Twin-Charging and Compound Turbo Charging
10-19-2009, 05:11 PM
#61
My new motor is a 4.0L version of the VQ35. If I were to use a Whipple S/C with a constant pressure ratio of 1.7 (0.7 boost), how much torqe/hp will it take to turn the S/C? I understand it will be a function of hp vs. rpm, but if there is a plot of hp vs. rpm available, this would be great to have.
Last edited by ttg35fort; 10-19-2009 at 05:13 PM.
10-19-2009, 06:02 PM
#62
Here's a couple of common ideas I usually use for custom positive displacement supercharger setups that have some small chance of working:
-Replace AC compressor with Whipple SC, but may not have enough longitudinal depth without a crankshaft pulley extension, or it may have clearance issues to the wheel well or crossmember
-Replace AC compressor with Whipple SC, but may not have enough longitudinal depth without a crankshaft pulley extension, or it may have clearance issues to the wheel well or crossmember
If I was able to put a supercharger in the A/C location it would be very easy to go on from there with my "remote" turbo setup. The plumbing would be perfect, because I route my IC piping through there (by the A/C) anyway.
Last edited by BoostedProbe; 10-19-2009 at 06:03 PM.
11-01-2009, 10:35 AM
#64
I have a question regarding how this setup works. Is the second turbo feeding the smaller turbo's compressor housing to further spool the 1st turbo? or is just using the first turbo's housing as a path to get to the intercooler piping?
What would happen if instead of feeding the big turbo's compressed air into the smaller turbos inlet, one would run the big turbos outlet into the intercooler piping? Would this be an inefficient way of doing it because the smaller turbo would be feeding compressed air into the big turbos outlet (which is reversed of how it supposed to flow), while the exhaust is flowing the opposite way and cause them to fight eachother till the big one eventually produces more pressure and overcome the smaller one? Just trying to understand the logic behind this, hope i didnt make my question confusing.
Also, do you think a compound turbo setup would be beneficial for small HP goals, such as 500-550WHP?
What would happen if instead of feeding the big turbo's compressed air into the smaller turbos inlet, one would run the big turbos outlet into the intercooler piping? Would this be an inefficient way of doing it because the smaller turbo would be feeding compressed air into the big turbos outlet (which is reversed of how it supposed to flow), while the exhaust is flowing the opposite way and cause them to fight eachother till the big one eventually produces more pressure and overcome the smaller one? Just trying to understand the logic behind this, hope i didnt make my question confusing.
Also, do you think a compound turbo setup would be beneficial for small HP goals, such as 500-550WHP?
Last edited by streetzlegend; 11-01-2009 at 11:22 AM.
11-01-2009, 12:27 PM
#65
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My suggestion would be to scrap all the compound turbocharging and suggest a more simpler easier way to do it. Displacement. Simple. I had the calculations figured out but basically on the same amount of boost (in my calculations I used 8 psi) a 4.5l stroked VQ made quite a bit more power than the 3.5 and also at a lower rpm. That right there saves time for spool up, then there is the added torque. Also whatever happened to the small compressor feeding into a larger compressor turbo, that the older gangs used to run back in the late 90's on RX-7's and Supras. I'm sure with the ball bearing geometry it would still be efficient. Especially when you consider a GT25 feeding air into a GT47 with also an anti lag system for track use. Only thing to fix is placement. Here is a decent read.
http://forums.hybridz.org/showthread.php?t=111606
http://forums.hybridz.org/showthread.php?t=111606
Last edited by *Boose*; 11-01-2009 at 12:35 PM.
11-01-2009, 01:54 PM
#66
1. The small turbo will help this system spool up quicker than if someone were only using the larger turbo.
2. Each turbo only needs to provide a portion of the total boost. This primarily is a benefit for cars running high boost. As I noted, I have not seen compressors that are well suited for running this system on our cars because we don't really need much boost.
What would happen if instead of feeding the big turbo's compressed air into the smaller turbos inlet, one would run the big turbos outlet into the intercooler piping? Would this be an inefficient way of doing it because the smaller turbo would be feeding compressed air into the big turbos outlet (which is reversed of how it supposed to flow), while the exhaust is flowing the opposite way and cause them to fight eachother till the big one eventually produces more pressure and overcome the smaller one? Just trying to understand the logic behind this, hope i didnt make my question confusing.
Not at this point in time. The turbos I have found so far are not very efficient at the low boost levels each turbo will be operating at in a compound turbo system. Essentially, we need turbo compressors with higher trim values. That should shift the compressor maps lower on the boost ratio axis.
