I have a Lunati 383 with flattop pistons with -4cc valve reliefs, I still need to buy the heads/cam. The motor was originally built for alot of nitrous, but I have now come across a good deal on a P1SC and want to get it. It comes with a 9# pully but I would like to get at least 12#'s from the unit. What compression ratio do I need to be shooting for? I was thinking of 76cc AFR's which would give me about 9.6:1 compression. Is that enough? I have read where people are running 8 or 8.5:1 on blower motors. I dont think I can get that low with the pistons I have. I am trying to get around 200-250hp from the power adder, should I just stick with the nitrous or is it possible with the motor I have. BTW I am not worried about "streetablity" this is mostly just for racing. With some occasional weekend trips. I will do some more searches but any insight and knowledge on this would be greatly appreciated. Please let me know if you need any more info on my particular set up.

Clint

 

Well, you could go with the 9.6:1 compression, but if you are going to be racing it, you might want to go more around 9.0 or lower. Also, I don't think you would be happy with the P1SC. That is more of a street blower and the boost curve is flat and it doesn't produce much down low. Depending on how much of a deal you can get on it, you can have the P1SC upgraded to a D1SC for about $1200. You would be much happier with the D1SC. The boost curve is much more aggressive, and it comes on sooner because the impeller is helixed, rather than straight like the P1SC. I would HIGHLY not recommend the P1SC in a race car. Just not nearly efficient enough.

 

I run a 383 with D1 @ 12 psi. I shall try 15 psi soon. I currently run a 54cc chamber afr 190 head. I also have
-28cc JE pistons. 9.5:1 compression. Works good, but I purchased a large Spearco intercooler. The intercooler is critical. I had a p600b. The D1 spins up much faster.
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97 383 M6 ATI-D1 Msd 72#/hr with LT1edit+Acceleronics drive and dual walbro 255 lpr

 

hey guys-
good thread... i'm at this stage also.
so what would be the greatest cr one can run w/ race fuel and the P1?
i'm confused... i too have a 383 with flats but 55cc heads putting me at about 11.5.
funny thing was i ran a V1 with S impeller and a wet nos to a 10.34.
could it be the addl fuel from the nos and perhaps my cam that helped prevent detenation?
the cam is 232/242 duration 510/525 on 110 sep with int c/l @ 106.
thanks- doug

 

Well it doesnt sound like much of a deal anymore. If I have to upgrade the head and intercooler I would not be gaining anything. I guess I will just have to either stick with nitrous or save up for a D kit.

 

Forgive me if i am wrong, but that is definitaly not a blower cam.

 

yep you're right... it is not a blower cam. it did much better with a progessive two stage nos, 10.02. i think that is what allowed me to run the sc w/ such high cr. lotta overlap in the cam allowed for pressure to escape. just was wondering... i sold off the V1 but picked up the P1 for a good price so i was trying to incorporate a blower again. looks like a tear down is in order new pistons and cam.
later-
doug