I am pretty familiar with boosting and the 420a engine, i built my own kit, 8-10 psi, and it has been great since, but i have a question that i have a mental block on...

Basically, would it be a good idea, or possible with our engine's, to boost on a 10.1 compression ratio? given the headgasket swap and whatnot to make it realistic... this would provide awesome power, but i am not sure where the downfalls would be, cause i know i am not thinking about it all the way around, so if you guys could please be gentle with me, and let me know what you think, that would be awesome..

thanks :thumbsup

the main downside to high comp is that it makes it a lot harder to tune. there's much less margin for error when you're running high comp. i think the people who kept stock comp and turbo'd ended up blowing their engines eventually. i can only imagine how much harder it'd be if you raise it...

-marc

='95 RS 5spd Red=
Matrix CAI
A'pexi Turbo N1
Hanabi 8000k HID
SPAL Deluxe Power Windows
Nakayama GT5 17's
Ractive STB
GSX Calipers
AEM Rotors

255 is fricken short

it been done before and the person is still on this board.... but i think he sold his turbo kit.....and he never blew his engine... plus he use to juice before he turbo'd

>the main downside to high comp is that it makes it a lot
>harder to tune. there's much less margin for error when
>you're running high comp. i think the people who kept stock
>comp and turbo'd ended up blowing their engines eventually. i
>can only imagine how much harder it'd be if you raise it...
>
>-marc
>
> ='95 RS 5spd Red=
>Matrix CAI
>A'pexi Turbo N1
>Hanabi 8000k HID
>SPAL Deluxe Power Windows
>Nakayama GT5 17's
>Ractive STB
>GSX Calipers
>AEM Rotors
>
>255 is fricken short

Well we all know with a well tuned engine, the stock engine holds up just fine under moderate boost levels up to 10psi, mine has for a long time now... so has others on this board that put the time into the research. And what i was thinking about raising it is, the 10.1 compression pistons you put in are forged, so you think that it would beable to take more pounding... you might not beable to run AS much boost, but with that compression, you wouldnt have too...you see people not satisfied around here at 14+ psi, because they lowered the compression, and in turn lowered the HP, and need to recrank boost levels to see the power back, let alone make more. even if a company made forged 9.1 compression, that would be awesome... i really would like to talk to someone who has tried this before, or has a technical defenition of what would happen...

thanks guys :thumbsup

I boosted with 10.5 compression for almost a year. ran up to 13psi on it. the low compression block is back in the car now. not cause the other blew, its just a LOT harder to tune correctly, and stay on the safe side. i sold it to a local guy who wants to go all-motor, or possible spray on it. the high compression motor had noticeably more crisp throttle response, but it just wasnt feasible with my future HP goals. i just did it to "experiment" anyways. if its your only mode of transportation, i wouldnt do it. if you have an extra block(as in my case) or the $$$ to back yourself up if you make a tiny mistake tuning and pop the motor, then its definitely fun.


1997 Silver RS
Wiseco 8.8:1 Pistons(back to low compression!)
Eagle Rods
T3/T4 Turbo
Custom FMIC
Greddy Exhaust
440's
Most current 1/8th mile time: 8.3@90mph 2.015 60'(Nitto Drag radials, i suck)

>I boosted with 10.5 compression for almost a year. ran up to
>13psi on it. the low compression block is back in the car now.
>not cause the other blew, its just a LOT harder to tune
>correctly, and stay on the safe side. i sold it to a local guy
>who wants to go all-motor, or possible spray on it. the high
>compression motor had noticeably more crisp throttle response,
>but it just wasnt feasible with my future HP goals. i just did
>it to "experiment" anyways. if its your only mode of
>transportation, i wouldnt do it. if you have an extra block(as
>in my case) or the $$$ to back yourself up if you make a tiny
>mistake tuning and pop the motor, then its definitely fun.
>
>
>1997 Silver RS
>Wiseco 8.8:1 Pistons(back to low compression!)
>Eagle Rods
>T3/T4 Turbo
>Custom FMIC
>Greddy Exhaust
>440's
>Most current 1/8th mile time: 8.3@90mph 2.015 60'(Nitto Drag
>radials, i suck)

Cool... i think thats what i was looking for.. because of the high compression, would you say there is a cap on potential HP? if so i wouldnt be interested in going that route, but i really like boosting on the stock compression right now, and was looking for more of a failsafe way then lowering compression... it looks like that might be the only way huh? i just didnt like the idea of cranking the boost up to regain lost hp in compression... well thanks guys.. any more comments are welcome
:thumbsup