Hey guys, I finally decided to build my stroker. I got a bare 2 bolt LT1 block, had it blasted and my machine shop is putting a 4340 eagle forged rotating assembly with h beam rods and JE pistons. I am purchasing I believe a set of trickflow LT1 heads, 195 CC intake, 75cc exhaust and 62 cc combustion chamber. My machine shop told me the 62cc will raise my compression, so hes ordering different pistons for me to keep the compression at 9.5:1 until I slap the heads on and it will go to 11:1 which is where he wants it. I was originally going with the cc503 cam, but someone told me that is too mild now. What kind of cam should I go for? Should I have these heads ported? I want it to be streetable, but still make great power. Fully forged internals. I dont want it TOOOO streetable. I guess Im kinda making it force me to get a 4 banger to drive around . Also are 30# injectors going to be too small for this or should I upgrade??? Im trying to get this motor put together and installed in less than 30 days. Thanks!

 

Those 62cc heads will lower your compression ratio, not raise it. Stock cc is 52-55. Also I would upgrade to 36# injectors. The cam in my 383 is similiar to a CC306 or GM847. Its really lumpy at idle and I still drive it daily.

 

My guy told me the rotating assembly is going to give me 11:1 compression with the flat top pistons I chose. He said with the 62cc chambers it will probably go up to like 12 so he was going to go with different pistons to bring it to about 9.5:1 so when I add the heads it will go to 11:1. Does that sound alright? He wanted me to get something in the range of 72cc. I know he knows what hes doing, but Im a little vague on the rotating assemblies and compression.

 

Does he believe the stock heads are ancient 76cc crap???
Does he comprehend the fact the engine was 10.4 stock?
MANY a built LT1 rolling around a 12:1 or more on pump gas.

Would not run as cast Trickflows.

Sounds to me like he might not know much about the LT1. The bottome half is basically gen 1 machining to that is pretty much the same. It is compression, camming and heads that have to be treated differently and given what you say I don't know that I would trust this guy with that just yet. You might have to educate him some.

Honestly for the vast majority of folks ported stock heads are a great choice, the Trickflows if ported by the right place are great but the cost/benefit is not there for most applications.

www.advancedinduction.com does great head work, to stock castings or the Trickflows.

I would have gone with something other than Eagle too. Hit and miss quality wise, some guys have great luck other drive over the rotating assembly before 1000miles, Scat is better for the money and Compstar is MUCH better for little more money.

 

He could have setup the deck height pretty high to get that comp ratio. Many factors make up static comp not even considering dynamic comp ratio. Like chamber size, deck height, stroke length, piston volume cc (dish or dome), gasket (crushed) thickness, bore size, gasket bore size, etc... Talk to your builder again as chambers those size with the typicall -5cc flat top pistons will give you a lower comp ratio as stated. To give you an idea I am running 10.5:1 with my setup with AFR heads and 64cc chambers and SRP flattop pistons.

 

This is all true, a lot of folks run eagle with no issues at all however compstar is notorious for the ultimate budget crank, I am running on 12:1 93 octane just to back up your statement.

 

Going to a head with a larger combustion chamber than a stock head does NOT increase the compression ratio. It lowers it. Doesn't matter how much he "knows".

 

might want to try a different shop

many builders are stuck in a certain school of thought and will pretty much try to refute any information you bring to them imo. can be very hard to deal with because they can prove to be narrow minded many times and will build the motor they think is right not neccessarily what you want or need.

he's also operating under false assumptions of what adds/removes compression, what head to run, what head you have, etc. not the kind of guy I want to spend my hard earned money on for what's looking to amount to lack-luster results.

 

First of all dump the builder and move on. I personally would stick with the stock castings as far as heads go. Unless you plan to spend your money on heads only to spend more money to send them of for extra porting. The stock castings can and will flow just as good if not better than the trick flows.

I do not know much about AI but I have personally delt with Lloyd Elliot and he is awesome. He will help you with your heads and cam, help you get your build on it's way and help you with the compression ratio you want, not what someone else want's for you. I recently delt with a machine shop and they TRIED to tell me what I want, but before I walked out the door they decided to see things my way. Here is a link to Lloyd's site.

http://www.elliottsportworks.com/lt1.html

 

I was going with stock heads, but figured after I bought the stock ones, and valve springs, locks guideplates and retainers, and machine work, I would have spent just as much money to buy aftermarket. This guy has a 68 Camaro with a 388 w/a blower, that runs 9's with no NOS. I might be misunderstanding him. Maybe he assumed I was going with 72cc combustion chambers so when I told him I was getting 62cc, his thought on compression was that it was going to be higher than he planned.

 

I did my own research and drove my builder to do my first 383. That was a 11.2:1 SCR and 9.2 DCR. The specs of my current 383 are below.

You need to understand this stuff yourself as you are spending good money and just letting it happen. get online and find those SCR and DCR calculators.

This guy does not seem to know LT1's.

BTW, I ran both on pump gas and minimal change from stock timing maps.

 

Words like probably and should have no business in a conversation about compression ratio. It can be calulated very exactly. If he is not calculating compression ratio and isnt willing to crunch the numbers then I would not trust him with a build. You cant go buy what piston manufacturers say the compression should be because things like head gasket deck height etc all play a role in what you end up with.

If you really want to split hairs everything should be poured to make sure the volumes are what you think they are and then adjustments made from there. Its only really important to do that if you're pushing it though alot of times the stated specs are that value or slightly larger meaning you end up with less compression than they told you it would have.

Plenty of people can build very nice gen 1 sbc's that does not translate over to other platforms like the lt1, they all have thier quirks and things they like and dont like. I dont want to be on anybody's learning curve.