Marshall Johnson

I don't post much, but here's the deal: I have a Tec built Garrett style T04s turbo in my rex. I have a street ported motor, Tec II, etc... (see the car here: merritr.com). The question is: should I change my turbo to something more exotic? I don't want to change my manifold, so I was looking at some of the HKS/Garrett Gt ball bearing turboes. I looked at the GT30 and the GT35, but I'm not an expert on turboes by any means.

My goals for this car are max RELIABLE power on pump gas, with the occassional race gas jaunt. I know tuning has a lot to do with that, but would a more exotic HKS turbo help enough to justify the cost? I don't want some turbo that merely comes on 200 rpm sooner than my current one. And I don't want to change my manifold, hoping (almost positive) that the GT series turboes bolt up to the T04s manifold.

And thanks in advance for suffering through my rambling post.

Marshall Johnson

Is there anyone out there that knows anything about the Garrett/HKS Gt series turboes?!!

carcrazy

If you are running a T04S, this is an awesome turbo - I am guessing you are not and this is the reason for your post.

There are some questions that need to be asked:

1. Is the turbo working correctly?
2. How much boost are you making?
3. Any weirdness going on?
4. How much power are you making?
5. Have you tuned or dynoed it?
6. What are you trying to achieve?

Let me know, this will help with other users replying as well.

More info please.

Rick

Poweraxel

The HKS T04R will do quite nice

Marshall Johnson

Don't get me wrong, the turbo makes plenty of power. It's a T04s, built by tec, with a .55 a/r, p-trim. I don't have a dyno sheet around, but the car has been tuned continuously for 3 years at PFS (I've been running this setup for 3 years).

The bottom line is I'm an absolute perfectionist and I was interested if the HKS/Garrett series of turboes would net me any benefit worth changing the turbo for. I don't necessarily care if I don't make more top end power. A flater powerband would be cool. Basically I'm just weighing my options here.

carcrazy

Interesting...
The .55 a/r trim is quite conservative. The HKS kit that I have is a .96 a/r or something like that. This seems to be awesome with little or no lag. The AVC-R is limiting boost as low as 2300 rpm (you can tell by the clicking of the regulator).

Anyways, you have lots of options. Here are a few:

1. replace the turbines/setup with a higher a/r. This will give you more boost/air and may give what you are wanting (more thrill!)
2. Replace the turbo with a T04E. This might be good to go with one from X S Engineering. A local shop that is reputable would be great also. If you are running a T04S - you don't have to change. Just change the a/r.
3. By all means, talk to PFS. They know your car and they are reputable. Pettit has been around and are well known.

If you are willing to tolerate some lag and want a hellacous top end - go with a T-51KAI and be done with it!!! This will give you all the power you would ever want - just a little peeky. It definitely won't run out of air at 8,000 rpm.

Rick

HWO

all this T04E vs TO4S vs T04B stuff is crapola. Its all to do with the A/R ratio of the exhuast housing, weather or not it is divided housing, what trim the exhuast wheel is. what compressor it has and what A/R compressor housing it has.
A T04B (water cooled) with a 1.15A/R divided exhuast housing with a P trim wheel, and a 60:1 or H spec compressor and 0.70A/R compressor housing when mounted on a descent exhuast manifold, - that being one which is totally divided all the way into the turbo, will spool at around 2800rpm or there about, earlier on a ported engine (around 2000-2300) and provide enough flow for 8500rpm without going beyond efficency if held below 20psi. That set up is good for anything upto 550-580 HP at the flywheel (460HP @ the wheels on the US dyno's) on a 13B provided you have enough fuel on tap.

A 0.55A/R is too small and that is your restricter at this point.

Marshall Johnson

Hey guys! Sorry I haven't been real specific about my goals. The reason I haven't been specific is I wanted to see what was out there! The car is a street car though, so I really don't see the need for a monster turbo, like a T-51r. I mean claiming 700hp is nice, but that would require 118 octane, mega boost...etc..etc.. and this is a car I want to make max power on street gas.

In light of that, I would have to say that 1 bar of boost would be the max for almost all situations (maybe race gas and higher boost once in awhile). I was looking at the HKS gt-series because they are T04s style turboes, with dual ball bearings, and water cooling. I also have a guy I can get them from. Or, I could just upgrade the a/r, which I just might do.

