rx7tt95

This is going to be an ongoing thread as I tune the car and gain more experience with this turbo but I wanted to do a semi in-depth writeup on my trials/tribulations in getting this thing in the car.

But before I start, I have to thank two shops. First Sean at A-Spec spent an ungodly amount of time with me on the phone and via the internet trying to get me what I needed. My original intent was to just "slap" in a ball bearing GT40 but that did not pan out due to supply/demand issues, no fault of A-specs. Even though Sean wasn't going to make a huge sale off of me, he still took the time to answer all my questions and help me locate parts including the needed V-band adapter for my downpipe. In the end, I could only get my hands on a non-ball bearing GT40.

Secondly, I have to thank Nick Riefner from N-Tech Engineering who put his own project 350Z on the back burner (along with a lot of other stuff) and stayed up all night with me to install the turbo. Without his expertise, it never would have happend. More on that later.

Now that I'm done with the brownosing , on to the turbo. What I have installed is a Garrett GT4082. The GT4082, as the last two digits indicate, features an 82mm compressor exducer (58mm inducer) with a .94 hot side featuring a 77mm compressor, 73 trim turbine.

I am swapping in the GT4082 in place of a modified GReddy T78. I "thought" it was equipped with the 88mm version of the GT40 wheel but after examining it further, it doesn't appear to be a GT series wheel like I was told. Exducer diameter is 10mm larger than the GT40 at 92mm and if I remember correctly, my inducer was 65mm. The turbine side was 74mm exducer, smaller than the Garrett GT turbine with 4 more blades (10 for the GT, 14 for the Mitsu).

The installation, initually, looked pretty straight forward. For the record, it's going on a GReddy manifold, not anything from A-spec so it's something completely untested in terms of fitment. The turbos are of similar size and both are oil lubed/cooled only, no water jacket. the GT40, if you do not include the long V-band turbine discharge, is a bit shorter front to back than the Mitsu, esp. through the CHRA.

Once we removed the old turbo, two things became very apparent when pre-installing the GT40. First, the model I had has a slightly different bolt spacing from a standard T04 footprint. Second, due to the length of the turbine discharge and size of the V-band, the turbo would not fit due to interference with the lower intake manifold. Nick had an XS engineering intake manifold lying around but the bolt pattern for the wastegate was HKS specific and not compatible with the GReddy. So that was out of the question. In the end, we decided to cut the discharge off the turbine housing and weld on a 3" ID V-band adapter. This is fair warning number one...I have a feeling that out of the box, this turbo will not work with many of the manifolds out there due to the discharge. It will probably be necessary to have the turbine modified as I have done. i would suggest having this done by the turbo shop and not by your local installer/machine shop. Due to various fiascos, it took almost 15 hours to modify the turbine and locate all the necessary parts. Your results may vary Once we had determined we were going with a 3" downpipe/V-band setup, we had the mild steel CNC milled adapter A-spec sent milled down to use a smaller V-band clamp and allow for more clearance. Problem is, the CNC operator took too much of a cut initially, spinning the adapter out of the chuck and shattering it. Crap. So...from scratch, we milled a new one and I managed to locate a Turbonetics 3" V-band (the actual OD of the flange is about 3.5" FYI, and the 4" is really about 4.5"). I called just about every turbo shop in Central Florida looking for this adapter. Bill Hartzell of Florida Atlantic Turbo had one at home and he let us stop by and pick it up after he got off work. Great guy and very knowledgable about the GT series. He was surprised I actually had one and knew what the advantages were (more on that later).

So after much work, we managed to get the turbine housing modified and Nick welded on the V-band adapter. You'll need stainless rod and a TIG welder to mate mild steel to cast iron, no need for Nickel 99 rod. This was verified by several sources/engineers. Nick did an impressive job of welding everything up and it was the first time he'd welded mild to cast iron. He has skills.

The rest of the installation was "relatively" easy. A few strange items include the CHRA not having a full 360 degree rotation on the turbine side. There are four bolts so only two positions are possible. The compressor section rotates just fine. Amazingly, the alignment of the turbo was about identical to the T78 meaning the existing downpipe didn't have to jog to the left or right by more than a few mm's or so. As it's a bit shorter front to back, I have a bit more filter room up front. Not enough to run a different filter, but slightly more none the less. Even though the turbine side was rotated with the drain pointed down, it isn't directly down but at a slightly engine inboard slant. I would recommend a hose with an internal spring to keep it from collapsing as it's bent to make the turbine drain to the oil pan receptacle. One note, the turbine oil drain is pre-threaded. Not sure what the thread is. I already had a milled aluminum drain adapter with a screw-in barbed fitting (5/8). I had to tap into the CHRA (8mmx1.5) to screw in the aluminum adapter. It doesn't take much effort to drill and tap it either.

