If everything works out, I will go through you to get replacement ball bearing parts.

 

Does anyone have any info on the GT-K series? I'm looking at going this route with my build. I want to have the best turbo for the job and right now I'm looking at the gtk350 or the gtk450. If I go with the 450 I'll have to do some modifications to the cold side pipes and maybe the hot side, havn't been able to find a whole lot of info. The PTP kit that I'm going with is set to mate up with a t4 60 trim stage 5 bb. Any advice you gurus have would be nice

 

^^
Do you have compressor and turbine maps? I asked a while ago when they were first being released and was told they were not yet available.

 

wanted.

I am not familliar with all the new names of ball bearing turbochargers. I just do "bolt on" upgrades to existing cars with turbochargers.

Bryan@BNR

 

Afraid I do not red, all the info I could find on the turbo itself is what is in that gif.

 

I was looking at Turbonetics GTK series turbos back when I was considering building my own system. The lack of information, compressor and turbine maps, among other things, is why I decided to not use them.

Plus, they are rather pricey compared to Garrett snails.

 

I have refused to use Turbonettics stuff ever since the valve broke in my racegate after just 2 or 3K miles. I spoke to the parts manager at the time and they told me that the valves weren't for individual sale which that week they evidently decided not to sell the pieces which were in their parts catelog. He also said to me in these exact words.... "Well the bad thing for you is you have to buy another wastegate, but the good thing for us is we sell another one!" That was the end of that... They can keep their Garrett knock off stuff b/c thats all they sell.

 

The GTK 450 has a 4" inlet. That's could present serious packaging problems. With a compressor inducer listed as 2.29" and presumably the 2.95" exducer, it appears to be the T04E 60 trim I mentioned way back earlier in this thread:



The stage 3 turbine wheel is still kind of small, considering most older rotaries making power are running the P-trim.

Trim Exducer Dia. Major Dia.

T3
Stage I / Std. 1.898 2.319
Stage II 2.122 2.559
Stage III 2.229 2.559
Stage V 2.437 2.795 (not positive about the stage 5 measurements)

T4
N 2.071 2.922
O 2.296 2.922
P 2.544 2.922
Q 2.693 3.111




We can also compare the GTK 350 to some of the other stuff that's out there. It is listed as a stage 2 turbine wheel. That is really small for this application--similar to the size of the turbine wheel on 2nd gen stock turbo, according to Bryan's measurements (which I very much appreciate!).

The GTK 350 is listed as .63 A/R on the hotside. That's small too--there is an FD running on the rx7 forums (Howard Coleman is his name, he's done a lot of experiments with alcohol injection) running custom twins with stage 5 turbine wheels and a .82 A/R hotside--two of them, one for each rotor (old style motor which have two exhaust ports). He is doing around 500 on pump + meth.

With that restictive hotside and turbine wheel you will get a lot of backpressure. More backpressure = higher exhaust temps and higher chance of detonating, but quick response. The turbine housing is probably equal or smaller in size to the 18G's, which is a 16 cm ^2 and I have been told that is equivalent to a .83 (not positive on that). a .63 A/R is like a 12 cm^2 turbine housing.

Here is a conversion chart I found (cannot 100% vouch for this)

9cm^2 - .48 A/R -- like a later Evo 16G hotside or a Holset HY35 on the automatic Cummins Rams
12cm^2 - .63 A/R -- Holset HX35 on manual tranny Rams
16cm^2 - .83 A/R -- Greddy turbine housing on Rx-8 18G and also I believe the 20G used on the FC Greddy kit
18cm^2 - 1.00 A/R -- Holset HX40/H1E housing
22cm^2 - 1.15 A/R -- Holset HX40/H13 housing


Getting back to the GTK-350,

With a compressor wheel inducer of 2.170" (about 55 mm) and probably an exducer around 3" (76mm), it seems to be the T04E 54 trim. See turbonetics catalog http://turbocharged.com/catalog/comp_wheels.html



With that kind of wheel, you might as well get Bryan to do a 50 trim wheel (same as GTK 325) in a modified Greddy 18G and save some hassle.

