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drmatera drmatera is offline
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Join Date: Aug 2009
Location: Nicholson, Ga
Posts: 2,160
There are many good debates about compression vs boost

Lets look at the facts

an engine makes x amount of power at sea level ( 14.7 atmospheric pressure )

Theoretically if you double the atmosphere you will double the engines output.

So a 150 hp engine boosted to 14.7psi would make 300 hp / With that basis a 180 hp engine will make 360 hp at 14.7 psi. So if 300 hp is your goal you can then lower the boost pressure to about 10psi and forgo the intercooler.

So by increasing the engines efficiency (ie: higher compression , better flowing heads, better cams) you would need less boost to hit a certain hp target.

Pressure creates heat. So the lower the boost you run the less the turbo heats the air. On a car with no intercooler that's important.

Decide on the amount of power you require. Size your turbo to achieve that power at the lowest pressure ratio and you will have a great running car.

Now, personally when I rebuild my 930's engine it will have 9:1 compression and I will run as much boost as I need to get to my target hp. And I think it goes without saying that I WILL run the appropriate octane fuel for the job.
Old 07-14-2011, 02:58 PM
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