00MaroonZ28

iTrader: (3)

Has anyone here ever done one on an LS motor? Thinking of going turbo in the near future and saw how the Gen III RX7 had the sequential turbo set-up to help low and high end power. Figured it looks like a good idea for a street friendly car you and really boost up at the track. I tried the search and didn't see anything.

JAX04

iTrader: (17)

So your worried about low end.?????

00MaroonZ28

iTrader: (3)

Not really. Bigger displacement helps with low end torque. What I'm saying is it eliminates the turbo lag a larger turbo experiences. It seems like a good idea and wanted to see if anyone has tried this before on an LS motor.

chuntington101

Best way to minimies lag is to pick the correct turbo(s) for the job. What are you trying to do with the car? Drag? Road race? Street?

Drag, you can always use a little two step or tran break (if Auto) to help.

Road Race, Simplely make sure you are in the right gear for the corner.

Street, dont worry too much as you will blow the tires out anyway.

Chris.

00MaroonZ28

iTrader: (3)

A 6 second street car!

big reg

iTrader: (28)

It is only practical on smaller engines like the rx7 rotary and 2jz in the Supra. Coming from the import world myself I can tell you most did away with it on Supras especially by converting them to run in parallel by rigging the waste gates. It made more topend power this way.

And it obviously wasn't popular as most changed to big single turbos anyway. It only made sense in the OEM world when it came to marketing the cars as most buyers associated turbos with lag.

Somebody09

what about using a single, electric turbocharger for that instant, no-lag power?

or a less efficient, belt-driven one. like this:

the latter is probably cheaper

SS67SS

Just build a TT LSx with ball-bearing 6262's

If you have "lag" with that setup, you are doing it wrong.

TurboJoe@Straightline

I've looked into this a ton an am thinking about doing on on a fbody but purely for the wow factor. Compound boost setups really are more geared towards smaller high rpm motors. On Ls motors a properly set up turbo will make all the same power then a compound set up. Also in some cases low rpm boost is not a good thing.

The theory behind it though I find mesmerizing! Exhaust to first turbo with a wastegate set to 8psi dumped back into the down pipe merged to the secondary turbo with an additional wastegate to regulate boost. The intake track is equally impressive! The small turbo draws charge air via large turbo...cool stuff!

00MaroonZ28

iTrader: (3)

I can see how the RPM range can make them more effective over our motors. A 9k rpm range on a smaller displaced motor leaves a broad a range to climb for power. I saw the concept of it and it actually seemed like a good idea for tons of power all over the rpm range, therefore good for tearing up the street or race course.
That's exactly what I was thinking. It's an interesting idea and that's why I posted up. I wanted to see if anyone has attempted this and what were the results.

thunderwagen

iTrader: (3)

There is a guy on performancetrucks right now, Vicalma, who is doing a compund setup on his 90 Chevy with a 4.8. Kyle at KBracing built the kit. I think he is in the process of getting it finished up and seeing how it goes.

There have been a couple guys try the compound thing with a magnacharger and turbo but they couldnt control the boost

00MaroonZ28

iTrader: (3)

2 wastegates and bov's? Did he run each turbo off each manifold? I would see where running off the motor and exhaust would be better for spinning a large turbo. Just wondering how they did their set-up.

95bowtie

This is how it works

smokeshow

iTrader: (17)

Compound boost is only really useful when the pressure ratio capability of a single turbo is not sufficient. On gas engines we don't often have that problem though, because most turbos would easily hit 40+ pounds on a gas engine if they were allowed to in a free-floating setup. Sequential boost however is a different thing entirely. I built a sequential boost setup several years ago with a roots blower and a turbo and it worked very well. Not cost-efficient though.

00MaroonZ28

iTrader: (3)

Explained a lot. Thanks for the link.
I figured it's not cheap especially 2 different types of FI on the engine. I'm just throwing out the idea to see what the possibilities on one of these motors are.

The Alchemist

iTrader: (19)

Have you considered a centrifugal supercharger? Take a NA motor that makes good power, toss on a centri blower, and you'll add linear power all the way to redline. As cool as it may be to have an instant 10, 15 psi or whatever, on the street, it's not beneficial because traction is also linear as the speed increases, so your power should also increase as your speed/rpm increases. It's a cool feeling to have your tires right at the edge of losing traction through the entire rpm range, which is what a centri blower gives you thanks to a linear boost curve.

Reject

iTrader: (24)

man dont tell the diesel crowd about it's only for high reving tiny engines.

The diesel world uses that, but they are only going 90+ psi

no big deal

smokeshow

iTrader: (17)

Lol, I was thinking the same thing.

p8ntslinger676

The best advise i can give is don't do a compound setup. They are a giant waste of time, money and add unnecessary weight to the car on top of that they will give you more issues then they're worth especially if not done correctly. If you choose the right turbo(s) from the get go you shouldn't have any issues spooling them. And Marc, the guy in the video went back to a single precision 67 because of the issues that he had with the compound setup.

allout06

iTrader: (11)

on the caterpillar diesel engines i build at work on our high altitude 20cyl C-175 engines. we compound boost 6 turbos the size of beach ***** lol.