SCM61- Turbine wheel questions

[Caithness]

I've seen several people who are using a different turbine wheel in their SCM61. I haven't found any concrete info explaining exactly what they're using, or what the difference in performance is between the wheels.

Looking at Precision's site, this is the wheel they list for the SCM6152, the standard T350 76 trim

2.795	2.437	76   T350

But if you go to the t3 flange turbo section, you find these possibilities:

600	SC-5252E	60mm	2.320"	3.000"	60	3" / 2"	360 Race	0.63	T350	2.795"	2.437"
630*	SC-6152E	61mm	2.416"	3.227"	56	3" / 2"	360 Race	0.63	T350	2.920"	2.420"
650	SC-6169E	61mm	2.416"	3.227"	56	3" / 2"	360 Race	0.63	T04	2.920"	2.420"
680	SC-6176E	61mm	2.416"	3.227"	56	3" / 2"	360 Race	0.63	T04	2.920"	2.542"
700*	SC-6369E	63 mm	2.476"	3.310"	TBA	3" / 2"	360 Race	0.63	T04	2.920"	2.420"
700*	SC-6376E	63 mm	2.476"	3.310"	TBA	3" / 2"	360 Race	0.63	T04	2.920"	2.542"

First off, you see the SC-6152 is offered with a different T350, which is a 69 trim. Then there are two different T04 options, a 69 and 76 trim, but the first one seems to be the same thing as the T350 69 trim!

Anyway, As far as I can tell from google searches, the 2.920/2.542 76 trim T04 is the P-trim wheel that many people have mentioned using instead of the T350 that comes in the SCM6152, the 2.795/2.437 76 trim T350. The primary purpose for creating this thread is to get user input on why you chose the P-trim wheel, what the rest of your setup is like, and how it affected spool and power production.

The second purpose is to see if anybody can clear up the confusion between the various T350 and T04 wheels listed, especially the "T350" with the same specs as the "T04" beneath it.

The third purpose is to fulfill my own selfish needs by asking what people think would be the best option for me. I'm going to be running a 2.0 with FP2x cams at first, with a max RPM of 9k. Then, down the road a bit, I'm going to do a 2.3 and switch over to the 3x's, with a max rpm of 8k. As the majority of P-trim users in the past were using it with a 2.3/2.4, I'd like to know how it will work on the 2.0, and also what benefits it has over the T350 on a 2.3.

 

[Initial DSM]

hey whats cookin..i my self have a scm6152e..very nice turbo spool up is great and made alot of power..if u go with the 6169 or the 6176 them turbine wheels might be alittle to big for a 2.0 ..thats what presion told me , u can go with a gt35 if u like its the same turbo as the sc6152e but has the same turbine wheel as a gt35r..but its non ball bearing the R stands for ball bearing ..what manifold u gonna be using still a mitsu flange ..then u need a scm6152e..that will be ## best bet

 

[Caithness]

Yeah, I'm going to be using my Evo III manifold for the forseeable future. If I went with a tubular manifold I don't know if I'd go T3, T4, or maybe even look for a divided T4 (do they even make these for our cars?) and just buy the proper housing... assuming a T4 housing will bolt straight up, as I haven't looked into it that far. I'd have a lot of research to do before making that move but that would probably be the last mod I'd make.

I haven't been able to find much info on the "GT35" turbine wheel. It seems like there's a lot of confusion about that wheel and I keep finding conflicting information in threads here. A guy on the local board said that it specs out to a 2.68" inducer and 2.44" exducer which would make it what, an 83 trim? Another guy in that same thread said it was worth 10hp and 100 rpm spool on a ~500 hp car. Supposedly you can order it for around another 100 dollars and if it were a straight T3 the name would be "GT3561". That's just another option, I guess, though just as with the P-trim there's disturbingly little information and real-world experience to guide me.

 

[Dark_Horse]

They do make T04 divided exhaust manifolds for our cars. http://ongreenperformance.com/Products/Specail%20Items/HKS%20T4%20Manifold.htm It's a bit tricky to get it to fit, but it's definitely possible.

 

[XakEp]

I'm actually wondering what anyone knows about the PTE SC-6376E turbo. Thoughts?

