Full-Race Twinscroll 35R + AMS 2.3L + GBR Race Team Build = FAT powerband
Jul 16, 2009, 08:08 AM
#17
Newbie
Join Date: Dec 2008
Location: USA
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
Geoff,
I have been following the development of twin scroll for a while now, and I'm very interested. But I'm troubled by always seeing the torque dropping sharply after 5500 rpm. Do you now if cams are causing that or is it backpressure in the turbine? What are some backpressure ratios for your twin scroll setups, especially the 1.06 35R's?
I appreciate any info...
Thanks!
I have been following the development of twin scroll for a while now, and I'm very interested. But I'm troubled by always seeing the torque dropping sharply after 5500 rpm. Do you now if cams are causing that or is it backpressure in the turbine? What are some backpressure ratios for your twin scroll setups, especially the 1.06 35R's?
I appreciate any info...
Thanks!
Jul 16, 2009, 08:51 AM
#19
In this particular case, the engine is fitted with BC 280 cams, which fared somewhat poorly in comparison to some other cam sets (see: AMS Cam Test), so that could be one attenuating factor. On the other hand, we have to take the torque curve in context with the PR and effiency of the compressor and limitations of the factory head (especially with stroked setups). In other words, the greater the torque, the sooner it is likely to begin tapering, which can create an illusion if we compare a given curve to one whereby the engine generates less torque, albeit with a flatter curve.
Finally, I agree that monitoring PR on the turbine side of such tests would add greatly to the TS discussion. I'm going to consider doing that myself.
Jul 16, 2009, 01:52 PM
#21
Evolved Member
yah, they are very similar. Sure, post up that t/a car's dyno sheet.
I think that you should also start doing testing with the exact same size turbo's, one being twin scroll and one being the normal single scroll and use stock motor evo's (sponsor 2 stock guys, one single, one twinscroll) and show the public precisely what the twinscroll does on the dyno and more importantly at the track, imho.
does a twinscroll really help a drag racer? I think if you can prove that point, there will be a lot more believers..most big hp guys are drag racers anyway
(yes many do believe, but some STill don't(dave buschur for one), I understand this is not what the threads about...but let's just see how a twinscroll time attack car does against the single scroll cars..i think through the curves it could really make the awd shine)
Sadly, the subi 2.5 should be outshining the 2.3 stroker evo, but it's not. The subi's just never last with big power :sigh:
I think that you should also start doing testing with the exact same size turbo's, one being twin scroll and one being the normal single scroll and use stock motor evo's (sponsor 2 stock guys, one single, one twinscroll) and show the public precisely what the twinscroll does on the dyno and more importantly at the track, imho.
does a twinscroll really help a drag racer? I think if you can prove that point, there will be a lot more believers..most big hp guys are drag racers anyway
(yes many do believe, but some STill don't(dave buschur for one), I understand this is not what the threads about...but let's just see how a twinscroll time attack car does against the single scroll cars..i think through the curves it could really make the awd shine)
Sadly, the subi 2.5 should be outshining the 2.3 stroker evo, but it's not. The subi's just never last with big power :sigh:
Jul 16, 2009, 02:33 PM
#24
yah, they are very similar. Sure, post up that t/a car's dyno sheet.
I think that you should also start doing testing with the exact same size turbo's, one being twin scroll and one being the normal single scroll and use stock motor evo's (sponsor 2 stock guys, one single, one twinscroll) and show the public precisely what the twinscroll does on the dyno and more importantly at the track, imho.
does a twinscroll really help a drag racer? I think if you can prove that point, there will be a lot more believers..most big hp guys are drag racers anyway
(yes many do believe, but some STill don't(dave buschur for one), I understand this is not what the threads about...but let's just see how a twinscroll time attack car does against the single scroll cars..i think through the curves it could really make the awd shine)
Sadly, the subi 2.5 should be outshining the 2.3 stroker evo, but it's not. The subi's just never last with big power :sigh:
I think that you should also start doing testing with the exact same size turbo's, one being twin scroll and one being the normal single scroll and use stock motor evo's (sponsor 2 stock guys, one single, one twinscroll) and show the public precisely what the twinscroll does on the dyno and more importantly at the track, imho.
does a twinscroll really help a drag racer? I think if you can prove that point, there will be a lot more believers..most big hp guys are drag racers anyway
(yes many do believe, but some STill don't(dave buschur for one), I understand this is not what the threads about...but let's just see how a twinscroll time attack car does against the single scroll cars..i think through the curves it could really make the awd shine)
Sadly, the subi 2.5 should be outshining the 2.3 stroker evo, but it's not. The subi's just never last with big power :sigh:
Jul 21, 2009, 12:03 PM
#26
hey guys -- thanks for the discussion, if anyone is interested we are having our annual SUMMER SALE WITH THE BEST PRICES WE"VE EVER OFFERED. huge discounts on twinscroll manifolds/kits, stock location headers/FP turbo combos, etc. check it out: https://www.evolutionm.net/forums/ev...ml#post7288543
if youre building a time attack car, the twinscroll 35 is REALLY a dialed setup out-of-the-box. IMHO (and mike specks fwiw) the Full Race twinscroll 35 is the most competitive turbokit available for a time attack evo
thank you very much for acknowledging that 
yeah, the compressor is definitely happy at 22psi! It will be really interesting to see the setup with a more optimal set of camshafts ..
