I've done quite a bit of reading, so before you all bash me, hear me out. I've done the math, looked up the compressor tables, crunched and re-crunched the numbers. Anyone please feel free to correct me, but I have, and intend to use, two garrett 60-1 turbos. Both are .96 turbine A/R, one is .64 and the other is .71
My math tells me that these two turbos, run in a twin setup, will stay in their peak efficiency zone if maintained from 8-15psi of boost(1.5-2.0 pressure ratio).
I tried to calculate as much conservative tolerances as possible, but what I have been reading in this section of the forum is honestly making me second guess choosing the 60-1's.

Can anyone provide some guidance?
The cam is also making my head explode.. ive read both ways as far as lsa, but it seems right around 580 lift and 24x/25x would do the job..

 

are you building the ls1 427? or do you already have it? i'd build 427 LSX 6bolt headed block for big boost.

 

I got the block already machined and darton mid dry sleeved, honed and decked. I got it on a good deal ($1800 for block, diamond pistons, ARP mains & head studs all shipped)
I have katech 806 cnc'd heads. They flow right around 290/280 at .060 with 66cc chambers.
I plan to use a 427 rotating assembly from texas speed with -32cc wiseco pistons and NOT total seal rings(opinion? i've read lots of discussion on this..) with a 4.000" 24x crank and eagle h-beam rods.

 

and nobody cares to drop their .02?

 

the garrett 60-1 turbos will be WAY small for that size of motor! I would go with something closer too the TC-70

 

Spend the extra coin and get some thick deck cylinder heads. They will be more likely to keep the head gaskets intact. I wouldn't even screw around with production think deck heads.

Considering a 364ci LS2 with stock crank and forged rods/pistons has been low 8's with a healthy turbo.....

What et/mph are you shooting for? That 427 will have lots of potential. Crazy fast.

 

Why go with two diffrent sizes on a V configuration? That method is used for Inline 6's rotaries (2ZJGTE, 13B). With a 427 built for boost twin TC70 should get your rocks off quite well

 

so 60-1's are "WAY" too small? i was only shooting for right around 750 at the wheels. so the heads are junk for my app? what about some AFR 225's?
apparently i have many more hours of research to do. i'll be on the hunt for some more good write-ups and books.. i have a good stack going already.

 

I would go with the new LSX-LS3 heads or the Mast Motorsports LS3 heads.

 

Why? Neither has been tested and proven.

OP, the AFR225's would be a great choice. Making 750 hp with a 427 is going to be pretty easy. Why not run a single 88mm with a t6 flange?

The 60's are too small for your cubes.

 

Are AFR 225's comparable? it would seem since they are big bore heads they might do the trick.. I was under the impression that heads had much less of an effect on turbo motors than NA.. but hey I apparently was wrong about the turbo selection.. so maybe I should just hock all this crap and buy a PS3 and need for speed..

 

So if i'm doing this as a long term, bomb *** setup, AFR 225's, t70's, -32cc pistons, and a tranny from a sherman tank? If 750 is going to cage the beast, how much HP would put a medium stress on the engine and turbos? I haven't looked at the compressor maps for the t70s yet(not that it would matter with my map reading skills.. lol)..

 

900 flywheel...

 

L92 heads don't work? HMM work pretty good for the 800rwhp I have. These just have a thicker deck and better flow numbers.

 

No, they flow better and have a thicker deck. Velocity (head flow design) is not as big a deal but volume is.

 

That makes sense Killer. So I'm actually still looking at the same over all project, just have to change out some parts on the front end to be where I want when I finish.

Next question.. I've seen a LOT of discussion on cams for turbo motors.. everything from wider is better, to overlap is better(concerning sep. angle). In a four stroke gas engine, scavenge seems to be negligible, but reversion a much bigger problem. Is there anything out there definitive?

 

There seems to be many schools of thought on this. My thinking is that in a street car type build, you should have atleast a couple degrees of negative overlap. There are alot of different ways to get there. If your goal is only is only 750-800 HP, you don't really need much of a cam. It will also depend on what heads you end up with as to how you would setup up the split on duration. My thinking is to use the smallest cam that will do what you need in order to make street driving as pleasurable as possible.

 

Killer what do you think a reasonable HP goal for that setup is?
427 ls1, afr 225, twin t70? it seems the project scope is changing again.. lol

 

I didn't say that they wouldn't work. I said that they haven't been proven. I am talking about the NEW LSX-LS3 casting or the NEW Mast Motorsport heads. Being a test dummy usually doesn't work out well for me. My pockets just aren't deep enough. L92's have been proven to flow well but they have also been proven to lift easy.
1000 rwhp should be easy by 18 psi or so. Should be able to hit your 750 target by 10-12 psi. Maybe less boost.

 

thats about what i was going for; i'd like to keep the pressure ratio around 2.0 if possible so that the turbos stay in their best efficiency zone.. adding less heat to the charge air and all that.

well.. sounds like its off to the classifieds section to get rid of some stuff.
thanks all for your input.