 

[Initial DSM]

Hi Hi

 

[1SloColt]

I run a sc61 with p-trim turbine wheel in a bullseye housing. The p-trim and bullseye housing spool around 4400rpm in 3rd gear on my stock longblock 2.0L. On 21-24psi it feels pretty solid, but the increase in power per 1psi of boost increase is not what you might expect. As soon as I start going over 24psi the power increase per 1psi boost increase is very noticable, as thats where the turbine housing/wheel combo must like it. The p-trim is very popular among t4 pt67s and and turbos of that size. The gt35 turbine wheel has a 2.453" exducer, and 2.67" inducer. (2.453^2)/(2.67^2) x 100 = 84 trim. The gt35 wheel flows better than a p-trim even though its dimensions are smaller. The t350 wheel is a decent wheel but with the precision housing on it you'll suffer some topend performance. The p-trim should be slightly laggier, nothing to worry about but it'll definitely flow better up top, along with a gt35.

 

[Caithness]

Thank you for the information. I've decided that when I'm ready to order the turbo I'll call around and get price quotes on the gt40 56/gt35 84. The p-trim upgrade seems to be about 50 bucks, if the gt35 upgrade is around 100, I'll go with that; basically get a standard bearing GT35R. I'll gladly sacrifice some transient response and a bit of spool for a $500-600 savings.

 

[1SloColt]

The 35r really doesn't spool much better than a sc61, maybe 100rpm from the 35r cars I've driven and worked on. But yes the transient response is a bit better, though my sc61 has really good response between shifts. When I race it there is zero time where it has to overcome lag and respool between shifts. Might as well go with a gt35, which runs a standard 360 degree thrust bearing, great turbo, just missing the reliability of the ballbearing center section.

 

[Caithness]

Yeah, I've heard 100rpm at most. I wouldn't buy a ballbearing turbo for the spool. The transient response doesn't bother me at all, because I've got a NLTS limiter.

 

[Dark_Horse]

What about something like this?
600hp dual ceramic BB center section that's rebuildable. Or they've got a 700hp BB version too.

 

[AndrewD5418]

So instead of creating a new thread, I hate bumping this but has anybody ever tried the sc61 with an o-trim wheel? It's smaller than a p-trim wheel on the exducer. Idealy how would the spool up be compared to the p-trim?

P-Trim
2.544" exducer & 2.922" inducer
64.6mm 74.2mm

O-Trim
2.296" exducer & 2.922" inducer
58.3mm 74.2mm

 

[JusMX141]

I'd imagine the O-Trim would have more backpressure than the P-Trim and the T350/52 being that the exducer is smaller. This would make it the least desireable of the three when paired to the GT40 compressor.

The P-Trim is just old tech....who cares about spool, a large wheel has to flow good, right? The T350/52 is a newer design which spools quicker and flows almost as much air as the P-Trim, so it would be the best choice of the three depending on your turbine housing choice.

What I never understood is why companies like Bullseye paired the P-Trim turbine to the V-and M-Trim compressors....way to pair a 60+lb/min turbine to a 40lb/min compressor. WTF

 

[Car Cannibal]

I have the 61/52S (61/62) in the PTE T4 .68 housing and it's a bear to spool on a rebuilt 2.0 with mods. Considering I'm auto and only getting 3200rpm on the footbrake, it's not the proper exhaust housing for sure or probably the proper ex wheel without Nitrous or the new 2 Step that's coming out.

If you're a manual, keep the stock heavy flywheel, get the studderbox and the new billet 60/62 turbo. It will spool the same but make more power, I'd consider the T4 .58 housing or the T3 .63 unless you're a track car.

It's a really powerful turbo but don't be fooled, it spools up pretty slow and the exhaust housing and wheel will determine your street fun factor.

 

[AndrewD5418]

I'd imagine the O-Trim would have more backpressure than the P-Trim and the T350/52 being that the exducer is smaller. This would make it the least desireable of the three when paired to the GT40 compressor.

The P-Trim is just old tech....who cares about spool, a large wheel has to flow good, right? The T350/52 is a newer design which spools quicker and flows almost as much air as the P-Trim, so it would be the best choice of the three depending on your turbine housing choice.

What I never understood is why companies like Bullseye paired the P-Trim turbine to the V-and M-Trim compressors....way to pair a 60+lb/min turbine to a 40lb/min compressor. WTF

61 series uses the 35r compressor wheel though.