A 4.071 bore & 4 inch stroke in an LS3 yields a 417 CID engine,and Cathedral Port heads+Fast 90-92MM intake work good.

Would a 11+:1 CR with a hydrallic dual pattern cam(ie N2O cam), assumming good heads make 570-630 FWHP on E-85?

What cathedral port heads do you folks recommend?

I hear a 417 LS3 stroker is prefered to a 427 for FI or N2O.

 

What's your budget? I love my Trick Flow heads, and AFR heads are also great, but they're expensive

 

I'm running AFR 225's on my 416 and my compression ratio is a bit over 11.8.
It runs fine on 91 octane fuel. Can't say much about E85 as I have no experience with it.

Jimbo

 

Next R&D "bullet" about to hit the dyno.... - LS1TECH

You'll need a slightly different cam.....
A sleeved LS2 427 is fine....

For a big shot, you might consider a 3.8x crank LS3 and a longer rod ala the AES assemblies.

 

lol are you going 4.071 just to call it an 417 rather than the normal 4.070 for a 416? and actually 4.071 is still a 416. Why not go 4.080 and get a 418?

 

With E85 I'd go with 12:5

The 90 Intake will NOT help with you goals....
and yes 418ci is prefered over 427ci if you're talking about LS3 block even though there are a couple of member that done 427ci LS3 with over 200shot for a long time..

For the heads way too many choice and it depends on your $$$$$

 

With E85 I would go 13.5, maybe even 14:1. It seems that differences between power level on E10 vs E85 is only substantial with at least 13:1. I'm running 12:1 on E85 now and differences between my E10 tune were minimal. It's nice to run the option of switching back to E10 though with a simple calibration change.

 

A ton of interesting thoughts here, thanks fellows.

I thought the 4.071 bore was the most common overbore for LS3's.

What is the max overbore on an LS3 stock sleaved block?

If I had built a 4.071 bore LS3 with a 3.8 stroke crank(396 vs 417) how much would I leave on the table as far as HP/TQ "off the bottle"?

A 12:1 CR would be a great compromise CR for N/A & N2O but don't know how good 13:1+ would be with E-85 & a 100-250HP shot,if I ran N/A only a 14:1 might be the trick.

Is the Fast 102MM intake available for Cathedral Port heads?

 

I'd stick to 4.085" for a max bore size on 6.2 block

4.068, 4.070 and 4.080 are common piston sizes.

 

Yes a 102/102 combo is all they make now....

 

Too bad Fast killed the 90 & 92MM intakes.

Glad to see some E-85 users.

Anyone using a GMMP carb'd intake with EFI?