my build thread, e30 with a 9 inch

[someguy2800]

Hey man, very cool update, i follow your thread for a long time, keep up the good work 
I would suggest to put as big of a wastegate as you can into the exhaust manifold that feeds the turbine of the large turbo because the exhaust volume will need to be relieved, otherwise the exhaust is kind of trapped before the small turbine and the pressure will moon.

I would also suggest to think about an aftercooler between the compressor outlet of the lp turbo and the inlet of the hp turbo, or at least measure the Temps there, the heat there could create a problem for the compressorwheel of the hp turbo.
There is a very good multiple years long thread from Kevin jewer on yellowbullet (if i remember right) regarding compound turbocharging a 4g63 mitsubishi. You can find very good information on this topic there, he tested very much and made very good results.
I think he put two wastegates between the exhaust manifold to bypass the small turbine of the hp turbo so the exhaust can flow freely directly into the big turbine after the small turbo is spooled up so there is no restriction.

I think Shane t did the same on the 3 turbo compound setup (billet sr20 engine or so).

I am very interested in compound turbocharging, but was never able to do it unfortunately.. Too many projects 

I know Kevin, I have spoken to him several times. He has done several different wastegating strategies. The strategy that I am using will avoid the problem having to bypass a lot of exhaust gas around the small turbine because I will be controlling the total system boost by dumping exhaust gas from before the small turbine rather than after it. If you put the control gate after the small turbine then you are essentially forcing the waste gas to go through 2 wastegates because it has to go through the bypass gate before it gets to the waste gate.

[OezyB]

OK cool then, i was not sure if dumping the waste gas from the exhaust manifold could maybe irritate or collapse the following two turbines or so. But it looks like you're setup is well thought out. I'm happy to see results soon.

Regards

[someguy2800]

OK cool then, i was not sure if dumping the waste gas from the exhaust manifold could maybe irritate or collapse the following two turbines or so. But it looks like you're setup is well thought out. I'm happy to see results soon.

Regards

It really no different than a normal turbo system, it is just dividing the work between two turbines instead of a single one.

[PEI330Ci]

Hey man, very cool update, i follow your thread for a long time, keep up the good work ����
I would suggest to put as big of a wastegate as you can into the exhaust manifold that feeds the turbine of the large turbo because the exhaust volume will need to be relieved, otherwise the exhaust is kind of trapped before the small turbine and the pressure will moon.

I would also suggest to think about an aftercooler between the compressor outlet of the lp turbo and the inlet of the hp turbo, or at least measure the Temps there, the heat there could create a problem for the compressorwheel of the hp turbo.
There is a very good multiple years long thread from Kevin jewer on yellowbullet (if i remember right) regarding compound turbocharging a 4g63 mitsubishi. You can find very good information on this topic there, he tested very much and made very good results.
I think he put two wastegates between the exhaust manifold to bypass the small turbine of the hp turbo so the exhaust can flow freely directly into the big turbine after the small turbo is spooled up so there is no restriction.

I think Shane t did the same on the 3 turbo compound setup (billet sr20 engine or so).

I am very interested in compound turbocharging, but was never able to do it unfortunately.. Too many projects ��

A lot to address here.

First, the mass flow through the turbine is massively miss-understood. The turbine flow maps published by 2 main vendors are actually a composite of averages, which creates a pressure ratio curve. At a given pressure ratio through the turbine, the shaft speed will be varied and the mass flow (Corrected) will be measured. So while you "read" a data point of say 35 lbs @ 2.0 PR, it's actually an average of the flow rates at all different measured turbine speeds at that pressure ratio.

The reason why I wrote the above, is to help explain this: A turbine that has a max rated flow of 25 lb can actually flow 50 or 100 lb in the right conditions. The point where a turbine normally "chokes" is when the compressor can't create that pressure. With a compound setup, the small turbo compressor doesn't have to create that pressure ratio alone, so you can end up with a LOT more flow through the turbine housing than would normally occur.

There are more problems experienced by people doing compound turbos with waste-gates that are too large, than being too small. The pressure on the poppet valve face is a factor, and most cars don't run a CO2 system to put 30 Lbs on the WG dome when trying to spool.

Most turbos need about 60% of total exhaust flow to stay in the middle of the compressor map. That means 40% of flow is going through the waste-gate. If you are going to be getting rid of that flow for LP turbo (Big turbo) anyway, why run it through the small turbine housing? This is what Kevin Jewer is doing with his current setups, and why Perry is going this path.

