Tell Me I'm Not Crazy...
 

I am in the process of building a LT1 and I need a sanity check. Here it is...

96 Camaro
357 CI 4.030 bore
Scat forged crank with a 3.5 stroke
Scat H-beam rods 6.125 length
HRC Ross pistons forged 2618 with CH of 1.125 and -5cc dome volume.
Ported 200cc stock cast heads with a 55cc CC, ported intake and 52mm TB.
Block will be splayed.
36# injectors
My compression with a .054" quench will be 13:1. I'm to understand my only option will be race fuel 104 or 110 octane.

Is this out of line? This is my first build and these are the parts I picked up at a good price. I am still learning so all inputs are welcome. I do plan on running a 200-300 shot of nitrous once the motor is dialed in. My goal is to get a car that can dig pretty deep into the 10s.

You want to keep your quench around .040 to deter detonation.
If you drive that on the street it'll get real old not being able to use pump gas
Stock heads won't be enough.

JMHO.

Grab some bigger injectors and a bigger fuel pump, make the switch to e85. Way cheaper than race gas, even cheaper than pump gas many times.

I do plan on upgrading the fuel pump but I thought 36lb injectors would get the job done. For a 355 I was thinking around 500 flywheel hp.

You can do that on pump gas and ported stockers, 255 pump and 36lb injectors along with a good cam.

I was merely speaking to the fact of you wanting to run alot of compression and nitrous. E85 is a great alternative to race gas but requires higher fuel delivery capabilities than normal gas.

Myltwon, sorry I misunderstood your post. E85 might me something to look into down the road that's for sure...

Unless I screwed it up, Summit's compression calculator puts you at a 11.24 CR with the information provided. I have a 383 with the same specs with a .039 quench and 12.48 CR.

https://www.summitracing.com/experta...ion-calculator

I don't do nitrous.

But if I did.....and was doing 200+ LB shots, I'd do it with a lot more than 36LB injectors.

IJS.....

KW

Wet nitrous kits function irrespective of the injector size.

I like this CR calculator because it includes head gasket bore:
http://www.csgnetwork.com/compcalc.html

I got low 11s CR assuming your pistons are flat tops with 5cc total valve reliefs (-5cc dish), 4.04 bore at 0.04 thick like a Cometic, 0.014 deck clearance (this is what my deck ended up at with the minimal amt taken off), etc.

I'm using Howards Cams #840312305 pistons. It says its a -5 cc piston. So when I calculate compression I use -5 for piston volume. Am I figuring this wrong?

Those are flat top with valve relief, not domed. The CC is added to the total CC at the top of the stroke.

That changes a lot. It's confusing sometimes as some calculators use -5 as a removal of CC space at TDC, while others use -5 as a removal of piston material thus adding CC to TDC.

With the specs you provided, you'll have 11.2:1 SCR. That SCR is pretty safe with even a small cam. But that quench is still pretty high.

Are you planning on machining the block? Maybe take the deck down a bit? If you leave the pistons in the hole .010" and used an Impala head gasket at .028" you'd quench at .038" and have an SCR of ~11.6:1. You could run a moderate size cam comfortably.

This is all assuming your head gasket bore is 4.120"

What cam are planning on running with this combo?

OK OK thats a lot better news. I can deal with 11.5:1 and run pump gas. Thank you explaining that. I dont have a cam yet but I will reach out to LE and have him spec one for me.

For reference I run 12.5:1 with 0.028" quench with no detonation issues on pump gas (91 octane). I do utilize a 24x conversion so the 0411 pcm gives me a better tuning platform, but that's where the key is...tuning.