the early ’60’s suicide door Lincoln’s were 2 bbl’s.
same 429 2-V was carried over into the 1970s as well (albeit with drastically-lowered compression ratio, EGR, and different cam grind).
Thanks for posting the article. It brings back memories. In ’67 i bought the Olds Turnpike Cruiser (Holiday Hardtop). I loved that car but 3 years later I regretfully had to trade it in for a station wagon – family expansion. My 2-tone TC was burgundy with a cream colored top. It had the electronic high capacity discharge ignition system. All I did was re-balance the distributor to my liking. I opted for the cruise control and the wire wheels with Red Line Firestones. The car was like a dream on the Interstates and even fun at the stop lights thanks to the robust 442 underpinnings. Even my wife enjoyed the occasional stop light challenges when someone next to her would rev the engine . . . . pouting lips, innocent stare and . . . she was gone at the green. Often I would manually shift the Turbo Hydramatic (up and down) with no problem at all. Also, I never needed to tune the car for high elevation driving, just drive up to Pikes Peak and surrounding areas and back down to Chicago: the car ran just fine wherever I went. Yup, I loved that car.
I wonder what one of these could run up to flat out? 125-130mph?
It would depend a lot on the gearing. Quite possibly, third gear would be too tall to let the engine develop enough hp to reach its potential top speed based on hp alone. Gearing for economy is not conducive to higher top speeds; quite the opposite, actually. The top speed in one of these might be a bit disappointing. Anyway, with 290 gross hp, it’s theoretical top speed with gearing to allow it to reach it might only be some 120 or so. 130? No way, given the aerodynamics of these bricks.
Car Life quoted 130 mph @ 4,100 rpm, but I’m quite confident that was a calculated rather than observed figure. I’m with Paul; 300 gross horsepower isn’t hay, but with that kind of drag area, the gearing, and the engine’s torque and breathing characteristics, a high top speed just isn’t in the cards.
My guess would be that at over 100 mph, you’d have a hard time getting the engine to pull more than about 3,500 rpm, which with the 2.41 gearing and standard tires would give you about 110 mph. Of course, by 1967, even that would have gotten you taken away in handcuffs anywhere but Nevada, so it was obviously an academic point.
I remember reading about this somewhere but had totally forgotten. I guess that I wasn’t impressed for some reason. Probably the low capacity 30mpg vw I was driving.
I am not a mopar geek but my cornet 440 with the 318 would do better than that IIRC. Had a 3 speed auto and 2 bbl, also IIRC. Guess there might be a common thread there because that Dodge was made for the highway.
The July 68 issue of motor trend had an article called Econoperforleration or something like that, it was a test of the 67s & 68s. I couldn’t find the article on the net though. I do remember that the efficiency got better on the 68s.
I remember a test that M/T did later, featured the 1974 pony cars. A 350 Z/28 got like 12mpg, while a firebird (it had a 2bbl 400, auto trans, & tall gears) got like 19 mpg. The acceleration numbers for the cars were great (Z/28) to average (for the firebird) even for today.
The test you’re thinking of was for the 1968 Oldsmobile line. I don’t recall the issue date off the top of my head and don’t want to wake anyone up right now digging for the issue, but I think it was from the summer of 1967.
In any case, yes, while the Turnpike Cruiser package was short-lived, it was in some respects a preview of the entire 1968 Oldsmobile line, where Olds enlarged displacement (if they could), retuned engines for greater low-end torque, and used lower numerical axle ratios. The results weren’t quite as dramatic as the Turnpike Cruiser, but the principles were the same.
I believe was also the reasoning behind the undersquare 400 in the 1968–1969 4-4-2. Previously, the 400 had been slightly oversquare (4.00×3.975 in.), essentially a small-bore 425. When the 425 was stroked to to 455 cid, Oldsmobile couldn’t actually enlarge the 400 without violating corporate policy, so they created a new 400 that was basically a small-bore 455 (3.75×4.25 in.) with a cooler cam that sacrificed 25 gross horsepower, but lowered the torque peak by about 600 rpm.
I have, what I think, is a related question. The 1970 Impala offered a 350 ci, 300 HP, 380 torque motor – that had a healthy 4 barrel carb. Or you could get a 400 ci, 265 HP, 400 torque motor with 2 barrel carb.
Why would you get the 400? I would assume it was an “upgrade” that cost more than the 350. But I don’t understand what it really gives you that is better?
