scm61 spooling at 6k!?!?!

[1sick91tsi]

Ok heres the problem the turbo just doesnt want to hit ful boost until 5800-6000. Once its there the car freaking flys!! I have it set at 23 psi and I can seem to figure out why its spooling so late. I have no exhaust leaks that I can find, and the car has no boost leaks. What could it be? And also is there anything I can do to improve spool up? Here are my mods and thanks for all the help guys!!!!


stock block with 120k, arp head studs, fp2 cams, pte scm61, full 3' magnaflow exhaust, ported 1g o2 housing, test pipe,custom 3in intake pipe, magnecor plug wires, k&n air filter,2g maf, 650cc injectors, turbonetics extranal gate, 2g ported ex.manifold, halman boost controler, fluidyne rad, slim line fan, buschur front mount with short route piping, greddy type s bov, 2g o2 housing, s-afc, key diver stage 3 chip with extended fuel and timing maps, data logger, autometer egt gauge and boost gauge,

 

[95redgsx]

sounds about right , I have an agp 61 w/4bolt t/3 exhaust housing and a custom tubular manifold .63 a/r and I get full boost around 5300-5500 rpm . a tubular mani and or a garrett exhaust side will help spool a little bit

 

[1sick91tsi]

i was thinking about the tubular header but i need to find on that will work with my wastegate. did u swap the header on after you had the car running or all at once kind of thing. just trying to find out if the header actually helped for sure. thanks agian karl-

 

[92awddsm]

garrett exhaust side will help spool a little bit

Actually, a garrett turbine housing(unless it is a .48a/r) will hurt spool. A pte scm turbine housing is roughly a .52-.55a/r. A garrett .63 a/r turbine housing will decrease spool by about 3-500 rpm.

With the scm 61 spooling that slow, I would check cam timing and a/f ratio. With the ex cam off a tooth or 2, spool will be slow but top end will be outragous. With a rich fuel mixture in the mid range, spool will also be slow. Do you have a wb o2 to check a/f ratio? I am running a scm 5252e which is a 60-1 with the same turbine wheel(p-trim) as the scm 61 but an ever so slightly smaller compressor wheel. I see 25psi by 4300 rpm with an 11.8-1 afr with a similar setup as you.

 

[GVR4592]

I think that's way off, I just looked at some Dsmlink datalogs of SCM61's on stock 2.0's, and they were spooling up around 4500-4800. I know it gets old hearing this but, how did you check for boost leaks? Are you sure there are no exhaust leaks pre-turbo? What spring are you using in your wastegate and where is the wastegate mounted? Can you post a datalog of a 3rd gear run from around 3000 rpms?

 

[95redgsx]

i was thinking about the tubular header but i need to find on that will work with my wastegate. did u swap the header on after you had the car running or all at once kind of thing. just trying to find out if the header actually helped for sure. thanks agian karl-

I did every thing at once so I cant say for shure how much quicker it made it spool . on a side note the same exact turbo hit full bost by 3500 rpm on my srt4 . guess the bigger displacement really helps spool

 

[GVR4592]

Actually, a garrett turbine housing(unless it is a .48a/r) will hurt spool. A pte scm turbine housing is roughly a .52-.55a/r. A garrett .63 a/r turbine housing will decrease spool by about 3-500 rpm.

With the scm 61 spooling that slow, I would check cam timing and a/f ratio. With the ex cam off a tooth or 2, spool will be slow but top end will be outragous. With a rich fuel mixture in the mid range, spool will also be slow. Do you have a wb o2 to check a/f ratio? I am running a scm 5252e which is a 60-1 with the same turbine wheel(p-trim) as the scm 61 but an ever so slightly smaller compressor wheel. I see 25psi by 4300 rpm with an 11.8-1 afr with a similar setup as you.

The PTE Mitsubishi housing is .63 A/R. A/R doesn't really mean much though, it's like saying, "I have a 50 trim". You can have a 50 trim that flows 49 lbs/min or a 50 trim that flows 95 lbs/min. It's a ratio, and it isn't an indicator if size.

 

[1sick91tsi]

"92awddsm" i think you might have the best idea, the car is running rich. i had it set rich for saftey measures but if you say leaning it out may help sool up i will try that. i know that there isnt any boost leaks, i have tested it already. are you running a stock ex. manifold by the way? oh and the wastegate spring is set so it opens at 12 psi. its mounted on tnumber one runner of the manifold as well. thanks guys

 

[Tom N]

That spool is slow for that turbo.
I agree with the checking the cam timing and a/f.
There is a problem there.
I can spool a GT35 to 30psi before 5k on a 2.0
Also a equal length tubular will help top end but dont expect to see any quicker spool with one over a factory manifold.

 

[1sick91tsi]

im pretty sure the timing isnt off but i will check. and i know the car is running rich in the mid range so i will try leaning it out and see what happens. is there anything elese i should look for to help with spool? thanks for all the help guys it really appriated.

 

[95redgsx]

a gt35r uses the same compressor wheel and its bb , I can see how it would spool quicker

 

[Tom N]

a gt35r uses the same compressor wheel and its bb , I can see how it would spool quicker

I did not say I had a GT35r. I said I had a GT35 which is not BB. And yes it has the same 56 trim compressor wheel. Which is why I used it as a example.

 

[92awddsm]

The PTE Mitsubishi housing is .63 A/R. A/R doesn't really mean much though, it's like saying, "I have a 50 trim". You can have a 50 trim that flows 49 lbs/min or a 50 trim that flows 95 lbs/min. It's a ratio, and it isn't an indicator if size.