Regarding spool: When you build a race engine, you want it to operate well within a certain RPM window. Our cylinder heads don't support flow above 8000 RPM very well, so that is usually the top of operating window. (This has to do with the ratio between the inlet valve area and the cylinder bore) 5000 RPM is usually the bottom of this RPM window, which is actually pretty broad in terms of a motorsport powerband. The mass flow of a 3.0L engine on it's own won't start to spool an 88mm turbo until 6000 RPM, but when it's helped by the HP turbo which started to generate positive pressure under 3,000 RPM, it will be creating more boost than is probably needed at 5,000 RPM. Downsize this to a 4G, and it's a pretty similar situation, but with a little more RPM. (What Kevin does) The catch is that I'm thinking of a manual transmission setup, and Perry is running an Auto. He doesn't need much RPM, he just needs boost. But the spool is likely to be more than he needs in first gear....

On the compressor temps, I have built a fairly large spreadsheet over the past few years to calculate this exact thing. Without any inter-turbo cooling, I calculated HP turbo outlet temps upwards of 500 deg F. The thing is, none of the big 5 turbo companies want to talk about what they are making their turbo compressor wheels out of, so we really don't know what the temp limits are. What I will say, is that there are plenty of examples of non-inter-turbo cooled compound turbo engines that are not experiencing failures for this reason. Engine hardware is usually the main issue, followed by turbo over speeding. The reason that Shane T and others use 2 charge coolers is that they are trying to maximize charge density to make more power. If you are already making too much power with 1 intercooler, there is probably not a good case to add a second.

Do you have any BMW projects to share? (I'm always interested in seeing new things)

[someguy2800]

I would absolutely love to do interstage cooling but it is impractical to package in the chassis so that discussion is a dead end. In regard to the rpm, back when I had the S476 and stock M50 intake manifold my car made peak power at 7800 rpm. I never dyno'd it with cam setup I have in it now and the GDM intake manifold, but the ECU predicted mass air flow was still climbing at 9000 rpm. I am actually changing to a slightly shorter trumpet on the GDM manifold and GDM ported head so I am hoping for peak power at 9500 RPM. The reason for moving the rpm band higher is to manage cylinder pressure. These cylinder heads are actually really good. The primary reason they don't typically make high rpm power is because the intake runner length and the cams.

[PEI330Ci]

I would absolutely love to do interstage cooling but it is impractical to package in the chassis so that discussion is a dead end. In regard to the rpm, back when I had the S476 and stock M50 intake manifold my car made peak power at 7800 rpm. I never dyno'd it with cam setup I have in it now and the GDM intake manifold, but the ECU predicted mass air flow was still climbing at 9000 rpm. I am actually changing to a slightly shorter trumpet on the GDM manifold and GDM ported head so I am hoping for peak power at 9500 RPM. The reason for moving the rpm band higher is to manage cylinder pressure. These cylinder heads are actually really good. The primary reason they don't typically make high rpm power is because the intake runner length and the cams.

Do you have a target torque you are chasing?

What have you done with the power steering and alternator to handle 9500 RPM?

[someguy2800]

Do you have a target torque you are chasing?

What have you done with the power steering and alternator to handle 9500 RPM?

Ideally I would like to make 750 ft lbs from 5000 to 9500 or 10,000 rpm.

I don't have power steering. I've run the stock alternators with stock belt ratio to over 9000 rpm but I've killed 2 in the last few years. Last year I designed a 25% underdrive crank pulley to go on the GDM damper and travis had it made for me. The stock water pump also cavitates above 7000 rpms and stops pumping so the underdrive pulley would help with that also but I going to an electric water pump anyway.

[OezyB]

A lot to address here.

First, the mass flow through the turbine is massively miss-understood. The turbine flow maps published by 2 main vendors are actually a composite of averages, which creates a pressure ratio curve. At a given pressure ratio through the turbine, the shaft speed will be varied and the mass flow (Corrected) will be measured. So while you "read" a data point of say 35 lbs @ 2.0 PR, it's actually an average of the flow rates at all different measured turbine speeds at that pressure ratio.

The reason why I wrote the above, is to help explain this: A turbine that has a max rated flow of 25 lb can actually flow 50 or 100 lb in the right conditions. The point where a turbine normally "chokes" is when the compressor can't create that pressure. With a compound setup, the small turbo compressor doesn't have to create that pressure ratio alone, so you can end up with a LOT more flow through the turbine housing than would normally occur.

There are more problems experienced by people doing compound turbos with waste-gates that are too large, than being too small. The pressure on the poppet valve face is a factor, and most cars don't run a CO2 system to put 30 Lbs on the WG dome when trying to spool.

Most turbos need about 60% of total exhaust flow to stay in the middle of the compressor map. That means 40% of flow is going through the waste-gate. If you are going to be getting rid of that flow for LP turbo (Big turbo) anyway, why run it through the small turbine housing? This is what Kevin Jewer is doing with his current setups, and why Perry is going this path.

