Carl Byck

The more research I do the more I think I'd like to put a T66 in my car. At the same time I'd like to take advantage of the relatively low cost, and great performance of the Garrett GTBB series Turbos. With this in mind I've been comparing the specs on various GT turbos to the Turbonetics Q trim T66. I am basing this on a 1.00 ar T66 since I know of a couple of guys who are using it on a T66 with good results. A GT40 comes the closest, although the compressor turbine pairing in the Garrett catalog seems to use a larger turbine than the T66 with a comparable compressor.
Turbonetics T66 specs(assuming I am reading their catalog correctly)
compressor;
90mm wheel,2.58minor,3.584 major=52 trim
turbine;
78mm, 2.693 minor, 3.111 major=75 trim, 1.00ar

Garrett GT40 Ball bearing

82mm 50 trim compressor, 77mm 73 trim .94 ar turbine
or
88mm 54 trim compressor 77mm 84 trim 1.34ar turbine
QUESTIONS;
How will the first Garrett option spool compared to the T66, and how will the ultimate HP compare?
Should I try to get the larger Garrett compressor with the smaller Garrett turbine (almost the same as a T66 Qtrim) ie
T66-- 90mm 52 trim compressor, 78mm 75 trim 1.00ar turbine
GT40-88mm 54 trim compressor, 77mm 73 trim .94ar turbine
Does anyone know if the dispacement recomendations in the Garrett catalog are based more heavily on compressor or turbine sizing?
Garret lists the suggested displacement for a GT35 @ 2.5L-3.2L, and a GT40 @ 3.5L-5.0L, and since a GT35/40 uses a GT40 compressor I am guessing the displacement recommendation relates more to turbine size(yes?)
I'm still thinking the 35/40 is a bit small for 550rwhp, Comments? (am I completely lost?)
Thanks, Carl"
The search continues......

Carl Byck

Anybody running a straight GT42? If you are which one?, Best RWHP i've heard about with the 35/40 was 488@22 psi by an Aussie. I believe that the hp was "adjusted" with the "1.15 conversion factor"

TYSON

Talk to Magnus about the GT42. The dimensions in that GT series catalog are not the same. His GT42's are custom built from experimenting with the 7. 905 264 1989

93 R1

Thats one big ************.

Carl,
I'd be interested in the outcome of your quest for the perfect turbo. I'm shooting for the same power output and drivability that you are seeking. Keep us posted on what happens.

Justin

Carl Byck

I will certainly share. I would guess that there are a couple of guys who are there, and just not talking. If that is the case it's a shame. Similar efforts with my 97 Supra on Supra forums yielded dozens of helpful emails. Check this site to see what I mean. http://www.moreboost.org/turbos.htm
This was a collaboration by many different Supra owners to help everyone in selecting the best turbo for their goals. I'm not trying to start a war, but for all the different posts I've made on the topic, I have yet to see a dyno chart or a turbo spec from anyone making this kind of power(550+), nor has anyone(other than yogi) been able to give me any real direction other than criticizing my existing set up. I understand why the drag guys may not be participating(different goals), although they could probably help me quite a bit. If I sound frustrated, it's because after posting eleven different threads on three forums, I find myself working with a turbo builder who doesn't know rotaries, because he's the only shop that doesn't answer with "you need a GT35/40, they can make 700horsepower". Just for the record until anyone posts a dyno that shows different, 500 is absolute max on that turbo...
So here is the challenge RX7 community, let's put our heads together, and come up with a turbo that can make 550rwhp@18-20psi, and 600@24. The turbo will make full boost by 4000 rpm, and max power by 6500. At this point I think the bigger of the GT40s, or a hybrid of that turbo is the best bet. These turbos are full ball bearing, oil,and water cooled, and best of all should cost no more than 1200.00-1400.00.
I know I have a lot to learn, so lets all help each other, the whole community benefits. Thank you to everyone who has contributed so far, let's keep after this. Carl Byck

AJC13B

Garrett TA45
72 cover with 68mm compressor blade
1.05 exhaust housing with 68mm turbine blade



This was on 26psi (As can be seen on the dyno run, 272kpa = 26psi) and C16.



This was made on 22psi and 98RON pump fuel. The compressor cover was the same however the exhaust size was 1.22 housing with a 73mm blade. The turbine blade was also damaged prior to this dyno run.

Those dyno runs have not been adjusted for US based dynos.

The GT42 turbo will make the peak numbers you need but not within the rpm limits you want. I got that info from Vlad at Rotorworx in Victoria Australia. He is running one of those turbos on a 13B and the car is running 8.6 @ 150mph+.

The only way to make that turbo come on earlier is to put a much smaller exhaust housing on it, which the turbos simply don't come with. To do it, you need to get a housing machined which adds to the initial price along with purchasing the housing you want/need.

Enjoy

RICE RACING

You will be hard pressed to make the power you want (550rwhp & 600rwhp) @ 6500rpm, with boost in that range. 18+ & 24psi.

I would say that unless you try to artificaily cool the charge by spraying the IC or running an ice pack you simply will not reach those numbers.

Now if you street port or go larger and use a little more rpm, say peak power @ 7500rpm or 8000rpm then you will be on your way to achieving the kind of numbers you are after. I could very well be wrong, but I think you will find it real hard making the power you want to at those pressure levels @ 6500rpm. I use 8500rpm limit on my car (and I use the limit quite allot) and it seems to be very reliable, why don't you consider using a little more rpm ?

Carl Byck

Thank you AJC, and Rice. Great info, Steve, any chance we could see one of Vlads dynos on the GT42?Magnus,would you be willing to post a couple?
I'm thinking that if I can get a good selection of dynos like these with the exact specs on the turbos and engine porting,(should results on methanol be included?) I can share those with the turbo builder,and Garrett. I realize that all these dynos have dozens of variables, even so I think they can be used to show approximate power at a certain rpm. Steve I believe you are quite active on the Au forums, perhaps some mates on those forums have dynos that would help. Rice, I can raise the goal for max power to 7500, but since this a road race application I'd like to stay as moderate as possible for longer engine life. Rice, what are you running? I think it's reasonable to say that this goal will require a good sized street port. My main reason for sticking to the goal is to accomplish something that hasn't been done yet, however,
as more people participate we can adjust the goals a little to coincide with reality(hate to do it). I think using the GT CHRAs will help us to realize the power as soon as is possible. so for now i'd say the fact set looks like this;
street ported engine required
full boost by 4000 rpm
max power by 7500 rpm
can we do it at 24psi?
Thanks, Carl

AJC13B

No chance getting dyno sheets from Vlad