My compound turbo set-up

[autotalon]

I find this fascinating. I understand why you run the larger compressor into the smaller one. I always thought that the way to compound is to run the small compressor into the large turbine, There by reducing lag. Is that another way of doing it? Is there a reason why you didn't do it this way?

 

[99gst_racer]

No, this is the traditional configuration for compound turbocharging. The smaller turbo is the primary and is the one doing the work. The larger turbo simply supplys the smaller turbo a higher atmopshere. The quick spool of the primary is what makes for high boost at a low RPM, and big low-end torque numbers.

 

[Artago]

BMW 5 series diesel uses the same set up.

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[jrdrew5]

so after all the work u have put into it, why would u just up and sell it, when u havent even took it to its full,??

 

[99gst_racer]

WTH! Kittens, right when he was covering the best part?!?

so after all the work u have put into it, why would u just up and sell it, when u havent even took it to its full,??

Yup. I only built this just to see how well it worked. And now that I know it works great, and I've had 2 summers worth of learning and tinkering with it, I'm ready to tackle the project again with some changes and subtle improvements. I had planned to be selling this from the start. I just didn't want to get crazy with sch-10's and ball bearing turbos until I knew exactly what to expect. And now that I'm moving the alternator to the back and switching to an electric power steering pump, I have many more beneficial options for the locations of the turbos.

 

[MidShipCivic]

I find this fascinating. I understand why you run the larger compressor into the smaller one. I always thought that the way to compound is to run the small compressor into the large turbine, There by reducing lag. Is that another way of doing it? Is there a reason why you didn't do it this way?

Compressor feeding turbines??

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[jrdrew5]

WTH! Kittens, right when he was covering the best part?!?


Yup. I only built this just to see how well it worked. And now that I know it works great, and I've had 2 summers worth of learning and tinkering with it, I'm ready to tackle the project again with some changes and subtle improvements. I had planned to be selling this from the start. I just didn't want to get crazy with sch-10's and ball bearing turbos until I knew exactly what to expect. And now that I'm moving the alternator to the back and switching to an electric power steering pump, I have many more beneficial options for the locations of the turbos.

Mabye throw a 20g in there well hopefully this time it wont take u 2 summers, i cant wait for the end results, then again in my opion it will never been done

 

[94awdcoupe]

Paul, just to clarify I think 16g is too big. i would use a smaller primary like 14b or 13g or maybe even T25 or 11b, and 35r for secondary.. That would result in a broader power band. The first turbo only needs to kick in the 1500-4000 range. The second from 5000 up. The extra exhaust flow of first turbo makes second turbo spool 1500 rpm faster than its normal 5000rpm. The 11b / 35r combo would give torque curve closer to what Norris ended up with but on a smaller scale.

 

[dsm-onster]

To make the primary gate open more because it doesn't flow enough ??? HA!

 

[bsbllfit7]

all this info may change the game of 4 cylinder turbocharged cars. think of cars with much higher horsepower with super broad power ranges. Idk bout you but if i was looking for a faster car id love to see this. Throw one of these systems on an evo or sti and wow!

 

[Kevin Jewer]

The first turbo only needs to kick in the 1500-4000 range. The second from 5000 up.

It doesn't really work this way with compound turbocharging, unless you're talking about each turbo separately. That being said it would be fun to try a 14b (I wouldn't go any smaller). The problem is that getting it to spool any earlier just makes the drivetrain problems worse. The 16g combo is already pushing it for the AWD manual drivetrain parts IMO.

 

[blakktalon]

Things seem so much clearer when jeremy clarkson explains them to me... i love that guy, best job EVER

 

[99gst_racer]

Paul, just to clarify I think 16g is too big. i would use a smaller primary like 14b or 13g or maybe even T25 or 11b, and 35r for secondary.. That would result in a broader power band. The first turbo only needs to kick in the 1500-4000 range. The second from 5000 up. The extra exhaust flow of first turbo makes second turbo spool 1500 rpm faster than its normal 5000rpm. The 11b / 35r combo would give torque curve closer to what Norris ended up with but on a smaller scale.

For a compound configuration to be at it's best, both turbos need to be able to be functioning in as much as the RPM band as possible. I'm not in any way trying to knock you, but I truely believe that you don't quite understand how this is working. My 16g doesn't quit working at any point. Not even when it hits full boost and it's gate is open. The system doesn't use a small turbo for spool down low and a big turbo for boost up top. There is no "kicking in and out" for anything. It's a system that uses a smaller, efficient turbo to supply the engine, and that turbo is simply fed a higher atmosphere from a larger turbo. Both turbos always run at their respective pressure ratios all the time, just as they would if ran individually. A smaller primary would only make for less power in the higher rpms.

