Andial951

Is this turbo still available and if so can the above comment be proven?

Porschefile

Yep, it's still available. Proven how? With actual hp Porsche results? Not likely as too few have pushed the power limits that high with our cars and I have yet to see any posted info on actual stage 4 numbers. I'm basing my claims off of the measured size of the wheels, and the real world results I have seen of Precision Sc61's as well as other similar sized turbos on similar sized motors to ours. Once you know the wheel's inducer/exducer size, compressor housing size, and exhaust housing size that's all you really need to make a fair comparison. Short of a DBB center section, there isn't any "secret sauce" that can be done to the center section that will have some massive effect on power output or spool. The Sc61 comes with a larger turbine, so this stage 4 is only going to make LESS max horsepower. Let me reiterate, the turbos specs are the following:

Compressor - 61mm inducer / 82mm Exducer
Compressor housing - TO4E, 3" inlet, 2" outlet, .60 a/r
Turbine - 57mm inducer / 65mm exducer
Exhaust Housing - Turbonetics replica KKK #8 housing
Check the first page for pics of most of this stuff.

Take a look at Precision's Website You can see that the compressor specs match up to the SC61's, however the turbine specs match up to the SC6031E. Not to mention the compressor housing is a Precision Turbo housing. Just FYI but, the Sc61 uses a real gt35r compressor wheel. Check Here for the official Gt35r compressor specs. Also, you can see the 35r uses a larger 68mm 84 trim turbine.

Some people would have you believe that a Porsche is so "drastically" different that no comparison can be made with other cars, however that's false. It can give you a good general idea on power output capabilities. Things like head design can drastically affect this, though I didn't make any comparisons to Hondas or other cars that have insane cfm flowing heads which can cause a turbo setup to produce much higher than average hp numbers. Case and point, I've seen a few Hondas/Acuras pushing 680-690rwhp out of relatively small ~2.0L's. The displacement may be small, but when you have a modded motor that can rev to 9-10k rpm, you can actually take advantage of the efficiency of larger turbos like the 35r.

As for the Lindsey Super 75, just read the Description They say it's a 67mm 75#/min compressor wheel. The only Garrett wheel that matches those specs is a T4 T67 compressor. Also, check Lindsey's S75 Description . They even list the turbines that are available, so ultimately you have all the info necessary to get a good idea of what that turbo can do. In short, it is a T3/T67 hybrid, which is a huge friggin' turbo! With a larger #10 hotside you could technically push as high as ~650rwhp. Don't even get me started on the full T4/T67 LR offers (the T4 Super75)! That turbo is HUGE for a 4cyl, and capable of making in excess of 700rwhp under the right conditions (.81 or larger hotside). BTW, here is a link to a T3/T67 to give you an idea what I'm talking about Link.

To summarize everything, the stage 4 is basically a Precision Sc61/60 hybrid or a 35r compressor and T31 turbine. It's a 61mm compressor and 57mm turbine, whereas the Super 75 is a 67mm compressor and turbine is your choice of a T350 (61mm) or P trim T04 (64mm). The S75's wheels are physically larger by a pretty substantial amount, so logically it will only spool slower. The S65 basically has the same 61mm compressor side though I believe LR offers both a T31 and T350 turbine for their S65. I'm going to start searching and will try to find some dynos of various cars to post up, though it will take a little bit of time. I'd highly recommend searching on various forums like 240sx forums, srtforums, etc for Precision Sc61 dynos to get a general idea. Just remember the stage 4 is going to make slightly less power. Let me know if you have any other questions, and I'll see if I can find some dynos to better illustrate what I've talked about.

Pauerman

Very well said Porschefile. I only wish more guys around here would recognize your observations - good post.

333pg333

He's good like that!

Rogue_Ant

+1


Rogue

Porschefile

Thanks Pauerman, that means alot to me especially coming from you! Thank you as well Rogue_Ant and Patrick! Now, off to find some dyno charts.

toddk911

"In short, it is a T3/T67 hybrid, which is a huge friggin' turbo! "

Yes it is, but I still get 1 BAR by 3,900 and can still make power at 20+psi to redline

pk951

That's the kind of info we need more of around here.

toddk911

I have had several PM's with Porschefile and he is VERY knowledgable.

He also put to rest a lot of the "magic dust" crap for me at least, on some turbos on the market etc.

