Garrett Medium Frame Gtx Turbos

[AngryRB]

ah ok, well hopefully it will be on full boost before 4000rpm, i noticed micks gtx3071 took until 3800rpm ( correct me if wrong) which i thought was a bit late, cause mafia's came on full at 3200 which is big difference,housings may have been different.

The claimed 10% increase in flow doesnt seem to be true in that case, atleast on those boost settings and rev ranges, maybe with an external gate and E85 the hotside isnt as bad, and the compressor is able to get closer to its max efficiency then.

oh well ill see what happens with mine and then re-assess any improvements.

cheers.

[wolverine]

With the GTX3071 the extra compressor flow was compensated by upping the cropped turbine wheel to a full GT30 60mm version. It seems to have made it behave like the GT3076 but with better response.

Scott this just isn't quite right on two points.

There have been several versions of turbos with different trim 71mm compressors and various turbines from 53mm to 56mm to 60mm turbines. (GT-RS, 2835, 3071wg, 3071 etc etc)

Mick's GTX3071 made less power everywhere than my GT3076 with the same tuner on 98 ron. Once Mick went to E85 the car was much more lively and definitely one of the nicest RB25 you would ever hope to drive (and it is a better drive than mine) however E85 would also give a similar leap in performance from my car if I cbf using it.

I do not believe the GTX is a step up in this frame.

[scotty nm35]

I believe there is more to gain from his setup still, I wouldn't be surprised if he could crack 350 at the same boost with a bigger exhaust, good manifold or better intake/cooler arrangement. How else do you explain my auto getting the same power output as his other than the rear housing?

Give it some time, and a few more well sorted cars will be getting those kind of results. Mine is hardly maxed, still has a 3 inch intake, stock airbox and cut down cooler to cause restriction.

[wolverine]

Compressor is maxed out is the explanation. You both made similar numbers on similar dynos with different AR turbine housings. Dyno variation is also a factor, your original number from the hi-flow you had were on the high side due to calibration issues of the dyno if memory serves so your peak number with the 1.06 Tial housing was pretty much right on the money imo on a DD dyno.

Mick's car is one of the best sorted RB's and without doubt it is the best one I have driven but I would bet my left nut he would have more power and earlier with a GT3076 on his car with E85.

ps. mine showed clear signs of restriction on the dyno on 98 ron, maxing out at 290ish.

[scotty nm35]

When you say the compressor is maxed, that only means the compressor can't flow any more with the current setup, that can be caused by many factors though as you are well aware. (My tuner said the compressor was maxed at 300kw before the exhaust upgrade.) I have no doubt there are gains going to a larger intake but I literally can't fit it in there on my setup, even though its running a map sensor now. Peak power was only at 23psi so there should be room to move yet.

I was hoping to push it to 350 as that was my current goal but there are a few hurdles with parts design I need to address, I have no idea what that power would equate to on an RB but I would have thought the auto would rob a fair chunk of it. Perhaps the .82 rear just isn't big enough? I will know soon as I have one here to try out.

All in all its doing a great job for its size, perhaps I will go down the aftermarket cam path to reap more top end gains (the VQ25det only runs around 8mm lift) but my goal was to see what the stock engine is capable of and I would rather just get a bigger turbo I think.

[Dale FZ1]

Scott I don't think it matters quite so much whether you or Mick can (even if he wants want to) achieve 350kw. Application (road, drag, circuit) counts for a hell of a lot, as does whether it has suitable delivery to put it to the ground. A larger 1.06 housing and/or fabricated manifold and/or attention to reducing restrictions may yield a slightly different result, but I believe Wolverine in his assessment of the importance of E85 in that setup. I just don't think that GTX3071 has any more to give. I think any changes would alter the character and delivery, but not the number (if that is what is being chased).

I do consider the 71 vs 76 exducer is an important variable when talking about response. Haven't yet seen any of the GTX compressor maps, but going by the established characteristics of the GT series, the 71 will have to spin faster to do its thing. Wolverine's comparisons on the pump 98 tends to bear that out. Having said all that, I'd like to see Mick's setup with the 1.06 housing. Its midrange oomph is ridiculously good (and fun) to the point you'd wonder how/where/why there would be a need to make it any different other than to put it to the ground more effectively.