And I'm not trying to improve spool anymore. I'm very happy with where's it's at. Norris' set-up worked great across the board, because the supercharger was working much better across the board than a really small turbo would.

It's also worth noting that my 60-1 spools just as quick as it did when I was running it on it's own with a my old JH Racing divided manifold. It's not slowed down at all by recieving exhaust and wastegate flow from the first turbine.

 

[91stocker]

Do you plan on getting some more dyno time in on the current set up before you sell it?

 

[99gst_racer]

It doesn't really work this way with compound turbocharging, unless you're talking about each turbo separately. That being said it would be fun to try a 14b (I wouldn't go any smaller). The problem is that getting it to spool any earlier just makes the drivetrain problems worse. The 16g combo is already pushing it for the AWD manual drivetrain parts IMO.

For my car, the power feels like it comes on much smoother than it does with a larger single turbo. There's no big hit. And I think that helps helps quite a bit in preserving the drivetrain. The slipping clutch was probably helping too.

Do you plan on getting some more dyno time in on the current set up before you sell it?

No. But the next one probably won't make much more power. I'm very satisfied at around 600 WHP. I'll definitely have a dyno chart for the next set-up, which won't be much more different in the powerband.

 

[Kevin Jewer]

It's definitely more linear! On the single turbo, if I lad to lift, and then got back on it, the car would want to drift right into the wall before it reapplied the tire. I can do the same thing on the compound turbos with no drama, it feels more like a V8 than a 4 banger. You can really see it in the dyno graphs too. Same total power, very different curves.

The big torque numbers still scare me on a manual drivetrain even without the big hit, but I've been traumatized over the years.

 

[94awdcoupe]

For a compound configuration to be at it's best, both turbos need to be able to be functioning in as much as the RPM band as possible. I'm not in any way trying to knock you, but I truely believe that you don't quite understand how this is working. My 16g doesn't quit working at any point. Not even when it hits full boost and it's gate is open. The system doesn't use a small turbo for spool down low and a big turbo for boost up top. There is no "kicking in and out" for anything. It's a system that uses a smaller, efficient turbo to supply the engine, and that turbo is simply fed a higher atmosphere from a larger turbo. Both turbos always run at their respective pressure ratios all the time, just as they would if ran individually. A smaller primary would only make for less power in the higher rpms.

I understand quite well how the compound system works. You consistently misconstrue my points. But that is not a surprise since you are the guy who thinks cars on the dyno with slipping clutch will rob HP numbers. When any dyno operator can tell you a slipping clutch will spike your torque numbers. My statements were simply geared toward selecting two appropriate sized turbos in a compound turbo setup. I do not think the first turbo is stepping out of the way. Not sure where you get that.

And I'm not trying to improve spool anymore. I'm very happy with where's it's at. Norris' set-up worked great across the board, because the supercharger was working much better across the board than a really small turbo would.

I wouldnt be happy with the spool numbers you got. The local built FP black spooled fast (46psi by 4000rpm) and it has nothing to do with being an evo and not a dsm. I play with the FP HTA turbos on my DSMs and get same/or better numbers as evo setups do.

Norris setup works better because its a better design system over compound turbo charging as you have made. In HIS setup the primary turbo( supercharger) does indeed step out of the way of secondary large turbo.

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In your setup I would run a smaller turbo 13g at same pressure ratio or maybe even less your 16g is at and run a 35r at higher pressure ration than your 60-1 is at. It would not lay down up top any more than it is now and would spool much sooner. 70lbs is going through the 16g compressor now. I think it can be made smaller and still move 70lbs if not more.

It's also worth noting that my 60-1 spools just as quick as it did when I was running it on it's own with a my old JH Racing divided manifold. It's not slowed down at all by receiving exhaust and wastegate flow from the first turbine.

Not sure what your point is here? The compound system spools faster than a 60-1 by itself. And flows more air.

 

[mountaineerjeff]

um correct me if im wrong, as im just kinda jumping in here, but doesnt that make it a sequential setup? not a compound setup.

oh and one other thing. a slipping clutch is obvious an inability to transfer power. (by the simple definition of slipping) if it cant be transfered then it cant be measured. so if you have power that isnt measured than that means your actual numbers are higher than your recorded/dyno numbers. So if his clutch is slipping, then he actually made way more power than what his dyno sheet shows.

 

[94awdcoupe]

um correct me if im wrong, as im just kinda jumping in here, but doesnt that make it a sequential setup? not a compound setup.

oh and one other thing. a slipping clutch is obvious an inability to transfer power. (by the simple definition of slipping) if it cant be transfered then it cant be measured. so if you have power that isnt measured than that means your actual numbers are higher than your recorded/dyno numbers. So if his clutch is slipping, then he actually made way more power than what his dyno sheet shows.

slipping clutch looses power on the street. on the dyno the rpm goes up. since the dyno uses rpm as measuring parameter it has no way to know clutch slipped. it thinks the engine accelerated that much faster. and there fore gives higher HP numbers. I am not making this shit up. talk to any one who has a dyno. ask them what happens to torque curve when clutch slips.

there is so much crap on forums sometimes its hard to wade through it.