And now I think I see the answer. the 400 used regular gas, the 350 300HP was premium.
The Turbo-Fire 400 (and the conceptually similar Ford 400) also lowered the torque peak quite a bit — down to around 2,000 rpm. I think those 400s were really intended not as an alternative to the 350-4V (or Ford 351-4V), but rather to the 350-2V. The easiest way to think of them is as as station wagon engines, intended for people who needed a little more muscle for hauling loads, but weren’t that interested in performance per se and didn’t want to sacrifice too much in the way of fuel economy. The 350-4V had more power, but wouldn’t have been as well suited to, say, towing a trailer.
(I have heard of people trying to turn the 400s into performance engines, but looking at those engines’ bottom end specs, my reaction is, “Er… good luck with that.”)
What bottom end specs are you talking about for the 400? Both the 400 Chevy and 400 Ford have been used for performance builds. The Ford 400 has the same bottom end as a 351C, but with larger main bearings (3″, same as a 351W). What’s the problem with the 400 Chevy, other than the short rods? In fact John Kaase has won the Engine master challenge several years in a row with a 400 Ford (using a stock block).
John Kaase Ford 400 Engine Masters
http://www.popularhotrodding.com/enginemasters/challenge/0910em_friday_october_9th_engine_masters_challenge_finals_updates_and_results_sponsored_by_rottler/
Car Craft – Chevy 400, 400 hp and 450+ ft-lbs, cast iron Vortec heads
http://www.carcraft.com/techarticles/ccrp_1105_how_to_build_a_400ci_small_block_chevy_torque_monster_for_2500/viewall.html
T. Myer 400 Ford – almost 400hp and 450ft-lbs on 87 Octane, Ford Cast Iron heads
http://www.tmeyerinc.com/category-s/1889.htm
400hp and 450-ft-lbs from both 400’s with cast iron heads, sounds like a decent engine to build for the street if you ask me. Maybe they aren’t they cheapest or easiest choice, but these 400’s can be built.
From Wikipedia – the reason 400’s originally weren’t popular for performance builds:
“The 400 differed from other small blocks in that the cylinders were siamesed (to allow for the 4.125″ bore) and therefore required ‘steam’ holes in the block, head gaskets, and heads to help alleviate ‘hot-spots’ in the cooling system at the point above the siamesed cylinders. Overheating and damage are likely if head gaskets or heads without ‘steam’ holes are used on a 400 block.”
They have found favor since, however, thanks to their reputation as torque monsters.
They also had unique main bearing and rod bearing journals, not to mention unique connecting rods.
Like other’s have said, the 400-2bbl engine was designed for low-end power. They had an abundance of low end torque which made moving a big heavy car feel more “effortless” with minimal throttle input. That said, they ran out of breath when revved up. The Caprice had the 400 as it’s standard engine for several years, the high torque engine seem to coincide with the Caprices smooth driving.
Thank you for the replies. Mine had the 350 and so I was always curious.
The other curiosity I have is – what was it like to drive a car with Powerglide 2 speed transmission? I have never ridden in a Powerglide and just can’t imagine a 2 speed transmission.
There probably isn’t much to imagine. I have no idea what the torque multiplication/gear ratios or anything might be but I used a 57 chev 283 with pg from 2005-2007 ad my dd. Parked due to gas prices.
I remember that as a kid I knew that if you wanted to get out of Dodge fast you started in low and manually shifted. I guess the reason for that is contained below. They started in second. Mine started in first and the biggest difference from my impala with thm 350 was one less audible shift if you were listening for it. Real life experience was accelerate and go without much thinking. Because of the rpm range I am sure there was a difference at the gas pump.
Mine is absolutely stock but I think there is a different transmission in it’s fairly near future. Will keep the pg just in case I change my mind. Worse than the pg were the vacuum wipers which are going to go. I don’t know what all I intend to do with it but the first thing is a shelter and up on stands. Work starts on that not later than next week.
These are really impressive results for such a car, especially considering how bad a lot of the post-energy crisis cars using the same formula were. Never would have guessed that the 4-4-2 suspension was included in the Turnpike Cruiser package, that’s really cool.
For American cars from the malaise era, sluggish performance is sometimes blamed on low (numerical) axle ratios, but I think in reality most of those engines worked best with tall gearing and would have just buzzed right past their power peak with quicker ratios. It’s actually kinda similar to how a CVT works (in practice, not in function). While accelerating from a standstill, the gearing forces the engine to stay within its (low) power peak longer while providing more multiplication than a higher gear would. Get up to the desired speed and the transmission upshifts to put the engine back at optimal revs for cruising.
