Kevin's Compound Sequential Twin Turbo Design

[CanisLupus]

No proper Graph available? Revs vs hp/nm would be Nice.

[V8KILR]

I've decided to pull the TH400 out and put my Getrag V161 back in the car. Testing on the street with the compound setup, it still doesn't launch as hard as I want it to with the auto and nowhere near as hard as it used to launch when I was manual.

 

Unfortunately this means the compound setup is coming out. Despite showing great promise for spool, the rear down pipe doesn't leave any room for the clutch master cylinder where it bolts to the firewall. I'll be going back to a small single turbo setup (probably a MasterPower 6564) bolting on to the SPA manifold (to keep it simple), and with E85 it should still make pretty good power. With the Precision 6870 showing such good results, I may look at running that turbo later on if it can clear the strut tower when bolted to the SPA manifold.

 

There were still some issues with the compound setup with oil drain leaks and the big issue was that the thin wall stainless pipes were getting red hot with just one dyno run and the associated heat issues that can cause. Both are fixable, but not easily so and made harder by needing to allow for the clutch master cylinder.

[mellonman]

Thats a shame dude but , I take my hat off to you for giving it a very good try,

[Shane]

Sterling effort though and good luck with the new direction, that's the car not the boy band.

[Mattia]

On 11/9/2013 at 5:41 AM, V8KILR said:

I've been thinking of doing a sequential turbo setup for a while now as a means of getting more boost at lower rpm, so that I can run a lower stall in my TH400 converter. A lower stall will allow me to have a converter that holds more power and has less converter slippage, which results in more power to the rear wheels.

 

Having looked at every compound, sequential, and twin turbo setup that I could find on the internet, there wasn't one of them that I was happy to install in my own car due to various fitment, cost and complexity reasons. Therefore I decided to design my own sequential turbo system.

 

They say a picture is worth a thousand words, so here's a diagram of how it works.

 

https://jza80.mkivsupra.net/imports/2013/11/112.jpg

 

This sequential setup is basically a compound turbo setup on the exhaust side (but with identical size turbos) and a sequential setup on the intake side. This means you get all the advantages of a compound turbo setup for spooling the turbos, but with none of the disadvantages of the compound setup such as the boost being too high for a gas engine. Also both turbos are exactly the same size, so you don't get any issues with different size turbos fighting each other in the sequential setup and having the large one potentially overpowering the smaller one.

 

By spooling the second turbo with the gas exiting from the first turbo, the second turbo will spool much quicker then if it was just receiving some exhaust gas diverted from the first turbo, as most other sequential turbo systems do. This means that instead of having a big dip in the torque curve when the second turbo comes on-line, there should be little to no dip in the torque, resulting in a torque curve more like a large single turbo.

 

This setup is super simple and only requires 3 devices to be controlled, which is simpler then any other sequential turbo setup I've seen. There are two wastegates, one used for each turbo and they are set to exactly the same boost level. These wastegates need to be controlled separately as the two turbos will require different duty cycles on the wastegate to maintain the same boost level. This can be done via two boost controllers or via one boost controller and one aftermarket ECU. There is also one combined reed/air intake valve (with an attached actuator) required that needs be opened when the second turbos boost catches up to the first turbos boost pressure. This could either be done using a Hobbs switch set to the same pressure as both wastegates are or by an aftermarket ECU controlling the flow of boost pressure to the air intake valve's actuator.

 

My design uses a proper high flowing manifold to the first turbo, eliminating the ugly and often poor flowing log manifold seen in many sequential designs. Here's a drawing I did to show how my sequential setup will be implemented in practice on my 2JZ-GTE Supra engine.

 

https://jza80.mkivsupra.net/imports/2013/11/113.jpg

 

My design uses a 3.5" down pipe between the #1 and #2 turbo, a 4.0" down pipe for the #2 turbo and the 60mm wastegates have 3.0" pipes to maximize the flow. This is the 2JZ-GTE intake air control valve I will be using. The curved section will be removed to make it straight through.

 

https://jza80.mkivsupra.net/imports/2013/11/114.jpg

 

I am planning on changing my single turbo 2JZ-GTE Supra to this setup over the next winter season and I will update my website with the results from this setup then. My setup will use two Turbonetics 60mm wastegates, the Supra OEM reed/air intake control valve (50mm) and two MasterPower race series R6164 (61mm) turbos. These turbos are good for 700hp each on gas when run around 30-35psi boost, making for a potential of 1400hp from both turbos on gas or 1500+ hp when using E85. I use E85 and my goal is 1000whp through the TH400 gearbox which is around 1300hp. This will hopefully be achievable with around 35psi boost.

 

As this is a different design to what anyone else has done, its possible that it may require some tweaking to work correctly. After discussing this design with a friend, there are two areas that I think may cause issues. One is that the 60mm wastegate from the #1 turbo may not allow enough exhaust flow around the #1 turbo resulting in excessive back pressure or over boosting. The other is that the #2 turbo may cause too much back pressure in the #1 turbo's down pipe, which will reduce how quickly the #1 turbo spools. Both these issues can be resolved with some design changes if they do occur.

 

All constructive comments and suggestions are welcome.

Hi, the job was great but i rather think it would have been more satisfying if you’d have had put in sequence a 50mm or less and a 70 mm or more for obvious reasons