the FP red is certainly a great performing turbo -- after all its a twinscroll, dual wastegate turbo! The reds work great, especially with our prostock tubular manifolds 
(we are having a killer sale on these combinations right now!).
while the stock location turbos do work great, they are not cheap and make it really difficult to upgrade further or swap in different turbo components... thats where the Twinscroll T4 setups really make sense. They are exceptionally versatile since any turbo from Garrett, Borgwarner, Turbonetics, ITS, FP, preicsiion, etc will all bolt up.
i believe the fuel used was 100octane unleaded, but i will find out for sure
hey jalal -- did you happen to see Indub's 40R evo? that was a 2.4L and is a complete monster... my rb26 is worked to hell and is head-to-head with his 40R evo...
great comments anders -- you are absolutely correct that dropping torque on a twinscroll setup is indicitive of exhaust flow restriction (ie backpressure). this can be caused by camshafts, turbine housing, turbine wheel, downpipe, exh, etc. Obviously, if this vehicle's torque held flat to redline this car would be making obscene power at low boost. there are a couple things to consider:
-the cams are obviously not optimal. Fortunately the guys at GBR know what theyre doing and they degreed the cams in to get them working right... this meant adjusting the cam gears 7 degrees. I think this is a major factor and while this customer is very happy with the setup so doesnt want to make any changes just yet, I am eager to see the results of putting in a better set of 280s (like kelford or tomei) and then dialing them in on the dyno. FWIW the cams were quite poor performers with the stock cam gears... dialing cam gears in is critical IMHO.
-the 35R turbine wheel is a fantastic design and works remarkably well for its size. The only issue currently is the availability of twinscroll turbine housings for it. Garrett has promised they will release some new housings in 2010, but for the time being we have 1.00 a/r and 1.06 a/r to choose from, and in my opinion they are both a little bit small/restrictive at higher boost for the 35R -- hence the reason we usually do not recommend twinscrolling the hta turbos. For anyone who wants more power than this can provide the 63mm GT4088R is an excellent option. Weve proven the twinscroll 40R to spool as fast as many singlescroll 35R setups out there, yet it PUMPS air and makes some pretty big power. Mark Shead at MADevelopments in the UK uses our twinscroll 40R kit on his time-attack winning machine
-this car is making massive torque early as ted mentions and its on a stroker motor, so the torque dropoff looks even more severe. FWIW you should take a look at 2JZ supra engines, they drop off even harder especially with stock heads/intake manifold (ill put a bw vs garrett 2jz comparison up we just finished)
great to see you here ted, hows the twinscroll setup workin - any updates planned for this summer?
keep in mind, if you want to twinscroll any of the HTA turbos they can work well, but i believe the twinscroll 40R would make more sense...
thank you very much for acknowledging that yeah, the compressor is definitely happy at 22psi! It will be really interesting to see the setup with a more optimal set of camshafts ..
(we are having a killer sale on these combinations right now!). while the stock location turbos do work great, they are not cheap and make it really difficult to upgrade further or swap in different turbo components... thats where the Twinscroll T4 setups really make sense. They are exceptionally versatile since any turbo from Garrett, Borgwarner, Turbonetics, ITS, FP, preicsiion, etc will all bolt up.
hey jalal -- did you happen to see Indub's 40R evo? that was a 2.4L and is a complete monster... my rb26 is worked to hell and is head-to-head with his 40R evo...
-the cams are obviously not optimal. Fortunately the guys at GBR know what theyre doing and they degreed the cams in to get them working right... this meant adjusting the cam gears 7 degrees. I think this is a major factor and while this customer is very happy with the setup so doesnt want to make any changes just yet, I am eager to see the results of putting in a better set of 280s (like kelford or tomei) and then dialing them in on the dyno. FWIW the cams were quite poor performers with the stock cam gears... dialing cam gears in is critical IMHO.
-the 35R turbine wheel is a fantastic design and works remarkably well for its size. The only issue currently is the availability of twinscroll turbine housings for it. Garrett has promised they will release some new housings in 2010, but for the time being we have 1.00 a/r and 1.06 a/r to choose from, and in my opinion they are both a little bit small/restrictive at higher boost for the 35R -- hence the reason we usually do not recommend twinscrolling the hta turbos. For anyone who wants more power than this can provide the 63mm GT4088R is an excellent option. Weve proven the twinscroll 40R to spool as fast as many singlescroll 35R setups out there, yet it PUMPS air and makes some pretty big power. Mark Shead at MADevelopments in the UK uses our twinscroll 40R kit on his time-attack winning machine
-this car is making massive torque early as ted mentions and its on a stroker motor, so the torque dropoff looks even more severe. FWIW you should take a look at 2JZ supra engines, they drop off even harder especially with stock heads/intake manifold (ill put a bw vs garrett 2jz comparison up we just finished)
In this particular case, the engine is fitted with BC 280 cams, which fared somewhat poorly in comparison to some other cam sets (see: AMS Cam Test), so that could be one attenuating factor. On the other hand, we have to take the torque curve in context with the PR and effiency of the compressor and limitations of the factory head (especially with stroked setups). In other words, the greater the torque, the sooner it is likely to begin tapering, which can create an illusion if we compare a given curve to one whereby the engine generates less torque, albeit with a flatter curve.
keep in mind, if you want to twinscroll any of the HTA turbos they can work well, but i believe the twinscroll 40R would make more sense...
Last edited by Geoff Raicer; Jul 21, 2009 at 12:07 PM.
