Help me select my twin turbos.
08-22-09, 11:01 PM
#1
Help me select my twin turbos.
So I'm tearing my turbo first gen apart this winter to add some major additional mods.
Currently, I'm running a S5 TII motor, with a generic To4B turbo, haltech, 1680 secondarys, blah blah snore.
the plans are
E85
1680/2400 fuel injectors.
8an fuel system.
large street port,
E6X
Twin turbos.
My reasons for going twin are; cool factor, cool factor, and cool factor. Also, I dont see it as a huge cost increase vs a single, as wastegates will be internal, so one less expensive part, and less manifold work. I plan to weld up a stainless manifold using sch40 pipes and bends from McMaster. I plan to run 3in from the turbos and collect to a 4in exhaust from there.
the goal is 500hp minimum, with 600 as sort of secondary goal.
so I've narrowed down to two turbos, the GT28R and the GT28RS (the "disco potato")
Im leaning toward the disco potato, somewhat due to its famous history for being a turbo that can make a LOT of power with a minimal amount of lag.
I was also looking at a .64 exhaust housing for both turbos.
Any opinions or suggestions?? Is a 1680/2400cc setup enough to make 600hp on E85??
FYI here is a pic of my current setup, I made just over 300rwhp with this at 14lbs of boost on my university's mustang dyno. I think the compressor was a huge bottleneck in the system. (so you know I'm for real and not just blowing smoke)
Currently, I'm running a S5 TII motor, with a generic To4B turbo, haltech, 1680 secondarys, blah blah snore.
the plans are
E85
1680/2400 fuel injectors.
8an fuel system.
large street port,
E6X
Twin turbos.
My reasons for going twin are; cool factor, cool factor, and cool factor. Also, I dont see it as a huge cost increase vs a single, as wastegates will be internal, so one less expensive part, and less manifold work. I plan to weld up a stainless manifold using sch40 pipes and bends from McMaster. I plan to run 3in from the turbos and collect to a 4in exhaust from there.
the goal is 500hp minimum, with 600 as sort of secondary goal.
so I've narrowed down to two turbos, the GT28R and the GT28RS (the "disco potato")
Im leaning toward the disco potato, somewhat due to its famous history for being a turbo that can make a LOT of power with a minimal amount of lag.
I was also looking at a .64 exhaust housing for both turbos.
Any opinions or suggestions?? Is a 1680/2400cc setup enough to make 600hp on E85??
FYI here is a pic of my current setup, I made just over 300rwhp with this at 14lbs of boost on my university's mustang dyno. I think the compressor was a huge bottleneck in the system. (so you know I'm for real and not just blowing smoke)
08-23-09, 10:37 AM
#6
Racing Rotary Since 1983
iTrader: (6)
having designed, developed twins and run my setup since 04 and 18,000 miles...
you don't want the gt30 turbos. too much air. the 76 makes 52 pounds and the 71 makes 50.
unless you want to deal w more lag than the gt4294 that makes 84 pounds forget it. a couple of people have built twin gt30s and neither ran properly and are not currently running to my knowledge.
the GT28RS and the GT25/40 AKA GT2876 present different problems.
GT28RS Disco has a 5.706 square inch compressor average area and a 3.108 square inch turbine! the GT25/40- 2876 has the same turbine wheel.
that makes the hotside 54.4% Disco and 59.5% of the cold side. way too small for a rotary.
i run TO4E 46 trims w Stage 5 hotsides.
my cold side is 4.99 square inches. my hotside is 5.408 square inches or 8% Larger than the cold side. stable low EGTs. happy motor.
the 46 trims make 42 pounds per minute or 84 for the two, exactly what a GT4294 makes. we are talking gross air.
84 pounds per minute times 14.471 is 1215 CFM/ 1.92 is approx 630 Max rear wheel rotary hp.
the GT42 makes max Net air (57 pounds) at 29.4 psi. my 46s make 55.3 Net at 25 psi.
as to spool i make 200 rwhp (SAE) at 4300.
i am currently switching down to .63 housings from my .82 to increase midrange.
good luck on your project. use T3 5 bolt housings and combine them w ATP's Ultimate Wastegates. V band 3 inch downpipes into a Burns Stainless 2 into one.
howard
you don't want the gt30 turbos. too much air. the 76 makes 52 pounds and the 71 makes 50.
unless you want to deal w more lag than the gt4294 that makes 84 pounds forget it. a couple of people have built twin gt30s and neither ran properly and are not currently running to my knowledge.
the GT28RS and the GT25/40 AKA GT2876 present different problems.