One of the more interesting cars I owned was Pontiac’s fullsize take on this theory – a 1970 Catalina 4-door hardtop with the low compression 400/2bbl, THM400 and a 2.56:1 rear end. Only 265HP (gross), but 400lb-ft of torque! I think the best I ever got was 12mpg, but I never really did any sustained highway driving with it. The primary goal here (as with Chevy’s 2bbl 396) was being able to run on cheaper regular gas, but it all worked in very much the same way as the Cutlass Turnpike Cruiser. Aside from the crummy mileage and being a nightmare to park, everything else about the car was great. The drivetrain was silky smooth even compared to the best modern automatics and completely effortless around town.
That said, given the choice between this type of setup and an engine that makes it’s peak power near redline, I’d almost always choose the latter. That’s the way my brain expects an engine to work: more revs = more power, which will always yield better performance as well.
A lot of workaday American engines of that era just didn’t have the breathing for engine speeds much beyond about 4,000 rpm. Obviously, some of the hot performance-oriented engines on which the magazines usually focused were capable of considerably more than that, but your typical bread-and-butter V-8 might get to 5,000 rpm, and then only if you were feeling both patient and cruel.
It doesn’t necessarily have to be about super high-revving engines, I’d just rather have power come on progressively as opposed to a big lump of torque being available off idle that never builds to anything more as revs increase. The Turnpike Cruiser engine actually isn’t even that bad – 4,600rpm horsepower peak (figure 4,400 since gross ratings were optimistic in this respect too), flat torque curve maxing out right in the middle of the rev range and a transmission that was probably set up to upshift under 5,000rpm even at WOT. That means power would have only began falling off about 400rpm before redline. You get a progressive increase from a standstill, but it would still have some juice left in the higher revs if you gassed it and kicked down to a lower gear at 50MPH or so.
What I really dislike are the later American V8s that made their peak power closer to 3,000rpm and would just produce lots of noise if you asked them to go any faster. I realize that given the total lack of power available in these engines, most people would actually prefer it all to be front-loaded for effortless cruising and plenty happy to think that their 307-powered Cutlass Supreme felt like it had some “real pep off the line!” or whatever. Personally, I’d rather trade some of that instant torque for a more flexible and responsive engine, even if it meant having to press the gas pedal a little harder at stoplights. Even better yet would be a much smaller and peakier engine with a wider range of gearing, which is exactly what modern cars became.
FWIW, I suspect that the net power peak of the TC engine was considerably lower than 4,600 rpm. The aforementioned Chevrolet 400 Turbo-Fire, for instance, had a gross power peak of 4,800 rpm, but a net peak of only 3,200 rpm. That kind of spread between the gross and net power peaks was not uncommon.
Interesting article and informative discussion. I was intrigued with these at the time (teenager, of course). One thing that caught my fancy was the high speeds attainable in each gear. Maybe it’s time for a do-over!
You can still get a car from GM that makes 400lb-ft of torque and will hit 90MPH in 1st gear!
Only in California, Oregon and one East Coast state (NJ I think), unless they’ve cut back from that to conserve gen1 Spark gliders until the Bolt is in production.
i WOULD LOVE TO FIND 1957 Cutlass Cruiser. I had a two door, light gray on bottom, black Vinyl top (Material no sure on), black interior, front bucket seats. Does anyone know of one in excellent condition?
My ’63 LeSabre will top that mileage on the highway. We lived in Ohio and would drive to Western Pa. with it and regulary got 24 and as high as 27 mpg in the 1970s. In ’09 I took it back to Ohio for the Buick Regional and got 27 once again. This is with Twin Turbine Dynaflow , 2.73 rear end and two barrel with the 10.25 c.r.
Even if a ’63 LeSabre was pushed out of an airplane flying 27 miles above the earth’s surface, I’m pretty sure it would burn more than a gallon of gas before it hit the ground.
Yeah — I don’t doubt that it could get decent figures on the highway, but those numbers would make me suspect the car had the wrong speedometer/odometer gears for the axle ratio (a not uncommon problem back in the days where cars offered a gazillion ratio options).
It would have to be from a spaceship or an balloon at that level.
The theory continued on. My grandparents had a 1970 Delta 88 with some sort of ‘turnpike’ option. The car had a 2bbl. 455, Turbo 400 trans., and a very tall rear axle. It was an excellent highway cruiser.
