Thread: too low compression?

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i am building a 454 for a 78 camaro, the parts i have will get me about 7.5:1 compression is this too little? i plan on getting a centrifugal supercharger, but will this engine work until i can afford the charger? also it is a street driven car and what boost would i have to run to make it perform well on the street while using hypereutectic pistons and cast crank and rods(under 5500 rpms).

bored 30 over
stock crank, rods
speedpro dished -4 cc supercharger/turbo pistons
heads/ polished 781's

at that compression, you could run up to 10 PSI, you may want to oring the block tho. 7.5:1 is fine.

It might run with that low of compression and no blower, but it is going to be one anemic BBC!!!! Might as well keep the thing parked til you can afford the blower....

Originally Posted by Matt167

at that compression, you could run up to 10 PSI, you may want to oring the block tho. 7.5:1 is fine.

you do not have to Oring the block for 10psi fel-pros race head gaskets will hold that and the cometic mls head gaskets will hold much more yes i will not run that hot with that low cr i have run 10 psi on a 10to1 with 10psi with no oring big blocks

does anyone know how much horsepower this engine would have without the blower?

Originally Posted by seansz28

does anyone know how much horsepower this engine would have without the blower?

274 Hp @4k. just ran the # thru my dyno program

435 Hp @ 5k with a 6/71 blower

Originally Posted by pat mccarthy

you do not have to Oring the block for 10psi fel-pros race head gaskets will hold that and the cometic mls head gaskets will hold much more yes i will not run that hot with that low cr i have run 10 psi on a 10to1 with 10psi with no oring big blocks

Again I agree with what Pat has said here.
I know of a few guys that have run 15 psi on the Cometic gaskets.
I also know some cheap drag racers who have three years on the same Cometic gaskets.
I don't know if I would do this.
Seems rather risky.

Originally Posted by erik erikson

Again I agree with what Pat has said here.
I know of a few guys that have run 15 psi on the Cometic gaskets.
I also know some cheap drag racers who have three years on the same Cometic gaskets.
I don't know if I would do this.
Seems rather risky.

Maybe I am missing something,last time I checked o-ringingingingthe block was not that expensive..From what I have herd O-ringinginging would be best.

Originally Posted by BigTruckDriver

Maybe I am missing something,last time I checked o-ringingingingthe block was not that expensive..From what I have herd O-ringinginging would be best.

well you would be wrong

Explain

Originally Posted by BigTruckDriver

Explain

the lsm gasket is thin plates of stainless steel so it can not get push out from hi cylinder psi were a cheap head gasket could with just a fire ring. hi psi would move it out so o rings fix this but it is not cheap to o-ring a block if you do not do it right they leak the copper will not seal up the water ports with the O rings if to hi up so there is many draw backs to o -rings if you want to go back to a std head gasket you have o-ring groove to fix? hard to do. you have to over deck the block if the block needs a deck if you hurt if you have to take the o-rings and recut them in deeper if you have to put a sleeve in you have to re groove .the slm gasket work very good for hi cylinder psi so really balls out yes a o-ring ?will work but i am talking a full bolwn big block 1500 hp and the lsm could work here to ? lsm heads gaskets $170. copper 186.+ o-rings cutting the block + sealer .ics copper no o-ring s 170 so for a 10 boost i have used the fel-pros. a bit more the mls . full blown o-ring and copper