cobaltchev67

I'm a little new to the LS platform but have been doing a bit of reading....I'm familiar with SBC and BBC. My question is if YOU were to build a twin turbo LS platform engine, which displacement and bore/stroke engine would you choose to build and why?

The car it would be going into is a '67 Chevelle street/strip, 4 speed Jerico with V-gate, Gear Vendors Overdrive, an S-60 rear with TrueTrac/support cover/chromemoly pinion yoke, with 1350 solid u-joints, boxed lower trailing arms and frame braces....so the rest of the drivetrain should be good for quite a bit of power.

I'm looking for all kinds of opinions on this, including turbo headers, EFI setups you prefer either handling fuel and ignition or standalone fuel control while using something like an MSD ignition control, which turbos you would use, etc. Planning on using an LSX block and building from there....not going to cheap out on anything, this will be a well thought out project. Any suggestions for fitment are welcome.

This should be a fun thread to read and I hope you guys enjoy it as well, thanks for your input.

KCS

iTrader: (20)

I'd probably go with a 4.185" bore and probably a 3.90" stroke, depending on the power goal. I feel like that would be a good balance between getting the most displacement and allowing the parts to be reliable.

AES Racing

iTrader: (6)

What size turbochargers and how much hp?

cobaltchev67

Looking for somewhere around 800-1,000 reliable horsepower, if that is possible. I was thinking about a 427 but I read somewhere in a thread on this site the bore and stroke combination does not really suit a forced induction application.

I've looked at the Wrenchrat small block Chevy kits since I'm somewhat near them(they're on the east side of WA State, I'm on the west side of WA State), and they use anywhere from 60-1 or 62-1 Turbonetics units up to GT-K 66mm, 72mm, and 76mm turbos with a Gen1 383 to get up to about 820 HP. I'm guessing this is the arena I would be in.

I can fabricate my own system if that is necessary, probably following the 2 into 1 approach and then merging those into 1 but if there are parts out there that will fit I would use them. I'm thinking this may be necessary since it seems most Chevelle turbo cars seem to employ a manual brake master cylinder, and I have a hydroboost unit which hangs the master cylinder out there in the way of most of them.

Thanks for the replies. Here is the car in question, and the engine compartment I'm dealing with as it is currently:

3pedals

iTrader: (3)

I LOVE the fact that you plan on running a STICK SHIFT!!! I assume this is a drag setup since your using a jerico and a v-gate shifter, and so I see a problem in getting the turbo setup to be friendly with the clutch setup. It will be tough to build boost on the line without being able to load the motor against a converter. I know you can use the 2 step to help out, but it will never build big boost on the line like that.
I say go with a BIG centrifugal blower instead of the turbo's, OR go with an automatic trans and the turbos.
Of course my choice is 3pedals.
STICK SHIFT`s are FUN!

cobaltchev67

Yes, the car will stay a stick shift....I love 'em too . This car is not going to be caged and I'm not worried about loading it up for boost at the line, the goal is 135 MPH doing an 11.5, so I can be slow off the line without having to worry about a clutch issue and severe shock loads. Big centrifugal blower is not what I want to do as I'd rather have a street-friendly sleeper turbo setup(I prefer the noise of a turbo over a whiney supercharger any day), and an automatic is off the table....the car was an auto when I got it, and will never be again(other than the O/D).

It's my street/track toy and the current small block will likely go into a more dedicated track car, most likely another early Chevelle so I can do the LS mock-up in it and then do the swap without issue.

If you like transmission ****, this is for you(yes, I know the 3-4 shift lever is upside down in the picture, the previous owner put it on that way....why I don't know but I realized it minutes after I took this pic, which was immediately after installing the Gear Vendors setup) :

LS1-Master

I'd probably go with a 4.155" bore and probably a 4" stroke. 434ci

AES Racing

iTrader: (6)

That turbo system is nice, twins etc., however, no intercooler, if its going to be street driven IAT numbers will kill the deal.

twin 66mm could go with 364 - 390ci, generally stay under 400ci.
twin 76mm 427-434 is fine.

ideal, LSX block, 3.900" crankshaft, 6.100" rods, 1.200" CH piston, 4.155" bore size
works out to 423ci

427 piston with 4.000" stroke, pistons ring lands starts to get tight.

cobaltchev67

Ahh, yes, the intercooler....I have wondered at what threshold an intercooler is the best idea, IAT temps killing it for street driving without one would definitely make me put one in, no question about that. I'm liking the 423" idea, keep the stroke manageable and the parts clearances in check. Thanks for the insight on the turbo sizes AES, that helps a lot.

I will be reading up on intercoolers for efficiency and fitment, any brand/style/configuration that I should look at exclusively for this type of install?