high comp + boost theory
 

i was thinking if a high comp engine + boost combo would be a good idea ? :S
were im coming from
driving around town i usually try to keep the engine at low rpm to use less gas and to have it run quite as to not attract too much attention
with my small turbo (14b z6) if i punch it to make a quick lane change (with out down shifting) i build boost pretty quick and have the acceleration to change lanes or pass.
now i was planing to do a vitara build and get a bigger turbo but then i would have to down shift every time and some times you just need to react and not shift.
so what i was thinking is what if i went higher comp then stock and jut ran less boost, with a good tune for the set up would there be a huge difference or risk factor?
i was thinking this would give me better botom end power out of boost instead of boging like hell
wondering what you guys think

Re: high comp + boost theory
 

What about the same low comp pistons with added timing down low? Or is that a bad idea?

Re: high comp + boost theory
 

i've thought about this to for my old project...high compression will spool a turbo quick, & if the max boost was set real low, you can keep good off boost drivabilty & repsonse, with the added "turbo booooooost" when you need it, like an assistant

Re: high comp + boost theory
 

Look at people with b16, which there are a ton of. They seem to do well as long as there tuned right.

Re: high comp + boost theory
 

whats b16 like 10.5 to 1
what do you guys think would be the highest i should go?

Re: high comp + boost theory
 

Re: high comp + boost theory
 

10.5 isnt high compression thats what basically ever dohc vtec engine has had since 1989 so your not being that oh my god new welcome to about 15 years ago when someone first turboed a b series vtec motor




If you mean areas of mid 12's+ JG has built alot of them and all made huge torque. They also seemed to break alot at the track. Mid 10's and throwing rods half track is still kinda cool.

Re: high comp + boost theory
 

b16s are helped by their R:S. Pistons move quickly at high rpm=hard to detonate.

As for compression, the basic idea is you want to run the highest compression possible given the octane available. On E85, I wouldn't think twice on running 10's compression. On 93, I'd keep it max 10:1, but most want somewhere in the 9s. On 91 octane, I would be hard pressed to go higher than 9.5:1 compression if I was looking to make much over 300-350whp.

You won't see too many race cars running more than 9's compression with boost for the simple reason that at 700-800whp, and being limited to C16, running much higher compression, you wouldn't be able to make the 700-800whp, but maybe 650whp. You'd be octane limited. These guys want room to grow and want to keep their blocks together for a season or two at a time.

Re: high comp + boost theory
 

well id be using 94 octane and shooting for only like 300 whp with a 16g (already got one under my bed ;D)
pretty much pistons, rods and a HM port on the head
this build would be just for the hell of it to see what happens and to be a better DD

so unless you guys say its a really stupid idea im going to consider doing it

Re: high comp + boost theory
 

It is all about cylinder pressure. How you go about making it is up to you. I'm not sure how less boost and more compression would make less power. ???