Quote:
Originally Posted by Coheed
That's what everyone said about the 11.5:1 compression 2zz motor in the Celica. Yet there were a lot of people who turbo'd them. They made great power too.
10 years ago, if Toyota said they were bringing a 12.5:1 compression engine to market, people would say "Impossible! It won't work on 91 octane!"
13:1 is out of the question... right? Then the Prius was released. Overseas, they get 14:1 with 93 octane. Blasphemy!
Then mazda pushed 16psi boost through an engine at 9.5:1 compression in the MZD. People realized over 20psi from stock turbo with tuning, all on 91 octane.
I don't think 8psi is out of the question here.
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To be completely accurate, the Prius does not have true 13:1 compression because it's rev limited to 4000rpm and set up for very low volumetric efficiency, the actual peak cylinder pressures it sees probably correspond to a 10:1 compression ratio or so. (on a side note, to have a true 13:1 compression the apparent compression ratio would be like 17:1, which might work on 93 gas because there is so little residual exhaust left, but I wouldn't know...efficiency would be through the roof though)
That said, yes Mazda has a 14:1 compression "normal VE" engine that runs on 91 (not even 93!), and yes turbo motors have been doing okay on very high boost for a while. For an NA example though, there was a TRD 3S-GE package that had big cams, 13.1:1 compression ratio, ITBs and exhaust, making like 280hp on presumably 93, from well over 10 years ago :O Anyways, it's all in the tuning as you say.