Last edited by ttg35fort; 11-01-2009 at 04:16 PM.
11-01-2009, 02:03 PM
#67
My suggestion would be to scrap all the compound turbocharging and suggest a more simpler easier way to do it. Displacement. Simple. I had the calculations figured out but basically on the same amount of boost (in my calculations I used 8 psi) a 4.5l stroked VQ made quite a bit more power than the 3.5 and also at a lower rpm. That right there saves time for spool up, then there is the added torque. Also whatever happened to the small compressor feeding into a larger compressor turbo, that the older gangs used to run back in the late 90's on RX-7's and Supras. I'm sure with the ball bearing geometry it would still be efficient. Especially when you consider a GT25 feeding air into a GT47 with also an anti lag system for track use. Only thing to fix is placement. Here is a decent read.
http://forums.hybridz.org/showthread.php?t=111606
http://forums.hybridz.org/showthread.php?t=111606
BMW seems to differ with your opinion.
There are merrits to a properly designed compound turbo system, but you are correct that at this time it is not the way to go for our cars. As I noted, the standard Garrett compressors are not suitable for the boost levels we operate at.
If you play around with the formula I posted and the compressor maps, a GT25 and GT47 would not be a particularly good combination, even if you had the correct compressor trim.
There is no replacement for displacement. Ignoring weight, imo, bigger displacement is ALWAYS better. Unfortunately, we cannot ignore weight. I don't know how much the VK45 weighs, but VK56 weighs almost 200 lb more than a VQ35. That is a lot of weight to add to the nose of the car and will throw off its balance, thereby degrading its handling characteristics. In contrast, a typical turbo system adds about 100 lb. I have a 4.0L stroked motor being built, but I am still turbocharging. Even if I stroked it to 4.5L, it would not get me anywhere near my target HP in N/A form.
Last edited by ttg35fort; 11-01-2009 at 02:06 PM.
11-02-2009, 12:00 PM
#68
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Talk is Cheap, but honestly I dont think these systems are really as complex as people suspect.
One thing I want to toss into the mix:
Looking at things from the positive displacement POV, you have a pressure ratio at work. So at atmospheric pressure (14.7 PSIG), the blower then outputs x pressure. Lets say its 14.7PSIG for a hypothetical VQ35DE. Which means 29.4PSIG absolute pressure. 2 BAR of boost in other words. So you have a 2:1 ratio.
When you increase the pressure at the inlet, do you get a simple additon of boost, or do you get a multiplication? Lets leave temp/density factors out for a second.
Say you feed that 2BAR blower 14.7PSIG (1 BAR) at the inlet from a turbo. Do you get 3BAR? Or do you get the stuff below:
Feed 1 bar into a 2:1 ratio blower = 4 Bar? (2BAR Inlet X 2:1 Pressure Ratio)
I am inclined to think that the real result will be somewhere in the middle. When you look at all the inefficiencies involved, you wont get some perfect 4 BAR, but I'll bet it is over 3 BAR.
Moral of the story: Run a decent pulley on the Whipple, but run a soft wastegate spring to start to be safe. This thing might just make a lot more boost than you think from an intake valve point of veiw.
And I know I don't have to mention that water meth works wonderfully post turbo and pre-compressor in a positive displacement app
One thing I want to toss into the mix:
Looking at things from the positive displacement POV, you have a pressure ratio at work. So at atmospheric pressure (14.7 PSIG), the blower then outputs x pressure. Lets say its 14.7PSIG for a hypothetical VQ35DE. Which means 29.4PSIG absolute pressure. 2 BAR of boost in other words. So you have a 2:1 ratio.
When you increase the pressure at the inlet, do you get a simple additon of boost, or do you get a multiplication? Lets leave temp/density factors out for a second.
Say you feed that 2BAR blower 14.7PSIG (1 BAR) at the inlet from a turbo. Do you get 3BAR? Or do you get the stuff below:
Feed 1 bar into a 2:1 ratio blower = 4 Bar? (2BAR Inlet X 2:1 Pressure Ratio)
I am inclined to think that the real result will be somewhere in the middle. When you look at all the inefficiencies involved, you wont get some perfect 4 BAR, but I'll bet it is over 3 BAR.
Moral of the story: Run a decent pulley on the Whipple, but run a soft wastegate spring to start to be safe. This thing might just make a lot more boost than you think from an intake valve point of veiw.
