TeamRX8

iTrader: (25)

FC 13B with a BW EFR 7670, snagged it at RX7Club, owner is BlueTII, not even fully tuned, said it was rich on the top end, 20+ boost








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skc

20 PSI will not work on the renesis. Early power is nice however the drop after peak is alarming.

Motor like this would be good for drags and street but a pain at the track.

Brettus

iTrader: (2)

dyno is one thing ........... driving past the choke line on an undersized turbo on a daily basis ... is another .

Harlan

iTrader: (3)

20psi has not worked on a renesis yet, that doesn't mean it's impossible. I agree with the idea of having a higher pressure down low and intentionally dropping off into the higher RPMs. It gives you a better area under the curve, and I believe the engine can support it better than pushing high boost at higher rpms.

TeamRX8

iTrader: (25)

It's well documented that I recommend a 13B swap for turbo. At a minimum, a turbo Renesis should have rotors machined for deeper 13B apex seals. OD was one of the few that listened. Otherwise, who here has run E85 or 110+ octane with a solid build capable of running there?

Brettus, you crack me up. The undersize turbo is on your car

Unless you watched the FD3 video several posts back then you missed what the real potential was once they put a fresh built motor in. The fall-off dyno was from several years ago with an old, tired original factory FD motor.

Here's the FC with the 7670 above doing a 4th gear acceleration from 50 - 130 mph (if I read the speedo correctly)





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Brettus

iTrader: (2)

Yep ..did that 21/2 yrs ago

no-one ... why don't you show us how it's done ?

Yes it is(turbine wise) .... yet the compressor flows more than the 7670 one...............

If that flow map was correct........ it doesn't flow enough to efficiently run on a 13B(see thread title ) . The dyno/video do suggest otherwise ... dunno what to make of that .

Aside from all that ......... no it wouldn't fit on a greddy manifold

TeamRX8

iTrader: (25)

Sorry that I forgot about you making the apex seal conversion and some other aspects of your current build. You've done a great job BTW. But as you finally figured out, a compressor only actually chugs out what the turbine is capable of driving it to. The number of blades is a minor consideration. It's the actual sizing ratio that matters most. Flow maps also don't tell the whole story which all these latest EFR builds are demonstrating. Not only are the EFR compressor/turbines combination well matched for rotary builds, they provide low end response and boost well beyond past expectations/experience. I understand why you see it that way.

Both those setups are cranking out lowend torque like mad. You're at around 260 lb-ft at 5500 or so? You seem to be undervaluing the real power being demonstrated; area under the curve. There's no choke point to drive past. When an engine makes 300+ lb-ft @ 3200 rpm what you do is .... shift gears.

The show-us comment is a valid arguement. I'd love to, but it's not the direction for me yet. Tried to work together with a few people to demonstrate a few things, but nothing panned out yet. Not the same thing either since everyone always has their own ideas ...

Brettus

iTrader: (2)

The only way the 7670 could make that much power without overdriving the turbo would be if they were somehow able to defy the laws of physics that govern the 13B rotary engine . I accept that it makes the power ............. but way over the choke line for the turbo and thus at very high intake temps. How or even if they are dealing with that you didn't go into.
You also posted an amazing dyno for the 8374 . Now that turbo IS big enough to flow enough for a 13B in the 2.0PR and above range .

And yes I do fully appreciate the torque being made by those combinations .

TeamRX8

iTrader: (25)

Your concept of physics is the issue. His Pr down low is closer to 2.75 tapering off to 2.36. The general rule of rotary thumb is 10 lb/min for every 100 hp so your earlier 60 lb/min @ 2.1 Pr Renesis claim is a bit misguided IMO. Getting that kind if efficiency at that rate us a challenge unto itself let alone not blowing the engine.

There are other realities too. He had a low mount BNR Stage4. The 7670 was an easy bolt on. The 8374 moves up to a larger compressor. the basis of this thread was low mount too. 7670 likely can't fit, 8374 no way. This is why I posted up the 7163 instead. The reality is your end goal vs the results. We are only discussing the 7670 because you dismissed it based on perception. He wanted low end response and power for short sprints and autox, not extended high rpm max power.

9krpmrx8

iTrader: (46)

I am awaiting measurements on the 7163, from what I can find online I think it may fit on the Greddy manifold, we shall see. I hope it does.

Arca_ex

iTrader: (10)

10lb/m of airflow per 100WHP is a piston rule of thumb. Take that HP number and divide by 1.3 to get somewhere close. Even then there are a lot of other variables.