On the oil inlet side, it takes a standard T4-style adapter. I purchased everything from ATP Turbo. I believe Sean has the necessary parts too. My oil feed is a 4AN. For the block, you will need a 14mm to 4AN steel adapter from http://www.techna-fit.com. They also have swivel 4AN 90 degree fittings. I purchased new oil supply hose with pre-crimped ends from ATP as well.

We finally finished the installation at about 7:30am the following day and I drove teh 2.5 hours home to work a full shift (not fun). I kept off boost for a bit to break in the turbo. I am not yet tuned so I do not have dyno numbers. What I can provide is the general overall feel of the turbo compared to the T78. In a nutshell, they're WORLDS different in response. Everyone always says bigger is better but I tell ya, for daily driving in traffic, the GT40 is much much better than the T78. Boost response is about 2000 rpm better than the T78. The swell of midrange torque is amazing as is low-end boost response. I can only imagine how awesome the full ball bearing turbo would be. Compared to say a T04S, they're very similar with the GT40 "feeling" about 20-30hp stronger across the rpm range with better spool time. I always liked the stock twins and their responsiveness. While the GT40 cannot compare to say a modified sequential twin car, it does compare rather favorably with the boost response (low end) of a stock RX7. I get about 8-10psi by 3200rpm in 2nd and third gear and 17psi (and greater thanks to boost creep) before 4K rpm using an undivided manifold. In comparison, my old turbo provided 16psi by 5200rpm. I honestly think I have a "weak" engine as I did the porting myself (first time). I dunno...vacuum is good but I may have overdone the secondaries and exhaust port. None the less, the car is stupid fast. My goal is to get a few datalogs and post them to the datalogit list and have the car tuned in two weeks when I switch to weekdays off work. in terms of top end loss compared to the T78, I am sure there is some loss, but not much. The T78 (modified remember) would pull with no end to 8500rpm with no discernable drop-off in power (seat of the pants). In second, with the GT40, there doesn't seem to be too much of a dropoff if any, but it's sligtly different in feel. Again, I need to tune the car. It revs faster with the GT40 vs. the modified T78. The exhaust noise is greater wtih the GT40 as well. It actually changed the sound of the car from idle all the way up.

Here are a few pictures. First, the compressors side by side. Initially, I thought the 82mm would be waaay undersized. I don't feel that way now.

A-Spec Tuning

Well let me just say, after all the crap we went through I'm glad your initially happy, you deserve it. I would like to add you do have the smaller wheel, my only reason for repeating this is I really don't want people to take the "Top end loss" statement and direct it torwards the 40R. The GT series wheels are some of the best wheels on the market, they provide extremely wide power for their size, I have talked to quite a few of the bigger guys in the turbo industry and those wheels are regarded as the best out there, most of the aftermarket stuff doesn't come close as far as map width and performance. It really does require you to think a little different about application.

I can't believe you broke that flange I sent what a waste

And yes so every one knows I can get and provide any service or piece ATP can and some they can't. This is not meant as a slam on them, I know them well and we are good friends, It just gets tiring for me to always see go to" ATP " when I'm right here on this board for you guys.

Good luck Michel, and I just thought of this why not take the nice larger wheel and put it on the new turbo, it is the GT wheel you wanted after all.


-Sean

rx7tt95

Hrm...I didn't think that I was able to post this topic. My browser quit on me and I thought I lost everything. Anyway, I retyped the entire post on the nopistons forum with more pics of everything. I don't feel like going through the hastle of trying to post all the images here.
http://www.nopistons.com/forums/inde...0&#entry474698

rx7tt95

Agreed Sean. It's also why I mentioned it's not the same turbo you are using. If there is a loss in top end, and there must be based on size comparisons alone, it's slight and I am untuned with the new turbine/compressor combo and haven't redlined it in the two magical gears, 34d and 4th. I still plan on going full A-spec BB kit in the not too distant future regardless. As we discussed, this would be somewhat of an experiment. I think it's a good turbo and definitely better than a T04S. As is the 35/40 and I am sure the new 40R! One thing that puzzled me was that someone from Rotto Diesel/Big Red Turbo in Miami commented that BOTH turbos (4082 and 4088) are rated the same HP wise. Looking at the compressor map, it appears that the 82mm wheel needs higher boost levels to achieve the same hp levels but stays efficient waaaaay up there in boost level while the 88 has better efficiency at lower boost levels and higher CFM demands. This may be why I didn't grenade my motor at 1.4kg of boost yesterday. That and the fact I'm pig rich at those boost levels. Tuned in a safety factor above 17psi on the PFC.