I have looked at a TON of catalogs and specifications on turbos, and I have come to the conclusion that most of turbos from smaller shops (GTK, Sound Performance, Precision Turbo, etc) just mix and match parts from that Turbonetics/Garrett catalog I posted if they are using T series. In this case, the size chart actually lists "E54" as in T04E 54 trim. Otherwise these resellers will just use straight up GT series stuff. I'm not some kind of turbo genius, and clearly looking at catalogs isn't rocket science. That's why I appreciate Bryan just coming out and telling us what he puts in his hybrids. HKS usually takes Garrett stuff and clips the turbine wheel or swaps out a housing with another off-the-shelf housing, then marks up the price.

 

I'm doing a top mount so packing isn't a problem at all. So from what you're saying, the 550 would be a better match with the stage 5 wheel? I supose the modifications would be the same from the 450 to the 550.

I understand that alot of people have the GReddy set up however some don't. Very little has been discused on just the best turbo, packing be damned. I'm personally very interested in this field.

 

I would stay away from that entire line of turbos. They seem to be designed for high horsepower 4 cylinder applications. The hotsides are too small in comparison to the family of compressor wheels it is using. The GTK 550 is a T61 compressor which is basically a GT35, but the stage 5 wheel is still on the smaller side for that. The closest journal bearing equivalent to GTK 550 which I would recommend is the Aspec GT3574 . (that's their name for it, there is no 3574 in the Garrett catalog). It is a GT35 journal bearing compressor wheel with a P trim turbine wheel and T4 inlet.

http://www.a-spectuning.com/html/products/gt3574.htm

call them up and they can probably sell you just the turbo and wastegate and you can source your own manifold. Tell them you need an undivided turbine housing.

Otherwise, look for turbos that are used on Supras.

 

Well I have officially been talked out of the GT-K. The snail I'm going with is a 60-1, P-trim, .70AR T-4. I'm going to see if I can get the water cooled varity as I don't want the cooling load to be passed off to the oil coolers which we all know are lacking already.

 

I ran that exact turbo on my old setup, although it was oil cooled. It is often called the T04S. The FC stock oil cooler is the size of a small FMIC though so it wasn't a big deal.

 

.70 AR is too small.
Minimum .86 AR.
You might want to consider a .92 AR if you can.

 

.70 a/r is fine for 330-350 RWHP. It will be a great spooling turbo. If you want more than 13 psi/350RWHP, I would suggest finding a bigger housing.

 

The 60-1 is an awesome turbo. I loved it for street use as that's what I had years ago on an old RX-7. I ignored other recommendations and used it instead. No regrets. I had a 1.32 a/r divided housing with a clipped P trim wheel but that was on a 13B with my custom exhaust sleeves. Awesome setup with quick spool. The secret was the sleeves as without them spool would have been horrible.

 

It will spool REALLY quick, that's for sure.

It will also cause a significant amount of pressure before the turbo and very high EGTs as a result.

 

Jeff, my reasoning behind the .70 is to have a fast spooling turbo. My goals are to sit at 10psi normal with capability to run a max of 13 and I don't want to be a dyno queen. If my logic is flawed let me know as I value your opinion more than my own.

 

It's still better than those absolute piece of junk Greddy turbos for the RX-8! They're so pathetic that I wouldn't use one for a paperweight.

 

"Fast" might be one way to describe it.
Completely uncontrollable and spiky might be another.
Even with an .86 AR, you will get ALL of your boost before 3700 RPM.

 

.86 it is then. See my problem is I had the GReddy back in the day, and really enjoyed the fast spool, I just didn't enjoy the problems I had with it. I suppose I should listen to you and get the turbo you recommend as I'm sure you’re going to get rather acquainted with it when I move to Phoenix You should check out my build thread to get the full scope of what I'm doing, if nothing else just look at the parts list.

 

Just as a point of comparison, the GReddy turbo's AR is 1.0.

 

Sooo am I good with the .86 or should I go with something else?

 

Hmm, I have the 60-1, P-trim, .70AR T-4 and i dont have full boost till 4k rpms. Mine isnt the ball bearing option though. You can check the dyno's in my thread.

 

Don't hold back RG tell us what you really think LOL

Set up right the Greddy is a great upgrade to a sock rx8 with power levels that most people will be happy with . I actually don't find any issue with just treating it like a 4 port and revving to 7600 ish .
99% of any hard driving i do ie windy roads etc I don't ever want for more power up top IEover 7500 because most of the fun is in the 4000 - 6500 range anyway . This range is where the greddy shines

 

& once more, slowly, why not a 3071r, especially since 'someone' has done all the R&D on it for a Renesis app?