Garrett GT BB turbo sizing

[Doug71zt]

I'm thinking of dropping cash on a GT series BB turbo for my L30ET. Is anyone actually running one on their car right now. I'm going external WG off of the manifold, so it will be a T3 flange turbine housing, 4 bolt exit, I'm thinking .82 A/R. Anyone know the boost threshold with the .82 housing? For compressor, I think the T04S housing .70 A/R but not sure of the wheel. Maybe a GT35 or GT40 setup. Looking for solid information and suggestions.

 

Thanks - Doug

[RB26powered74zcar]

I passed this post onto a friend TimO, who will gladly get back to you with his experince on his GT35r/L28T

[240Z Turbo]

Doug,

I am a GT distributer and sell the GT35R turbocharger. BTW, I give discounted prices to Z folks. For a street car you may want to run the smaller .63 a/r turbine housing, but for all out power applications you should run the larger .82 a/r housing. The .63 housing will flow quite well to support 500hp@wheels. The T04S compressor housing w/4" inlet is standard on the GT35R. We can have the inlet cut down to 3" and we can vary the flow of the compressor wheel from 50-65lbs/min or 500-650hp worth of air.

Joel forgot to give me a shameless plug considering I just got him two GT25R turbochargers for his RB26 swap

http://www.speedshopthagard.com

[Doug71zt]

Thanks for the legwork, joel! I didn't really think I was breaking new ground here, but it seems that there are not too many guys running the BB turbos.

 

James - I've been following your RB plenum posts - an RB26 is my next step after the L series' last hurrah in my car. I'd like to get streetable mid - 11's out of the stroker motor I'm building. I'm interested in the GT series because I think that the flow of the compressor better matches the L series than the T04E60 .60A/R that I'm running now. I think that I may be right on the surge margin at lower speeds and airflows, as the response is somewhat variable on small to moderate throttle openings. I'm an helicopter engineer by trade, and I'm pretty sure by the sound of things when I'm running through the twisties, and on and off the throttle, the compressor is loading up and stalling when it's not spooled right up.

As my car is somewhat of a do-all compromise machine, I don't want the crazy hit of power at 4.5 K - I am more interested in power that the car can put down. So - I think the .63 would be better for me. The GT35R comes with the T350 - 10 blade wheel - right?

What do you suggest for a compressor - Is the .70 A/R too big for me? What trim? I have a Bell 24"x 3" x 6" long IC in the mix with 2.5" piping, similar to Scottie's IC.

And lastly - I know - a lot of questions - Would it be reasonable to use this GT turbo on the RB26 when I upgrade? Or is something bigger required? I don't have a problem ditching the twins on that engine. 2X the cost for a turbo upgrade? No thanks.

 

I would like a price if you could spec out what you think I need. Reply with your thoughts on the board for the sake of everyone else, and then PM if you want.

 

Thanks - Doug

[240Z Turbo]

The GT35R comes with the T350 - 10 blade wheel - right? What do you suggest for a compressor - Is the .70 A/R too big for me? What trim? I have a Bell 24"x 3" x 6" long IC in the mix with 2.5" piping' date=' similar to Scottie's IC. And lastly - I know - a lot of questions - Would it be reasonable to use this GT turbo on the RB26 when I upgrade? Or is something bigger required?

Thanks - Doug[/quote']

 

Doug, let me answers these question short and sweet. Remember, the GT turbochargers work better for several reasons. As compared to non GT turbochargers they can use smaller wheels to flow the same amount of air so you have less inertia when trying to spool and for transient response. Also, the BB center section provides increased spool due to less drag. Finally, the aerodyamics of the GT wheels allow them to cut through the air more easily when spinning in excess of 50K rpm.

 

- The GT35R uses the 84 trim GT turbine wheel. This is the standard wheel for that turbo. I get confused when folks say the 10-blade GT turbine wheel. I had a long talk about this with my turbo guy and he was also confused. There are not as much interchangability issues with using the GT compressor wheels on non-GT turbochargers, but the shaft is integrated into the turbine wheel so there are definitely interchangability issues with using a GT turbine wheel on a non-GT center section.

- The .70 a/r is just fine and is standard. No great need to change a/r on the compressor side. The .70 a/r is matched for efficiency reasons when using the higher flow wheels, i.e. 62lbs/min.

- IC and piping is fine, may want to use 3" from IC to TB for all out power applications.

- The turbo would work well on an RB. The turbo will actually make more power on the RB than on the L, it is more a question of the efficiency of the head. You should easily be able to generate 600hp on the RB with the proper setup. Granted, this is based on your willingness to run high boost.

 

I will send you a pm for cost. Remember, the GTR turbos are quite expensive in comparison to non-GTR turbos.

