Correct me if I'm wrong, but steel and ceramic bearings shouldn't be the reason for the response.

I would expect the weight of the rotating assembly to be the limiting factor. Obviously, ball bearing turbos

do spool faster than journal bearing, but I'm unaware if ceramic makes that much of a difference.

A small improvement but it certainly isn't the main reason they are so responsive.

I figured. The lightweight turbine is probably the majority of the reason.

I think this whole exercise by Garrett is an admission of failure .

We can't do what BW have done with turbine wheels so lets just repackage what we already have. Use a slightly better compressor design but combine that with the expected output numbers to match what Precision do so it looks like we got heaps more power. Throw in a reverse rotation turbo for special effect and the punters will never notice that we really didn't achieve anything.

I would agree. The reverse rotation aspect is really neat, but I'm surprised it took anyone this long to mainstream them. The turbo on my Dodge is a TD04 variant, but rotates the opposite direction. From a packaging perspective, it is long overdue.

The problem with reverse turbos is that everything is unique to those turbos, so good luck finding aftermarket turbine housings.

I see they have changed the turbine maps for the GTX3584RS now . However the new maps make even less sense than the old ones did .The AR's and wheel trims aren't even the same as the listed options. Looks like someone at Garrett is determined to f it up !

The GTX3584RS has a larger compressor wheel and the turbine map says its a 76 trim wheel, but the specs listed show a 84 trim wheel that is identical is size to the old GT35R.

I really am confused on what Garrett has been up to. They improve the compressor, but seem to ignore the turbine

Nothing against Garrett... They make solid gear. But the proof is in the pudding. Their Exhaust wheel is prob maxed out in terms of performance... and or They either arent willing to fund the R and D at the moment to develop a competitor to Borg Warners Gamma-Ti Turbine wheel.... Compressor wheels are easy.

The ARs are even different : 0.83,1.01,1.21 in the specs vs 0.7,1.0,1.15 in the turbine map.:icon_tdow



https://cimg9.ibsrv.net/gimg/www.rx7...175d4aee6d.jpg

That turbo isn't divided, so it's not worth a crap anyways...

I'm pretty sure ATP will do a divided turbine housing for it . Does seem strange that none of the gen11 turbos have a divided option.

That GTX3584RS has very slightly better compressor surge line than the old standby T04Z with really about the same compressor map besides and much smaller 68/62mm exhaust wheel vs 74/65mm of the T04Z.

Poor match for rotary compared to T04Z in my opinion. :icon_tdow


https://cimg2.ibsrv.net/gimg/www.rx7...2701a50e78.jpg

Depends on what it actually flows-hopefully Garrett will get their shit together and get the correct map up soon . It could be that it flows similar or even more with the 1.21 hsg .

Garrett have finally got the correct turbine maps up for the new RS turbine :
Here is the comparison with the old turbine of the same size . Comparing old 1.01 with new RS series1.01
it looks like a gain in flow in the order of 3.5%...................


https://cimg3.ibsrv.net/gimg/www.rx7...b6f502b4f8.jpg


https://cimg4.ibsrv.net/gimg/www.rx7...cdcc89840b.jpg

Garrett is actually killing off all of its divided P trim housings too.. 1.0 units died a long time ago, now the .84 and 1.15s are on the chopping blocks..

https://cimg3.ibsrv.net/gimg/www.rx7...b6f502b4f8.jpg


https://cimg4.ibsrv.net/gimg/www.rx7...cdcc89840b.jpg

Just noticed the the max efficiency of the new rs wheel is 78% .. vs 70 for the old .
According to my mickey mouse comparison on matchbot , this would put the GTX3584RS 68mm wheel with a 1.21 AR housing at about the same backpressure as a normal 74mm wheel in a 1.45 housing ..........

Could be merit in this new design as the spoolup has to be better than a normal 74mm wheel .

For a typical street rotary under 450whp, wouldn't you want a 1.01 AR or lower?

The 1.21 seems like it would take some time to spool up.

I think we are talking about more like 600+ rotary whp for the 3584 with a 1.21.

Spoolup is relative to wheel size as well as AR . A 68mm in a 1.21 is going to spool up better than a 74mm in a 1.21 . Which I think is what Garrett is trying to achieve with the RS wheel. Less flow ,but the same backpressure and better spool than a larger wheel in the same sized housing.

Sorry, a bit late to this party - was just pointed this way, hope it's not too late to join.

When you refer to the 74mm turbine, there has been talk about T04Zs and also the EFR range (and Matchbot)... are you talking about the T04Z 74mm turbine?

The distinct concern I have with these things is as you have alluded to, the exhaust back pressure will likely be higher with the GTX3584RS hotside than the T04Z with all other things being equal... and the choke flow on the 67/84mm Gen2 compressor drops as you travel over 2.5PR which means its not a high boost friendly compressor, which lends itself to potentially quite high pressure differential across the motor if you try to hit the GTX3584RS's claimed peak flow. Part of me wonders if it's even possible when attached to an actual engine.

Was not referring to any turbine in particular . Just saying that ,due to it's 78% efficiency, it should offer similar back-pressure to a larger turbine of around 74mm.

Is now ..........

Garrett T3 Twinscroll Turbine Housing in Ni-Resist For GT35R/GTX35R 1.01 A/R : atpturbo.com

according to the ATP site the RS is avail w a T4 1.06 divided... BTW, non-RS hotside housings are not compatible.

Howard what are your views on the EFR 9174 compared with 9180? Also what would the advantages be of going alum chra ?
Thanks for your input.

Lots of good info. Saving for later!

Can this list be updated. It's of great help to all the community.