GT28RS Disco has a 5.706 square inch compressor average area and a 3.108 square inch turbine! the GT25/40- 2876 has the same turbine wheel.
that makes the hotside 54.4% Disco and 59.5% of the cold side. way too small for a rotary.
i run TO4E 46 trims w Stage 5 hotsides.
my cold side is 4.99 square inches. my hotside is 5.408 square inches or 8% Larger than the cold side. stable low EGTs. happy motor.
the 46 trims make 42 pounds per minute or 84 for the two, exactly what a GT4294 makes. we are talking gross air.
84 pounds per minute times 14.471 is 1215 CFM/ 1.92 is approx 630 Max rear wheel rotary hp.
the GT42 makes max Net air (57 pounds) at 29.4 psi. my 46s make 55.3 Net at 25 psi.
as to spool i make 200 rwhp (SAE) at 4300.
i am currently switching down to .63 housings from my .82 to increase midrange.
good luck on your project. use T3 5 bolt housings and combine them w ATP's Ultimate Wastegates. V band 3 inch downpipes into a Burns Stainless 2 into one.
howard
08-23-09, 11:03 AM
#7
so your saying the hot side is the problem on the Disco potato's which I can understand. I've had some trouble understanding turbine flow maps, and honestly dont really understand them at all.
I was looking at the Disco's compressor map, it would seam that a pair of them would be ideal (at least on the compressor side) for a rotary running up to 25lbs of boost. I'm not sure but I think 50-60lbs of air is about what my motor would be eating at that pressure ratio.
as far as the exhaust side. you probably know more than I do, but from ATP's website, the compressor is 60mm and turbine is 54mm
so the compressor is 4.38 sqin and the turbine is 3.54 sqin. so the hot side is 80% of the cold side.
I know that the rotaries like the big open exhaust side, I run a 1.15 Ptrim on my to4, and although I dont have an egt, I can tell that it tends to stay cool considering the heat of a rotary.
In addition, doesn't the use of ethanol negate the negative effects of higher EGTs because of the fuels colder burning temp. I live in Minnesota, the most E85 friendly state in the union, so this will be a E85 ONLY vehicle.
Thanks for your input, it is greatly appreciated.
I was looking at the Disco's compressor map, it would seam that a pair of them would be ideal (at least on the compressor side) for a rotary running up to 25lbs of boost. I'm not sure but I think 50-60lbs of air is about what my motor would be eating at that pressure ratio.
as far as the exhaust side. you probably know more than I do, but from ATP's website, the compressor is 60mm and turbine is 54mm
so the compressor is 4.38 sqin and the turbine is 3.54 sqin. so the hot side is 80% of the cold side.
I know that the rotaries like the big open exhaust side, I run a 1.15 Ptrim on my to4, and although I dont have an egt, I can tell that it tends to stay cool considering the heat of a rotary.
In addition, doesn't the use of ethanol negate the negative effects of higher EGTs because of the fuels colder burning temp. I live in Minnesota, the most E85 friendly state in the union, so this will be a E85 ONLY vehicle.
Thanks for your input, it is greatly appreciated.
Trending Topics
08-23-09, 01:30 PM
#8
Racing Rotary Since 1983
iTrader: (6)
"from ATP's website, the compressor is 60mm and turbine is 54mm
so the compressor is 4.38 sqin and the turbine is 3.54 sqin. so the hot side is 80% of the cold side."
compressor is 60 mm X 76 mm. or: 2.362 X 2.992. or: 4.382 sq in X 7.030 sq in.
add 4.382 to 7.030 and divide by 2 to get average wheel area which is 5.706.
turbine is 47 mm X 53.8 MM. or: 1.85 X 2.12 or 2.688 X 3.523. add and divide you get 3.105 average wheel area.
3.105/5.706= 54.4% way too small.
when i started my twins i took the advice from the vendor and started w .48 hotsides and stage 1 wheels. i split both housings due to the backpressure. my hotside wheels were larger than the disco wheel.
howard
so the compressor is 4.38 sqin and the turbine is 3.54 sqin. so the hot side is 80% of the cold side."
compressor is 60 mm X 76 mm. or: 2.362 X 2.992. or: 4.382 sq in X 7.030 sq in.
add 4.382 to 7.030 and divide by 2 to get average wheel area which is 5.706.
turbine is 47 mm X 53.8 MM. or: 1.85 X 2.12 or 2.688 X 3.523. add and divide you get 3.105 average wheel area.