If you could find it, one of those would make an everyday cruiser today. I have a feeling that a blueprint job + a modest port & polish job, 4 to 2 to 2 headers with a sensible exhaust system, electronic ignition, modern low rolling resistance radials and – if budget is not tight – a Gear Vendors overdrive would result in 20-30% improvement on what Olds quoted back then… Then of course there is enough on the after market to make it go round corners and stop as almost as well as a modern car…
See, with the stock axle ratios and THM, I don’t really see the point of overdrive with a car like this. With the original 2.41 gearing, you already had 31.5 mph/1,000 in top or thereabouts and even the 2.56 to which they switched after launch gave you about 29.5 mph/1,000. Adding an overdrive on top of that would have the engine barely above idle at any legal highway speed. You might just end up constantly kicking the variable-pitch stator (on ’67s) out of its cruising range and getting more slippage, which would hurt more than it helped.
Porting and polishing doesn’t seem like a worthwhile expense with an engine tuned like this that is designed and geared to rarely see more than 3,500 rpm even in first or second. As for the rest, you could get the ’67 TC with radials (195R14), capacitive discharge ignition, and a climate-controlled carburetor (allowing carburetor jetting to be optimized for a constant 100°F) as factory options and the contemporary road testers had most or all of those options. Modern equipment might be incrementally more effective, but even then, Oldsmobile did about as much of that as was practical for an assembly-line car of the time.
I could see getting 10 percent better economy, perhaps even 15 if you went to the expense of blueprinting, but not 30 percent.
You may be right there… forgot about the variable-pitch stator – this is really like splitting those gears, is it not? I would still find 25 MPG (assuming your best case scenario) to be very impressive for a non-injected/electronically managed engine like that, in a car having these aerodynamics. I have in my geriatric brain a vague recollection of Mopar products also doing very well in 1950s mileage runs, with even better results that the above; supposedly they used the same approach + reliance on the Hemi’s efficiency?
Yeah, pretty much. So did Lincoln for a while, although some of those economy runs were focused on “ton-mpg” (essentially fuel economy relative to mass) more than actual observed mpg. But if you have a fairly mechanically and thermally efficient engine, particularly a high-compression one, and you’re prepared to sacrifice performance in tuning and gearing, you can get some fairly impressive steady-state figures.
Where you lose out, of course, is in stop-and-go driving. A heavy car with a torque converter automatic like the Turnpike Cruiser is not going to get 25 mpg in ye daily commuting grind even with an expensive tuning job, although mileage will certainly still be better than a regular 4-4-2 (not saying much by modern standards!).
I have some experience with running extremely tall gearing to get good mpg. I had a clean 91 S-10 pick up, it was a standard cab, short bed 2wd model. It had a few options like cruise, auto trans, a/c, & a 4.3l. I installed a gear vendors on it, the rear gear was a 3.08. So if you compute the tranny’s overdrive & the GV gearing, the top overall gearing is close to 1.60 to 1.
The mileage was low 30s in the summertime, high 20s in the winter. I could run the truck with the a/c & cruise on at 50mph, the tach read 1100rpms, it didn’t complain at all. I did install a high flow water pump & ran mid grade because it tended to spark knock a little.
It is interesting how 20 MPG was once this magical number to aim for because these days 20 MPG is gas guzzler territory. My daily driver is my first vehicle to get over 20 MPG more often than not and it is a nice change.
My mother’s 69 Delta 88 4 door hardtop had a 2 Bbl carb with, I think, 350. That was a heck of a car…it got retired in 1978 when the steering box had gotten so worn that my mom refused to drive it…got traded in for a brand new 1978 Dodge Omni, of all things.
I don’t recall any discussions about fuel economy with the Olds.
Interesting stuff!
For John Lane — the Powerglide was verrry slow when first an option, and, in my opinion, became adequate at best.
Much livelier was Chrysler’s 2-speed, Powerflite, which was good enough to make you forget you only had the two speeds. This was because it had overall transmission torque multiplication much higher than others. For instance, its ratio of 4.47 compared to 2.45 for Dynaflow, which was similar to Powerglide. The ratio even bested Hydramatic’s 3.82.
My understanding is that the PG torque converter has a torque multiplication of 2:1. Combined with either the 1.76 or 1.82 first gear, that makes for an overall torque multiplication of close to 4:1. Unless you’re talking about the very early PG that didn’t start in first gear, But that’s ancient history.