The other interesting thing I could play around with is water injection... so many options.... ha ha

AJC13B

You all need to get over this lag thing.

My turbo cuts in at 4500rpm or thereabouts and pulls like a train till I shift at 8500 or so.

With a .55 a/r the thing would have boost at idle and die above 6500.

I had the same turbo as HWO mentioned but with a 1.0 rear and it died hard about 7000.

HWO> Forget the H3 compressor blade. I had one on my original Cosmo engine and it was a piece of **** turbo. Compressor surge in 3rd is not a good thing.

------------------

HWO

Steve, there is 2 H spec compressors, Peter is running one on his 1.32A/R divided exhuast T04B, that thing is making 530HP @ 15psi and 590hp @ 19psi.

His compressor is the larger of the 2 H Spec, obviously not the H3.

Cheers
Shane

HWO

Being in one of the lands downunder i have no idea what the T04S in the XS engineering kit is.

I would suggest finding out what the compressor is, and if it is a 60:1 or similar simply upsize the exhuast housing to something around the 0.96 or 1.15A/R reigon. coupled with a well done manifold the car should become a different animal.

Marshall Johnson

The turbo I am looking at is a Garrett/HKS Gt35, which according to my sources, has a T04s style compresssor with a 1.15 a/r, dual ball bearing design, and water cooling. I am not as clear on the design of the exhaust side, but I think that it is a bit smaller than a straight T04s 1.15 a/r of the same size. Another big attraction of this turbo is its water cooling.

IGY

A TO4S is a 60-1 AR 70 compressor side w/a P trim exhaust. A TO4R is a 62-1 AR 70 compressor side w/a P trim exhaust. First of all the flanges on the GT series turbos are HKS specific. A GT 35 is a ball bearing TO4R w/a custom exhaust side(somewhere between T4 and T3).

Marshall Johnson

Hey! Thanks a lot IGY! I finally hear from someone that knows about the HKS/Garrett turboes. Interesting information. Do you happen to know a web site I can get more info at. HKS Usa's corporate site basically sucks.

machinehead

I have a brand new T61, .84 devided ex housing, water cooled, polished compressor housing, never installed I'd make you a sweet deal on...
Its been sitting in my garage for 2 months sealed in plastic and I just can't bring myself to go single.
I also have a barely used Greddy T78 manifold, and a innovative turbo race gate which is also brand new...

HWO

that means a T04R has too smaller exhuast housing for a 13B making good power then.

Whats the exhuast housing A/R on the T04S, it has the good on the compressor side but what about the exhuast?

IGY

The GT35 has an exhaust side that is between a T4 and T3(for size reference only). They can do this because the turbo is ball bearing. So, they can make the same top end power w/ this turbo, but spool much earlier. The TO4R and TO4S use the same exhaust housings as a P trim TO4E. I currently have a TO4S w/an AR 1.00 housing.

Marshall Johnson

So, in light of IGY's comments, which I think have a great deal of validity, should I go with a Gt35? It shouldn't be too much of a bother to weld a new flange on my manifold and possibly adjust the downpipe a bit. I don't think the downpipe will really require any modification, I already have a v-band clamp on it.

The design of the Gt35 does sound very tempting though. A large compressor side that spools relatively quickly. The only worries I'd have would be the amount of stress on the turbine shaft. But, I'm sure HKS and Garrett have that under control.

Marshall Johnson

Another concern I have is the backpressure created by the smaller exhaust housing used on the Gt35. Sure the smaller housing is good for fast spool up, but will it still allow for good top end power production. I mean will it make similar power to a straight T04r. Somehow I doubt it will, though I'm not really concerned with making 700hp. If the turbo can flow enough for 500+ on race gas and make 400 rwhp on 1 bar boost I'll be happy.

fast13b

Hey folks MAYBE when he said .55 a/r he meant for his COMPRESSOR housing. That's what mine is

Astro

are you running yours yet?
any opinions/comparisons to your older setups?

Silver7

You could always get a T04E/S turbo with a water cooled bearing. Then get the dual ball bearing option. You can also choose your compressor and exhaust A/Rs. To me this sounds like what you are looking for and it will definitely bolt up to your existing manifold.

Silver7

I always thought the T04S used a larger compressor wheel than a 60-1. I learn something everyday...