3.105/5.706= 54.4% way too small.
when i started my twins i took the advice from the vendor and started w .48 hotsides and stage 1 wheels. i split both housings due to the backpressure. my hotside wheels were larger than the disco wheel.
howard
08-23-09, 04:22 PM
#10
Im starting to lean back towards a Gt35R. I think its limit is about 550hp, but that is really still way more than I need in this car. Plus, I didn't realize that I can get it with a T4 divided 1.06 turbine, which would match up to my existing manifold and exhaust, which brings the price down considerably.
The problem I see is that a Pair of GT28RS turbos have almost perfect compressor maps that would make a very broad power band, but are not available with a turbine housing that works well with the rotary exhaust. To get the right exhaust housing it would seem I have to step up the compressors to a size that makes much more power than I'm looking for and will suffer in the mid range.
If you don't mind me asking; what are the exact specs on your twin T4 setup, including waste gate, etc.?
08-23-09, 06:52 PM
#11
Racing Rotary Since 1983
iTrader: (6)
the GT3582r is an excellent turbo... better than most understand. primarily due to high efficiency, i e creating less heat in the compressor function.
that said, it is not a 550 rotary rwhp turbo. it flows max 62 pounds.
62 X 14.471 is 897 CFM/ 1.92 = 467 max rotary hp. bolt it on a piston engine and you can make a bit over 500.
since the GT3582r is more efficient than many turbos and the 1.92 comes from less efficient turbos,,, maybe you can add 10%. maybe.
the TO4Z/A-Spec GT500r may be the most efficient at reasonable boost levels.
it is, as you know, a larger turbo.
average compressor area:
GT3582r 6.386 square inches
TO4Z/A-Spec GT500r 7.002
73 pounds per minute gross, 51.1 net. 550 rotary rwhp.
specs on my turbos:
TO4E compressors and cover 3 inch intake, 2.5 exhaust.
46 trim compressor wheel
50.8MM X 74.9 MM. 4.99 sq inches.
water and oil cooled centers. journal bearing w 360 degree thrust bearing (essential)
stage 5 turbine wheel
61.9 mm X 71 mm
5.408 sq inches.
.63 T3 rear housings
wastegate is internal using ATP's Ultimate Wastegate and AGP modular billet aluminum actuators.
2 three inch downpipes.
42 pounds per minute max.
most net air is at 25 psi (70% efficiency.)
hp target (max) is 600.
i have dynoed at 507 SAE rw at 20 psi boost
here's the sheet... this is w .82 rear housings so the spool and mid range did not work for me. i now have .63 housings and dyno next week. i am expecting better midrange and to dyno out at 25 psi.
hc
that said, it is not a 550 rotary rwhp turbo. it flows max 62 pounds.
62 X 14.471 is 897 CFM/ 1.92 = 467 max rotary hp. bolt it on a piston engine and you can make a bit over 500.
since the GT3582r is more efficient than many turbos and the 1.92 comes from less efficient turbos,,, maybe you can add 10%. maybe.
the TO4Z/A-Spec GT500r may be the most efficient at reasonable boost levels.
it is, as you know, a larger turbo.
average compressor area:
GT3582r 6.386 square inches
TO4Z/A-Spec GT500r 7.002
73 pounds per minute gross, 51.1 net. 550 rotary rwhp.
specs on my turbos:
TO4E compressors and cover 3 inch intake, 2.5 exhaust.
46 trim compressor wheel
50.8MM X 74.9 MM. 4.99 sq inches.
water and oil cooled centers. journal bearing w 360 degree thrust bearing (essential)
stage 5 turbine wheel
61.9 mm X 71 mm
5.408 sq inches.
.63 T3 rear housings
wastegate is internal using ATP's Ultimate Wastegate and AGP modular billet aluminum actuators.
2 three inch downpipes.
42 pounds per minute max.
most net air is at 25 psi (70% efficiency.)
hp target (max) is 600.
i have dynoed at 507 SAE rw at 20 psi boost
here's the sheet... this is w .82 rear housings so the spool and mid range did not work for me. i now have .63 housings and dyno next week. i am expecting better midrange and to dyno out at 25 psi.
hc
Last edited by GoodfellaFD3S; 08-24-09 at 08:54 AM. Reason: GT3582R, not GT5382R :) just wanted to fix that to avoid future confusion.
08-23-09, 07:14 PM
#12
thanks for all the info, it is much appreciated.
I'm starting to more lean toward a GT35R or GT40R, like I said, this is in a FB, and a Series 2, model S at that, I think the lightest Rx-7 ever made, and I've stripped a lot off of it.
I'm thinking I'm gonna stick with the single now, and probably go with the Gt35R, and push it as far as it will go. I've been reading through numerous old threads, and a few people have made over 500 with it. I think with the E85 fuel, a large street-port and a good tune and I can make 500 happen. Though twins are still in the back of my mind with the cool factor.
