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Once again - we are in agreement.
Maybe you are my long lost brother, Wayne.

Porschefile

Precision's stuff is made from Garrett components. Precision just makes their own compressor/turbine housings (which are actually pretty nice compared to stuff like Turbonetic's housings) and a few different custom wheels. Just FYI:

Precision SC50

Precision SC50R (Same as above but ball bearing t3/t4r center section)

Lindsey Super 48 (Courtesy of Frank@Work)

Notice any similarities? The wheels and compressor housings are identical. The center section would be too, though I believe Frank's Super 48 has the oil only center section. The SC50 series are just 50 trim t3/t4's. To be honest, I might be a bit off. I'm positive they are Precision turbos, however Precision carries a large number of different wheels in the 50-63mm range so, instead of a 50 trim, it very well might be a SC32 which is slightly larger than a 50trim, and is a 55mm 54 trim. Either way, they are definitely Precision based. Here's some Precision links in case anyone's interested:

Easy to read turbo chart This one has a few typos such as the SC34 being listed as a 57trim when it's really a 56trim, but it's close enough and at least it's an easy chart to reference.
Most up to date but harder to read turbo chart

Although I have no substantiating evidence to support it, it's also my belief that the following turbos are Precision based:

Super 61 -> SC60
Super 65 -> SC61 (has a real Gt35r compressor wheel)
Super 75 -> SC67
Super 85 -> I have no idea but, that monstrosity must be a 70-72mm T4 Compressor to move that ridiculous an amount of air (85lb/min)! Mad props to anyone with the cojones to use one!

I wish LR would carry some of Precision's other SC series turbos as there are some pretty nice ones out there, such as the SC34R which is a ballbearing 56trim, basically a Gt30r, but with the right center section to make for an easier install on a 951.


Attyjeff, you might consider having Lindsey install a #10 housing on your turbo, as that should help you a decent amount towards reaching your goal. The turbo itself isn't exactly "small" however that exhaust side is fairly restrictive. That will drop the necessary pressure ratio down a bit too so you wouldn't have to run stratospherically high boost pressure or anything. Anyways, just giving another point of view. It doesn't take a monster turbo like the Super 75 to accomplish what you're looking for.

attyjeff

this has been very interesting, I wonder if L/R would take a trade in on my super 48, its not that old, I think I may want the super 65 after reading all of this, mmmm, I am wondering about the web cam now, and if I get the super 65 and the web cam, do I have to change the lifter springs ect?

Geneqco

Thanks ST... So TQ should peak at 4500 rpm and you should reach max boost by 3700 rpm.

I guess if you wanted to use a smaller turbo to have max boost earlier... you could do that with peak TQ still at the optimal 4500 rpm but the downside would be lower HP - ie, TQ would drop off more in the upper rpm range?

Geneqco

So PF, are you saying the Super 65 uses the Gt35r compressor wheel, or that you think it might?

Obviuosly the GT DBB get some benefit from its DBB design, but do you think most of the benefit is from the wheels used? If so, do you think the Super 65 might not be that far behind the Gt35r in terms of its spool characteristics etc?

You also mention Precision's SC series and give SC34R as an example of an 'easy fit Gt30r'... are there other 'easy fit equivalents' in this series?

Why the disappointment LR doesn't carry them, can't you just source them elsewhere or does LR modify them to make them easier to fit?

evil 944t

Yes, you can buy them directly from Precision.

Geneqco

Hope you don't mind another question ST... I'm really just wondering how soon you'd want boost to peak... or what level of boost you'd want by what rpm assuming you had good suspension setup and 11" wheels with widest tyres to fit w/ouy body work. In other words, if your looking at maximum acceleration rather than just a lot of wheel spin (I don't want to trade top end for wheelspin but am happy to trade top end for acceleration), how should your boost curve look?

Thanks

A.Wayne

30-35 psi between 3900-4300 , with shifts at 7800 rpm , life really starts at 30 psi by 40 psi, you will experience a slight narrowing of your vision , scary at first , then you realise , this is what it's all about, I want to be here... Boost there really is no substitute , PsssT

333pg333

Scott,
You can certainly trade top end for acceleration by switching out to an S2 cw&p and putting in one of those nice lsd's + some suspension that allows you to apply power with the least amount of wheelspin.
I have to finish this by saying that my KW's are not proven over say 300hp so I am not speaking from that point with any authority. I am basing this on my experience with the former engine and quite a few other owners of KW's (mostly UK) but we will have to wait a few weeks more to try in excess of 400whp. I am still very confident though.

