Trading SAAB Stories: Driving Impressions Of Turbo Lag

Driving my ’93 SAAB classic 900 through the main downtown stretch of our town in Michigan’s Upper Peninsula, I spotted another c900. It being the first c900 I’ve seen up here, this was quite the unicorn sighting.

I left a note under the windshield wiper, letting the owner know we are in the process of moving. I have a small parts cache, and he could pick through and take whatever he fancied.

The fellow saabista, Matt, is a kindred soul. He offered (well, I asked) to take his turbo for a spin, since I’d never driven the turbo variant. His car is a 1990. The 2 liter turbo produces 165 hp (net) @ 5,500 rpm and 188 ft-lbs of torque at 3,000 rpm. My 2.1 liter n/a has 140 hp (net) @ 6,000 rpm and 133 ft-lbs at 2,900 rpm. Both are 5-speed manuals. The gear ratios feel identical.

Driving Matt’s SAAB was enjoyable. Actually, I had a Cheshire Cat grin on my face, whenever the turbo was in boost. But, it also left me feeling a bit underwhelmed. I expected the turbo to be… more. It certainly didn’t have rocket like acceleration I was expecting. Boost builds slowly, and below 3,000 rpm, it actually felt more lethargic than my n/a.

This is probably due to my car’s naturally aspirated motor having a higher compression ratio, better designed fuel rail and injectors, higher pressure fuel pressure regulator, and better breathing head and intake manifold (swapping the 2.1’s head and intake onto a turbo motor is a common mod).

Around 4,000 rpm, the turbo pushed me back in the seat, and the turbo whine is fun. The 100cc difference in reciprocating mass also makes the turbo creamier when revving. It would be nice for passing on grades, or driving at elevation. But, having now driven both, I don’t feel as though I’m really missing out on much.  However, and this is a big however, Matt’s car does have 533,000 miles on it, yes, over half a million, so it is likely that a few ponies went astray over that distance.

My biggest take-away was how much turbo technology has improved. I owned a 2015 Ford Fiesta ST with the 1.6L ecoboost producing 197 hp @ 6,000 rpm and 202 ft-lbs of torque at 4,200 rpm. 32 more horsepower, from a engine 400 cc smaller (premium fuel required).

My mom drives a 2016 F150, with the 3.5L ecoboost. Prior to that, my parents owned a 2013 Escape with the 2.0L ecoboost. Both those vehicles have/had a steady diet of 87 octane. It is astounding how much lower in the rev range the Fords build boost, and how linear the power band feels. The trade off being, the smaller/quicker-spooling turbos run out of steam earlier in the rev-range. But, how many drivers want to rev the piss out of their vehicle to hit the power band?

The F150 has a bit of turbo-lag, off the line. Accidental chirping of the tires can happen, when it hits boost. Though, in comparison, the SAAB’s turbo feels positively obtrusive.