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My compound turbo set-up

95g-s-x

Proven Member
142
2
May 27, 2010
Warren, Maine
Im toying with the idea of a compound setup. What would be the disadvantage of putting the large turbo first in the exhaust stream but still feeding the small turbo compressed air from the large turbo? Just curious because it seems much easier to find a place to put the small turbo.
 

bastarddsm

Proven Member
5,416
1,252
Aug 26, 2003
Mendota, Illinois
You would have to keep the cold side plumbed in the normal manner. Big > Little > engine. I supect that having the exhausts plumbed Engine > Big > Little would make the setup a little laggy as the big turbo would eat up all the energy from the exhaust.

Plubing it the normal way gets the little buy lit first, then when it has excess exhuast energy it bypasses it directly to the big one.
 

Kevin Jewer

DSM Wiseman
1,451
229
Jul 25, 2002
LaRue, Ohio
I want to try that arrangement on the mighty max or something. I wanted to try it on the new setup I made for the car for for packaging reasons I had to stay with the conventional arrangement, but I'm trying a different WG strategy with it. At any rate, the big turbine won't be taking out much energy since the compressor won't be doing any work during small turbo spool up. Some power is required since it's spinning, but it should be negligible, and there will be some heat loss of course, but I think it will still work fine. Especially in compact setups like we tend to end up with. Needs to be tested though. The main advantage I would be looking for is reduced WG requirement for the small turbine, since anything not needed by the big turbo is dumped first rather than rerouting it all around the small turbine. If there's a packaging advantage in a particular case, even better reason to be the guinea pig. :)
 

JusMX141

Moderator
15,065
1,102
Dec 13, 2005
Greensburg, Pennsylvania
Paul's old compound setup is still alive...recently received some updates in the off-season including repairs to some cracks, and modification to allow additional clearance as there is now a .55 a/r Bullseye housing on the small turbo. All of the hot parts are now ceramic coated as well.

Setup is currently a billet KTS 20G with a 9-blade Kamak/Kinugawa turbine that I built paired to a HP6766.

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95g-s-x

Proven Member
142
2
May 27, 2010
Warren, Maine
95gsxracer, that's what I was thinking. This setup should only require one external waste gate before the big turbo and dump right to the down pipe.

I can't imagine it would hurt the spool of the small turbo all that much
 
Last edited:

crash89

Proven Member
3,535
171
Mar 5, 2008
Janesville, Wisconsin
I dont want to stray too far off topic, but whats changed on the car? Last year it was making sold 9 second passes and now you guys are just doing 1/8 testing?

This compound stuff still blows my mind! I looked at that car for a good 15 minutes and still didnt understand how it worked, seems ass backwards to me. still cool to see nonetheless!
 

Kevin Jewer

DSM Wiseman
1,451
229
Jul 25, 2002
LaRue, Ohio
I believe John had mostly parted out the car and had the shell for sale. I'm not sure where his turbo setup ended up. The new owner bought the car from John and had him do much of the reassembly, and fab the majority of the new turbo setup. Then it came to me and I finished up the rest of the mechanicals, boost control, rewired the whole car, etc. Months of long hours. I put in all the same tricks I've learned with my cars over the years. Then I started with testing and tuning, the best part. The car doesn't have enough safety gear to run below 10.0 at my local track and the owner doesn't want it, but they were kind enough to let me keep it above 10.0 even though I was technically breaking the 8th mile ET limit. On the brakes right after the 8th it was still running low 10s at 60-80 mph.

Best 8th mile time was 5.99 at 117, at which point I called it done. Once the car was sorted out and the tune dialed in, there was no point in running it further and moved on to other projects. I have no doubt in my mind it's capable of low 8s. It really is a killer car. It was very reliable, very raceable, and a blast to drive. I'm sure I mentioned it before, but it made 37 psi at 3700 rpm, and that's all it ran down track when I ran it. It's capable of ~60 psi. I saw mid 50s boost at 5200 rpm stalling it up on the brakes. I'm excited to see what the owner can get out of it.
 

Kevin Jewer

DSM Wiseman
1,451
229
Jul 25, 2002
LaRue, Ohio
Spencer, yes. I added a lot of it, but he didn't want more bars. It seems to only be missing the D bars. Then window net and engine containment pan are all that I can think of.
 

Kevin Jewer

DSM Wiseman
1,451
229
Jul 25, 2002
LaRue, Ohio
I got some preliminary data from my new setup on my car (3582HTA and 4505HTA) and it looks very good so far. I'll post more once I get out to test it again at more typical boost levels. But so far it's running within a few tenths of my best at 15 psi less boost and 30k less shaft rpm on the 4505 (compared to last year running it as a single. WOT to launch boost/RPM in 2.6 seconds and there's room for improvement there. Lots of sensors this time too, including shaft speed on both turbos. New WG arrangement and boost control setup. Upstream injection all over the place. Etc.
 

Kevin Jewer

DSM Wiseman
1,451
229
Jul 25, 2002
LaRue, Ohio
Well, two of them technically. :D I was logging shaft speed last year on the 4505 so I already have some comparison data there. FP can set up the sensor for you if you have a way to log it.
 

Kevin Jewer

DSM Wiseman
1,451
229
Jul 25, 2002
LaRue, Ohio
Minor update. My car went 8.3 at 163 at the shootout with relative ease. It left with 53 psi, but the tires spun bad and the 60 foot was only 1.28. So that was on pace for a real low 8. Not a bad start. It's also doing it with much less MPH, showing the compounds doing some work in the front part of the track. Back pressure is a little higher than I wanted, a few psi over boost. But the car is so easy to stage and run I don't even care anymore. In between head gasket failures I'm still collecting data from the turbo/fuel setup, and it still looks good. There are still a couple things I can do for back pressure that I may try. One is the turbine housing on the 3582 small turbo, I went with the .68 instead of the .82 at the last minute. It spools so easily I can definitely get away with the larger housing.

Kait ran the white 2g in ST32. After putting a 16v system in it after it tossed an alternator belt in Q1, and switching it over to methanol to help it spool up at the higher DA, it did pretty well. Best pass was a 9.3 at 147 in E1 with boost still in the upper 30s. The 60 foot was over a tenth off, but that was my fault. It blew a pipe off in E2, also my fault, I thought I went around and beaded them all. Missed one. I think it would have gone an 8.9 at that boost. Kait had no trouble sliding it into the beams at 42 psi. Pretty good boost for 3500 rpm. I'm continually impressed by how well this setup performs. The 90mm wilson TB is a big mistake though, and one of the only let downs in this setup. That, the catch can setup, and the alternator setup could all use work. All easily fixed.

In short, I'm still a big fan of compound turbos. :) I've got a couple more setups to build, which I'm looking forward to.
 
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