[Doug71zt]

James - Thanks for the quick response. I think the confusion with the 10 bladed GT wheel is because Turbonetics makes a T3 10 blade stage V wheel. I was told that the GT series shaft is metric sizing, so there is no interchange with the T3 CRA.

What size of external WG do I need for this set-up? 38mm, 40mm?

 

Thanks - Doug

[240Z Turbo]

Atleast the 40mm, I also am a dealer for the Tial Wastegates

[TimO]

Doug,

 

I’m a distributor for Garrett, Tial, Electromotive, Fedonza, TWM, SPEC and more. Most importantly I run the Garrett GT35R twin ball bearing turbo on my z and its amazing. I went from a t3/t4 60-1 p trim to the GT35R GT40 compressor wheel, .83 ar turbine side. My motor is a 2.8 F54, P90 by Gerolomy, Elgin cam .515/.490 274/266 114 L/C, TWM’s etc. I can tell you that with the GT35R, my z now feels like a big block Chevy!!! It completely changed the characteristics of my motor. Boost response is immediate with virtually no lag and I begin to make boost 6-800 rpm sooner. The compressor wheel is so efficient that I had to turn down my two stage boost controller (first and second gear) from 16psi to 13 because of wheel spin, while at the same time I was able to increased my high setting from 18psi to 20…..on California gas!! Not dyno’d yet but I should be in the 450+whp range on a daily driver tuning calibration.

 

Based on my personal experience and talking with Garrett I think the .63 ar is too small for your z if you’re running a built z motor (decent head, cam, forged pistons etc). If your z needs a .63 ar then you are probably wasting your money on the GT35R. I also wouldn’t cut the inlet down to 3 inches. That defeats the purpose of the air flow capabilities of the GT35R. I run the 4 inch and it’s great.

 

You will need a flange for your downpipe. The t4 series will not fit and Garrett does not make one yet for the GT High Performance Series. We can get one for you!! All of the GT series turbos utilize a water cooled bearing housing. The water fittings, oil inlet and drain are all different from the std Garrett T4. A constant supply of water must be plumbed to the 14mmx1.5 threaded holes front and rear. The oil inlet on the top of the bearing housing is a7/16-24 inverted flare. This must be supplied with a constant flow of CLEAN oil at pressures no greater than 60psi. And the oil drain is a two bolt flange with 8mm1.25 threaded holes. This flange is the same spacing and configuration as the standard Mitsubishi oil drain found on TD05 and TD06 bearing housings.

 

Our company is new but I’ve worked on z’s and 510’s for over 30 years. We have killer prices and we give even deeper discounts to z and 510 owners. Our web site will be up in about three weeks. Let me know if you want pictures of my GT35 installation. If you have any questions or just want to chat, our tool free number is 888-629-1047, or you can call me on my cell 916-838-2509.

 

Where ever you buy your turbo or go for advice I will tell you, the GT35R turned my z into a monster. I love it!

 

Tim Ogburn

S and T Motorsports

Sacramento and Atlanta

[TimO]

Joel,

 

BTW -Thanks for the plug.

 

TimO

[240Z Turbo]

Doug' date='

Based on my personal experience and talking with Garrett I think the .63 ar is too small for your z if you’re running a built z motor (decent head, cam, forged pistons etc). If your z needs a .63 ar then you are probably wasting your money on the GT35R. I also wouldn’t cut the inlet down to 3 inches. That defeats the purpose of the air flow capabilities of the GT35R. I run the 4 inch and it’s great.

[/quote']

I feel like I just got reamed with a tractor through the rectum! I can say there is not substitute for 1st hand experience so if the .83 is working then that is what you should run. Keep in mind his setup, custom exhaust manifold and tripple TWM throttle bodies. I said you "MAY" want to use it, but TimO has offered his wisdom and let us know the .83 works very well on his highly modified setup.

The option to cut down the inlet to 3" is for folks who will maintain a mass air system if they choose to run the JWT setup. The effects of cutting down the inlet are neglible, in my opinion, to the airflow which is largerly dictated by the compressor wheel/housing combination. Remember, you can choose not to run the T04S compressor housing and use a TO4E compressor housing(3" inlet) and the combination works quite well. This is usually done because of space constraints. I am currently twin turbocharging a ZR1 corvette using 2x GT30R turbochargers (GT35 compressor wheels) and using a TO4B compressor housing(2.75" inlet). This combination is not ideal, but is used because there is not room for anything larger. and should support the desired 900hp on our stage II setup.

Considering Tim and I get our turbo's from the same Garrett Distributor he should learn to play nice

I will not try and one-up TimO so here is a pic of his GT35R setup

BTW TimO, is that a 3"-4" reducer hose on the inlet of your turbo? Won't that, "defeat the purpose of the air flow capabilities of the GT35R?"

