I was discussing SR upgrades with a friend. I am going to help engineer his 98 M/C for circuit racing. I wouldn't think that it would too difficult, but I have never heard of it being done.
I am assuming that you would need to build a custom exhaust manifold but i know a couple of good shops that could make an iconel unit that would work well.
I imagine a pair of T25 sized turbos on a SR would give some very good power with little to no lag.
Discuss>>>
Has anyone tried to twin turbo the SR?
Well I still need to do a little R&D still...
But I think it is very do-able. I need to work out issues with the MAF and plumbing but I think it would bring the SR into a whole new world of power.
I know a lot of people will ask why when a simgle turbo setup can produce huge power. Similar to any other single turbot setup i.e. supra & rx-7.
But from an engineering stand point the area under the curve is what's important. Especially in circuit racing where torque is used to accelerate out of corners. By reducing the turbo size while doubling the number of turbos I can gain a lot of torque and dramatically lower the rev level where the turbos start to create power.
Also since each turbo is doing half as much work to create the same boost levels turbo life will be extended. With the turbo only working half as hard the boost charge can be cooler producing more horsepower at the same boost pressure.
I know a lot of people will ask why when a simgle turbo setup can produce huge power. Similar to any other single turbot setup i.e. supra & rx-7.
But from an engineering stand point the area under the curve is what's important. Especially in circuit racing where torque is used to accelerate out of corners. By reducing the turbo size while doubling the number of turbos I can gain a lot of torque and dramatically lower the rev level where the turbos start to create power.
Also since each turbo is doing half as much work to create the same boost levels turbo life will be extended. With the turbo only working half as hard the boost charge can be cooler producing more horsepower at the same boost pressure.
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charlotte240
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Ummm........ just a thought here.......since there are only two cylinders pushing each turbo, the lag would, in theory, stay the same. There's half the exhaust flow pushing the turbos; doubling the lagtime, but half the airflow demand from each turbo; halfing the lagtime. The only real difference is that now the engine has to drive two compressors instead of one so the lag would increase marginally due to increased rotational mass.
This makes sense in my head, and it just seems like everybody doesn't realize that the exhaust gasses have to be divided.
Here's an idea though........we don't like ceramic because it's weak. we do, however like it because it's light and more prone to spooling. TITANIUM INTERNALS!!! :ylsuper
Seriously though, if you want good spool up and decent top end, get a decent sized turbo, make sure it's ball bearing, make sure your manifold is smooth flowing and has a decent collector so that the enertia of the exhaust presses on the impeller and not just the fact that it's pressurized, and lastly, have a HUGE exhaust because we all know that a turbo works off of the pressure delta (that's the difference in pressure for the layman)..........also, wrapping your runners on the manifold helps keep it hot.
That'd probably be cheaper and yield better results than a custom twin turbo because with the twin setup, you'd be more worried about making it work instead of making it work efficiently.
This makes sense in my head, and it just seems like everybody doesn't realize that the exhaust gasses have to be divided.
Here's an idea though........we don't like ceramic because it's weak. we do, however like it because it's light and more prone to spooling. TITANIUM INTERNALS!!! :ylsuper
Seriously though, if you want good spool up and decent top end, get a decent sized turbo, make sure it's ball bearing, make sure your manifold is smooth flowing and has a decent collector so that the enertia of the exhaust presses on the impeller and not just the fact that it's pressurized, and lastly, have a HUGE exhaust because we all know that a turbo works off of the pressure delta (that's the difference in pressure for the layman)..........also, wrapping your runners on the manifold helps keep it hot.
That'd probably be cheaper and yield better results than a custom twin turbo because with the twin setup, you'd be more worried about making it work instead of making it work efficiently.
I can see the logic, but...
If you look at other bi-turbo cars like the Z32 and Audi S4 you can see that using two smaller turbos is a very effecient way to produce power. Although you only have half the engine pushing each turbo, you have less rotational mass per turbine. This will allow a faster boost gain over a similar flow single turbo design.
