ginomobile/teg

Hi everybody, my brother has a v-tec 1993 prelude, and we had a strange question that maybe somebody on here could answer... we were wondering ...why when turbocharging the prelude we have to lower the compression of the pistons instead of just keeping high compression and have lower psi from the turbo running through the engine, wouldn't it make the same amount of power as running more psi with lower compression pistons?
Any input would be helpful, thanks .

smakdown

Im no expert on turbos but as I understand it the whole point of lowering the compression when going turbo is not for power purposes but for safety. A turbo charger raises the compression of the engine, so if you are already sitting at 10 or 10.5:1 ratio...a turbo could put you in the upper 11's:1 which could potentially damage the engine if its not built for a ratio that high. Lower your compression to 9:1 and you'll avoid any danger of high compression.

ginomobile/teg

but the thing is that it almost seems like lowering the compression of the pistons is useless, because all you would have to do is run less boost in your engine and and you would have around the same amount of power.
I know its a weird ass question. Does it create more power when there is more boost+ low compression pistons or, is it more powerful with high compression pistons and low amounts of boost?

Snoopy

it's all in the tuning! yes you can have high compression (11+:1) and still run boost. but at that point you better run race gas with a really good tune.

most people drop the compression for safety. most people only have access to 91 or 93 and need their cars to be daily drivers.

Snoopy

that is so wrong i dont know where to begin

Snoopy

two engines, all things being equal, same turbo same boost, one with 10:1 the other with 9:1, the engine with more compression will make more power. but it all goes back to what i said earlier.

smakdown

Um but i pretty much said the same thing you did..."most people drop the compression for safety. most people only have access to 91 or 93 and need their cars to be daily drivers."

and like I said I no expert on turbos so I really don't care if its wrong or not.

boostup88

you can run your motor stock even with high compression ,I know a guy with an s2000 who turned out 460hp at 10lb of boost on a stock motor with a g30r garrett.you need to tune the car well and make sure you retard the timing enough not to detonate.The strenght of the internals is really important stock or otherwise.If its a good engine it could take it.It is though better and safer in the end to run a built motor if you boosting especially if you looking for high hp.
Before I built my motor I ran 8lb with a JRSC all day at the track, the motor was fine even though I bent a fork in the transmission.At the time I was running 12.9s with slicks.Olso I did quite a few top end runs north of 150mph.

ludeboom

read the book "maximum boost" by corky bell...
ive said it so many times before
that its all i can say now

props to snoopy :grinpimp:

boostup88

I have and read that book as well as the one about supercharging,homie