1997 cobra bulit motor question's

[Shroutc]

Hey guys im new to this site. but i have a 1997 cobra that ive recently re-built. heres the run down
icon forged piston .10 over
forged eagle rods w/arp bolts
4340 race bearings
stock high flow oil pump
stock forged 8 bolt crank
arp head studs
spec cluch
KenneBell supercharger 1.7 model
pully is 2 7/8 in which i think is a 8-9 psi pully but only produces 6 psi on my gauge.
bbk x pipe (no cats) with flow master 44's

what my question is the stock compression ratio is 9.85.1 and my engine builder suggested 8.7.1.. was this a good chioce? and would it be ok to drive it and only hit full 6psi of boost about 3-4 sec every once and a while without a tune? and would i need a new tune with this lower compression ratio?

 

[mvp performance]

Higher compression would have been my choice but to each their own. Get it tuned by a good tuner as well.

 

[hweb30]

At 6psi you could run more compression if you wanted to. DO NOT run the car without a tune though, the air from the supercharger could lean out the a/f and then you wouldn't have an engine anymore. Think of it this way, what's cheaper the couple hundred dollar tune, or the rebuild you'll have on your hands when it blows

 

[F8L BYT]

Hey guys im new to this site. but i have a 1997 cobra that ive recently re-built. heres the run down
icon forged piston .10 over
forged eagle rods w/arp bolts
4340 race bearings
stock high flow oil pump
stock forged 8 bolt crank
arp head studs
spec cluch
KenneBell supercharger 1.7 model
pully is 2 7/8 in which i think is a 8-9 psi pully but only produces 6 psi on my gauge.
bbk x pipe (no cats) with flow master 44's

what my question is the stock compression ratio is 9.85.1 and my engine builder suggested 8.7.1.. was this a good chioce? and would it be ok to drive it and only hit full 6psi of boost about 3-4 sec every once and a while without a tune? and would i need a new tune with this lower compression ratio?

Where are you at in Indy? And who is building it? I would suggest around9.2-9.5 CR. You definitely should get a tune, its worth spending 500 dollars rather than spending 4000 dollars on a blown up engine right? What car do you have and where at in Indy?

 

[Chris _Scott]

Buddy of mine ran like 8lbs on his KB, meth, and a 50 shot on just a canned tune from KB(5lb and no other power adders were what the tune was for). Stock longblock.. So 9.85:1 compression.

Beating the shit out of it for years and it was still kicking when he started his new build, still amazes me, lol.

 

[Shroutc]

Where are you at in Indy? And who is building it? I would suggest around9.2-9.5 CR. You definitely should get a tune, its worth spending 500 dollars rather than spending 4000 dollars on a blown up engine right? What car do you have and where at in Indy?

The cars a 1997 black cobra with tan interior.I'm in Indianapolis near mcordsville. I had the heads and block redone at quilin's (greenwood, IN) by Dustin "Dan" he said with the piston he suggested there were only three options 8.7.1 or 9.5.1 or 11.1 "flat top" pistons. he origanly suggest flat top then I said is it ok with me running only 6psi of non intercooler boost on my kenne bell? then he sent them back after that was said. And ordered the 8.7.1 witch at the the time I thought it would be ok cuz of the fact the newer 03/04 cobra C/R is only 8.5.1 ... Looks like I'll just half to up the psi to get the same power.