And I know I don't have to mention that water meth works wonderfully post turbo and pre-compressor in a positive displacement app
11-02-2009, 03:16 PM
#69
The issue with the large SC's, such as the whipple, is the amount of power required to turn them. Turbos extract energy contained in the exhuast gases, and thus are significantly more efficient. The downside is the turbo spoolup time, otherwise known as turbo lag. The twin-charged systems are an attempt to reduce the amount of energy required to spin the SC, while still getting the benefits of high boost/air flow. Compound and Sequential systems do away with a SC, so there is not the continual drag on the motor. With the turbos presently available, a sequential turbo makes more sense, but some sort of valving system is required. Compound turbos would be a really nice solution if the right turbos are available, but so far I have not found suitable turbos to be available for our cars. For cast iron motors running high boost in excess of 40 psi, presently available turbos should work well. Perhaps if the BMW compound turbos become commercially successful, more turbo options will become available in the aftermarket that are more suitable for our builds.
11-03-2009, 04:01 AM
#70
Another good option is the truck turbos that are avaliable for fairly cheap on Ebay. Many of them come with variable vane technology (which you can opt to use or not to use) and are readily avaliable for a small price. My friend picked one up rebuilt for about $400 and put it on his RX7. No lag what so ever and the single turbo only maxs out at about 500hp. With that in mind it is not a super pig turbo and it is actually fairly small.
Just another option.
Just another option.
It is multiplication
The issue with the large SC's, such as the whipple, is the amount of power required to turn them. Turbos extract energy contained in the exhuast gases, and thus are significantly more efficient. The downside is the turbo spoolup time, otherwise known as turbo lag. The twin-charged systems are an attempt to reduce the amount of energy required to spin the SC, while still getting the benefits of high boost/air flow. Compound and Sequential systems do away with a SC, so there is not the continual drag on the motor. With the turbos presently available, a sequential turbo makes more sense, but some sort of valving system is required. Compound turbos would be a really nice solution if the right turbos are available, but so far I have not found suitable turbos to be available for our cars. For cast iron motors running high boost in excess of 40 psi, presently available turbos should work well. Perhaps if the BMW compound turbos become commercially successful, more turbo options will become available in the aftermarket that are more suitable for our builds.
The issue with the large SC's, such as the whipple, is the amount of power required to turn them. Turbos extract energy contained in the exhuast gases, and thus are significantly more efficient. The downside is the turbo spoolup time, otherwise known as turbo lag. The twin-charged systems are an attempt to reduce the amount of energy required to spin the SC, while still getting the benefits of high boost/air flow. Compound and Sequential systems do away with a SC, so there is not the continual drag on the motor. With the turbos presently available, a sequential turbo makes more sense, but some sort of valving system is required. Compound turbos would be a really nice solution if the right turbos are available, but so far I have not found suitable turbos to be available for our cars. For cast iron motors running high boost in excess of 40 psi, presently available turbos should work well. Perhaps if the BMW compound turbos become commercially successful, more turbo options will become available in the aftermarket that are more suitable for our builds.
11-03-2009, 11:57 AM
#71
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But I'll bet you only need about 20LBs of TQ to turn your average positive displacement blower at 6000RPM.
Variable vane stuff is very cool, we work with it a lot in our diesel customers, but one thing is the expense. Modern diesels in the US have a lot of fairly poorly thought-out emmisions controlls that result in spiking EGTs and soot build-up. The variable vane turbos have thus far had some problems coping with that. And while a VQ is not going to make nearly the amount of particulate matter that a 6-7 liter diesel will, it can hit the kinds of EGTs that have caused problems in some diesel turbos. And a new Cummins variable vane turbo runs about 3500 bucks last I checked
11-03-2009, 01:31 PM
#72
^^^^
I recently saw a "Top Gear" episode in which they stated that at full tilt it took about 120 hp to turn the supercharger on one of the new Jaguars. To me that seemed awfully high, and it was Top Gear, so I took it with a large grain of salt.
I recently saw a "Top Gear" episode in which they stated that at full tilt it took about 120 hp to turn the supercharger on one of the new Jaguars. To me that seemed awfully high, and it was Top Gear, so I took it with a large grain of salt.
11-05-2009, 01:16 PM
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The oft-quoted number for top fuel dragsters is that it takes 400HP just to run the blower. In that case I beleive it. Looking over internet wisdom, I see a lot of people claiming 50-100 HP, but often they are trying to sell turbos.
I suspect it's something on the order of 20-50.
But I trust Clarkson 100% They are very objective.