With V-8s, the ’60s Powerglide typically had a converter ratio of 2.10:1 at stall. The unit used with the Chevy II four and most sixes was 2.50:1, except the Corvair, which was 2.60:1.
Dynaflow only had a 2.45:1 ratio in 1953–54, by the way. By the early sixties, Twin Turbine/Turbine Drive gave you 3.10:1 or 3.40:1 in Drive, depending on whether or not the throttle was floored.
(I’ve just gone through an exhaustive examination of early GM transmissions, so this is fresh on my mind.)
Thanks for fascinating article,Wasn’t the GTO available with a similar concept?About the same time frame.
Sort of. You could order the GTO with a low-compression (regular fuel) 2V engine and a tall axle ratio, which I believe was combined solely with THM. The package wasn’t quite as elaborate as the Turnpike Cruiser and didn’t have some of the Olds gadgets like CD ignition or the temperature-controlled carburetor. I think it was intended less as a fuel-saver special or special package and more as an alternative for people who liked the idea and look of a GTO, but whose insurance agent just cackled unsympathetically at the very thought.
I’ve never seen a road test of a 2V GTO and I don’t know if Pontiac even provided any to road testers (who more frequently got the hotter engines with a little or a lot of help from Royal Pontiac’s Bobcat tuning kit).
Paul, it’s interesting to see you reference the eta engine. My parents’ 528e was a lemon, but when all systems were go it was a terrific car to drive on the highway, displaying the same virtues for which the Turnpike Cruiser received praise a decade and a half earlier.
The combination of a high geared (low numerical) final drive worked well when most American cars were equipped with big, slow turning engines that produced lots of torque at low RPM. Unfortunately that same combination is often counter productive in modern cars, most of which have smaller engines, usually with overhead cams, that produce less torque and at higher speeds. An example is the Ford Mustang, nearly all of the V6 versions ship with a 2.73 final drive, which, along with the six speed overdrive transmission, permits highway mileage in the low 30’s. The problem is that for the 2011 model year Ford switched from the 4.0 liter “truck” V6 to a 3.7 liter DOHC V6; an engine that develops more power (and more smoothly) than its predecessor but needs to be revved higher to get it to move. In the real world fuel mileage suffers (at least in stop and go driving) because one tends to use more throttle in order to get reasonable acceleration. Both the 2011 Mustang I used to own and the 2014 Mustang I have now had the 2.73 gearing; they both would achieve around 32 MPG on the highway but driving in town would drop this to around 18-19. I finally decided I wanted better acceleration and swapped in a 3.55 final drive in the 2014. Gas mileage around town is no worse and might actually be better, because it takes less throttle to take off. Highway mileage is down 1-2 MPG but the trade off is much better throttle response. Of course if I was concerned about fuel mileage at all I would drive a Prius or perhaps a palindromic Honda but what fun would that be.
(Thanks for re-posting this one, Paul—it was new to me.)
I see that Cruising package had a slightly less-long-legged axle for ’68–but it’s nice to know it was available in the Vista Cruiser wagon, which would have been a neat way to roll up a lot of comfortable miles–hauling plenty of stuff/people if need be–and not getting nicked too badly on the gas (cheap though it was then):
My 68′ Electra with a 4bbl 430 2.73 rear end (and 28″ tires) has turned 18mpg with the ac running If I hang around 65mph. I have heard from older Buick guys that they would get 20mpg with pure gasoline rather than the 10%+ ethanol blend available in California today.
60mph is achieved at 2k rpm on the button with 235/70 15 tires
City mileage is around 9mpg because of the short trips I take (and daily full throttle blast). If I am very nice and disciplined it gets 10-11 mpg in the city.
I remember reading a motor trend review of the 1964 442. The original car used a high compression 330 inch 310hp motor. The test car had a 4 speed and I think a 3.42 or 3.23 rear end. On the freeway they reported 20+mpg around 60mph
Since I happen to have the latter test handy, it was Motor Trend, September 1964, written by Bob McVay. The original 4-4-2 (which was four-speed only) had a 3.55 axle. They reported 19.8 mpg at steady legal California freeway speeds (65-ish mph) and 24.1 mpg at a steady 55 mph in fourth.
My memory was better than I thought! I had not seen that article since 1996 when I bought my car!