Porschefile

Attyjeff, the Super 65 with a T350 (stage 5) turbine and #10 or larger housing is a real 600whp potential turbo. IMO, that's a bit overkill for 400whp. Something smaller with a T31 (stage 3) turbine and larger hotside (#10) would work fine. I just noticed the other day that LR is offering a new turbo now, the Super 53, though unfortunately they say it only comes with the T350 turbine which is overkill for anything less than 500whp. If you can get a #10 turbine housing put on your Super 48, or maybe get LR to do a T31 and #10 on the Super 53, either of those would allow you to break 400whp without too much trouble. IMO, the T350 turbine should never be used on any 4 cylinder that won't see above 500whp as it will just add unnecessary lag. Same goes for the P-trim T4 turbine, which really shouldn't be used on any 4cylinder below 500-600whp. Hell, I wouldn't use a P-trim onm a 4cylinder unless you were looking for more like 650-700+whp as the T350 would work fine and be significantly less laggy. Motors with more cylinders and/or significantly larger displacement are another story entirely though.

IMO, it's also a bad idea to get a turbo that is a combination of fairly large wheels (like the Super 61, 65, and 75), but restrict it with something ridiculously small like the #8 turbine housing (I can't even believe LR offers the #8 on those). Ultimately, that leads to a setup that is laggier than necessary, has more backpressure than necessary, has extreme turbulence in airflow which leads to obvious problems, etc etc. Nine times out of ten there are smaller turbos that will get the job done MUCH more efficiently. Cramming big wheels in small housings leads to poor airflow characteristics that really doesn't serve any purpose. Things like compressor wheels need a proper diffuser area in it's housing to properly accelerate the airflow with minimal restriction. Not having a properly sized housing will have the air slamming into the housing walls at odd angles which will lead to significantly increased back pressure, decreased power output, and the list goes on. While it can and will make a huge turbo spool up a little bit better, it will still not spool anywhere near as fast as a smaller turbo that is properly sized. Just FYI for the future, all of the Super 61, 65, and 75 series turbos with a T350 or P-trim and a #10 or T4 hotside are all 500-650+whp turbos. Anyone using those turbos for no more than 350-450whp could get away with significantly smaller turbos and have significantly better response. Doing so, with something like a #10 or T3 .63a/r or T3 .82a/r would still provide better response than a big turbo with a small turbine housing, and the top end curve wouldn't look so bad. I just wished someone made a simple conversion for these cars (maybe a crossover and turbo mount or something) to use standard Garrett T3 hotsides as that would make things quite a bit easier.

Porschefile

The Precision SC61 series does in fact use a Gt35r compressor wheel, and Precision even acknowledges this (can't remember where I saw it though). To be honest, I'm not entirely sure what percentage of the GT series improvements are as a result of the center section or the new wheels. I'd tend to think it's probably pretty close to a 50/50% for each. Ball bearing center sections almost always improve efficiency as a basic rule because they usually maintain much tighter clearances on the shaft therefore the entire rotational assembly is kept from having much play. The reason that increases efficiency is because as the rotational assembly is spinning at say 100-150,000rpm, any small amount of play can have huge amounts of drag on the shaft as it rotates "out of round" against the bearing walls. Needless to say, that can result in a huge parasitic loss and the turbo would have to work significantly harder to maintain the same pressure.

IMO, the SC61 or Super 65 with a ball bearing center section is close enough to a Gt35r that it should provide you with ~90-95% or more of the same performance a Gt35r would. The turbine is very similar sized to a Gt35r's as well. The only major difference is what turbine and compressor housing are used. Gt35r's come from Garrett as standard with a T04S 4" .70a/r compressor housing. Adding a smaller T04E 3" like on the LR turbos and a different turbine housing like the Turbonetics KKK replicas will have some different effects on the overall nature of the turbo compared to a true Gt35r, but it should still provide relatively the same response (assuming a DBB center section, though I don't know if LR offers this) and overall performance/power output as a Gt35r with similar sized Garrett housings. In the import world, I have lots of acquaintences that have used the SC61 and many of them have found that there really isn't any significant difference in performance from a 35r, at least not enough for the price difference.

Well, it's not disappointment really. I like LR's turbo prices and it looks like they are offering some nice stuff. I'm just very particular about everything so I always manage to find something to complain about. I only say I'd wish they'd offer the entire Precision SC lineup as I think having more options is always a good thing. Other than that, lately I'm on a bit of a tangent over the K26 turbine housings after finding out some shocking info from various individuals such as Pauerman. I guess it just never clicked in my mind until now but, K26 housings are somewhat comparable in overall size to Garrett T25 housings, or maybe just a bit bigger than that however they are definitely smaller than T3 housings. They're much too small IMO.

