Me and a friend of mine built a 355 lt1 with cc503 cam in a 95 Formula, it hasnt been tuned yet, but i was wondering if anyone has used this combo and what kind of hp am i looking at (ballpark est)?

MODS:
350 Lt1 block bored .30 over to 355
Stock crank
4340 rods with speed pro pistons
Comp cams cc503 cam
Gasket matched alu heads
12:1 CR
ported intake throttle bores with 58mm TB
1.5:1 full roller rockers
chrome moly pushrods
400lb open pressure springs rated at .600"
Stock Opti with MSD cap and rotor kit on taylor 10mm race wires
MSD streetfire coil
BBK shorty headers through hi flow cat and hooker catback 3"
255l/hr fuel pump
32lb/hr injectors
LT4 knock mod
chrome moly retainers and keepers

getting it dyno tuned soon, but i just wanted to know what kind of numbers i can expect. Looking for 400 or more

 

did you send out the heads to get ported? If not, and it's an auto tranny, you should be under 340 RWHP.

 

12:1 with that cam??

Whats the PN for the piston?

 

Good compression for a LT1 355... what piston? It would have to be a dome of +1 cc to get there.

Anyway, most bolt on stock bottom end LT1's with stock heads will make 330-340whp with the CC503 cam and longtubes. With your extra compression and fresh shortblock, but with shortys, I'd see 350whp tuned. Auto may be 10-15 less.

Seems like a lot of compression for that cam...i'd rather see a CC306 on a tighter LSA for that setup.

 

Pistons are speed pros: http://www.summitracing.com/parts/TRW-8KH631CP30/

Felpro .41 headgasket

I was afraid of the cc306 not working with the stock heads Some people said it was too much lift, so i went with the 503 because it had less lift than the hotcam so i knew it would work and it also had the duration and LSA i wanted. love that lopey idle. Its an M6 with stage 2 clutch btw According to flow chart, these heads flow best at around .500 anyway. This was my first build too

 

you need to recalculate your compression ratio.. just dont sound right with those pistons

heres a link to a compression calulator http://www.csgnetwork.com/compcalc.html

 

i might be wrong but i think where you misunderstood on those piston.. is where it says +5cc piston head volume thats a 5cc dish

 

Assuming zero deck and 5cc reliefs and .041" gasket, you are at 11 to 1 compression.. PERFECT.

On stock heads you really dont give up too much with the 503 vs 306. 306 will out power it up top but gives up some in the mid range. I've seen 350-360whp from stock longblock LT1's with the 306 cam on manual cars. 340-350 with the 503 cam. The range overlaps so you may or may not give up any power.

But you can run the 306 on stock heads. Dont have to run 1.6 rockers so the lift aint bad. BUT 1.6 rockers will work my buddy runs that cam on his LT1 with 1.6 rockers just fine.