My 65 had the high compression 4bbl 330. It was a very good engine when mated to a th350 transmission. Much more responsive than the stock 2 speed Jetaway. Mine had a 3.08 and got 12mpg around town but 15-16 on the freeway. If I knew then what I know now regarding tuning I’m sure I could bump the freeway efficiency closer to 18 mpg.
I miss my Cutlass but prefer the 64 model
My two big takeaways:
1) There was plenty of engineering talent in Detroit in the 60s. Plenty. I think that has always been true but market/cost constraints force decisions that no one really likes. It looks to me like the quality of engineering these days is also superb.
2) Plenty on engineering talent and knowledge in the CC Commenters group too.
I’ve always believed there’s been no shortage of automotive engineering talent in a nation of gearheads. The problem is, we seem to have a shortage of farsighted executives. Is it just the Peter Principle?
Another irony is why America, a nation of firearms enthusiasts, couldn’t design or even build a recoil- or gas-operated automatic cannon competitive with Europeans & Russians, for even after WW2, the US couldn’t get the HS.404 to work reliably. Maybe here it was just a case of Military Stupid, another long-standing problem.
As we are at the dawn of electric vehicle: I am wondering in say 30 years time, young people in the future era will look at all the transmissions, final drives, drive shafts, exhaust systems, engine roars, complex vacuum, springs, gearing, multiple different oil etc etc and say to themselves: WTF
Tesla, the first of the new era process of no tranny, shaft, etc etc.
In fact, a self driving EV basically encourages an Uber like transportation system where folks just request a ride on their cell or whatever devices – then a self-driving EV will appear and take you wherever ….. no ownership issues, no parking, no maintenance, don’t need training to drive. Come to think of it, your home suddenly become bigger as garages could be converted into living space. Young people of that generation could not understand why geezers like me would want to own something so complex and problematic. Just like how we can’t quite get the allure of complex mechanical type writers or SME tonearms.
Interesting article with some technical points I’m not familiar with. To get 20 mpg from an engine the size of a 400 cu in V8 is commendable. My father’s 70 Cutlass Supreme four door hardtop had a 350 V8 with a four barrel carb. When he switched to radial tires around 1971, he could get around 20 mpg on the highway at a steady 65 mph.
I agree with one of the other commentators that achieving 20 mpg in a V8 powered sedan was a kind of standard by many back in the day.
Very impressive bit of engineering. And it makes perfect sense if you consider how the average motorist drove back in those days. Unlike today, where every traffic light seems to start a drag race, most people didn’t use a lot of revs so an engine with plenty of low end torque made a lot of sense. Sure, magazine testers might whinge about low redlines, but most drivers never used all the available revs anyway.
Dad learnt on a Model T, so that dates him. He never had an automatic. As I remember, he always changed out of first gear once the car reached a brisk walking pace, put it in top by about 20mph and pretty much kept it there except for using second for slow corners in town. That technique seemed to keep up with fifties/sixties traffic just fine. When I started driving, I understood his method; the 200 inch ’67 Falcon had enough low end torque that you just didn’t need a lot of revs, and I’ve tended to drive close to the torque peak ever since.
Great article, Paul–I too, had no idea that the TC package was offered, and it sounds like a great idea, but administered at the wrong time in the days of cheap gas.
I’ve long preached the merits of *usable power*, and to consider where the power peaks are on both horsepower and torque. One of my cars is a ’91 Thunderbird SC, and in my mind, it’s one of the best engineered cars ever produced in America. It gets 16-16.5 mpg in the city (not sure about the highway, but it’s very good), and in factory form, puts out an insane (for 232 cubic inches) 315 ft lbs of torque at 2800 rpms, which is something that you can really feel. Factory 3.27 gearing and limited slip differential as well, and it’s still good on the highway. Most people probably looked at the engine specs at the time and thought that 210 peak horsepower wasn’t all that impressive, considering that the 5.0 litre put out about 225 (I believe), but again, it’s all about where the engine makes it’s power. Some pushrod engines still make great power…..not necessarily lots of top end, but technically speaking, some restriction in an engine can be a good thing, because that’s what builds up torque. It’s also the reason why you don’t race flowbenches (or for that matter, nobody races a dyno sheet) because an engine needs air velocity to really be effective at lower and mid RPM’s.