I'm starting to more lean toward a GT35R or GT40R, like I said, this is in a FB, and a Series 2, model S at that, I think the lightest Rx-7 ever made, and I've stripped a lot off of it.
I'm thinking I'm gonna stick with the single now, and probably go with the Gt35R, and push it as far as it will go. I've been reading through numerous old threads, and a few people have made over 500 with it. I think with the E85 fuel, a large street-port and a good tune and I can make 500 happen. Though twins are still in the back of my mind with the cool factor.
08-23-09, 08:47 PM
#13
Racing Rotary Since 1983
iTrader: (6)
i do need to correct a major error on my part re the GT28RS.
the compressor is 47.2mm X 60mm NOT 60mm X 76mm.
doing the math, the wheel is 3.549 sq inches and the turbine is 3.105 or 87% of the compressor which is fine.
doubling the turbine area for twins and you have 6.21.... compared to 5.171 for the GT3582R.
not bad on an absolute basis
the GT3582R turbine is 5.171... stock FD is 5.25
sorry for the wrong numbers..
the compressor is 47.2mm X 60mm NOT 60mm X 76mm.
doing the math, the wheel is 3.549 sq inches and the turbine is 3.105 or 87% of the compressor which is fine.
doubling the turbine area for twins and you have 6.21.... compared to 5.171 for the GT3582R.
not bad on an absolute basis
the GT3582R turbine is 5.171... stock FD is 5.25
sorry for the wrong numbers..
08-23-09, 10:27 PM
#14
cool, so the Gt28s would probably work out pretty well then.
the way I see it. (with supporting hardware, fittings etc.)
the gt35 is $1500
the GT40 is $2000
twin GT28s is about $3000 (as I have to redo all the oil and coolant lines), (actually, I dont have coolant lines on my current turbo so that doesn't count :P) and a new manifold and at the minimum a new downpipe.
but I could also sell my current manifold, turbo, and downpipe to some FB, TII swap person and get like $500 or so.
the way I see it. (with supporting hardware, fittings etc.)
the gt35 is $1500
the GT40 is $2000
twin GT28s is about $3000 (as I have to redo all the oil and coolant lines), (actually, I dont have coolant lines on my current turbo so that doesn't count :P) and a new manifold and at the minimum a new downpipe.
but I could also sell my current manifold, turbo, and downpipe to some FB, TII swap person and get like $500 or so.
08-24-09, 08:57 AM
#16
Original Gangster/Rotary!
iTrader: (213)
Based on all I've read and seen, I would look into a T4 35R. Negative on the 40R.
With the 35R your little first gen will rip down the road, you'll have plenty of power and good response. Pretty sure Sean/Zero R (A Spec) has them in stock and ready to ship out.
With the 35R your little first gen will rip down the road, you'll have plenty of power and good response. Pretty sure Sean/Zero R (A Spec) has them in stock and ready to ship out.
08-24-09, 09:40 AM
#17
Full Member
Join Date: Jun 2006
Location: Lancaster, PA
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
sooooo should we change the title of this thread to "help me select my single turbo"?
what were the major deciding factors of staying with a single setup?
money could have been one but judging by the title of the thread i thought you were serious about twins and that wouldn't be a problem.
what other factors contributed to this? I was excited when i began reading this thread... only to find out your running another run of the mill 35r, it would be nice to see another well organized twin setup for reference
good luck witih the project though
what were the major deciding factors of staying with a single setup?
money could have been one but judging by the title of the thread i thought you were serious about twins and that wouldn't be a problem.
what other factors contributed to this? I was excited when i began reading this thread... only to find out your running another run of the mill 35r, it would be nice to see another well organized twin setup for reference
good luck witih the project though
08-24-09, 01:03 PM
#18
Currently, I have an Ebay to4b on an reworked, rewelded Ebay stainless manfold, with an Ebay HKS clone 40mm wastegate. Behind that is a crush bent mild-steel 3in exhaust with stainless magnaflow mufflers.
Despite all the crap that the ebay stuff get, this system works great and makes a lot of power.
My main plan here is to totally redo the engine and supporting systems to run E85, as it is readily available almost anywhere here in Minnesota and is dirt cheap.
Although my system works well now, Im concerned that if I just bolt up a gt35 and near double the horsepower, things are going to start breaking.
A T4 GT35 would bolt straight up to my existing system, so that makes things easy. But its also not nearly as cool as a twin system, and probably wouldn't make as much power or as broad a powerband.
