And this is what I came up with for the charge piping between turbos. Simple, effective, and it'll fit well.
The B16G has been gone through. Now it's got a fresh rebuild (courtsey of Justin - jusmx141), a new 15* clipped turbine wheel, and a brand new 7cm2 turbine housing with a welded flapper. Soon to sport a polished compressor cover.
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-Paul Volk-
'99 GSX
'91 TSI
Paul, just couldnt wait any longer lol.. Your gonna be at the lanes meet.. Can you get it done in time lol... I must ask- Can i please get a ride in it!?
I seen this is person and damn is it sick... looks good man and good luck..
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-=John Whalen=-
WH1C w/ .55ar BEP
I almost hate looking at the pictures of the work in progress because they make me really want to see the finished product. Each picture just keeps getting better and better. This thing is nasty looking
I am curious to see if the boost from the larger turbo causes the smaller turbo to self destruct. Also I see that rediator finding a new home once the downpipe is installed.
now theres something different! Good luck with it, im still trying to wrap my head around the dynamics of how thats going to work but i think i understand! ok after thinking it thru i have a few questions. I understand the concept the smaller turbo spools up fast and is boosting then the larger turbo kicks a larger amount of boost at the engine when it finally spools.
My question is this, looking at the example from the diesel twin design, when the small turbo is spooled and say boosting 10psi, then the big turbo kicks in and kicks 30 psi straight into the smaller turbo, which would then go into the intercooler piping and eventually into the intake manifold.
How can the smaller turbo make use of the boost? Basically you got this tiny turbo which has an small efficiency range and is good for small boost, which is great until the extra 30 psi comes and crams it way into the small turbo, wouldnt any gain be lost from the larger turbo by trying to cram 40 psi into a turbo thats only meant for 10-20 psi aka 14b? it would be way out of its efficency range and the exhaust turbine housing wouldnt be able to flow that much right? Even if the 40 psi somehow made it threw the small turbo wouldnt this cause the small turbo to literally self destruct? Let me know if i need to rephrase the question for clarity.
The smaller turbo is compressing already compressed air, this multiplies the pressure ratio. So now the smaller turbo is spinning at the same speed it normally would be but has much more airflow. I think...read the article in the OP, it explains it pretty well.
now theres something different! Good luck with it, im still trying to wrap my head around the dynamics of how thats going to work but i think i understand! ok after thinking it thru i have a few questions. I understand the concept the smaller turbo spools up fast and is boosting then the larger turbo kicks a larger amount of boost at the engine when it finally spools.
My question is this, looking at the example from the diesel twin design, when the small turbo is spooled and say boosting 10psi, then the big turbo kicks in and kicks 30 psi straight into the smaller turbo, which would then go into the intercooler piping and eventually into the intake manifold.
How can the smaller turbo make use of the boost? Basically you got this tiny turbo which has an small efficiency range and is good for small boost, which is great until the extra 30 psi comes and crams it way into the small turbo, wouldnt any gain be lost from the larger turbo by trying to cram 40 psi into a turbo thats only meant for 10-20 psi aka 14b? it would be way out of its efficency range and the exhaust turbine housing wouldnt be able to flow that much right? Even if the 40 psi somehow made it threw the small turbo wouldnt this cause the small turbo to literally self destruct? Let me know if i need to rephrase the question for clarity.
Think of it by way of pressure ratios. Take a single turbo car running at sea level - it's compressor inlet is taking in atmospheric pressure (14.7 psi), so it's a 1:1 ratio. The compressor then multiplies that pressure to create the boost that you read on your boost gauge. Now, imagine if that turbo was getting twice that much air (2:1 PR) because it's being fed by another compressor. It will then multiple that inlet pressure ratio by whatever it's pressure ratio is set as.
I plan to run each turbo at a 1.75 PR initially, and once I get into fine tuning, I plan to up the 60-1 to a 2:1 PR.
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-Paul Volk-
'99 GSX
'91 TSI
The smaller turbo is compressing already compressed air, this multiplies the pressure ratio. So now the smaller turbo is spinning at the same speed it normally would be but has much more airflow.
Bingo!
Quote:
Originally Posted by evileclipse909
I am curious to see if the boost from the larger turbo causes the smaller turbo to self destruct. Also I see that rediator finding a new home once the downpipe is installed.
The smaller turbo doesn't care what it's inlet pressure is. Whether it be 10 psi, 14.7 psi, or 25 psi, it will opperate the same and continue to compound whatever it is fed. Diesel guys have been doing this for years and years.
The downpipe clears the radiator just fine. I did have to indent the radiator a bit with a torch and a ball peen hammer to clear the T4 turbine housing, though. It's pretty much a tight squeeze everything with this set-up. It would fit much nicer in a 1G engine bay.
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-Paul Volk-
'99 GSX
'91 TSI
In my opinion this type of setup creates a more linear power curve and thereby prevents tractions loss in the exact manor that DSM_PWR stated. The other benefit is that the very same linear power curve limits the sudden & nasty drive train killing power spikes that you would expect from a single turbo system.
Ill just have to get my ass up and out to hartford. I have my plate full of shit to do for 2 weeks so i will give you some time to let the other guys get some rides lol... Ill will hit you up. Thanks man. OO ya are you going to have it ready for Lanes??
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-=John Whalen=-
WH1C w/ .55ar BEP
Last edited by Defiant; 05-27-2009 at 09:10 PM.
Reason: "U" is not "you".
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.
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.
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-Paul Volk-
'99 GSX
'91 TSI
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?
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.
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.
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Maurice G.
98 TSI Stroked and Stalled
.... Ya i just read that article and it makes sense. Good explanation