There’s been dyno tests with things like headers, where they’ve analyzed where power is made or lost. In some cases, you gain a small bit of breathing on the top end, but lose a ton of torque throughout most of the powerband, where it is, consequently, the same power that you need to get your car moving. Head design also plays a huge part in the proper camshaft, because there’s so many variables that go into it, and port shape, valve design, exhaust port design all play a big role. I’m a firm believer in the short side radius effectiveness, because I’ve tested some heads with a vacuum and a string at various valve lifts, and the short side is the path of least resistance–shave off too much or from the wrong area, and you just lost your quickest and most effective way out of the heads and picked up CFM and flow, but at the expense of velocity.
I’ve rambled on here long enough, but that’s a shorter version of some important principles, and also elaborating on Paul’s original point.
This concept sort of jumped the shark by the late 70’s…I have a ’79 Mark V with the Ford 400, 2bbl and a 2.75 rear. However, it is saddled with emissions hardware and pumps out 158 net hp., 315 ft./lbs. torque, with a 4600+ lbs. weight. It gets 10-12 mpg, city or highway. If you have to keep the throttle wide open most of the time, the concept doesn’t work so well.
The problem in the 70’s, is that for some inexplicable reason, the auto manufacturers dropped the compression ratios drastically. Obviously they were under pressure from the EPA, but compression makes power and creates efficiency, and with those large engines, dropping the efficiency still makes no sense to me. I’m wondering if back in the carbed days that they had to drop the compression that much just to meet a certain MPG, but it still doesn’t seem very efficient to me.
higher compression results in higher cylinder pressures which means higher nox emissions.
High cylinder pressures and low nox generation have not been a reality until more precise fuel metering and timing only a computer can do.
Unleaded gas is the reason you’re looking for. Nox emissions are a factor but not so much with widespread use of EGR.
Ah, okay, EGR and NOX make sense, with unleaded…..I figured that it must have been a problem with carbed setups and before mass air flow and computers in the cars. I can imagine the auto makers being irate, because they were going to draw the criticism of everyone: consumers that would complain about reduced power and still poor fuel economy, and the emissions police with the engines not meeting a certain criteria.
Spark timing advance is also a cheap way to create power and efficiency, but I also wonder about how much the spark timing was retarded, in order for the engines to not detonate with unleaded. Leaded gasoline allowed for more aggressive timing. Does anyone know how much the timing was usually pulled? With unleaded and a carbed setup, I can only imagine how frustrating it was for engineers to come up with a solution where you could get better MPG’s, but without totally giving up efficiency in the process.
I had a 1971 high-compression 429 Ford, and a high-compression 1969 Cadillac 472. I ran the highest-octane gas I could find in them, plus Bardahl’s instead-o-lead.
I tried the retarded ignition timing on them, to see if I could get away with running lower-octane fuel, for less than a week. 4-5 degrees retarded just killed the power (from being able to break tires loose to not being able to). I couldn’t stand the power loss and chose to pay more at the pump instead.
The loss in power was primarily from the lower compression ratio.
That’s good to know. In my Thunderbird SC, it has an octane plug that you can pull that will allow the car to be ran at less than the 91-92 octane that Ford recommends. It pulls a few degrees of timing, and it’s a very noticeable difference. I only tried it for a few kms to see what it felt like, as a test…..I’ve never pulled that plug since (especially since I just don’t want to run the risk of detonation).
Yeah, my ’78 Mercury Grand Marquis has the 460. It gets around 7-10mpg city, and max at about 15 highway (if I keep it around 55-60). It has the C6 of course, with 2.47 gears. Ridiculously (numerically) low, but I can cruise 70-75 all day without it revving up.
I had a 1967 Olds Cutlass turnpike cruiser. It was my first new car that I ever bought. I was working for Honeywell in Mass when I bought it. The car had lots of touque. I could stomp the gas at a lite and the titles would squeal until it shifted into second gear. I als believed that the transmission had a variable pitch stator which gave it a lower gear ratio when you got on it.
Interesting article. I bought one back in the late 70’s & kept it for a few years. I do remember it getting pretty good gas mileage. I didn’t know that it had the 442 suspension but that would explain the rear sway bar.
Unlike most subsequent big block “economy” motors, the engine in theTurnpike Cruising (L66) package had a 10.5 to 1 compression ratio and required premium fuel. The specification box at the beginning of this article is somewhat misleading, as those specs seem to be pre-production numbers. Production vehicles used a 2.56 axle ratio and horsepower was 300, Six months ago I wouldn’t have known any of this, but since then I’ve been consumed with finding out as much information as possible about this car. I purchased a 67 convertible with the TC package, currently undergoing a professional restoration. The car has factory A/C, bucket seats, console, and the rally pac gauges. We are adding power windows and trunk release, should be done in May
Tires: UniRoyal Radial Ply
size – 195R-14
recommended inflation, psi – 26
From the Car Life Article. http://www.oldsmobility.com/old/carlife_apr67.htm
And, they didn’t go all Firestone Exploder, either!
