i built the motor listed in the sig for N/A high compression using a -12cc piston and 54 cc chambers. well, N/A is just not cutting it, and nitrous isn't really what i want to use. Basically, i'm lookig wondering if i can throw on some 70cc afr heads to bring the compression down to the lower 9's, making it more boost friendly. i'd rather have a turbo, but that setup is going to be more money for me. I'm thinking of a used supercharger kit, most likely a procharger kit. I'm just wondering if i can safely run 8-10psi on that setup with an intercooler. it's all forged, but the rings are not gapped for boost or nitrous, just stockish gaps. piston to wall clearance is .004". If you can run 6 psi on a stock bottom end, i can run 10 on this bottom end, right???? I'm just looknig at options becuase N/A just isn't enough and i really like having that power there all the time. i like nitrous, but i'd like to go another direction with this.
also, would this kind of boost require me to have a vaccum system for the brakes??? thanks

 

well i was pushing 8psi on my stock bottom end and had stock ported heads. i blew a head gasket and my pistons and heads were junk after that. if i were you i would spend the extra money and get blower pistons/rings.... your car could last 500miles or 10,000miles its a guessing game.. plus the garage that tuned my car i was told beat on it pretty hard on the dyno so i'm sure that caused some of my issue..

 

Even though you have a stronger engine, ring gaps and compression could come back to haunt you. Might get by with good intercooling or meth/h20 cooling and 10#, but that's just a guess.

Vacuum is not really an issue because the booster stores enough vacuum to work the brakes.

 

i know ring gaps are extremely important, but the pistons are blower pistons. only a -12cc mild app. piston, but i an get compression down to 9.0-9.2:1 with large chamber afr's. I jsut have a hard time believign that it wouldn't handle 8-10psi. I've seen 2 or 3 100+k mile lt1s run vortechs on 7psi for tens of thousands of miles. stock everything. completely beating the **** out of it. I know it's no ideal for boost, but i was thinking i can get by pretty safely. ? not sure and the booster stores vaccum, but boosted engines don't produce vaccum. on a mild setup, it will produce some, but not much vaccum at all. the booster holds enough for about 2-3 pumps of the pedal. then what? lol

 

You know if you're going to get bigger heads anyway, why not get some really good ones and give N/A another chance?

 

Your brakes willl be fine. You're not going to be pumping them 2 or 3 times. You're under boost, you apply the brakes with the stored vacuum, and the car slows down. When it is slowing down with your foot off the gas, you have tons more vacuum.

Your rings might be just fine, or not.

 

I'm obviously not the professional on boost, which is why i'm seeking advice. I'm still just having a hard time believing 8 psi would overtake my motor, when guys are running around on stock everything 150 shotting the hell out of it and boosting the **** out of it. it just makes me wonder if there is something I'm really missing.

as for N/A. i love N/A but to make big power you need one or more of the three main things. 1-cubic inches 2-big cam 3-great heads. 1-358cid is good, but no big block. 2-the cam i have is pretty big. borderline comfortable in daily city driving so i don't want to go bigger there. 3-good heads are doable, but what gains can i expect to see out of great heads on my setup? If i could make 430-450 to the wheels with great heads and the cam i have, i'd be extremely happy, but i'm havingmy doubts. with boost, i have a streetable daily driver and crank out 450-500 rwhp pretty safely. n/A would be most cost effective, but i'm not sure i can make enough power and still be a daily driver. i'm currently make 363rwhp on stockish heads, cam and a ported intake with all bolt ons with 900 miles on the engine. thas all through the hooker catback. i know i can get this setup to go 380rwhp by getting the motor broke in and switched to royal purple, and by getting a less restrictive exhaust, but again, i'm not sure how much i can gain. I don't really want to go swapping cams but if i have to i will. anybody suggest me towards 420-450rwhp streetably and still getting gas mileage??

 

8psi would be pushing it for everyday street use with your set-up.
what is your cam spec?

 

cam would be custom grind. let me clear this up. it'd be a 9.2:1 358 with diamond pistons, 4340 i beams, and a forged crank. stock rings gaps. I would be pushing it with8psi?? lol

 

What are you're piston to cyl wall clearance? and Top Ring end gap?

It's been my experience that if crappy tuning doesn't bite you in the *** running 7+psi on stock internals (knock and detonation) the stock ring end gap will. I'm just thinking off hand, but I believe my stock top rings were measuring out to .012". Now with the hypercrapptic pistons, under boost heat bottles up in the top of the piston and bye bye ringlands. Even with the better heat transfer properties of the forged slugs you're running, I have a hard time believing you're ringlands will stay intact unless you're rings are properly gapped.

I've seen stock hypercrapptic's gapped to .028" and it GREATLY increases longevity of the motor. I don't know the recommended gaps for you're specific pistons, but I *think* forged FI apps are normally around .024" range.

Do what you want with the car. I'd recommend trying to make more power via N/A since you're goals seem reachable. But if you WANT FI...then all I have to say is do it right the first time, or prepare for it to backfire...

 

re-ring it and i would feel safe with 15psi as long as you have a good tune.
so you are going to get another cam?...

Another way to get to you 450rwhp n/a would be to swap in an LSX

 

i know an ls motor is a superior design, but lt1's are'n too far behind with head/cam numbers. not enough to make me swap out my 3k investment for an ls motor. honestly, i wouldn't mind trying to continue n/a, i just want to maintain drivability and decent fuel mileage. i'm getting 24-25 highway now. ultimate, i will havge a 99-02 SS that i will build right for a turbo, but i'm just tossing ideas now.

 

go ahead and boost it then but when something lets go don't say we didn't worn you. if your worried bout gas mileage then you shouldn't build the motor up or add a blower...