mochman

1: I didn't like the way the Turbonetics turbos handled the oil pressure/volumn produced by the 951. It's simply too high.

2: Yes I run an oil restrictor. It's a .050" restrictor

3: There is a problem with the factory air/oil seperator whereas the pull on the crank case blow by line back into just before the turbo is too high. The result is oil being pulled back into, and in front of the turbo. That was rectified with an aftermarket (and modified) Greddy oil seperator, with a 3/8" copper line plumbed back to the oil pan to drain any oil caught. The factory knew this and installed a restrictor in the top of the factory air/oil seperator. It works great until you get over a certain power level per cubic inch (somewhere around 380+ RWHP on a 2.5L)

4: The engine mount has to be cut back to provide clearance for the turbine housing as the Garrett turbine housing is much larger physically. It will not fit onto a stock motor mount. It will hit the side of the motor mount and prevent you from bolting the the turbo down properly or worse.



TonyG

 

Cool it looks like my 951 may become a track car after a recent eng fire so that's why I ask I'd rather do a real garrett and solve the backpressure issues. I'll let you know if I have any other questions. Thanx

 

Hi Tony,
I pressume the P trim is a bigger turbine
right ? Tony since you've put in so much
effort with the turbo, why did you not go
straight to the GT 25 or GT 30 turbo's
Thanks

 

J Chen

You are correct about the trim of the turbine wheel.

I didn't go to a GT series turbo because of a lot of things.. money, getting it to fit, which one to use..., and most importantly, I spoke to quite a few people in the "know" about the GT turbo. And although everybody said that they were good, nobody said that in the size I need, that it would be better than the 60-1HiFi. In fact, the comments that I always heard is that the 60-1HiFi is a "damn good compressor..." or "stay with the 60-1HiFi", or "you're not going to get anything more over what you've got now...", etc...

That said, and the fact that I'm at over 400RWHP on the car now, what more could I really get go going through all the work to try out a GT series turbo? "How much" is left on the table?

The answer is probably nothing or very little. Certainly not enough to justify the cost.



But will justify the cost is a larger intercooler. Now there's where a "lot is being left on the table".



TonyG

 

I'm a little disappointed that the ignition is not up to the task; too bad you have to make a drastic change in plug gap. I always thought that the stock ignition was very good (with new parts). Going to a colder plug generally makes it worse.

 

Hi Tony,
You inspire me to try & get as much out
of the 2.5 L. How much does a GT series
turbo cost in the US ? I can get at GT 3540
at USD 1150 in Thailand. Before I got my
60-1 HiFi, I read about the hassle of fitting
a non KKK turbo to the 951. Now that I've
began to fiddle with the car, I realise that
it's not as problemetic as what people are
saying. Given that labor cost is much cheaper
here, it does not cost alot to make new flanges
or even new crossover & down pipes to fit
the GT turbos. Hell, maybe I might change my
mind & go for the GT25-TO4s which is a very
good match for the 2.5L.
Lastly, you mentioned that KKK hot housing
are very restrictive as compared to what,
Garrett T3's or T4's only.
Thanks again Tony for sharing your experience.

 

What was the comment about stock ignition being a problem over 5500? And Tony, where the hell did you fit the Greddy catch can?

 

Hey NZ951,
Should'nt you be in bed at this hour ?

 

TurboTommy

The stock ignition is very good. But to do what I'm doing is asking a lot of it. We're talking about 2x the power that it was designed for.


J Chen

The KKK hot side generates high back pressure period. There are other alternative turbos that can provide less... (but don't necessarily bolt on w/o modifications).

You can't make a blanket comparision. But on the 951 engine, a T4 turbine side is about as good as it's gonna get with respect to reduced back pressure as a general rule.


NZ951

I'm having slight ignition misfires at the 400+RWHP mark with a complete brand new OEM ignition system (coil, plugs, wires, distributor cap and rotor). Plugs gapped to .028", NGK-R.

A/F ratio is right at 12.3:1 according to the Horriba.

And there is no detonation.


The plug gaps are going to have to come down to closer to .020", and possibly a higher power ignition coil be added.

With respect to the Greddy catch can:

I run no power steering, thus no power steering resovior. The Greddy unit sits bolted to the power steering pump resovior bracket.

TonyG

 

Hi Tony,
Thanks for the reply. Regards to high
back pressure of the KKK hot side.
Is it due to the design of the volute
thats causing it. What about the T3's ?
I see alot of ricers using this combo
for faster spool.
Thanks Tony

 

Tony-

I was just wondering why you have put off replacing the intercooler for so long. Would you recomend not replacing it unless you are making serious horsepower, or is it something that would have helped significantly earlier on in the evolution of your car? If it was just a cost issue, I hear ya, but the dollar per horsepower gain with a new intercooler must be lower than some of your other performance mods, no?

Thanks a lot,
Ben Z.

 

Hi Tony,
One more question. I have notice
that the intake manifold is under
heat soak all the time. Have you
address this problem already ?
Thanks Again

 

J Chen

I can get off the track or even in normal city driving, and my intake manifold is cool to the touch.

All you have to do is to insulate the turbine housing, back about a foot to cover both the turbine in/out pipes.

Use safety wire around the entire thing to form a wrapper around the hot parts. Don't tighten the wire tight either. It should be on the loose side.

Use Thermotec aluminized heat insulation. You buy it from Summit Racing. Costs about $75 for a piece big enough to do 3-4 cars. It's also sold as a Thermotec Header Blanket (same thing).

TonyG

 

Ben Z.


The more power you make, the more air you push through the intercooler, the bigger the restriction the intercooler becomes (true for any intercooler).

The stock intercooler is more than enough for anything under somewhere around 350RWHP. As you go above that, it becomes more and more and more of a restriction.


Why have I not replaced it? Good question.

I'm the kind of person where if I can't do it perfectly, I won't do it. I'd rather wait. Given that statement, there are people out there that make larger intercoolers for the 951. They are ok. But I want something better, bigger, with custom ends tanks of my design (not theirs), with end tank internal baffling, and with the cores running in the opposite direction (90 degrees) to the end tanks compared to what I see sold out there for our cars.

Lindsey makes a modified end tank intercooler mod. That's fine, but it's nowhere near what I need for this car, thus to spend $500 only to have to really do it again later doesn't make sense. The larger Lindsey intercooler is nice, but I don't want to change the lines of my car to fit that in. Personal taste.

Also, I want ducting. Good ducting. Just sticking an intercooler in front of the radiator is not enough. It's got to have sealed ducting to prevent air from going around it to the radiator.

Lastly, size. I need one about 2x bigger than what is being sold for these cars.

Given all the above, I've come to the conclusion that the only way to do the job right, is to go to two side mounted radiators, then use the radiator space for a large intercooler.

I've already done all the preliminary measurements, and there's enough room. The problem is time, money, and getting someone that can fabricate it that is located near me.

So there it is...


TonyG

 

Hi Tony,
Thankf for the advice