I know that, Im no newbie to dsm's or turbo's for that matter. The pte is advertised at .63 a/r but has been proven to only be a .52-.55 a/r. This has been covered many times and someone always has to disagree because pte "advertises" it as a .63 a/r. On the same note, comparing apples to apples, a larger a/r on the same turbine housing will increase volume on the convolute of the turbine housing which decreases velocity and increases spool time. Now, take a pte ".63" a/r turbine housing and compare it to a .63 a/r t3 garrett turbine housing and spool is a lot slower on the garrett housing but with higher rpm flow characteristic. I wasnt comparing the a/r of the 2 housings, I was stating what they were and how they differ in spool times. I was making a correction to "garrett exhaust side will help spool a little bit" with "Actually, a garrett turbine housing(unless it is a .48a/r) will hurt spool. A pte scm turbine housing is roughly a .52-.55a/r. A garrett .63 a/r turbine housing will decrease spool by about 3-500 rpm." This statement was based on both factual information and personal experience.

And yes, Im running a ported and coated 2g manifold.

 

[GVR4592]

I would like to see where it was proven that the PTE housing is .52-.55 A/R. I'm not arguing with you, I just need to see some sort of evidence that supports the statement.

 

[92awddsm]

I would like to see where it was proven that the PTE housing is .52-.55 A/R. I'm not arguing with you, I just need to see some sort of evidence that supports the statement.

I have seen it a couple of different times but didnt make a mental note when I saw it. When I do run across it again, I will send you some links.

 

[T9S1i]

oh and the wastegate spring is set so it opens at 12 psi. its mounted on tnumber one runner of the manifold as well. thanks guys

my advice would be to get a stiffer spring for your wastegate. If its opening at 12psi then thats most likely the problem. What wastegate are you using?

Remember the wastegate diverts exhaust gases that spool the turbo from spooling the turbo, so you dont want that to happen until you are at full spool. Id go for a 15-20 psi spring if you are going to run over 20psi of boost.

Also, are you using a boost controller or just running it off the wastegate? Are you sure its hooked up correctly if so?

 

[1991GSXAWD]

Something doesn't sound right, I have the same exact turbo, at 4500 it really starts coming to life and should reach your desired boost by 5000 rpms, I would say that your timing is off or you are way too rich, do you have any logs? I'm also running Keydiver chip ( 2 Maps). where is your static fuel pressure set at? Exhaust cam off a tooth? As far as exhaust housing goes, for street use the "M" housing works better.

 

[Slippi84]

The PTE Mitsubishi housing is .63 A/R. A/R doesn't really mean much though, it's like saying, "I have a 50 trim". You can have a 50 trim that flows 49 lbs/min or a 50 trim that flows 95 lbs/min. It's a ratio, and it isn't an indicator if size.

Trim and a/r are not a like. As long as your talkin about the same type of housing(t3,t4,bolt on) a/r is directly related to spool and top end. While yes saying I have a 50 trim doesn't mean much as it's a ratio when talkin about t3 hosuing which seems to be the case in this discussion saying it's a .55 over a .63 is important and relevant.

 

[1sick91tsi]

ok thanks for the help guys looks like i had a leak at the wastegate, and a small one at the turbo to manifold in the back, would have never known if i had not taken it off. now its hitting full spool at 5k. sound about right?

 

[Newlogics]

Ok heres the problem the turbo just doesnt want to hit ful boost until 5800-6000. Once its there the car freaking flys!! I have it set at 23 psi and I can seem to figure out why its spooling so late. I have no exhaust leaks that I can find, and the car has no boost leaks. What could it be? And also is there anything I can do to improve spool up? Here are my mods and thanks for all the help guys!!!!


stock block with 120k, arp head studs, fp2 cams, pte scm61, full 3' magnaflow exhaust, ported 1g o2 housing, test pipe,custom 3in intake pipe, magnecor plug wires, k&n air filter,2g maf, 650cc injectors, turbonetics extranal gate, 2g ported ex.manifold, halman boost controler, fluidyne rad, slim line fan, buschur front mount with short route piping, greddy type s bov, 2g o2 housing, s-afc, key diver stage 3 chip with extended fuel and timing maps, data logger, autometer egt gauge and boost gauge,

Something doesn't add up here. If you're running 2G mani and 1G 02 housing, where exactly is external wastegate mounted?

 

[Coup D E'Tat]

To add another reference, I spool a .63 T3 SC61, 20PSI by 4500 in third with FP2's and a SMIM on stock 7.8:1. With sometiming adjustments, it may dip lower than that.

Just a thought for the .63 vs. bolt-on spool discussion.

 

[GVR4592]

Trim and a/r are not a like. As long as your talkin about the same type of housing(t3,t4,bolt on) a/r is directly related to spool and top end. While yes saying I have a 50 trim doesn't mean much as it's a ratio when talkin about t3 hosuing which seems to be the case in this discussion saying it's a .55 over a .63 is important and relevant.

That read's similar to a post I made a couple months ago.

http://dsmtuners.com/forums/showthread.php?t=231083&highlight=turbine+family

I'm well aware of this, and we weren't comparing housing of a single family, it was a comparison of Garrett T3 and PTE Mitsubishi.

 

[1sick91tsi]

waste gate is mounted on #1 runner of the 2g ex. manifold.