11-07-2009, 05:37 PM
#76
Another good option is the truck turbos that are avaliable for fairly cheap on Ebay. Many of them come with variable vane technology (which you can opt to use or not to use) and are readily avaliable for a small price. My friend picked one up rebuilt for about $400 and put it on his RX7. No lag what so ever and the single turbo only maxs out at about 500hp. With that in mind it is not a super pig turbo and it is actually fairly small.
Just another option.
Just another option.
The 997 tt uses vvt and it pulls like a r**** ape from basically idle, but we can get similar results by using the 530bb. This is why again i say using a larger laggy centrifugal s/c on tiny turbos would be good.
You bring in a good point, the s/c does take power to make power, which is why a small tt kit is ideal... (im being stubborn because.... i was born that way?
). I bet we would likely see a dyno graph with two lives... at first a jump in torque and then a slight negative slope where the s/c is spooling and somewhere about half the way through the rpm band a huge wall of power hits.... point of inflection should be around peak torque (on the tt engine) if the s/c is properly sized. Anyone follow what i'm saying? Maybe I will draw it out...EDIT: that would worry me about the turbo's actually now that I think about it...
Last edited by Resmarted; 11-07-2009 at 05:40 PM.
11-08-2009, 01:30 AM
#77
have u looked into power enterprise GTR 35 quad system ? might give u a hint..
i not sure but wouldn't this system fit on VQDE or VQHR or if u swap you swap your manifold with GTR35 ( i know GTM are working on that for VQDE but not sure if GTM Fit GTR manifold on our VQDE yet or not.) !! since all the pulleys in the same place as GTR i guess ?
i spoke personally with sam about swapping gtr manifold on vqde and he told me its due-able but need spacer to fit that was 7 months ago
link
http://www.youtube.com/watch?v=1aSR5Vd4eRM
'Nissan R35GTR, VR38DETT, Power Enterprise QUAD-charger system (Stock IHI Twin turbo & Twin Rotrex C30-94 Super Charger: 400ps x2 flow rate, at down stream of intake). The system is designed for 700HP (670+WHP) with huge low to mid-range torque gain benefiting road course and time attack racers'
i not sure but wouldn't this system fit on VQDE or VQHR or if u swap you swap your manifold with GTR35 ( i know GTM are working on that for VQDE but not sure if GTM Fit GTR manifold on our VQDE yet or not.) !! since all the pulleys in the same place as GTR i guess ?
i spoke personally with sam about swapping gtr manifold on vqde and he told me its due-able but need spacer to fit that was 7 months ago
link
http://www.youtube.com/watch?v=1aSR5Vd4eRM
'Nissan R35GTR, VR38DETT, Power Enterprise QUAD-charger system (Stock IHI Twin turbo & Twin Rotrex C30-94 Super Charger: 400ps x2 flow rate, at down stream of intake). The system is designed for 700HP (670+WHP) with huge low to mid-range torque gain benefiting road course and time attack racers'
Last edited by 350z-900whp; 11-11-2009 at 08:07 PM.
01-09-2010, 11:53 AM
#78
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Compound Twin Charging
Hi guys,
I have just finalised my plans to make a compound twin charging kit.
It is effectively eight turbochargers and four superchargers working in the same way but the four superchargers are inturn the forcing into four more turbochargers seperately. This eliminates the problem of spooling a big supercharger into a small super charger which is usually what is thought of when thinking of a compound twin charge, but this can not be done as you will break the shaft that runs the smaller supercharger and be left with no charge at all.
My system is very complicated and very hard to achieve, but I hope to do it to my Range Rover in 2010/2011 and later a Custom Carbon Fibre Space Frame Mitsubishi Evo. I just thought that you might want to try a simplar version of what I am attempting to do. If so, here is what you need to do.
First you need three turbochargers (one larger than the other two which should be identical) and one supercharger (should be powerful, but not to big to over power the turbocharger). The first turbocharger, and the biggest, is to feed into a smaller turbocharger, therefore giving you the standard compound turbocharge. Then with the supercharger, pipe this into the third and final turbocharger. Then make/buy a two into one imput joiner and connect the pipes up and mount the chargers.
This is a monumental design and I am very pleased with the prospects of getting over 3,000bhp from my Rover V8 with Dakar Rally in mind custom internals, but with this compound twin charging in the simpelist form will find the 350Z approximately 850-1,500bhp which is briliant.
If you would like digrams, drawings or more information then please write on the post and I will get back to you as quickly as possible.
