Anyone have documentation from when Mazda was developing '99 turbos?
 

Does anyone have data from when Mazda was developing the '99 spec turbos?

Reason I ask is I am interested in trying twin EFR 7163 mixed flow turbine turbos.

I ran across this quote from Yamamoto regarding the development of the '99 spec turbos though-

The latest trend in high-performance turbo technology is a "diagonal flow" turbine. Mazda asked Hitachi to come up with several candidates of this design, hoping it would boost the engine's output. They did not quite match the rotating piston engine's unique characteristics. Back to the tube, as it were, to research basic flow dynamics. The fruit of the toil is the "ultra-high-flow" turbine, with its blade length extended and its shape less acutely curved, enlarging gas passage and reducing flow resistance. Turbo response in the low speed zone has been greatly improved. The turbocharger adopts a smaller diameter turbine, 50 mm (1.9 in.) now versus the previous unit's 51 mm (2.0 in.), again reducing inertia mass. The new "ultra-high-flow" turbine realizes about a 10% gain in efficiency, according to Mazda's turbo engineer. The twin ultra-high-flow turbochargers supply a maximum boost of 74.7 kPa (10.8 psi) at 6500 rpm to the previous high-flow instruments' 62.7 kPa (9.1 psi) at the same rpm.


Well, I am worried the "diagonal flow" turbine is a term for mixed flow turbine...

Mazda themselves haven't been able to make up their minds on the turbines for rotaries though, so I want more info. By Mazda not making up their minds I mean the 12AT turbo was conventional turbine, 13BT turbo was "high impact" (straight blade at exhaust entry), the 13B-REW was conventional (cupped blade entry) and then the '99 13B-REW "ultra-high-flow" was 1mm smaller wheel but less exit curve (like clipped turbine).

But, I would like to hear what they found regarding "diagonal flow" turbines on a rotary.
http://www.hindawi.com/journals/ijrm...20.fig.002.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...5dc111f778.jpg

Original vs '99 spec exhaust wheel-

https://cimg9.ibsrv.net/gimg/www.rx7...1e1ef1c8b9.jpg

https://books.google.com/books?id=ds...harger&f=false

^^
Not Mazda related, but this paper has some good info.

Steady flow versus Un-steady flow. I guess the rotary would be biased toward steady flow exhaust compared to a 4 stroke piston engine.

Twin EFR 7163?
Do it! I want to see that :)

i would think the 7163 turbine wheel is too big, the exducer area would be about equivalent to single 3" exducer, right? twin 6258s or 6758s would spool like crazy

i want to try just a single 7163, the turbine wheel size looks to be very close to factory FC size, but i wonder how much the "mixed flow" will help

gxl90rx7 i would think the 7163 turbine wheel is too big, the exducer area would be about equivalent to single 3" exducer, right? twin 6258s or 6758s would spool like crazy

i want to try just a single 7163, the turbine wheel size looks to be very close to factory FC size, but i wonder how much the "mixed flow" will help

Yeah, I think the 7163 in a stock S5 manifold/housing would be an awesome turbo for ~300-400rwhp at high boost (auto-x racing like I do) or 250-300rwhp on the streets on pump gas.

I already have single 7670 from my FC and though the torque is great from 3-5,000rpm it drops hard after that. For my FD I was thinking of a way to carry the torque into the higher rpm and get even better spool.

Planning for sequential twins not parallel since its on my FD and there are a couple PnP aftermarket ECUs that can support it now.

I was also considereing twin sequential 7670 since I already have the one turbo- that is what has me second guessing the 7163.

I do like the compressor map of the 7163 better than the 7670 since I don't have to run 24psi to get into the peak efficiency island.

Here is my single 7670 dyno-

https://cimg4.ibsrv.net/gimg/www.rx7...b7964bfab1.jpg

You could always make some crazy tube high mount sequential mani.

You guys do realize that EVERY rotary sized EFR surges in the lower RPMS at high boost right? Meaning you physically just cannot cram more into the engine in these ranges( 3500rpms and less). The 8374 will already make 15psi at 2500rpms, and 30+ above 3400rpms. What is the point of twin EFR turbochargers? I would assume to break the 8 to 1200rwhp range, no ?

When you say they surge, are you basing this on experience of audible surge or based on an airflow and pressure ratio estimation and plotting on the compressor map?

shawnm565

You guys do realize that EVERY rotary sized EFR surges in the lower RPMS at high boost right? Meaning you physically just cannot cram more into the engine in these ranges( 3500rpms and less). The 8374 will already make 15psi at 2500rpms, and 30+ above 3400rpms. What is the point of twin EFR turbochargers? I would assume to break the 8 to 1200rwhp range, no ?

I never had any impression that my EFR 7670 was surging and it makes sense that it wasn't yet since it was barely out spooling/powering the 8374 on the low end from what I can tell.

I think I needed more exhaust velocity to get it to its surgeline.

However, I want even better response/low end power without sacrificing top end power is why I am thinking dual sequential 7163s.

I love that stock 3rd gen sequential feel. With the stockers dialed in with MBC its perfect power band. Just want more of it.

I have considered sequential GTX2867R or GTX2871R in stock exhaust sides (kinda like BNRs), but I think its going to breathe better rotating that rear turbo so they aren't dead headed and then making 2 tight 90 degree bends in a single little 3" downpipe.

NOT trying for huge hp, just the ability to run 25+psi on the low rpm for torque and still have some top end grunt.

More than just audible, the engine will shake pretty bad on his 8374 car, and my 9180 car.