Hypothetically: two t25's can spool faster than a single T51 and produce similar power
An example that can be more closely compared to my idea would be the RB twin turbos. The RB is regularly converted to a single turbo for peak power, but is usually upgraded with dual turbos for racing. A big piece of this puzzle is the area under the curve. By using two instead of one you spool earlier creating more low down torque.
This is why I am researching the idea. It is entirely possible that I am nuts, it doesn't work well, or even at all. But if it does I want to find it and see the details. I am still limited by the SR itself and how much boost can it handle (although this may be a great idea to utilize the displacement of the KA). However if I can get boost at lower RPM's and still carry it to cut off I will make a very potent racer
Hypothetically: two t25's can spool faster than a single T51 and produce similar power
An example that can be more closely compared to my idea would be the RB twin turbos. The RB is regularly converted to a single turbo for peak power, but is usually upgraded with dual turbos for racing. A big piece of this puzzle is the area under the curve. By using two instead of one you spool earlier creating more low down torque.
This is why I am researching the idea. It is entirely possible that I am nuts, it doesn't work well, or even at all. But if it does I want to find it and see the details. I am still limited by the SR itself and how much boost can it handle (although this may be a great idea to utilize the displacement of the KA). However if I can get boost at lower RPM's and still carry it to cut off I will make a very potent racer
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Bryants95240sx
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teriyakibroccoli
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keep in mind that the supra and rx7 use similar sized turbos but they both have a "sequential" turbo system to kick start (pre-spool) the 2nd turbo.
As for the statement two t25s can spool faster than a single t51 and produce similar power...... why aren't more people doing that then? That also is dependent on what type of power goal you're trying to hit.. not to mention the t51 was a turbo that was not designed to be auto-x'd.
As for the statement two t25s can spool faster than a single t51 and produce similar power...... why aren't more people doing that then? That also is dependent on what type of power goal you're trying to hit.. not to mention the t51 was a turbo that was not designed to be auto-x'd.
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Hijacker
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Re: I can see the logic, but...
Goose93 wrote:If you look at other bi-turbo cars like the Z32 and Audi S4 you can see that using two smaller turbos is a very effecient way to produce power. Although you only have half the engine pushing each turbo, you have less rotational mass per turbine. This will allow a faster boost gain over a similar flow single turbo design.
Hypothetically: two t25's can spool faster than a single T51 and produce similar power
An example that can be more closely compared to my idea would be the RB twin turbos. The RB is regularly converted to a single turbo for peak power, but is usually upgraded with dual turbos for racing. A big piece of this puzzle is the area under the curve. By using two instead of one you spool earlier creating more low down torque.
This is why I am researching the idea. It is entirely possible that I am nuts, it doesn't work well, or even at all. But if it does I want to find it and see the details. I am still limited by the SR itself and how much boost can it handle (although this may be a great idea to utilize the displacement of the KA). However if I can get boost at lower RPM's and still carry it to cut off I will make a very potent racer
http://www.nissaninfiniticlub....turbo
Dori dori put it best
You can't compare a Z32 turbo setup to an S13 setup. V-6 needs a twin setup, one for each bank, while the S13 is an I4.Dori Dori wrote:You are backwards. Twin turbo setups cannot run very high boost levels and they create more heat at high boost levels. Consider that with a twin turbo setup, you are generally using smaller turbochargers which inherently create more heat at lower boost levels than larger single turbo setups and are way out of their efficiency range at higher boost levels. This is why in the JGTC, when they they used I6's that were originally twin turbo from the factory, they used large single turbo setups instead of twin...higher psi at higher rpm w/ greater effieciency and lower heat levels (probably also for less points of failure too).
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charlotte240
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well I seem to be in the minority.
rebuttal quick list with a reminder, this is reasearch.