Just one last thing the brains behind this kit is 16 in March, so starting young!!
I have just finalised my plans to make a compound twin charging kit.
It is effectively eight turbochargers and four superchargers working in the same way but the four superchargers are inturn the forcing into four more turbochargers seperately. This eliminates the problem of spooling a big supercharger into a small super charger which is usually what is thought of when thinking of a compound twin charge, but this can not be done as you will break the shaft that runs the smaller supercharger and be left with no charge at all.
My system is very complicated and very hard to achieve, but I hope to do it to my Range Rover in 2010/2011 and later a Custom Carbon Fibre Space Frame Mitsubishi Evo. I just thought that you might want to try a simplar version of what I am attempting to do. If so, here is what you need to do.
First you need three turbochargers (one larger than the other two which should be identical) and one supercharger (should be powerful, but not to big to over power the turbocharger). The first turbocharger, and the biggest, is to feed into a smaller turbocharger, therefore giving you the standard compound turbocharge. Then with the supercharger, pipe this into the third and final turbocharger. Then make/buy a two into one imput joiner and connect the pipes up and mount the chargers.
This is a monumental design and I am very pleased with the prospects of getting over 3,000bhp from my Rover V8 with Dakar Rally in mind custom internals, but with this compound twin charging in the simpelist form will find the 350Z approximately 850-1,500bhp which is briliant.
If you would like digrams, drawings or more information then please write on the post and I will get back to you as quickly as possible.
Just one last thing the brains behind this kit is 16 in March, so starting young!!
01-09-2010, 12:44 PM
#79
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Hi guys,
I have just finalised my plans to make a compound twin charging kit.
It is effectively eight turbochargers and four superchargers working in the same way but the four superchargers are inturn the forcing into four more turbochargers seperately. This eliminates the problem of spooling a big supercharger into a small super charger which is usually what is thought of when thinking of a compound twin charge, but this can not be done as you will break the shaft that runs the smaller supercharger and be left with no charge at all.
My system is very complicated and very hard to achieve, but I hope to do it to my Range Rover in 2010/2011 and later a Custom Carbon Fibre Space Frame Mitsubishi Evo. I just thought that you might want to try a simplar version of what I am attempting to do. If so, here is what you need to do.
First you need three turbochargers (one larger than the other two which should be identical) and one supercharger (should be powerful, but not to big to over power the turbocharger). The first turbocharger, and the biggest, is to feed into a smaller turbocharger, therefore giving you the standard compound turbocharge. Then with the supercharger, pipe this into the third and final turbocharger. Then make/buy a two into one imput joiner and connect the pipes up and mount the chargers.
This is a monumental design and I am very pleased with the prospects of getting over 3,000bhp from my Rover V8 with Dakar Rally in mind custom internals, but with this compound twin charging in the simpelist form will find the 350Z approximately 850-1,500bhp which is briliant.
If you would like digrams, drawings or more information then please write on the post and I will get back to you as quickly as possible.
Just one last thing the brains behind this kit is 16 in March, so starting young!!
I have just finalised my plans to make a compound twin charging kit.
It is effectively eight turbochargers and four superchargers working in the same way but the four superchargers are inturn the forcing into four more turbochargers seperately. This eliminates the problem of spooling a big supercharger into a small super charger which is usually what is thought of when thinking of a compound twin charge, but this can not be done as you will break the shaft that runs the smaller supercharger and be left with no charge at all.
My system is very complicated and very hard to achieve, but I hope to do it to my Range Rover in 2010/2011 and later a Custom Carbon Fibre Space Frame Mitsubishi Evo. I just thought that you might want to try a simplar version of what I am attempting to do. If so, here is what you need to do.
First you need three turbochargers (one larger than the other two which should be identical) and one supercharger (should be powerful, but not to big to over power the turbocharger). The first turbocharger, and the biggest, is to feed into a smaller turbocharger, therefore giving you the standard compound turbocharge. Then with the supercharger, pipe this into the third and final turbocharger. Then make/buy a two into one imput joiner and connect the pipes up and mount the chargers.
This is a monumental design and I am very pleased with the prospects of getting over 3,000bhp from my Rover V8 with Dakar Rally in mind custom internals, but with this compound twin charging in the simpelist form will find the 350Z approximately 850-1,500bhp which is briliant.
If you would like digrams, drawings or more information then please write on the post and I will get back to you as quickly as possible.
Just one last thing the brains behind this kit is 16 in March, so starting young!!