So 600/1.3 means about 460 rotary (except renesis) RWHP for 60lbs/m of airflow.

Arca_ex

iTrader: (10)

Also I thought EFR dimensions were published. Try here and select Performance Turbos or Google it. I know I have a dimensions sheet for my 9180 that I found online.

Performance Turbos | BorgWarner Turbo Systems

9krpmrx8

iTrader: (46)

Yeah I could find dimensions for most of them, just not the 7163 for some reason.

9krpmrx8

iTrader: (46)

Well I will measure the brand new BNR 60-1 I have at the house but I don't think the 7163 will fit.

A guy selling one (single scroll, T25) measured and gave me these measurements:

"11.25 inches overall length. about 7.75 inches wide."

Arca_ex

iTrader: (10)

It's in the link that I gave you... in the drop down select Performance Turbos. It's the very first link, Product Catalog. Page 26, 27, and 28. They show dimensions for the T25 open volute, T4 twin scroll, and the new V-Band unit...

9krpmrx8

iTrader: (46)

Yeah it doesn't give me the width from wastegate actuator to the other side of the compressor housing though, that is the one I needed most. And according to that .pdf over length is 10.1" so an inch off of what the guy who is selling them gave me. I hate people.

Arca_ex

iTrader: (10)

Assuming that the scale on their drawing is correct, the width from the outside of the wastegate actuator to the opposite edge of the compressor housing is approximately 11.75".

9krpmrx8

iTrader: (46)

I just got off the phone with Full Race, they measured it and said 9.25" from the outer edge of the wastegate actuator to the other side of the compressor housing. So, who knows, the guy selling it is going to send me pictures with the measurements, he says his measurements are accurate. BTW, Full Race has some great prices.

Brettus

iTrader: (2)

The reason it made ......only..... 400whp at that PR was because it was running over the choke line ... which is my point here . The same PR on the 8374 and it would be up around 500whp.
And that 10lb/min x 0.7 for a rotaryrule of thumb .......... is for flywheel hp not wheel hp . So if you do the maths ; to make 400WHP you need approx. 60lb/min . Put that on the 7670 flow map and then tell me it's running efficiently .........
I want to thrash this out with you because I think by suggesting that turbo would be good for the Renesis you are heading us down the same path we have been on for years . IE fitting turbos that are too small. I think (because of the high compression ratio) for the renesis we need even more efficient turbos ( bigger) than what the older engines are running .


And sure ... that 7670 would make great torque and make the car a rocket out of the blocks . But to run it efficiently at high rpm (6500 on up) you would need an EBC that was capable of reducing duty cycle as rpm increased.

Arca_ex

iTrader: (10)

Hope you were being sarcastic lol. My turbo is almost $300 more expensive there than most other places.

Their manifolds are definitely badass though and priced reasonably for what you're getting.

9krpmrx8

iTrader: (46)

The price they quoted me on the 7163 with was $150-200 cheaper than everywhere else

Arca_ex

iTrader: (10)

So they quoted you a different price than what is on their website?

9krpmrx8

iTrader: (46)

I just checked the site, and yes they did.

TeamRX8

iTrader: (25)

The owner doesn't want or need to run out full rpm because he can shift early without penalty. It's easy to do an area under the curve comparison given a specific rpm range to see which is actually superior; low rpm with short-shift or high rpm revved out fully. It's also not fully tuned out there yet. We'll keep tabs to see how it develops.

Again, I don't disagree that an 8374 is more efficient for mid-top power. We don't need to keep rehashing it because that will never fit in the low-mount RX8 position without re-fabricating the front RH frame rail & subframe.

I was wrong to quote 100 hp per 10 lb/min mass. It's 7 hp per 10 lb/min. I actually repeated an old posting mistake made by RotaryGod . If God can make a mistake, I won't run away and hide in shame

TeamStubbedmytoe

Brettus

iTrader: (2)

Sure you can short shift and still do well with that setup - no argument there . But with the upside also comes a downside ............... high torque at low rpm is harder on the drivetrain than high hp high rpm (lower torque)

I'm leaning towards the Precision 6266 myself . Not because it's the best turbo .... but because it will actually fit in a low mount position and is big enough to run at 2.0PR efficiently , right out to the redline .


Also toyed with the gtx3076 but even that is marginal at 2.0PR ...... the problem is no-one designs turbos specifically for rotaries .We need high flow at low PR. We could use smaller turbos if they just played around with the compressor trims to give us the ideal flow map.