 

[99gst_racer]

I understand quite well how the compound system works. You consistently misconstrue my points.

In all fairness, this is a discussion about compound turbocharging, and you're the one talking about compressors "kicking in" during certain RPM ranges.

But that is not a surprise since you are the guy who thinks cars on the dyno with slipping clutch will rob HP numbers. When any dyno operator can tell you a slipping clutch will spike your torque numbers.

Yes, I know how it works. Mine hit 1500 ft/lbs torque when the clutch slipped, which we all know isn't accurate. That's why the major slipping portion is missing from the graph.

I do not think the first turbo is stepping out of the way. Not sure where you get that.

Well, I got it from this statement of yours:

The first turbo only needs to kick in the 1500-4000 range. The second from 5000 up.

If you're talking about compound turbocharging here, then you're wrong. If you're talking about sequential or something else, then you're off topic and you're only confusing others.

I wouldnt be happy with the spool numbers you got. The local built FP black spooled fast (46psi by 4000rpm) and it has nothing to do with being an evo and not a dsm. I play with the FP HTA turbos on my DSMs and get same/or better numbers as evo setups do.

There you go comparing EVOs to DSMs again. That was probably on a stroker engine too, right? Because those are the only comparisons you've used thus far... My set-up isn't compressor limited at 68 lbs/min either. Got a datalog to back that up, btw?

I am happy with my spool numbers, and they definitely aren't getting worse. 99% of the 4G63 set-ups out there that are flow 75+ lbs/min, aren't spooling as quickly as I am. The fact that you're not impressed doesn't change the fact that the car hauls ass, makes great power, and it a complete dream on the street. I've met every goal that I set for myself with this endeavor, so this was a complete success. And I've never bolted something to my car that was worse than what it was replacing.

In your setup I would run a smaller turbo 13g at same pressure ratio or maybe even less your 16g is at and run a 35r at higher pressure ration than your 60-1 is at. It would not lay down up top any more than it is now and would spool much sooner. 70lbs is going through the 16g compressor now. I think it can be made smaller and still move 70lbs if not more.

So with all of your knowledge and experience with compound turbocharging, please explain to me your technical reasoning behind why decreasing the primary compressor in size will more the same airflow or more.

One thing that I did notice is that the less boost the primary runs, the slower the overall spool of the system. So that shoots down your "spooling sooner with less PR with the 16g" theory.

 

[MidShipCivic]

Why dwell into the subject with him when he hasn't posted this local ''HTA'' turbo dyno/car/engine setup?

This is what we call trolling.

 

[99gst_racer]

Trolling indeed. But I expect no less from a guy who's first post in this thread was shooting it down, saying that it wouldn't work at all because of the design. As well as "overspinning" the primary, and the primary is in the way of making power...

http://www.dsmtuners.com/forums/151866274-post74.html

And he also said I wouldn't be able to control boost because of obvious design flaws. Wrong again.

http://www.dsmtuners.com/forums/151868535-post102.html

All other cars and set-ups he's compared to mine were sequential (three times now), and on stroked and larger displacement engines. Give me a break!

 

[Slippi84]

You are the prime example of internet hear say and my boy told information mistaken for knowledge. You don't try and call someone out and say they're wrong with half ass statements like i don't THINK that's how that works.

 

[EclipticalGS]

With your power curve being so linear, Id say you just made a quicker spooling alternative to just using a larger single turbo, and you are seeing 80lbs/min of flow.......Jesus. Thats like a GT40 reaching full spool at 4500 rpms...Which doesn't happen.

Its also better with the linear torque, because isn't the quick and abrupt changes in torque (like the initial hit of a larger turbo) that puts the most shock and strain on drivetrain parts??

 

[91stocker]

Thats too bad the current set up wont see the dyno again. I was really hoping to see it make the claimed 75lbs/min and prove everyone wrong including me. The compounds run on cavs ive seen were very disappointing.

My ride is a "weekend warrior" so street-ability is pretty important. If the compound could make big numbers and keep it streetable id be all over it. So far though im still very skeptical. Not that my opinion matters, just pretty interested. I just have never seen a compound live up to the hype yet.

Nothing against kevin's accomplishments but for comparison those numbers have been made with a single 35r in an awd car and hes spraying on a compound with a massive S475. I think everyone expected 600hp from the set up mentioned in this thread and that's what it laid down and that's about what the 60-1 can do. I guess i was really hoping to see a 750whp dyno run and put all the doubts to rest.