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Forgot go mention this in the reply above; you further argue against yourself:
Originally Posted by Brettus
. IE it is ALWAYS (within reason) better to do more air compression outside the engine than inside.
Secondly : A 9:1 13b engine at say 14psi of boost makes approx. the same power as one at 10:1 . There is a small gain in efficiency in the 10:1 less a small loss from lower airflow due to slightly lower chamber volume. But power comes mostly from mass airflow.!
Air compression outside the engine begins at the compressor, and the mass airflow as well. Efficiency there matters as you found out with the Garrett G30 turbo swap. Once again it would seem as if certain points are not being perceived properly. Air is elastic/compressible. A more efficient compressor allows running a smaller (internal volume and radiator area blockage), less restrictive intercooler. Sure you can run a huge intercooler to overcome a crappy compressor, but when you can avoid that and don’t, it just compounds one kluge upon another, leading to a compromised system and end result.
The lower compression change is also going to be noticed in the off-boost and initial boost response. That can likely be overcome to some degree by making selections that will provide better turbo response. Which the compression change will be more forgiving of.
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So ok you proved my point ... you are bored and want an argument.
Your reply above however, is so confused and sloppy that I can't even understand the point you are attempting to make as it relates to what you quoted me on. Try again please.
Taken from this in depth look at the relationships : https://dsportmag.com/the-tech/educa...tio-101-part2/
Looking at 14psi, the difference in power between 9.5:1 and 10.5:1 is less than 1% and at zero psi it's less than 2% . This would be barely noticeable anywhere in the power curve.
But the reduction in knock tendency is huge by comparison.
Now lets look at what CR does for max. safe boost . Don't cry blue murder please ...I know this chart is not a rotary , not a turbo and not fuel injection . But it's the only decent chart I can find that gives a similar comparison.
If we take the difference between intercooled 10:1 and intercooled 9:1 we get an extra 8psi safe on pump gas. Not suggesting this is accurate for a Renesis ... what I am suggesting is that the gain is HUGE by comparison to any loss from thermal efficiency.
For reference only : 8psi would equal about 100hp vs the thermal efficiency loss of 1% being around 4hp.
another chart with similar info but showing the difference intercooler efficiency makes:
05-16-2021, 05:20 AM
