What up guys! I was just wondering, what are all the rotating assembly specs on a 427 stroker? Would a ported LT4 intake & heads flow enough for that motor? What intake&heads would you recomend for this monster motor? Any mild cam suggestions for that? I wanted to build a pretty mean motor, sounds like I'm on the right track so far, heh, 427!

 

Can you even get a 427 out of an LT1?

 

Mark Montalvo has built two different versions of 421's on the LT1 block.... 4.09 bore X 4.00 stroke and 4.03bore X 4.125" stroke. Both of these are major challenges. Anything over .060 overbore requires a thorough cylinder wall thickness check and possibly some relocation of bore centers to compensate for core shift. A 4.125" crank is going to take serious clearancing. A 4.06 x 4.125 427 would certainly be a challenge. Might want to think in more realistic terms, like 396 or 409. You can actually buy a 409 LT1 shortblock.

I would suspect that once you go above 400ci, you would need more head than a set of well ported LT4's would provide. A set of the bigger AFR's, or even some 18deg SBC heads converted to fit the LT1 block. Or the elusive 32V Dominion/Arao heads.

 

Ok, so you can only make like a 421 on an LTx motor. How'd they make that 427 in the phase III ZL-1, and the C5-R? That's what I'm looking for. Or is what you explained to me, the same way they did it. Where can I find those heads and also would an LT4 intake be big enough? Thanks alot for your help bro, I appreciate it.

 

With an LS1. 2002 Car.

 

The original Motion Performance ZL-1 from the 60/70's was a "big block" motor... 427 was a stock GM big block configuration. If you are talking about the "replica" someone built from a 4th Gen, or the C5-R, you are talking about the LS1, or "Gen 3" small block Chevy. That engine has absolutely nothing in common with the Gen 1 SBC (1955-1992, even later in trucks), and the Gen 2 SBC, which is the LT1. Well, they are all made by GM, and they all have the same bore spacing, and they are all "small blocks"... but that's it. The LS1 has completely different block, firing order, intake/exhaust valve sequencing, etc. The C5-R is built on a limited production ($6,000) version of the LS1 Gen 3 block. It is designed at 7L/427ci. The basic LS1 is 348ci, but can be sleeved and stroked upward of 435ci (maybe more, but that's the largest I've seen).

AFR (Air Flow Research) sells several aftermarket heads that will fit the LT1/LT4. Any of the paying advertisers will probably sell them. Arao makes the 32V heads, but they are a bit pricey ($5,000) and so far there has only been 1 or 2 LT1's that have run with them, and a couple more that will be done "someday". If you need info on the 32V Arao heads, go to the "Advanced Tech" board and do a search on "Arao"... there is a fairly lengthy thread covering what they make, including a set that is supposed to flow in excess of 400cfm.

If you use AFR, I think they will accept the LT4 intake. The Arao probably needs a custom intake, or an adaptation of a Gen 1 SBC intake.

 

So basically, it'll be easier to do it on an LSx motor instead. Ok, Thanks again!!!

 

Oh, also, I was talking about the new '02 ZL-1 camaro, I know there is the older '69 with a 427, I guess, but I saw the new one, and well, it's impressive. There's a short movie that I have with a ZL1 Phase III vs an, I guess, bolt on LS1 Z28 w/150 shot(I think) and the ZL1 pulled him from a roll, but at the end they were even. I think thats VERY impressive!