I had a bad feeling about the guy doing the CNC work on that flange before he even started to turn it. I could feel something was going to happen, sigh...

I would have upgraded to the larger compressor but time was of the essence for me.

Oh and my turbo came labeled on the box as a marine turbo. Strange...but has the same specs as listed in the Garrett Catalog. Looking at the pics, does it look the same as what you had at your shop? The strange discharge and all?

A-Spec Tuning

Looks exactly the same from what I see and it showed up as a marine app. for me also. I just wish I would of thought of swapping your wheel earlier, I could have probably still got it done in about the same time, maybe pushed you a day later than what your end result was. please keep us all informed as it goes on I am interested as well, just because of all we went through.

-Sean

Carl Byck

Sean, I am curious, I ended up purchasing the following; This is a Garrett GTQ wheel.
Compressor; 2.626(66.7mm) minor 3.307(84mm) major
Turbine; 2.693(68.4mm) minor 3.111(79mm) major
.81 AR
How does this size up compared to the 40R you are using? I believe these are the same specs as CARX7s turbo, but not BB. Thanks for the input.
'tt95, glad all is well now. Carl

rx7tt95

That sounds smaller than the 40R on the compressor side, larger on the turbine side. One thing I forgot to post is all these companies are using GT to describe their parts yet the specs dont measure anything in their catalog. Seems kind of fishy to me...Maybe the other Garrett markets have different wheels not available yet here in the states. Who knows...

Crapola on not thinking of upgrading...might throw the pressure ratio off though going to the 88mm wheel with the smaller 70 trim turbine though. Ill just mess around with this one for a few months and see what I cana get out of it and upgrade when the new car arrives and the 7 becomes a weekend warrior

Zero R

iTrader: (1)

According to what information given to me it looks like a PT67, according to my Garrett guy it is likely to not flow as much and may be a little less eff. than the 4088R. Take it how you will but that was what they said.


-sean

suganuma

Just for ***** & giggles...

Pasted from a post long ago:

MODEL TRIM EXDUCER MAJOR
T4 P 64.62 74.22
T4 Q 68.40 79.02

MODEL TRIM INDUCER MAJOR INLET SIZE MAP
TO4E 57 56.64 74.93 69.85/76.20 T4E-57
TO4E 60 58.17 74.93 76.20/101.60 T4E-60
TO4 60-1 59.03 76.20 101.60 T4-60-1
TO4 62-1 62.00 76.20 101.60 T4-62-1
T-SERIES TS04 58.42 83.92 101.60 TS04
T-SERIES T-61 60.96 89.92 101.60 T-61
T-SERIES T-64 63.25 93.22 101.60 T-64
T-SERIES T-66 65.53 91.03 101.60 T-66
T-SERIES T-70 69.09 97.79 101.60 T-70

Carl Byck

Sean, you are correct it is a PT 67 with a garret GT wheel(so says Precision). It is basicly a TO4R, a little less flow than the 40R. As far as "efficiency", if it makes my projected 450-500rwhp @22-25psi I am happy. Carl

Kaotic Dan

double post

Kaotic Dan

My understanding was that ALL Garret GT turbo's were stainless ball bearings. From speaking at length with my reps at Innovative and Turbonetics, it seems the GT wheel is very efficient however the stainless (as opposed to ceramic) ball bearings have a relatively short life. Due to that, niether company wanted to reccomend the GT series turbo's to me or my customers for street use.

From the sound of it, the only way you can get the GT series turbo without ball bearings is by useing some kind of hybrid setup with a standard center cartridge and GT wheels.

Can't wait to see the dyno numbers!

rx7tt95

That's not true...the ceramic ball bearings (esp. Turbonetics) are unreliable compared to the Garrett stuff which is used in MANY OEM applications including the Mazdaspeed Protoge and the new Mazdaspeed Miata. The Garrett GT Ball bearing center sections AND the plain bearing center sections are very durable. Innovative and Turbonetics are not Garrett performance distributors btw...

Garrett makes several plain bearing versions using the GT wheels. Just go to www.egarrett.com and download their catalog where it gives comprehensive information on all of the turbos offered including compressor maps and compressor/turbine measurements.

