# My 13B engine configuration (tentative)

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#### Lendo

##### Well-Known Member
No but a local Parachuting club flies something with a V8 and Belt Drive, never actually seen it but know the Pilot. I asked him to find out what belt and what drive, but to no avail.
George

#### rv7charlie

##### Well-Known Member
No but a local Parachuting club flies something with a V8 and Belt Drive, never actually seen it but know the Pilot. I asked him to find out what belt and what drive, but to no avail.
George
Early iteration of a glider tug engine from down under.
Current status using GM LS motor.

#### undean

##### Member
From my understanding, the Mistral Piper Arrow muffler collapsed internally, and restricted the engine output badly. Common failure mode, especially in a high temp, high frequency rotary exhaust. Stout and heavy appears best. Look at the RX7 mufflers! The rotary list has been experimenting with several muffler designs for years. The turbo versions of the 13B (13B rew tt) have a divider in the exhaust port; perhaps that allows the turbine wheel to last. But that engine also uses all Inconel hardware (all nuts and studs) and an Inconel manifold, so it’s a real consideration.
To add to your post from my time in the RX community: The primary reason the mufflers are large is to add volume for noise mitigation and deal with the heat. The 13BT and 13B-REW both have exhaust dividers. Both bifurcate the exhaust for their respective twin-scroll setups. Just about anyone who can afford it goes for Inco in their manifold. Especially racers as even thick Stainless, iron, and Ti will droop/crack/fail under the sustained turbo exhaust temperatures.

#### dwalker

##### Well-Known Member
To add to your post from my time in the RX community: The primary reason the mufflers are large is to add volume for noise mitigation and deal with the heat. The 13BT and 13B-REW both have exhaust dividers. Both bifurcate the exhaust for their respective twin-scroll setups. Just about anyone who can afford it goes for Inco in their manifold. Especially racers as even thick Stainless, iron, and Ti will droop/crack/fail under the sustained turbo exhaust temperatures.
The 13-BREWand the 13BT use the same rotor housing and very similar exhaust ports. There is no splitter or
divider" such as there is in the 13B NA.
The OEM exhaust manifolds, which are CAST IRON and NOT anything exotic, crack with regularity, and the overly complex heat retention device that passes for a manifold on the 13-BREW is especially hideous and a very large part of the reason why few, if any, FDs made it past 60K miles without an engine rebuild due to coolant seal failure (actual most common rotary failure, not "blown apex seals") and it is a reliability mod to go to a single turbo on the 13BREW.

Very, and I mean VERY few racecars in the general rotary community, from 13B-NA SCCA club cars to 900whp drag cars are using inconel exhaust manifolds. In my RX8 PWC car, which won not only sprint but also Enduro races (9 hours of Road Atlanta, etc.) we used the same 321 SS exhaust manifold for 3 full seasons of racing without issue. The Pro Formula Mazda cars used a SS exhaust system and an off the shelf Borla (Series Sponsor) muffler. I am sure Mad Mike is running Inconel, but again, not the best example.

Pictured is a 13BREW exhaust port. I thought I had a picture of the monstrosity that is the 13BREW TT manifold, but nope.

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#### undean

##### Member
The 13-BREWand the 13BT use the same rotor housing and very similar exhaust ports. There is no splitter or
divider" such as there is in the 13B NA.
The OEM exhaust manifolds, which are CAST IRON and NOT anything exotic, crack with regularity, and the overly complex heat retention device that passes for a manifold on the 13-BREW is especially hideous and a very large part of the reason why few, if any, FDs made it past 60K miles without an engine rebuild due to coolant seal failure (actual most common rotary failure, not "blown apex seals") and it is a reliability mod to go to a single turbo on the 13BREW.

Very, and I mean VERY few racecars in the general rotary community, from 13B-NA SCCA club cars to 900whp drag cars are using inconel exhaust manifolds. In my RX8 PWC car, which won not only sprint but also Enduro races (9 hours of Road Atlanta, etc.) we used the same 321 SS exhaust manifold for 3 full seasons of racing without issue. The Pro Formula Mazda cars used a SS exhaust system and an off the shelf Borla (Series Sponsor) muffler. I am sure Mad Mike is running Inconel, but again, not the best example.

Pictured is a 13BREW exhaust port. I thought I had a picture of the monstrosity that is the 13BREW TT manifold, but nope.
Where did I specify the exhaust port? Look at the exhaust manifolds. Both the BT and REW have a central combined volume which is then split prior to the turbo.

Good for that team managing to using a material not rated for those exhaust temperatures to survive them. It happens. It doesn't for everyone. Inco is safe and doesn't rely on the tune or other parts to survive.

#### dwalker

##### Well-Known Member
Where did I specify the exhaust port? Look at the exhaust manifolds. Both the BT and REW have a central combined volume which is then split prior to the turbo.

Good for that team managing to using a material not rated for those exhaust temperatures to survive them. It happens. It doesn't for everyone. Inco is safe and doesn't rely on the tune or other parts to survive.
The entire Pro Formula Mazda series- every single car- used 321SS for the exhaust headers. Not a team, ALL the teams. Prior to that the Star formula Mazda also used a spec 321SS Exhaust header.

