Someone please enlighten me.....Whats the difference between 500hp at 30psi or 500hp at 20psi? because to me 500hp is 500hp no matter how its done and can blow the engine either way if not properly tuned? Just crank the freakin boost man and tune on a nice low compression? I thought I escaped the honda world and its ways of thinking....even then I argued the whole high compression + boost, it never made sense to me and I had a turbo'd 8:1 sohc...

Low compression + High boost + proper logging and tuning = fun fun fun .... My best friends 1G is sickning, stock motor (7.8:1, I think?) 450hp, 50 trim, 25+ psi... who needs high compression?

and im sure shep runs high compression, no wonder his dsm is one of the fastest in the country riiiiight.....

 

it depend how soon the hp comes on in the lower rpm when it makes a difference... both may peak 500hp but with less psi it's most likely the power will come in sooner making it a fun drive.

 

Curt brown runs 9:1 on his 10 second stock turbo monster.

If you can get internals strong enough, you can go as high as you want with compression ratio. Just run less boost pressure. Problem is, it is easier to change boost pressure on the fly then compression ratio. It is just one variable in the equation representing cylinder pressures.

 

well higher compression is going to get the spool like 1k faster, making for a much more fun ride! we've delt with high boost regular stuff, we are trying to go with something new.

 

so from what i am reading here, higher compression motors produce more exhaust gas, which in turn, spools the turbo faster?

 

sounds interesting .....keep us posted

 

it doesn't necessary produce more exhaust gas, just hotter exhaust gas. the engine also produce more power when not in boost (similar to NA mode) during cruising speed (~80% of your driving) which also means you get better gas mileage.

 

did someone say better gas mileage?

hmm intresting

still wouldn't do it but... definitely not digging the raise in gas prices coupled with the less gas mileage... (if it were raise in gas prices OR less gas mileage I wouldnt mind, but its both)

 

What pump gas octane are you gonna run day to day,that should dictate your compression ratio.Here in Cali on 91 oct. i would not go over 9:1.With high comp.
it only takes 1 bad tank of gas and you will be starting from scratch again.Change the displacement and turbo size,not comp.

 

I'm not even going to tell you what everyone has already said, and that you fight anyway.

But my only question is, what is the point of waisting thousands of dollars on a 30r turbo kit, when your running stock and less then stock boost? I mean, spend thousands of dollars for less boost response, and... NOTHING else. Stock turbo will work fine.

 

Thermodynamics and Q efficiencey are neat things. Simply put in a closed system (what goes in must come out) turbine configuration Hin (heat energy in) with respect to Hout (heat energy out) is how the turbine wheel produces energy. The differential energy change is how much power (can be measured in watts, very nice unit to work with in this stuff) the wheel is able to absorb. Now what I see in lots of high compression builds is long stainless steel turbo manifolds that are not good as scavenging heat. Thus you end up with a late spooling high compression motor. You must decide if your going to build a turbo motor or a non boosted motor. They are compleatley different animals and must be designed as a system.

Some simple work with timing maps can easily create the energy you need to spool a turbo, and the shorter the distance and better thermal coulpling between the cylinder head to the turbine wheel the better the results. I want to say its on an exponential scale but that is just an assumption.

Ole’ reliable works for me. A cast manifold and 50 trim compressor with a nicely selected turbine wheel and housing. At 7.8:1 static compression I raise my dynamic compression (boost) to a level to lay #11’s through 100mph from a 3500rpm roll on.