My turbo is a Garrett manufactured turbo. It arrives in a box from Garrett fully assembled. It's a plain bearing GT40 turbo. The GT40R is about to be added to the catalog but is not there yet. Hope that clears it up a bit!
Michel

Zero R

iTrader: (1)

I will tell you the ceramic ball bearings are not going to have the lifespan that the garrett ones will, they will not recommend GT series turbo's becuase they are great turbo's(sounds silly maybe but they don't have them.) I will recommend a GTseries turbo over theirs any day to any customer I have. Think about this both companies you named use Garrett parts what does that tell you?

-Sean

Kaotic Dan

I stand corrected

rx7tt95

I have to correct myself too, IHI supplies the turbo (ball bearing) to the Mazdaspeed Miata, not Garrett.

flubyux2

sounds like you got your car set up pretty well. is there a reason you decided to go w/ the smaller Vband fitting? just so it would mate to your existing downpipe? or was it purely from an interference standpoint regarding the intake manifold? for my application, i didnt want to go w/ a downpipe or exhaust any smaller than 4"... so im just wondering.

i myself was originally looking at a GT35/40 (GT35R). after talkin w/ my friend who said thats what HE was going to use on his MR2.... i figured i may need to go a little larger to stay a few steps ahead... which has me lookin at the GT40. I think id be better off with the GT4088 rather than the 82...id rather go for the greater airflow at lower boost. the choke line for the 88mm compressor is at least a good 10 lb/min more than the 82mm wheel.

the onlything im thinking of is that you said the GT40 turbine pad is not the same as a T4. the bolt spacing for the turbine pad on the GT40 is 2.750" x 3.500". now im not sure what a T4 pad is supposed to be. now this is kind of a moot point for me since ill be fabricating my own manifold, so drilling custom bolt spacing is not an issue. what were you required to do in order to get your turbo on? or, how was the old bolt spacing different than the new GT spacing?

oh, and Your turbo came w/ gaskets for the turbine to manifold and the turbine discharge right?

im just trying to find out some more info cuz im actually planning to get one for my supra

in2twins

There is a guy in the Bay Area(cali) running a GT40BB on his MKIV Supra, ~850rwhp, check the california section on th Supraforum. Carl

Zero R

iTrader: (1)

The flange on the manifold was off, the flange on the turbo should be just fine standard T4. If you haven't got the turbo yet let me know, I can get them for you and pretty much at a better price than most anywhere else. Actually I believe there are only two places you can get these from right now Me and ............, well I let you figure that one out it's pretty easy but I can match their price.

-Sean

flubyux2

Lol sean, alright, that sounds good. ill be sure to keep you in mind. i have a couple friends down here who are able to order GT turbos, ill have to see about gettin some quotes on them. IIRC, a GT40 can be had for 3 figures, if you find the right people.

i just need to figure out what hotside i want to mate up to my 3.0L with a 7000rpm redline. not sure if i want a 0.94 or a 1.19. id like to get the 88mm compressor but it appears to be mated to the 1.34 hotside with the 84 trim turbine wheel Only. i think i read that one person had asked about mixing and matching the compressor and turbine wheels and the tech said its a bad idea because of mismatched sizes or something.... i may be limited to the 50 trim on the cold side... so i dunno

rx7tt95

Ok, the only reason I did decide to go with the smaller V-band was due to manifold interference between the 4" Vband and the lower intake manifold. This is because I am using a GReddy manifold and NOT the A-spec manifold. The actual footprint of the turbo is T4 but the bolt spacing is off. Not by much but I did have to move one side inboard about 1/4" and about 1/8" on the other.

You can only get an 88mm with the 1.34 or the 1.19 (special order) Sean may be able to get a custom hot side but I'll let him answer that :-)
Michel

rx7tt95

Almost forgot...no gaskets. None needed for the discharge (V-band). I used a genuine Garrett GT series gasket (for an italian market GT38R that I happened to come across, long story) that was very nice and more solid than even the GReddy gaskets which dare I say, I do like. I am positive Sean has gaskets though.

flubyux2

oh, ok, i gotcha now. ill be able to build in enough clearance for a "4 inch" Vband on the discharge. only thing i may have to worry about is the 1st bend coming out of the turbo for the DP... my manifold is more than likely going to be a top-mount, 6-2-1. but anywho, hopefully ill have some funds left in my budget and ill be able to make power close to what my engine is being built for

btw, ever come up to Tampa Bay area? id like to check out your setup

rx7tt95

Every now and again I do! Are you a member of MRCCFL? www.mrccfl.com. We'll be attending the Sebring 12 Hours as a group together. If you're a member you may be able to get two free tickets and a great spot amongst the show cars. I will naturally be there with my 7.

flubyux2

nope, im not a member, but sounds like an interesting proposition... off hand, do you remember what it costs to join?

oh, was the "R" model of that turbo available at the time? and whats that option cost?