Everyone is always arguing about wether to go high comp with forced induction or low comp. Well heres a nice little read for everything explaining many things and most important the pros and cons of going high or low comp.

Xcceleration

^^^^^^CLICK ME FOR MORE KNOWELEDGE!!!!!

 

i stopped reading after 8.5 to 1 is a good all around number...

 

Judging by the home page this looks to be 10-15 years old. Quite possibly an old Geocities page.

 

I'm sorry, but when the author says "I think" right at the top of a "why this is better" paragraph, that's it - game over. That isn't a source, it's just another guy with half the facts trying to say that his way is the best way. There is only ONE part of that entire page worth reading.

Higher static is better, up to the limit of the fuel. Period.

 

Uhh... I think everyone is missing the finer details of this thread. The link posted is in question before you even click on it due to WHETHER his KNOWLEDGE is relevant on the subject or not... I don't believe anyone here wants "knoweledge" on the matter at hand.

 

 

Great point! I misspelled a word

 

So does that mean that as long as you can get fuel to the engine the static compression doesn't matter? I understand the higher the better though.

 

No, it means that as long as your fuel can withstand the environment within the cylinder at high levels of compression and / or boost without igniting prematurely then the higher the better static compression to start with. Your fuel will almost always be your limiting factor in an all out engine build. You need to build the engine as a whole depending on what fuel you plan to use: 91, 93, E85, 110, etc (there are dozens) and choose the highest static compression possible that your tuner is comfortable with.

 

Couldn't have said it better myself.

I have a few friends that work at the local airport...really want to build an engine for 110LL.

 

I thought that 100LL was ill suited for high performance engines because theyre formulated to burn well at a steady load vs rapidly changing like in a car.

Heres the other thing. Cylinder pressure creates torque. Say you have two builds that make 300wtq and similar power figures, but one is high comp low boost, and one low comp high boost. The high comp engine is going to have a MUCH better curve, and the low comp is going to have a sudden build up of torque since its gonna not only take longer to build up boost, but because until it spools up the turbo the engine is just a flat out pig.

 

Cool thanks for clearing that up. I've been considering a mild turbo build on my kswapped hatchback and I've been reading up on which turbo to use (trying to fully understand compressor maps). I put a precision 5858 ball bearing on my last car and didn't like it much although it made 458whp on 93 octane at 27lbs. That all said I had a compression ratio of 8.8:1 and full spool didn't set in until around 4600rpms.

 

my stock f20c has 11.0:1 compression and it loves boost. Makes 442whp on straight 91 octane and it has 120,000 miles on the stock engine with the past 40,000 being turboed at this power level. makes over 600whp on e85. high compression and boost is great