Wow, this article has run several times judging by the many years in the comments. It’s a CC classic and memorable: I’m pretty sure I remember it from the first time around.
It makes me feel a lot better about the several 70’s and 80’s GM cars I owned that I always thought of as underpowered. Now I know they weren’t underpowered, they were just latter day detuned 442’s optimized for highway travel.
Put that THM in 1 or L, whichever it had, and I’d expect that’d drift easily. Big torque to break those wimpy 60s tires loose. Dorifto!
Wonder if the car in the intro pic is “gold with black top”? So many seemed to be as recall.
Regardless of the technical details, the naming of these (and the Mercury TC’s) would make no sense to more than half the country. As a kid in California with an interest in the history of transporation, I had read about turnpikes: in medieval England or in the colonial times in the US, roads with a pole (pike) that the toll keeper would open (turn) after the travelers paid the toll. Way before any internal combustion engines, and certainly no correlation to an economical Olds or a Mercury station wagon.
I too grew up in California, but we’d done some traveling so turnpikes were somewhat familiar to me. But I still think the concept of a toll road built with public dollars makes no sense.
“Presumably” the $$ goes to maintaining the road.
Toll road construction was not financed in the usual way, via the gas tax. They were mostly financed by bonds (borrowing), which were paid back by the tolls. Depending on the road, there were also some grants from the federal and state governments, but not necessarily.
The tolls paid off the debt, financed ongoing maintenance, improvements and expansion. The whole idea is that toll roads do not use “public dollars” (taxes) in the same way free highways do.
My first new car was a 1967 Olds Cutlass Turnpike Cruiser. With the low rear end ratio it still had a lot of get up and go because of the 400 hp v8 with 450 lbs of torque. The auto trans also had a variable pitch stator.
I was looking at ’66-7 Pontiac brochures Monday and noticed several of their lower axle ratios weren’t available with A/C. I can’t remember if that included the 389 or just the 326 and OHC 6.
I wonder if further improved mileage figures would have been achieved with a 4 speed manual.
Same axle ratio, or perhaps even slightly lower (numerically) could be used given the fact that first gear in a manual is usually lower than in an automatic. The torque of the 400 would still be plenty for launch, and you wouldn’t have the slippage at cruising speed. Or did this package use a lockup torque converter in the THM400 (or did that feature even exist yet)?
I know a manual wasn’t generally used in more prestigious models, but in this case in for a penny, in for a pound. Or am I overlooking something completely?
GM didn’t have lockup converters at that point and had abandoned its split-torque transmissions a couple of years earlier.
Oldsmobile considered the Turbo Hydra-Matic essential to the Turnpike Cruiser concept because the torque converter provided additional punch without a downshift, maintaining the low-rpm/wide-throttle-opening settings for which the valve timing was optimized. On the 1967, the TH400 had a variable-pitch stator, so torque demand in gear would first cause the stator blades to switch to high angle, as on older Buick automatics. The idea was to provide effortless low-rpm torque that kept the engine in its sweet spot.
A four-speed would have used less power and had no cruising slippage, but it wouldn’t have provided the torque characteristics the Turnpike Cruiser package was designed to create.
Also, with sixties gearboxes, at least the ones used with big engines, it wasn’t true that first gear was lower (by which I assume you mean higher numerically) than automatic. The “wide-ratio” four-speeds GM used in this period had a first gear ratio of 2.54. First gear in a TH400 was 2.48, plus the multiplication of the converter, which with the variable-pitch stator was 2.2:1 with the stator blades at high angle or 1.8:1 at low angle, giving a maximum “breakaway” of 5:46:1.
I am doing a slow rebuild of my total stock 68 Turnpike Cruiser. Would poss sell before paint and some body/interior clean up–but this is a once in a life purring machine. Low miles and as it sits should be good for another 100k.
The responses are fantastic education, for any gearhead.
These days held hostage to oil corps same as before…… the right cam, compression, the old guys really were on to something; Could retrofit today with off shelf EFI kit and get mid 20s easy.