His approach also about the fact that having a "Porsche" engine as not making much of a differecne from many other motors is refreshing. Just keep the basics in mind.

IT'S AN AIR PUMP!!!

Porschefile

Todd, I hope you aren't taking that as a knock on your setup, as I never intended it that way. Personally, I think it's pretty cool! I love big turbos as they just pull so much harder than more "properly" sized stuff! A higher boost threshold isn't all that bad IMO since you ultimately just have to row the gearbox a bit more. It's all a matter of personal preference really.

toddk911

No not at all.

Was just commenting on the fact that for being such a big turbo and having so much top end capibility, it still has 1 bar by 3,900 give or take.

I have heard some in here with stock k26/8 having 1 bar only a few hundred revs sooner.

Also, as many have said it is all about "useable power" and how bad a big, laggy turbo is. When some turbos in here are getting 1 bar at 2,800 or so and saying "tires spinnning even in 3rd gear"

Well, to me that is not useable power if you have to baby the throttle to get traction beause boost comes on so low. Or have to make sure you or going in a straight line before going WOT. There is a name for that.....it's called a 1/4 mile car

Porschefile

Actually, I'm pretty impressed with that low of a boost threshold as well. To be honest, I was originally expecting 1bar around ~4k with my 35r, though now I'm starting to suspect it might be a tad bit lower around the 3.7-3.8k range if not a bit better. I would've thought the S75 would be laggier, though maybe that's cause I'm too used to seeing the full T4 variants on Supras w/ .81 exhaust sides making 1bar around 3.8-4k rpm. That's not an accurate comparison to the S75 though since the full T4 flows quite a bit more air, though I still fall into the bad habit of thinking that way sometimes.

I have the same way of thinking. Personally, I don't feel the need to "race" from stop light to stop light or at least use the low-end power in such a manner when daily driving. I'm a little more laid back daily driving at lower speeds. I'd personally rather wait a little longer for boost, have the huge sledgehammer-to-the-chest acceleration from a bigger turbo, and have a better top-end powerband. I really don't mind a slight decrease in low-end as it's just a matter of shifting more (which I find to be fun anyways, I hate auto's!)and I rev my 951 out to 6-6.4k pretty often. I think, possibly, I may have been poisoned in this regard by my association with Supra guys early on.

toddk911

So assuming good tuning/chips, what do you think is a good level of boost to run my 75 at and still be in it's eff. range???

18, 20, 22, 25 ???

Porschefile

On the S75 the main thing I am am unsure of, which could have a drastic effect on efficiency and max boost levels, is the hotside. I am not entirely sure, but the #8 hotside appears to me to be about the size of a Garrett ~.60a/r T3 exhaust housing (possibly a little smaller like ~.58a/r. I have yet to verify this, however if that's the case it would certainly make sense for the spool levels you are seeing and it would severely limit the ultimate hp that the compressor is capable of. Speaking theoretically, if an optimal size exhaust housing was used (figure a T3 .82 or larger) then this turbo would be capable of handling around the ~25-30psi level. However, at that point then the real question is can the rest of your setup handle it. With a properly sized hotside to minimize backpressure at higher boost (typically a T3 .82 or larger 1.xx a/r, also probably at least a stg5 or t04 turbine), as I've mentioned before the S75 can produce airflow to support between 600-650rwhp at which point there are a ton of durability issues you'd be facing assuming you have all of the proper engine work to generate power at that level. So, please don't take my theoretical suggestions to mean that you should run 25+ psi as your engine might not be equipped to handle it yet for all I know. If the #8 housing is really only around the ~.60a/r range then I think you will start to max out closer to the 22-25psi range as you would then be seeing a huge amount of backpressure. I'm sorry I can't be more specific, but I am still not too sure on the sizing of KKK exhaust housings as they relate to the Garrett a/r standard that I am more used to. I think I will go do some research as this would certainly be good info to know.

333pg333

Well that's interesting as my K26/8 is about 3700-3800 for 1 bar provided I can trust my apexi ebc and my stock tacho. Also a very good point that seems to get severly neglected here. TRACTION. There is a proliferation of people saying that we should look for low down torque instead of upper range hp, but how much is too much? If we have all this power down low and run out of puff up top how do we put it onto the road? Mid-upper is my new catchcry.