[clint78z]

One thing to note about sizing a turbo is that the A/R will be one of the major factors of spoolup characteristics. I am not going to debate .63 or .83. One thing I will offer is if you choose a big wastegate it will allow you to run a smaller A/R and still allow you to flow enough at the top end.

You see the ristrictive smaller A/R housing can be bypassed through the large wastegate.

[D83ZXT]

Ummmm..

That's the wrong pic of TimO's (old set-up). I can tell because that's not the custom exhaust maninfold some of us bought awhile back.

 

You Boys play nice now LOL

 

Donna

[240Z Turbo]

That's the wrong pic of TimO's (old set-up). I can tell because that's not the custom exhaust maninfold some of us bought awhile back.

 

shhhhhhh

[Doug71zt]

This is good stuff - keep it coming! I'm thinking of machining a pad on the bottom of my cast manifold and mounting the WG dump tube directly to the manifold. This will stand off the WG a couple inches in order to reduce the heat conduction to it. Any problems that you guys forsee with this approach. Maybe even mount it below the exhaust housing of the turbo and straight shot the WG outlet into the downpipe. All it takes is SS tubing, a bandsaw, TIG welder and time, Eh James? Where did you source the SS bellows in you WG tubing? That is a nice piece.

 

Doug

[RB26powered74zcar]

Here is TimO's new turbo

 

 

[240Z Turbo]

Where did you source the SS bellows in you WG tubing? That is a nice piece. Doug

 

Doug,

http://www.spdexhaust.com sells the nice, but very expensive inconel/stainless bellows as used on F1 exhaust. The other bellows were purchased from turbonetics for about $50/per. The steel braided bellows can be purchased from most local muffler shops. BTW, when welding the dump tube to the cast iron manifold use a nickel rod. I believe we used a stick rod and knocked off the flux. You have to preheat the manifold and weld a little at a time, peening with a hammer between welds as they cool. This prevents them from cracking. The manifold must then be cooled slowly so the welds do not crack. Not difficult, but requires that someone have knowledge about what they are doing. BTW, you can just use some thick walled steel instead of stainless.

[TimO]

James,

 

My e-mail had nothing to do with you. I didn’t even mention your name. But I ask that if you want to suggest that I don’t know what I’m doing; make sure next time you have your facts straight. That picture you referenced is not a GT35, it’s my old t3t4! Furthermore, had I known that you would TRY to minimize my expertise with a picture I shared with you in the past, I would never have sent them or discussed them with you.

 

There is plenty of room in the z community for two or more Garrett distributors. The way I see it, the more guys who can offer turbos, etc at great prices and can provide technical support based on direct experience…the better.

 

Doug,

 

Regarding your wastegate placement question, we build a wastegate sandwich adaptor that places the wastegate directly between the exhaust manifold flange and the turbo inlet flange. This places the wastegate directly in line with all the exhaust flow without any welding on the exhaust manifold. I have a prototype on my z with the GT35 and it works great. We are in the process of having a small run of these adaptors built for the GT35. If you want to see what it looks like, take a look at the picture of my old turbo set up that James provided. It shows the same style adaptor we made for the t3t4. Let me know if you’re interested.

 

Regards

TimO

[RB26powered74zcar]

Well lookie whos back!!!!

 

Ummmm..

That's the wrong pic of TimO's (old set-up). I can tell because that's not the custom exhaust maninfold some of us bought awhile back.

 

You Boys play nice now LOL

 

Donna

 

 

 

I thought you may have got outa the Z world Donna. Haven't seen/ heard from ya in a loooong time.

Everything OK for ya??

[Doug71zt]

Hi Guys - I'm not thinking of welding the WG dump tube to the manifold. I'm going to machine a pad on the manifold, machine out a dump hole with a 4 bolt flange and bolt the SS dump tube to the manifold. This will allow me to run the narrow spacer that I have with the turbo, and gives me more room for the compressor discharge tubing to make the 90 deg to the IC. Also, it will probably make the stock manifold flow a little better on the top end as the WG flow will not be exiting the flange, it will be dumping straight down. I've ported as much as the manifold as I can reach (That was a ton of fun) and I think it will flow good enough for what I want out of the L series.

 

Donna - Good to see you back!

 

Doug

[Vintage-TechZ]

OK,TIM & JAMES,

I am in the process of building my AWD RB26DETT into my widened chasis (early S30).What will be the best GT bb turbo in your opinions for this .The car will be used for track and street events and will use my Wolf 3-D ECU.I will consider dual or single turbo applications,BTW ...PM me with prices so we can avoid those ugly retorts back and forth !

Tim ,I'll be in Sacramento on the 18th of this month ,and if you guys are NICE,I'd love to see your projects while there! (I also have a couple of Turbo'd S30's.)

So give me your thoughts....................Vince