compression for supercharger

I was looking at maybe getting a supercharger with 8 psi and switching out the pulley at a later date. My motor has 10.8:1 compression. Will I be ok with that or will I have to look into meth injection?

Thanks

what type are we talking about? what fuel?

procharger 600b. street car 93 octane on the street. if it is even a big enough s/c. someone was telling me to ask cause that may be way too small for a bb

Your 10.8 to 1 c.r. sounds pretty steep.
I currently am trying to figure out to make my A429 heads work (with 10.0 :1 CR) on my 512 so I can use my Procharger D1B. (pics show a mock-up )
110 octane racing fuel and methanol injection might work tho.

That 600b P/C sounds a bit small (unless you only rev it to 4500 rpm or so).

nada 50 wrote:I was looking at maybe getting a supercharger with 8 psi and switching out the pulley at a later date. My motor has 10.8:1 compression. Will I be ok with that or will I have to look into meth injection?

Thanks

You're gonna have to drop your compression unless you want to start running some of the more exotic fuels and trick parts. Alternatively you could send it to me and I'll run it on a 9:1 460, lol I wish...

the big problem with the small blowers like that on a big motor is the air is heated a lot. so you have hot air AND high compression. if you ran EFI and aluminum heads and reverse cooling with a very good radiator and took it easy I think you could make it work on 93 octane but for hard driving and racing you would definitely need 110 or more or better yet E85 or methanol.

You just need to run less boost thats all. I think a lot of the low compression ratio is an old school mentality that applied to roots blowers. They create a lot of heat and on a street engine you needed lower compression for driveability reasons. Newer blowers are much more efficient and don't create all this heat unless the blower is too small and you are spinning the heck out of it like whatbumber mentioned.

A newer method of looking at boost goes like this. Atmospheric pressure is 14.7 so we will just use 15 for my example. If your 8:1 smog motor makes 400 hspr at atmospheric pressure (no blower) if you were to add 15 lbs of boost it should theoretically double the horsepower or make 800 hspr in our example. So say you were looking to make 600 hspr you would run 7.5 lbs of boost to get there. Now if you could bump the compression, do some head work and make 500 hspr naturally then it would only take about 5 lbs of boost to make the same 600 hspr.

Less boost means lower intake temps and less strain on parts yet can make the same end result. And because you are running less boost you could get away with a lower octane then race gas. Now before the flamers start this is obviously an example and why would anyone add a blower to make only 600 hspr when you can do that without a blower with a BBf.

jasonf wrote:
Less boost means lower intake temps and less strain on parts yet can make the same end result. And because you are running less boost you could get away with a lower octane then race gas. Now before the flamers start this is obviously an example and why would anyone add a blower to make only 600 hspr when you can do that without a blower with a BBf.

Because blowers are . But in all seriousness, you can make 600 hp all motor, even with old iron heads!

Boost is only a measure of air flow resistance, not power.
Less boost is the best way to go to get the same amount of power as posted above.

My reasoning behind buying my D1B and making it work was because I want 750-800 hp under boost and have a decent idle.
Sure, guys make 700-800 all the time on the engine alone, but I doubt very few will make that with a 238-248 @ .050 cam.

Besides, there is no way I can fit a Victor intake and 3 inch air cleaner under my TC hood.

thanks for the info guys.
I don't want want to get a blower that has 6 or 8 psi and bring down the boost. I definitely don't want to say to anyone "That I have a blown bbf that makes a whoppin 600 hp"
Maybe I will look into a stroker kit and porting and polishing the heads (Edelbrocks) when that time comes. As it is right now I am hoping for 500hp.
\Thanks again

nada 50 wrote:thanks for the info guys.
I don't want want to get a blower that has 6 or 8 psi and bring down the boost. I definitely don't want to say to anyone "That I have a blown bbf that makes a whoppin 600 hp"
Maybe I will look into a stroker kit and porting and polishing the heads (Edelbrocks) when that time comes. As it is right now I am hoping for 500hp.
\Thanks again

Well you can make 500 with stock ported heads and if you want aluminum there are some better heads out there then edelbrock.

You can get Cometic MLS head gaskets in .120 from Lem to bring the compression down to run the blower

for the price of the heads, I couldn't go wrong. I would have gotton the a460 heads but didn't have that kind of cash at the time. (Still don't) I have
429 .030 over
edelbrock cj heads
weiand 8021 cj intake
cam from scott hyd flat Int. Exh
dur 240 248
lift 580 591
109.5 lobe sep 4.5 advance
870 - 950 carb Pro systems or Quick fuel
1.73 roller rockers
trw pistons
msd ign
csr elect water pump.

I am guessing it's gotta be close to 500. I hope or I will get rid of that and the car