The Z32 and S4 ( The S4 was a bi turbo 6 until last year) comparisons were merely to show small displacements still work with dual turbo systems. If you don't like those examples you can use any of the dual turbo RB motors as better examples.
The Nismo JGTC Sklylines and now 350Z use dual turbos.
The Supra and RX-7 are examples of how not to set up twin turbo cars. Using a sequential system provides a very un-predictable power curve and is genereally high maintenance. These cars a often converted to singles to get absolute top power not for circuit racing, also to remove bypass valve system.
Two t25 shafts may very well weigh more than a T51. This was more of a sample of concept than a proposed example of prototype. I am interesed to know if a dual turbo system on an SR @~400rwhp would be more efficient than a single.
Using a single turbo set up is generally significantly cheaper which may be partly responsible for popularity.
I did look at the other post and found a lot of un-informed information but the biggest downside I can see curently is cost, which does not equate to better performance. Displacement was brought up but that is a bogus argument. I can see an issue with only two cylinders pushing the turbo but that is more from an exhaust flow issue than anything else.
The Z32 and S4 ( The S4 was a bi turbo 6 until last year) comparisons were merely to show small displacements still work with dual turbo systems. If you don't like those examples you can use any of the dual turbo RB motors as better examples.
The Nismo JGTC Sklylines and now 350Z use dual turbos.
The Supra and RX-7 are examples of how not to set up twin turbo cars. Using a sequential system provides a very un-predictable power curve and is genereally high maintenance. These cars a often converted to singles to get absolute top power not for circuit racing, also to remove bypass valve system.
Two t25 shafts may very well weigh more than a T51. This was more of a sample of concept than a proposed example of prototype. I am interesed to know if a dual turbo system on an SR @~400rwhp would be more efficient than a single.
Using a single turbo set up is generally significantly cheaper which may be partly responsible for popularity.
I did look at the other post and found a lot of un-informed information but the biggest downside I can see curently is cost, which does not equate to better performance. Displacement was brought up but that is a bogus argument. I can see an issue with only two cylinders pushing the turbo but that is more from an exhaust flow issue than anything else.
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Hijacker
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it's less about displacement and more about exhaust pulses. This is the argument why an RB20DET will outspool and SR20DET. In an RBTT setup, you have three cylinders per turbo in that setup, so you have an additional exhaust pulse per turbo than you would on an SRTT setup.
You also can't compare a V engine to an inline engine in setup terms. The only time I've heard of a single turbo system on a V engine was porsche from way back in the days of F1 racing (the higher ups restricted dual turbo setups in hopes that things would go N/A. Porsche didn't like that). A V setup is almosts synonomous with dual turbo if you decide to turbo it. So in reply to the S4 being a 6cylinder engine before, it's still a V setup.
I don't know if the JGTC has switched to using the new skylines or if they continue to parade the old GT-Rs. But if its the new skylines, they run the same V engine as the 350s, so there again, you have the argument it's best to run a dual turbo setup because of the engine design. On older GT-Rs, it's been common practice to dump the dual turbo design in favor of a larger single turbo.
Also, while you call the Z32 and S4 small displacement engines, they still have more displacement than an SR. That makes a huge difference in exhaust flow and volumetric effeciency.
The thing about the single turbo being popular is because it is the proven better of the two arguments. My friends in australia have seen a lot of custom silvia jobs down there, and the only dual turbo I've heard of them talk about was in a show car. All the track cars run a single turbo setup. The volumetric effeciency of a dual turbo on an I4 is not better than a single turbo setup.
You also can't compare a V engine to an inline engine in setup terms. The only time I've heard of a single turbo system on a V engine was porsche from way back in the days of F1 racing (the higher ups restricted dual turbo setups in hopes that things would go N/A. Porsche didn't like that). A V setup is almosts synonomous with dual turbo if you decide to turbo it. So in reply to the S4 being a 6cylinder engine before, it's still a V setup.
