LS twin turbo setup for 68-72 Chevelle

[Blown353]

Changing plans on my car and switching to a Whipple 3.0 instead of the turbo setup on the LS2. I know the turbos have more power potential and it's far easier to tune power delivery and switch between multiple boost levels on the fly, but having recently tuned a car with a stick and a Whipple 2.9 that instant torque of the Whipple seemingly regardless of RPM is just stupid fun. So, here's a great start on a turbo setup for an A-body with an LS swap.

This setup was built in my 69 Chevelle. It will fit in a 68-72 A body for sure and should fit in a 64-67 A body as well. It's been mocked up for fab work but never ran. I built it around an LS2 with a Vintage Air Frontrunner accessory drive and a Quicktime bellhousing with a T56 Magnum. Some of the earlier pictures are when I still had the TKO installed, the car now has a T56 magnum which didn't change the fit.

Plan was to go for about 1000-1100hp at around 16-17psi of boost, which is what the turbos were sized for.

Turbos are Precision 6176RS with ball bearing and water cooled center sections. Exhaust housings are 0.81 A/R.

PTP blankets for turbo exhaust housings.

Uses flipped GM 6.0 truck manifolds for both heat retention and also for easy replacement in the future.

Hot side pipes from the GM truck manifolds to the turbos are 2.5" 0.065" wall 321 stainless mandrel bends sourced from SPD for maximum durability, with SPD 304 billet flanges at the turbo and manifold sides. Pipes were TIG welded with ER347 filler rod and argon backpurged.

Downpipes are 0.065" wall 3" 304 stainless with V-bands at the turbos and V bands to connect to the rest of the exhaust. TIG welded with ER308L filler rod and solar flux at each joint as well as argon backpurged. There are flex joints in the wastegate dump pipes to allow for movement so nothing gets stressed and cracks.

Exhaust from the downpipes up to the mufflers is also included (I'm keeping the mufflers and tailpipes as they're built to clear my torque arm and watts link setup, which was a real pain.) It's 0.065" wall 304 stainless, and at this point only partially welded. Front section from the downpipe V-bands up to the X is fully welded, but from the X back it's only TIG tack welded. Already has solar flux painted inside at all the butt joints, but I was going to backpurge too when finish welding. Tucks nice and high with a G-force crossmember and has flex joints at the front not to stress the downpipes. There are hanger brackets to attach the exhuast to the crossmember to take the weight off the flex joints up front.

Also have a large custom made Bell air to air intercooler and associated turbo to intercooler and intercooler to intake piping available. You will need to modify your core support to move the radiator back and up a bit to mount the intercooler, but I had the intercooler, AC condenser, a power steering cooler, and the stock hood latch all working together with no problems for many years with the old D1SC Procharger setup using this same intercooler. Also have the turbo to intercooler inlet pipes already made from aluminum mandrel bends with beadrolled ends.

44mm black tial wastegates included. They currently have 0.5 bar springs installed which was going to be my low boost setting.

Black and silver turbosmart Big Bubba bypass style BOV included with a couple of different springs for fine tuning as well as a K&N filter for the outlet to keep stuff out of the BOV.

Note: you will need to mod your inner fenders forward of the wheels for air filter access and to make room for the turbo oil drains, and also room for the turbo to intercooler piping. I was going to make removable panels so it would be easy to change the air filters from underneath while the car was on the rack.

I would also strongly recommend you build supports from the turbos back to the block or cylinder heads to relieve the weight of the turbos off the hot side pipes for maximum durabilty. I was going to make trusses out of bar stock and hang the turbos with heim joints so things could move around for thermal expansion.

Asking $3750 for everything. Because of the size of everything I really don't want to ship it. I'm near Lodi, CA and you can pick it up or I can deliver or meet you half way within a reasonable distance.

[Blown353]

Can't believe it's been almost a year since I posted this... lol!

Back to the top.

[ryeguy2006a]

I'm surprised that this is still for sale! That price is very reasonable. Instant torque is really fun, but I'll tell you it is nice to have traction once and a while. That's why my new project will eventually have a turbo instead of a supercharger. With Terminator X having a built in boost controller, you can run on wastegate cruising around, or turn up the dial and have all the boost. Free bump for a really nice looking kit at a very reasonable price!!

[Blown353]

I hear you about traction with a positive displacement supercharger... It can bite you if you aren't ready for it. My old setup with the procharger making 16psi was fun too, but at least at lower rpm it didn't hit as hard and was easier to manage.

My plan is to try and make my own electronic bypass valve controller for the Whipple so I can still do boost by gear, boost by rpm, and have a low boost and high boost tune by having the computer run the bypass valve instead of a simple vacuum bypass valve, similar to what Chrysler does with the hellcat engine by having the bypass valve controlled by its own throttle body actuator. I'm hoping I can somehow adapt an older BMW individual throttle body actuator for the job. There is a company (smoothboost) that makes something that might work, but if I'd prefer to adapt an OEM throttle body actuator for reliability and ease of replacement down the road.

[ryeguy2006a]

I thought about doing something like that with my LSA. Since the actuator is vacuum operated, the idea was to put a MAC Valve in line with the actuator and use the Holley EFI pwm output to control the amount of vacuum the actuator saw. Sounds like a great concept for the new setup. Don't mean to clutter up your thread. Great price on that setup. I'm sure that someone will bite.

Cheers,
Ryan

[Blown353]

I thought about using solenoids to control the common vacuum style bypass valve as well; it would certainly work. GM does just that with the dual port bypass valve solenoid to limit boost in limp mode or when temps get too high, and that's the easy solution which I might end up using.

Using a throttle body actuator with position encoders would be much more accurate and faster responding and allow for better control of the boost.

Still have to do a lot of digging for a solution. Hellcat bypass valves are reasonably priced, and I might be able to slice one up to use the motor and gearbox to drive the Whipple bypass valve.

[Blown353]

Back to the top in more ways than one... just put the exhaust up in the rafters to get it out of the way.