Regarding spool: When you build a race engine, you want it to operate well within a certain RPM window. Our cylinder heads don't support flow above 8000 RPM very well, so that is usually the top of operating window. (This has to do with the ratio between the inlet valve area and the cylinder bore) 5000 RPM is usually the bottom of this RPM window, which is actually pretty broad in terms of a motorsport powerband. The mass flow of a 3.0L engine on it's own won't start to spool an 88mm turbo until 6000 RPM, but when it's helped by the HP turbo which started to generate positive pressure under 3,000 RPM, it will be creating more boost than is probably needed at 5,000 RPM. Downsize this to a 4G, and it's a pretty similar situation, but with a little more RPM. (What Kevin does) The catch is that I'm thinking of a manual transmission setup, and Perry is running an Auto. He doesn't need much RPM, he just needs boost. But the spool is likely to be more than he needs in first gear....

On the compressor temps, I have built a fairly large spreadsheet over the past few years to calculate this exact thing. Without any inter-turbo cooling, I calculated HP turbo outlet temps upwards of 500 deg F. The thing is, none of the big 5 turbo companies want to talk about what they are making their turbo compressor wheels out of, so we really don't know what the temp limits are. What I will say, is that there are plenty of examples of non-inter-turbo cooled compound turbo engines that are not experiencing failures for this reason. Engine hardware is usually the main issue, followed by turbo over speeding. The reason that Shane T and others use 2 charge coolers is that they are trying to maximize charge density to make more power. If you are already making too much power with 1 intercooler, there is probably not a good case to add a second.

Do you have any BMW projects to share? (I'm always interested in seeing new things)

Hey man,
thanks for clarifying. I get your point, the small turbine wheel won't cause that much of a restriction because the compressor doesn't have to work so hard. As i said, i have no experience in compound charging, but i think the small turbine could still be kind of be a restriction with all the exhaust gasses (minus the wasted exhaust gas) has to move through the small turbine. But this is just an estimation. I didn't know Kevin Jewer changed his system from Bypassing the exhaust gasses around the small turbine to exhausting directly into the atmosphere, but if he did it, it seems to work.

Anyhow, i just wanted to share my thoughts, I'm looking forward to see some results. I hope the OP will insert a Pressure sensor into the manifold, would be nice to see whats going on there.

Regarding my Projects, i made a build thread a few years ago on this forum, but didn't update it. I have an e30 with m30 turbo. At the time i made the thread I was on a holset HX55 and now redid some parts, changed to a BW S372. Peak HP Numbers so far were 770 Crank HP.



Another Project i'm working on is essentially the same DBurt did on this forum, an e36 LS with twin s300 and TH400. The Problem is, i'm located in germany and to get such a car street legal is very hard (keep the headlight level actuator, full exhaust with catalytic convertor, heating system.. getting LS specific parts and so on is another problem). When i'm ready with the LS Project, i'll have to take apart the m30 in the other car, because the head is cracked, and some other things to do, there should be a couple more HPs to find














Sorry for the Off Topic. I hope to see some compund turbo Results soon

[someguy2800]

I do have pressure sensors in the exhaust before both turbos and after both turbos in the charge pipes. One thing to remember is that gas is compressible so the volume of gas going through the small turbine will be small because it will be at high pressure. For example if everything is working as it should when the boost pressure is at like 5 bar of pressure the exhaust gas going into the small turbine will also be at close to 5 bar of pressure, so even though it is a huge amount of mass flow, it will be compressed down into normal amount of volume because of the very high pressure. A 74mm turbine wheel will not be a restriction to a 2.8L engine on a compound turbo any more than it would be with a single turbo operating at the same pressure ratio. As the exhaust gas goes through the first turbine and the bypass valve it will expand to a much larger volume as the pressure drops, which is why the 2nd turbine needs to be so large.

Love your cars by the way, especially that M30

[OezyB]

Thanks man, appreciate that 😁

Can't wait for results 👍😎

[LoAdUpUrPaNtS]

Absolutely love the build. My brother and I are seniors in high school and took on an e30 as a project car. We both have experience in fabrication and wanted to take a stab at making a four link. Any chance I can reach out to you for some questions about the measurements and planning you did for your rear suspension?

[someguy2800]

yeah just send me a message on here or facebook

[FugiTECH]

yeah just send me a message on here or facebook

Hey man. Not sure how to Private Message but my question is if you weighed your car before and after the Solid Axle setup?

[tptrsn]

Hey man. Not sure how to Private Message but my question is if you weighed your car before and after the Solid Axle setup?

This is a great question! After seeing how much the rear suspension in my E36 weighs, I have been pretty sure that a car would be lighter by quite a bit with if converted to a solid axle.

[Nutzy]

BUMP for an update!