I don't know if the JGTC has switched to using the new skylines or if they continue to parade the old GT-Rs. But if its the new skylines, they run the same V engine as the 350s, so there again, you have the argument it's best to run a dual turbo setup because of the engine design. On older GT-Rs, it's been common practice to dump the dual turbo design in favor of a larger single turbo.
Also, while you call the Z32 and S4 small displacement engines, they still have more displacement than an SR. That makes a huge difference in exhaust flow and volumetric effeciency.
The thing about the single turbo being popular is because it is the proven better of the two arguments. My friends in australia have seen a lot of custom silvia jobs down there, and the only dual turbo I've heard of them talk about was in a show car. All the track cars run a single turbo setup. The volumetric effeciency of a dual turbo on an I4 is not better than a single turbo setup.
Okay just for the record
I know that by design V6 bi-turbos are different than an I6 bi-turbos for a reason. The comparison was only made to show the point of volume per turbo not being a major issue. The RB's also prove this point. 1 liter of displacement can provide enough energy to a turbo charger to produce more power.
I am also aware that the exhaust pulses are the negative issue when dealing with an I4 bi-turbo concept vs. an i6 bi-turbo concept. That is why I made the point of the exhaust flow difference. I wasn't that specific for a reason. I apologize.
The information about people in Australia trying the bi-turbo I4 concept is actually the type of information I am looking for. Thus the reason I asked the question.
I am also aware that the exhaust pulses are the negative issue when dealing with an I4 bi-turbo concept vs. an i6 bi-turbo concept. That is why I made the point of the exhaust flow difference. I wasn't that specific for a reason. I apologize.
The information about people in Australia trying the bi-turbo I4 concept is actually the type of information I am looking for. Thus the reason I asked the question.
You're trading a small amount of rotational inertia for alot more friction with a twin turbo setup. Not to mention double the cost of a single setup if you go with comparable turbos(ball bearing etc.).
I think you'd find that two 250rwhp capable turbos mated to an SR20 would spool almost identically to a single 500rwhp turbo. If there is any difference, it wouldn't be enough to write home about.
BTW - displacement is a HUGE factor in how a turbo spools up. The kinetic properties of the exhaust pulses are a factor, but good ole' mass flowrate will be the deciding factor at the end of the day.
I think you'd find that two 250rwhp capable turbos mated to an SR20 would spool almost identically to a single 500rwhp turbo. If there is any difference, it wouldn't be enough to write home about.
BTW - displacement is a HUGE factor in how a turbo spools up. The kinetic properties of the exhaust pulses are a factor, but good ole' mass flowrate will be the deciding factor at the end of the day.
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msaskin
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tenkawa_akito wrote:The only time I've heard of a single turbo system on a V engine was porsche from way back in the days of F1 racing (the higher ups restricted dual turbo setups in hopes that things would go N/A. Porsche didn't like that
Buick Grand National/Turbo Regal - 3.8 Liter V6GMC Syclone/Typhoon - 4.3 Liter V6
Both are single turbos
:icesangel
~matt
i have a apex single turbo on my 93 rx7 and i made 140 more hp than with it at the same boost and it spooled about the same. Someone makes a twin turbo set up for the rx7 that has 2 t28 and everyone that i have talked to says that it spools slow and it cost alot. i dont know how much you can compare this to a SR but i was just putting my 2 cents in
ive given up trying to convince people that twin turbos are beneficial in engines with two cylinder banks just to simplify installation and plumbing.
running two turbos off of an inline 4 is just retarded. your creating this plumbing mess just so you can say you have twin turbos, and in the end its gonna cost twice as much money to achieve the same power as a good single turbo.
tell you what. go twin turbo an SR, and come back and tell us how much money you spent, and how much it sucks.
running two turbos off of an inline 4 is just retarded. your creating this plumbing mess just so you can say you have twin turbos, and in the end its gonna cost twice as much money to achieve the same power as a good single turbo.
tell you what. go twin turbo an SR, and come back and tell us how much money you spent, and how much it sucks.