I have been wanting to redo the exhaust in full mandrel bent stainless anyways for some time. Im redoing practically everything else on the car; new fuel system, full engine rebuild, new suspension, v-mount intercooler, body kit, the WORKS. so an extra $2k to make this happen is not the end of the world.
I'm also looking at the Gt2871R now as well, as its compressor are a little more capable, being able to push as much as 75 lbs (together) at 25lbs of boost.
Coleman, do you happen to have any pictures of your turbo manifold??
Despite all the crap that the ebay stuff get, this system works great and makes a lot of power.
My main plan here is to totally redo the engine and supporting systems to run E85, as it is readily available almost anywhere here in Minnesota and is dirt cheap.
Although my system works well now, Im concerned that if I just bolt up a gt35 and near double the horsepower, things are going to start breaking.
A T4 GT35 would bolt straight up to my existing system, so that makes things easy. But its also not nearly as cool as a twin system, and probably wouldn't make as much power or as broad a powerband.
I have been wanting to redo the exhaust in full mandrel bent stainless anyways for some time. Im redoing practically everything else on the car; new fuel system, full engine rebuild, new suspension, v-mount intercooler, body kit, the WORKS. so an extra $2k to make this happen is not the end of the world.
I'm also looking at the Gt2871R now as well, as its compressor are a little more capable, being able to push as much as 75 lbs (together) at 25lbs of boost.
Coleman, do you happen to have any pictures of your turbo manifold??
08-24-09, 08:48 PM
#19
so your saying the hot side is the problem on the Disco potato's which I can understand. I've had some trouble understanding turbine flow maps, and honestly dont really understand them at all.
I was looking at the Disco's compressor map, it would seam that a pair of them would be ideal (at least on the compressor side) for a rotary running up to 25lbs of boost. I'm not sure but I think 50-60lbs of air is about what my motor would be eating at that pressure ratio.
In addition, doesn't the use of ethanol negate the negative effects of higher EGTs because of the fuels colder burning temp. I live in Minnesota, the most E85 friendly state in the union, so this will be a E85 ONLY vehicle.
Thanks for your input, it is greatly appreciated.
I was looking at the Disco's compressor map, it would seam that a pair of them would be ideal (at least on the compressor side) for a rotary running up to 25lbs of boost. I'm not sure but I think 50-60lbs of air is about what my motor would be eating at that pressure ratio.
In addition, doesn't the use of ethanol negate the negative effects of higher EGTs because of the fuels colder burning temp. I live in Minnesota, the most E85 friendly state in the union, so this will be a E85 ONLY vehicle.
Thanks for your input, it is greatly appreciated.
thanks for all the info, it is much appreciated.
I'm starting to more lean toward a GT35R or GT40R, like I said, this is in a FB, and a Series 2, model S at that, I think the lightest Rx-7 ever made, and I've stripped a lot off of it.
I'm thinking I'm gonna stick with the single now, and probably go with the Gt35R, and push it as far as it will go. I've been reading through numerous old threads, and a few people have made over 500 with it. I think with the E85 fuel, a large street-port and a good tune and I can make 500 happen. Though twins are still in the back of my mind with the cool factor.
I'm starting to more lean toward a GT35R or GT40R, like I said, this is in a FB, and a Series 2, model S at that, I think the lightest Rx-7 ever made, and I've stripped a lot off of it.
I'm thinking I'm gonna stick with the single now, and probably go with the Gt35R, and push it as far as it will go. I've been reading through numerous old threads, and a few people have made over 500 with it. I think with the E85 fuel, a large street-port and a good tune and I can make 500 happen. Though twins are still in the back of my mind with the cool factor.
08-24-09, 11:25 PM
#22
I think thats the way I'm going to go. God knows I wont be putting down 550-600hp on a daily basis, even if the E85 is cool with it. In a 2500lb FB (with my 220lb *** in the drivers seat), that is just asking for trouble.
I'll probably run the boost as low as I can get it to go with the wastegates, and turn it up for the track or the strip, or to just throw down some rediculous numbers on the dyno.
I honestly want to be able to flip a switch on a two stage boost controller and be able to walk on vipers and the such whenever I feel like it
. I can taunt c5 corvettes right now, and its very addicting when I see there faces afterwards.
I'll probably run the boost as low as I can get it to go with the wastegates, and turn it up for the track or the strip, or to just throw down some rediculous numbers on the dyno.
I honestly want to be able to flip a switch on a two stage boost controller and be able to walk on vipers and the such whenever I feel like it
. I can taunt c5 corvettes right now, and its very addicting when I see there faces afterwards.
