My compound turbo set-up

[99gst_racer]

What are you planning to do for cooling? E-85, meth? I would think that the air would be twice as hot since it's going through two compressors. Correct me if I'm wrong.

Great question. Originally, the plan was to use two intercoolers. I was going to squeeze a big sidemount in there for cooling between stages. But I soon learned that to be efficient, I would need to use another cooler the size of the FMIC that I already have - and there's just not enough room for that. Then, I considered spraying methanol between stages. Well, with a GM MAS and atmospheric dumped BOVs, that's just not feasible. So, I landed on direct-port methanol injection.

It's going to be a bit before I build the kit though. I'll be running it on 110 octane fuel for the first month or so. I'm hoping to eventually use meth injection and pump gas and run 35+ psi. I'll probably install the meth set-up when I send the compound set-up off to be jet-hot coated. It just has to fully prove itself before I drop the coin for the coating - and a large part of that means going to the dyno.

But, even still, each turbo is going to be running in the middle of it's best efficiency island. Each turbo is gated at only 11.5psi so they're not working up much of a sweat. I'm willing to bet that the air charge won't be much warmer at all, if any. But that also doesn't mean that there isn't room for improvement on the air charge temperature.

 

[habitatguy187]

But, even still, each turbo is going to be running in the middle of it's best efficiency island. Each turbo is gated at only 11.5psi so they're not working up much of a sweat. I'm willing to bet that the air charge won't be much warmer at all, if any.

That's pretty cool, I'm anxious to see how well your car does. What kind of numbers do you hope to see?

 

[Mr Peepers]

Ahhhh, I would really love to see how much meth between stages would help. Wish it was an option

 

[99gst_racer]

That's pretty cool, I'm anxious to see how well your car does. What kind of numbers do you hope to see?

I'd like to break 600 WHP. I guess that's one of my goals.

Ahhhh, I would really love to see how much meth between stages would help. Wish it was an option

Ehh, I wasn't really too crazy about spraying into a compressor wheel anyway.

 

[99gst_racer]

Pics of what I recently came up with for a downfiring compressor cover for the 16G:

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And the radiator hose that I made to clear the 60-1's compressor cover:

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[myturbo]

soo BAD ASS.

did you port the 16g comp cover before you welded the pipe to it ?


I THINK THE AIR WOULD BE COLDER DUE TO 2 TURBOS ,,i can explain?

 

[MIdsm]

The VW has a compound turbo setup in their Dakar racer. IIRC each stage is intercooled and there are both exhaust and intake diverter valves to regulate flow. I don't have the article with me but they bypass the small turbo at higher engine speeds as it would choke the intake flow and it would spin too fast due to flow through the turbine although it's given enough exhaust flow to keep the blades spinning. The article was in either race-tech or race car engineering.

 

[TunaTalon]

When you get the beast up and running and still haven’t littered the strip with driveline parts, consider a water/air intercooler between the turbos. Then you can give that front mounted heat exchanger its proper name of “aftercooler”. Like the engine that saved Britain, the Rolls Royce Merlin.

Good work.

 

[awddsm95]

Awesome project! Very interested to see how things turn out for you.

 

[toofast82]

I envy your fabrication skills so much

 

[evileclipse909]

You have anymore pics or updates today. I just think that people like you who think out of the box and have the fabrication skills to back it up are awsome. Keep up the good work and keep us updated.

 

[xlMcMlx DsM]

This setup on a 4g63 is gonna be sick man! I'm curious as to what/ how you're going to control boost, one MBC for each turbo fed off one pressure source maybe?

 

[myturbo]

There would be one MBC/EBC, you just make one line to the BC and then one line out with Y to go to the W/G's.

or a Vacuum block instead of a Y .which would be much better.

 

[bpestilence]

Very nice! I am glad that you routed the wastegate from the first turbo into the inlet of the second. Before I saw that pic I was worried that you were just going to dump it to the exhaust.

I just hope that the wastegates flow good enough. At least half of the entire exhaust flow is going to go through that first wastegate once you are into boost.

Seems like this setup should be able to make some rediculously high pressure ratios.

 

[99gst_racer]

Boost control will be by the wastegate springs only. No boost controller - at least not for a while.
I have a 'T' on the 60-1's compressor cover for both wastegates. And of course, the 16g's wastegate uses the top port to reference the higher atmospheric pressure due to the 16g's new inlet pressure.

And yes, I ported/blended the hell out of the compressor outlet of the 16g before welding to it.

Very nice! I am glad that you routed the wastegate from the first turbo into the inlet of the second. Before I saw that pic I was worried that you were just going to dump it to the exhaust.

I just hope that the wastegates flow good enough. At least half of the entire exhaust flow is going to go through that first wastegate once you are into boost.