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msaskin
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IvoryJ30t wrote:ive given up trying to convince people that twin turbos are beneficial in engines with two cylinder banks just to simplify installation and plumbing.
running two turbos off of an inline 4 is just retarded. your creating this plumbing mess just so you can say you have twin turbos, and in the end its gonna cost twice as much money to achieve the same power as a good single turbo.
tell you what. go twin turbo an SR, and come back and tell us how much money you spent, and how much it sucks.
Amen to that...I couldn't agree with you more.
It's much the same as people I've dealt with in the 3000gt/stealth world who want to rig up a single turbo setup. Granted, a single turbo V6 is a bit easier plumbing wise than a twin turbo I4, but it's still an un-necessary hardship just to be cool/unique/whatever
~matt
lets break it down.
now, to balance the exhaust, turbo one is gonna be fed by cylinders 1 and 4. the second turbo is gonna be fed by cylinders 2 and 3. anyone else cringing at the thought of that manifold?
now, two pod filters, one to each compressor inlet. a y pipe to join the output of the compressors, then a BOV, then to the FMIC, back up to the blow through maf, and to the throttle body.
now think of the downpipes. either two exhaust pipes under the car, or an equal length front pipe to join the downpipes, then out the back.
boost control. if you have two small turbos running at 15 psi, the engine is going to see 15 psi, not 30. just because you have two turbos at 15 psi, doesnt mean you have 30 psi of manifold pressure because the turbos will be in parallel, not series. you have 15 psi, but a very high flow rate. running turbos in series opens a whole new can of worms. see the other twin turbo thread for explanation.
get it?
oh, not to mention the adiabatic losses by running two small, inefficient turbos.
you try to make those two small turbos push 20+ psi, you wind up at like 60% efficiency. meaning only 60% of the heat created is due to adiabatic heat, the rest is heat created by the friction of the air being shoved through this small compressor and housing.
now, to balance the exhaust, turbo one is gonna be fed by cylinders 1 and 4. the second turbo is gonna be fed by cylinders 2 and 3. anyone else cringing at the thought of that manifold?
now, two pod filters, one to each compressor inlet. a y pipe to join the output of the compressors, then a BOV, then to the FMIC, back up to the blow through maf, and to the throttle body.
now think of the downpipes. either two exhaust pipes under the car, or an equal length front pipe to join the downpipes, then out the back.
boost control. if you have two small turbos running at 15 psi, the engine is going to see 15 psi, not 30. just because you have two turbos at 15 psi, doesnt mean you have 30 psi of manifold pressure because the turbos will be in parallel, not series. you have 15 psi, but a very high flow rate. running turbos in series opens a whole new can of worms. see the other twin turbo thread for explanation.
get it?
oh, not to mention the adiabatic losses by running two small, inefficient turbos.
you try to make those two small turbos push 20+ psi, you wind up at like 60% efficiency. meaning only 60% of the heat created is due to adiabatic heat, the rest is heat created by the friction of the air being shoved through this small compressor and housing.
Wow, got some neck hairs to stand up here.
Okay, believe it or not I am already aware of most of what has been said here.
Brief sysnopsis. I am aware of the technical difficulty and the cost. The general impression here is that these two elements make a bi-turbo SR project a bad idea. Not that it is impossible but highly un-recomended.
Interesting...
Brief sysnopsis. I am aware of the technical difficulty and the cost. The general impression here is that these two elements make a bi-turbo SR project a bad idea. Not that it is impossible but highly un-recomended.
Interesting...
Quote »oh, not to mention the adiabatic losses by running two small, inefficient turbos.[/quote]Just have to ask, what were you meaning when you used "adiabatic" in that sentence. Adiabatic means zero heat transfer across a system boundary(which is arbitarily choosen).