Then the thought of using a different spec turbo comes up. I'd think the GTX3576 offers a lot of scope for the person who wants more than a GT3076 or GTX3071 can offer.

[scotty nm35]

I agree Dale, The compressor must be running out of efficiency so its a losing battle but there is always a little more in it. I enjoy fine tuning the setup for greater flow.

How the power comes on is equally important. The 1.06 comes on a little softer, more linear and as such the tyres don't seem to break traction easily. The auto/stally would help too. I really need to get the front diff in though, its scary in the wet in rwd.

I have a retune next weekend and plan to try out the United e85, perhaps I can gain a little more from that? I also dropped the water temps by 10 degrees, back to 80, it can only help I guess. Hopefully it will take a little more boost this time. The plan is to make a few Subaru owners sad at the dyno day I have coming up.

[Lithium]

Just out of interest, here is a comparison done by E&H Motors in NZ using their 2litre track spec STI on the same boost level using E85 of a twin scroll GTX3076R versus a twin scroll EFR7670:

[GTScotT]

Now that is interesting.............................

Mostly disappointed in the EFR, but surprised at the like for like comparison.

[Lithium]

Really, how so? It outspools the GTX and makes more torque everywhere even running slightly less boost at points - the dyno plot I put in the EFR thread shows its also seeming more keen to make more power. Its basically like a slightly bigger turbo than spools slightly better and is a fair bit more responsive than a GTX3076R, making 200awkw by around 4200rpm on a 2litre on the way to making 415awkw with more to come. Its not a bad result.

[discopotato03]

Shame there isn't a 3076HTA for comparison . They are supposed to be the cats wiskers torque wise .

A ,

[scotty nm35]

The twin scroll .78 housing is pretty small for the 76 compressor though isn't it? It may be laggier but strangling it wont help the top end, the GTX results can't be compared to a T4 1.06 TS anyway. Shame they didn't try similar AR's, I wonder what the manifold differences were...

[Lithium]

I think it had previously run larger ATP twin scroll housings which had failed, I can verify that and manifold changes.

[BMYHOE]

So after lots of mucking around i finally got my GTX35 Twin scroll set up running.

fitted to a Built 9.5:1 RB2530 on E85, Currently the car is on a EPA/Run in tune for bedding in & passing emissions for engineering, so its only reving to 5750RPM and running 12.5PSI. no power figure yet but estimate approx 350HP at the moment.

changing from the GT35 to this i believe it has better spooling im seeing 12.5PSI at 4000-4200RPM in 2Nd gear.

the old GT35 would hit 24psi around 4500RPM

the set up at the moment is 6boost mani,GTX35, ATP 1.06 T4 Divided housing, 2x trial 38mm external gates, 4inch dump then reduced to 3inch for 2x VRss commodore CATs (for EPA), solid lifter conversion etc..

My emission test is 4th July wish me luck all

[scotty nm35]

Good luck, but will you need it running ethanol? Should pass emissions fairly easily I would have thought.

It sound like a very nice setup, got any pics?

Im hopefully going for my GTX3076 tune this weekend, not sure I want to push it too hard now since a head lifted and blew the head gasket. It was a big job to pull it all out for repair and L19 studs, don't want to do that again anytime soon...

[34GeeTeeTee]

Nice, look forward to seeing the results, but also how you go with the emissions test......

[Lithium]

Awesome, interested to see how the GTX35 goes - good luck with emmissions testing

[BMYHOE]

thanks guys hopefully it passes first go so i can go onto change exhaust & tune her up, if not i might have to add anther cat LOL

im using caltex e flex fuel the cams are 264in & 272ex with 10.5mm lift so it will be interesting to see if it passes

having trouble loading pics ...

Edited June 26, 2012 by BMYHOE

[The Mafia]

thanks guys hopefully it passes first go so i can go onto change exhaust & tune her up, if not i might have to add anther cat LOL

im using caltex e flex fuel the cams are 264in & 272ex with 10.5mm lift so it will be interesting to see if it passes

having trouble loading pics ...

Is your user name the same as your number plates?

[BMYHOE]

nah its not whys that