I recently saw that back in 2015 Feed switched from their old T04Z set-up in their Touge car to a CGC GTW6262 -edit- or possibly GTW6265? as that would seem to suit the rotary better (and coincidentally same compressor and exhaust wheel size specs as EFR 8374).


Skip to 4:54 in the video below (hey, didn't want you to miss out on anything)-

Response does seem sharper than their old T04Z, but it seems to "hit hard" as it comes into boost which isn't great on the touge.

I want to see EFR 8374 on a rotary run the Gusai touge sooo bad!

 

Hi
I'm still trying to understand the ins and outs of turbo calculations and turbo selection. This thread has been awesome yet I have not read all posts.
I have extracted the Turbo list and done some checks myself. Below is a link to my current spreadsheet if anyone is interested in my thoughts:

Shawky's Rx7 Turbo Information Spreadsheet

From all the reading and experience with my own car, my assessment is that the primary focus should be to reduce the exhaust pressure, improve exhaust flow and efficiency as this is the likely area affecting engine reliability, and constraining performance.
i.e. the stock Turbo is good to flow about 300RWP
The second spreadsheet looks at theoretical calculations for the compressor, and from that plots the air flow/pressure against the turbine efficiency map. Quite a different view that some information posted before:

Shawky's Rx7 Turbo Flow Calculations

What I have observed from this analysis, that if your inlet path is efficient (98%+) the the actual power outputs of real cars for boost levels used seems to align. The assumption of course is that the exhaust turbine can supply the energy and limit exhaust back pressure to allow the power to flow.
Hopefully I have re-ignited the debate

I am about to embark on my engine rebuild and performance upgrade....

Take care
Shawky

P.S. You don't need a dropbox account to download the spreadsheets.

 

I selected a Turbo SXE366 ball bearing (80mm Turbine 0.91 A/R, 66mm Compressor). You can view the Borg Warner MatchBot calcs etc on my build thread: Shawky's Turbo selection

 

need to add the new BW EFR8370 … 6.626 … 5.229 … 0.79 …, which imo is not going to do well on a 13B without a larger A/R than the present 1.05 T4 twin scroll being the largest EFR housing available for the 70mm ceramic turbine wheel. I envision Emap to be increasing rapidly passing 400 whp. Something in the 1.15 -1.25 A/R range is going to be more appropriate imo for using it into the lower 400 - lower 500 whp range.

which allows me to step up on my soapbox again and point out that the the turbo wheel area relationship theory fails to take a few things into account.

One is the relationship between a turbine wheel of one size and the A/R housing being chosen for it vs a turbine wheel of a different diameter and A/R. As demonstrated in this image grab from Borg Warner’s Matchbot program and the boxed in selections, you can see how a turbine wheel having a particular diameter and A/R turbine housing can be approximately matched by the next smaller turbine wheel size having a larger A/R.





So what does it mean?

Without turbine flow maps it’s going to be difficult to determine without some experimentation, but generally speaking the turbine housing A/R can be chosen to offset the turbine appearing to be over/under-sized relative to the compressor. It helps to not only have flow maps, but also to understand what peak lbs/min exhaust gas flow through the turbine housing is going to be needed.

Because the A/R value is only relative to a particular brand/type/size turbine wheel, not necessarily with a different brand, type, or size. If you have turbine maps though, and also a feel for the mass flow required, then you can match up your requirement pretty close before pulling the trigger. There will always be some variables involved, but you can avoid being completely out of the ball park.

Which then brings me to another point of contention; that not all impellers are created equal. Two impellers of a certain size and trim are not necessarily equal or all that close in mass flow capability. The newer Garrett G Series turbos in particular are an example of a smaller impeller outflowing larger older impellers through technology/design differences. As an example the new Garrett G30 turbine with 1.01 A/R housing having approx. the same flow map curve (within a few %) of the former and larger Garrett GTX35 turbine with 1.01 A/R housing. Which is exemplified by all the new G Series turbos being positioned on the front page list way down among much smaller older turbos, when in reality they outflow even the previous Garrett GTX turbos by about one model size.

If the turbo your interested in doesn’t have flow maps then you have no choice but to rely some on the manufacturer, but again if you have a feel for what mass flow rates are required, and also how to relate those back over into comparable reciprocating piston engine values, that will likely help them to make a closer selection for your need.
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which there is a hybrid Borg Warner SXE turbo available through AGP Turbo now as well: effectively an S200 SXE 62-70 … 6.54 … 5.27 …. 0.81 ….; the S257SX-E turbo retrofitted with the S362SX-E compressor wheel. What distinguishes this over the EFR8370 is that they offer 1.09, 1.15, 1.22, and 1.27 A/R turbine housings for it. Supposedly good for about ~530 max rotary whp with the 1.22 or 1.27 A/R housing. The turbine housings are all cast iron though with T3 twin scroll ports on a T4 flange, which does require taking a die grinder and angle transitioning the T3 ports out to the T4 size if you have a T4 twin scroll manifold.
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I'm very much looking forward to the S364 SX-R.

Heck, even the S258 SX-R could be a contender. Looks like they are starting to roll out, anyone had a chance to try one yet?

 

I tried to get information on the SX-R series for over a year now, even spoke with their engineers about them. This was about 6 months ago, but he told me that they put those in their brochures too soon.

I ended up getting the SXE 366 a few months ago. My luck, the SX-R with probably launch soon. Lol

 

I'm on a fresh SXE 366 too, haha. Oh well..

A few models of SX-R are available for pre-order at boostlab, so they must be pretty close. Pricing is very reasonable.

I'm guessing there might be some new EFR options around the corner, too, as the compressor/housings seem to be falling behind. What a time to be alive, haha, gotta work quickly to stay currrent!

 

close with BW for the last several years is 6-12 months, maybe more
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Garrett has finally released tech specs on their GXRace compressor/rotating assembly setups (absolute flogs put out a youtube hype video a couple of weeks [ormore]ago with zero texh detail and nothing on the website). A couple of these may prove useful on high overlap rotaries looking for some threshold/gear change response improvements.

As has been the case since the beginning of time, more lift path/lower trim generates more pressure for the same ahaft speed.

What you get: more boosts at lower shaft speed, higher peak boost.
the compromise: A few percent lower peak efficiency at the boost most users here actually use.


https://www.garrettmotion.com/racing...?term_id=13585