I keep rereading it and I'm not picking up what you're putting down... Are you referring to compressor efficiency? That's not at all related to the term "adiabatic."
Just an FYI if that's what you meant. Figured at least some edumacation in this thread might be worthwhile, since it seems some of our explanations are falling on deaf ears.
I keep rereading it and I'm not picking up what you're putting down... Are you referring to compressor efficiency? That's not at all related to the term "adiabatic."
Just an FYI if that's what you meant. Figured at least some edumacation in this thread might be worthwhile, since it seems some of our explanations are falling on deaf ears.
tenkawa_akito wrote:I don't know if the JGTC has switched to using the new skylines or if they continue to parade the old GT-Rs. But if its the new skylines, they run the same V engine as the 350s, so there again, you have the argument it's best to run a dual turbo setup because of the engine design. On older GT-Rs, it's been common practice to dump the dual turbo design in favor of a larger single turbo.
They are using new Z's now w/ VQ30DETT engines. Before they dumped the R34 they had also switched to the VQ30DETT. At the time they were running RB's though, they were all single turbo AFAIK. You are 100% right about engine design.
i might have misspelled it. heat gained or lost from compression or decompression of gasses.Def wrote:Just have to ask, what were you meaning when you used "adiabatic" in that sentence. Adiabatic means zero heat transfer across a system boundary(which is arbitarily choosen).
I keep rereading it and I'm not picking up what you're putting down... Are you referring to compressor efficiency? That's not at all related to the term "adiabatic."
Just an FYI if that's what you meant. Figured at least some edumacation in this thread might be worthwhile, since it seems some of our explanations are falling on deaf ears.
its why gasses get hot when compressed and cold when decompressed.
with turbos are rated efficiency wise, as a percentage, its saying how much of the heat the air is gaining by the compression of the air [adiabatic], and from the friction of the air and the compressor.
if the compressor is running at 50%, half of the heat gained is from the compression, and the other half is from friction.
even if you have a compressor that is 100% efficient, the air is still going to heat up due to it being compressed.
if im using adiabatic wrong, its been a few years since physics class...
THE ADIABATIC PROCESS
The adiabatic process is the process by which a gas, such as air, is heated or cooled, without heat being added to or taken away from the gas, but rather by expansion and compression. In the atmosphere, adiabatic and nonadiabatic processes are taking place continuously. The air near the ground is receiving heat from or giving heat to the ground. These are nonadiabatic pro-cesses.
However, in the free atmosphere somewhat
removed from Earth?s surface, the short-period processes are adiabatic. When a parcel of air is lifted in the free atmosphere, pressure decreases. To equalize this pressure, the parcel must expand. In expanding, it is doing work. In doing work, it uses heat. This results in a lowering of temperature as well as a decrease in the pressure and density. When a parcel of air descends in the free atmosphere, pressure increases. To equalize the pressure, the parcel must contract. In doing this, work is done on the parcel. This work energy, which is being added to the parcel, shows up as an increase in temperature. The pressure and den-sity increase in this case also.
The adiabatic process is the process by which a gas, such as air, is heated or cooled, without heat being added to or taken away from the gas, but rather by expansion and compression. In the atmosphere, adiabatic and nonadiabatic processes are taking place continuously. The air near the ground is receiving heat from or giving heat to the ground. These are nonadiabatic pro-cesses.
However, in the free atmosphere somewhat
removed from Earth?s surface, the short-period processes are adiabatic. When a parcel of air is lifted in the free atmosphere, pressure decreases. To equalize this pressure, the parcel must expand. In expanding, it is doing work. In doing work, it uses heat. This results in a lowering of temperature as well as a decrease in the pressure and density. When a parcel of air descends in the free atmosphere, pressure increases. To equalize the pressure, the parcel must contract. In doing this, work is done on the parcel. This work energy, which is being added to the parcel, shows up as an increase in temperature. The pressure and den-sity increase in this case also.