Technical Question re Forced Induction

[clarenceboddiger]

Ok I understand engines a bit, but something I keep seeing has me confused.
Why do Forced Induction engines use lower compresion pistons than their normally aspirated counterparts, why not just use less boost? I am obviously missing something as if that were the case people would do it.
So what am I not taking into account then.

[clarenceboddiger]

stevieturbo said:

read more.

I'm trying to, hence this post
Seriously though, my thoughts are the same as Munter's, if a 10:1 compression set up produces 10 times normal atmospheric pressure in the combustiion chamber at TDC then if you were to double the initial pressure to say twice normal atmospheric pressure by means of a compressor of whatever means, then the same set up would produce a compression pressure = to a 20:1 compression ratio on the initial version.So I still dont understand why less boost on the high compression wouldn't work.
PS Steviturbo if you can recommend a good book I would buy it as looking at your vid you obviously know what your doing (or you know someone who does).

Edited by clarenceboddiger on Sunday 3rd August 13:40

[clarenceboddiger]

annodomini2 said:

Because the compression of the cylinder does not add more oxygen to the mixture.

FI adds more oxygen, to which you can add more fuel, which equals more energy in the equation.

Higher compression and less boost improves off boost performance, but sacrifices peak power. Due to the total energy in the equation.

Lower compression is required due to the temperatures generated during cylinder compression of the mixture.

Great explanation, Thanks annodomini2,.
You said "Lower compression is required due to the temperatures generated during cylinder compression of the mixture." presumably due to the greater volume of Air/Fuel then?

[clarenceboddiger]

stevieturbo said:

Julian Edgar's 21st Century Performance is an excellent all rounder.

http://www.amazon.co.uk/21st-Century-Performance-J...

Forced Induction by Graham Bell ( or something like that ), and probably a couple of other books I cant quite remember...

Thanks Steve, I will order that up and get into it.