Seems like this setup should be able to make some rediculously high pressure ratios.

Yeah, both wastegates are going to be working O/T often. That's one big reason what I recirculated the 16G's gate. The OE cast manifold and 7cm turbine housing will become a restriction at some point, but the wastegate will be diverting a large amount of that exhaust energy around the restriction and directly into the path of the T4 turbo. Perfect.

I re-routed the 60-1's wastegate simply because I'm getting old and am willing to try having a quietier WOT. For once, I'd like to hear that turbo (i mean, those turbos) spool.

The 44mm gates should be fine. I'd hate to think I need larger.

Last fall, I figured out what it's flow rate would reach if I maxed out each compressor. IIRC, it was somewhere in the 120's PSI. Assuming of course all other restrictions aside. I won't even be tickling the thing to get what I want out of it.

 

[99gst_racer]

No new turbo progress pics. We're having our company car show this weekend, so that kills my free time to work on the car. So close to having it done for the show...

Just for shits and gigs, here's some progress on the rest of the car. Excuse the blurry pictures of the dusty parts. Everything needs a bath at this point anyway. Including the camera.

New front bumper. Yay! No more blitz!

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And I finally gave myself the comfy leather seats that I missed having. Can anyone guess which car they came from?

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[JEFFREYCASTGSX]

Hey man you some amazing fab skill, good luck.

 

[jrohner]

Yeah, both wastegates are going to be working O/T often. That's one big reason what I recirculated the 16G's gate. The OE cast manifold and 7cm turbine housing will become a restriction at some point, but the wastegate will be diverting a large amount of that exhaust energy around the restriction and directly into the path of the T4 turbo. Perfect.

It wouldn't work well to dump the 16G's wastegate anyways would it? You'd be losing a lot of exhaust energy that is very much needed for spinning the larger turbo.

Won't the compressor on the smaller turbo be a restriction to the 2nd turbo? Won't the compressor on the smaller turbo be a restriction to the 2nd turbo? I suppose the bigger one will pretty much be sucking air through the 1st by some point but wouldn't it still be somewhat restrictive?

I'm also wondering, when you do turn the boost up, if the wastegate should maybe be set to a lower boost pressure (like 20psi max) on the smaller turbo since that would minimize the exhaust back pressure / restriction. If nothing else, the smaller turbo could have a really soft wastegate spring (and a boost controller to raise the boost substantially) so it can blow open with exhaust pressure.

I'm eager to hear the results for the HP, spool, and of course, reliability. Great work so far

 

[Artago]

The whole setup looks awesome, can't wait to see the finished product to see what kind of numbers it makes.
What kind of seats are those and where can I get some?

Tom

 

[knochgoon24]

So, if they get SD to work on the Evo 8 ECU...

 

[GsXdSmKingGsX]

Good lord this is sick

 

[Zack Huffman]

Paul, . Seriously.

Like I said before, the exhaust manifold and plumbing is going to be the most important part, because it's actually going to see the total pressure differential across the walls of the piping and restriction of two turbines. As long as everything holds the heat and pressure you should be set, especially with the coatings to help hold thermal energy. Dialing in the cam timing will be interesting too I imagine.

So, if they get SD to work on the Evo 8 ECU...

It already does, depending on which ROM image you use and how willing you are to deal with annoying CELs. In order for us DSMers to take full advantage, they just need to get it working on a ROM image that doesn't throw a code for the cam/crank sensors, for example: the European or Australian domestic market ROMs.

 

[GS-T_Newboost]

the seats look like acura rsx type s seats. Are they?

 

[94awdcoupe]

I think this setup fails in design. the first turbo is simply in the way of making power. The compressor side is fine. Its the exhaust side that will not work like you hope. The 16g will overspin and die very quickly, the second turbo will not recieve enough exhaust energy through that small wastegate Compound turbo setups work well on diesels where they should stay. Diesels tolerate very high boost pressures because the engine itself runs off autoignition point of fuel/air charge.

The AMS design staged twin turbo was brilliant by design compared to this setup. They only had a few days to get car ready for event . they feared they wouldnt have enough time to work out bugs so they had to abandon the project.

I cant find pictures of that but a quick search found this new 1.9tdi with staged chargers
Fiat Powertrain: 1.9 JTD Twin Stage Turbo with 100 hp/liter

 

[tenn-gsx]

Won't the compressor on the smaller turbo be a restriction to the 2nd turbo? I suppose the bigger one will pretty much be sucking air through the 1st by some point but wouldn't it still be somewhat restrictive?

:

The 16g compressor is 2nd in line on the intake side which means it will pull the air through the larger compressor. By the time the larger compressor is doing any work the 16g will just be compressing the air even more so there won't be any restriction there either.