The Precision SC34R is very similar to a Gt3076r. Here are the following measurements:

SC34R - Comp. 56mm (Inducer) / 75mm (Exducer) 56 Trim, and 56.6mm turbine Exducer

GT3076R - Comp. 57mm (Inducer) / 76.2mm (Exducer) 56 Trim, 60mm turbine Exducer

Anyways, both of the turbos have similar sized wheels and are rated at similar power outputs. The difference is all of the SC series turbos have a standard sized Garrett T3 center section with all of the same basic dimensions. The standard T3 center section is what's on all of the LR turbos, and the nice thing there is that means it has the proper oil outlet flange pattern (check out the links I posted above for pics of the SC series center section) to bolt to our stock motor mount. The GT series center section is smaller in diameter, therefore it sits too low to physically bolt to the mount unless the alternator is repositioned. That means all of the SC series technically would fit without too much effort. It seems that most t3/t4 turbos people are using on their 951's with a 3" T04E compressor housing have to do a bit of grinding on the housing to fit it under the stock throttle body and intake, so it's not a 100% perfect fit, but it's certainly close enough that it's worth considering.

Turbonetics replica KKK housings are designed for the standard Garrett T3 center section and they have different housings for different turbines (stock k26 as well as Garrett stage 2, 3, and 5 turbines). The KKK replica info is at the bottom of this website Lindsey's prices are nice considering you really couldn't do it for hardly any cheaper yourself, and it sure would save you a lot of trouble but, it's certainly nice to know that it can be done on your own for those that like going that route.

I myself am considering going with an SC3431RE (SC34R) with a T3 4 bolt .82a/r hotside as it would bolt to the stock downpipe, or others designed for the KKK housing and then it would only be a matter of modding the x-over with a T3 flange as well as the other typical compressor housing fitment issues. After finding out what I have about the #10 housing, and how it is about the size of a T3 .63a/r (close enough anyways), I'm looking for a bit more exhaust side flow then that so I think I'm going to stick with a .82a/r on whatever SC series turbo I decide to go with. I've done enough research to come to the conclusion that that particular combo of wheels and housings should be good enough to produce 1bar by ~3.5k or possibly a bit earlier, however it would still be good enough to push 500+whp and the top-end flow wouldn't be nearly as restrictive as the smaller KKK housings so it would certainly help the overall power curve a bit. I won't believe that Porschefile guy though until he actually gets another project completed. He has a bad habit of changing his mind on the spot. lol Honestly, one of these days I might put my money where my mouth is, hopefully sooner rather than later.

Geneqco

Thanks AW... so you are talking absolute rather than gauge pressures?

Geneqco

Thanks Patrick,
I'll certainly be intersted to see some specifics... what the breakaway points are TQ, boost and rpm wise through the gears - if that makes sense.

I have thought about the S2 cw&p only a little so I'm not sure I fully understand... but to me, I think I'd rather not have my TQ curve moved that far to the right that it was necessary. I mean, aren't you really just compensating for a TQ curve that is perhaps a little too far to the right for the stock cw&p? Another thought is that if i can achieve similar to S2 cw&p with my stock cw&p by ealier boost and hence TQ curve, won't that promote better engine life because I'll be achieving similar results at lower rpm (I'm speaking generally here - I do understand that if you are talking specific tracks there may be gearing advantages due to change points etc)?

Geneqco

Thanks again PF, I always find your posts quite informative even though I understand you might be 'thinking out loud' through some of it - actually, i don't mind that at all, I think it helps me better understand how you come to your conclusions.

Dave did mention this new Super 53 when I spoke to him last - it wasn't on their web site yet at that time. I'll have a look and at the other links you posted... I'll probably have some more questions for you after that.

333pg333

I like your use of the term 'thinking out aloud' as that's what some of us do to varying degrees. It helps to do this and get the feedback from others which may sometimes mean a question is answered by another.
However, my focus is for the track. Our tracks are predominately pretty tight. If my setup is really going to be coming into it's own at the mid to upper rpm's (which the more I read and think about it, it is) then that won't be a problem on the track. The extra capacity of the motor (104.5mm pistons over the stock 100's) will more than compensate for some tq loss. The gearing, while playing a role in the tq and acceleration of the car, is still too long for Oran Park, Wakefield Park, and maybe even Eastern Creek, in stock form. Short of solid lifters my head will be very strong and I have the rev limiter set to a low 7k so for the moment I won't be really stressing the top end of the motor too much. Even when driving the car for those 4 days on .4-.5 bar and 4-5k rpms the extra tq was very noticeable. The big turbo (VS5)didn't feel laggy either. In fact the setup as it was felt like I could have pretty much stepped right into where I left off last season with the previous setup running more than double that boost. I have the distinct feeling that this car is going to be doing 1/4 miles easily into the 12sec region if I bother to go back to the drags.
Anyway this is OT on attyjeffs thread, sorry bout that. By the sounds of PF's suggestions the 400whp can be achieved with a change in housing.