396 LT1 on pump gas
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From: Phx Az
396 LT1 on pump gas Hi guys im currently building my first LT1 but im having problems on deciding what pistons and heads to use. Block is being bored 40 0ver, I want to use dome pistons but I do not know how big of a dome to use and what heads to compensate it with. I do not want to raise the compression too mutch because I want to be able to use 91 octane with out detnoting and being able to pass emissions. thanks guys.
With 54 to 58cc heads Domes arent needed!!! Thats old SBC tech Unless youve got a larger cc combustion chamber like 60cc to 64cc Piston choice really depends on Horsepower level & are you gonna spray it or boost it??? With stock 10.4 compression 87 Octane is good & 93 Octane is good for 12 to 1 & some have ran 12.5 to 1 I think So 91 should be a lil less than 12.0 to not have to pull lots of timing out LOTS of it is in your tuner & passin a smog test its ALL in your tuner!!! E85 might be a better choice if its plentifull in your area!! On my 396 build I dont have to worry about smoggin it 
Im gonna start with close to or a lil over 12.1 to 1 & 93 octane even though Ive gotta drive 20 miles south to Tx LoL But if I dont like that Itll get E85 & bigger injectors. Im sure others that are better on Octane vs Compression will chime in & add their input & tell ya the max you can get away with. Your cam choice will be critical too! Heads will get various opinions But my choice was Dart Pro 1 200cc heads BUT I bought em & sent em out for porting & new springs for the solid roller Im usin plus larger valves & all tolerances put into spec
Im gonna start with close to or a lil over 12.1 to 1 & 93 octane even though Ive gotta drive 20 miles south to Tx LoL But if I dont like that Itll get E85 & bigger injectors. Im sure others that are better on Octane vs Compression will chime in & add their input & tell ya the max you can get away with. Your cam choice will be critical too! Heads will get various opinions But my choice was Dart Pro 1 200cc heads BUT I bought em & sent em out for porting & new springs for the solid roller Im usin plus larger valves & all tolerances put into spec Last edited by warriorcustoms; Sep 19, 2012 at 11:57 PM.
Thread Starter
On The Tree
Joined: May 2012
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From: Phx Az
my first plan was too boost it on four pounds using a centrificul supercharger,but it is my first build so im a little low on funds so im thinking of just going N/A with nitrous ,my guy at the machine shop was telling me to use 64cc heads and dish pistons but wont that lower me on compression a bit too mutch? I live in Arizona the best we got at the pump is 91 octane and E-85 is'nt very common in my area=(, Thanks for replying bud!
Last edited by Alberto v05; Oct 13, 2012 at 06:48 AM. Reason: grammer
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What cylinder heads do you plan to run? Some cylinder heads have slightly different valve spacing called 60/40. They will require pistons with the notches in different places. Most cylinder heads won't need them though. Just something to think about.
How much nitrous do you plan to spray? If you are only going to dabble with a 150 shot, then do not get a "nitrous grind" camshaft it won't be needed. When you hear about motors built specifically for nitrous, they are talking about large shots 250+. Motors set up to handle amounts like that, will need special attention with regards to the camshaft and pistons.
How much nitrous do you plan to spray? If you are only going to dabble with a 150 shot, then do not get a "nitrous grind" camshaft it won't be needed. When you hear about motors built specifically for nitrous, they are talking about large shots 250+. Motors set up to handle amounts like that, will need special attention with regards to the camshaft and pistons.
I am using 14cc dished pistons on a 58cc chamber and a zero deck block to achieve 11.0:1 compression so you won't be even close to having to use a domed piston. You may have to use a custom piston to get the CR which best suits you. Best thing to do is to find a competent machine shop to use and take all your questions to them. If you are around the NE region I can recommend a shop for you.
Joined: Nov 2001
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From: LT1 land...the "409" of the 90s!
I am using 14cc dished pistons on a 58cc chamber and a zero deck block to achieve 11.0:1 compression so you won't be even close to having to use a domed piston. You may have to use a custom piston to get the CR which best suits you. Best thing to do is to find a competent machine shop to use and take all your questions to them. If you are around the NE region I can recommend a shop for you.
Flat tops and .042 head gaskets with a zero deck and a 58cc is just fine. 64cc ick!
if it is .010 down it will be high 11s to 12
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Verdad Gallardo well if 12 to 1 is good on 93 & stock compression is good on 87 Then Id shoot for in between Start collecting parts The good stuff aint cheap 
As far as heads youll prolly get a different opinion from every other guy on here BUT my vote goes with Dart Pro 1 200cc & find a great porter that does Lots of Darts & call it good Thats what Im doin & my car will be gettin a NX Maf ends kit & a Direct Port set @ 300 , 4L80E with stall & S60 rear diff
Start collecting parts The good stuff aint cheap As far as heads youll prolly get a different opinion from every other guy on here BUT my vote goes with Dart Pro 1 200cc & find a great porter that does Lots of Darts & call it good Thats what Im doin & my car will be gettin a NX Maf ends kit & a Direct Port set @ 300 , 4L80E with stall & S60 rear diff 