I am now very curious who in racing actually uses inconel headers in the exhaust for the 13B NA or Turbo. Can you give some examples?
Pretty sure Mad Mike does, because well, Mad Mike. Pretty sure Rob Dahm does not, but I can ask him. He is a bad example as well really, because he does not actually road race the cars. NONE of theGT2/GT2/GT1 SCCA cars I know of use anything but 321SS. I would have to make a call, but pretty sure Speedsource did not, Also pretty sure Downing did not use inconel, but thats another phone call, or rather text message.
Very curious now, please list examples.

#### dwalker

##### Well-Known Member
I actually stand corrected on t Mad Mike, his engine builder currently is using the Glease Manufacturing turbo manifolds exclusively in Mad Mikes engines. 321SS, Not Inconel.

#### rv7charlie

##### Well-Known Member
undean,
I think there may be a 'failure to communicate' (apologies to Strother Martin). You seem to be talking about dividing the exhaust to feed the turbo(s) at two inlets, while everyone else is talking about a little canted plate that's inside each peripheral exhaust port of the rotor housing on non-turbo 13Bs, but isn't in the turbo versions.

#### undean

##### Member
I retract my racers using inco statement. I cannot find the threads I was recalling when writing that post. I am quite surprised that your SS manifolds are lasting multiple seasons.

#### rv6ejguy

##### Well-Known Member
321 is extensively used on turbocharged aircraft engines where continuous (hundreds to thousands of hours) EGTs are at 1600-1650F. Some of the Reno racers see 1800F and are using 321 as well. Of course these engines don't have the acoustic energy of a Wankel...

#### dwalker

##### Well-Known Member
I retract my racers using inco statement. I cannot find the threads I was recalling when writing that post. I am quite surprised that your SS manifolds are lasting multiple seasons.
You had me genuinely curious. I know when I asked Jim Medere of Racing Beat about using inconel to build the turbo manifold in the PPIHC turbo 13B, running E85 making roughly 490whp, he basically laughed at me. I expressed concerns about the amount of heat in the manifold and the lack of air to cool it between race start at 8000ft and the finish line at 14,000feet. He told me I was overthinking it and to build what was proven to work. It did, in fact, work. Unfortunately I did a bad fuel calc and we ran out of fuel about 1/4 mile from the finish line. Who would have thought (or calculated) we would have been in boost enough to burn 8 gallons of E85 in 12 miles.
Still, the manifold was perfect and lives on to this day in a drift car somewhere in the Vegas area.

I spoke with a fellow that worked with SpeedSource and to some degree Downing, and they used 321SS manifolds with titanium exhaust. He did tell me that Dr Ianetti was working with some proprietary alloy in an exhaust system/muffler (the NRD- Noise Reduction Deveice) for the factory cars that after a 24hour race you could reach out and touch the runners. My guess is some sort of titanium variant, but probably of limited usefulness to me beyond simple "good to know". My buddy is reaching out to Dr Ianetti on other things and said he will pass along my number so we will have to wait and see if he gives me a call to discuss his findings, which will likely (largely) depend on what, if any, NDA's exist between Ianetti and Mazda, or if Ianetti is proceeding to market with the materials and deems it trade secrets.

#### Cardmarc

##### Active Member
The 13-BREWand the 13BT use the same rotor housing and very similar exhaust ports. There is no splitter or
divider" such as there is in the 13B NA.
The OEM exhaust manifolds, which are CAST IRON and NOT anything exotic, crack with regularity, and the overly complex heat retention device that passes for a manifold on the 13-BREW is especially hideous and a very large part of the reason why few, if any, FDs made it past 60K miles without an engine rebuild due to coolant seal failure (actual most common rotary failure, not "blown apex seals") and it is a reliability mod to go to a single turbo on the 13BREW.

Very, and I mean VERY few racecars in the general rotary community, from 13B-NA SCCA club cars to 900whp drag cars are using inconel exhaust manifolds. In my RX8 PWC car, which won not only sprint but also Enduro races (9 hours of Road Atlanta, etc.) we used the same 321 SS exhaust manifold for 3 full seasons of racing without issue. The Pro Formula Mazda cars used a SS exhaust system and an off the shelf Borla (Series Sponsor) muffler. I am sure Mad Mike is running Inconel, but again, not the best example.

Pictured is a 13BREW exhaust port. I thought I had a picture of the monstrosity that is the 13BREW TT manifold, but nope.
[

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#### Cardmarc

##### Active Member
I beg to differ. I have rebuilt several OEM 13brewtt engines. (93-98 as sold in USA?) and ALL had Inconel studs, nuts, washers and exhaust manifolds to the tts. I know because I ordered OEM replacements. Look it up. Aftermarket racer parts are another story. Your probably right about the lack of an exhaust divider, however. That I can’t confirm unless I go to my shop next door. I’m getting older, I’ve rebuilt so many 13bs I get confused. Perhaps I’m thinking of the peripheral ported engines I’ve assembled for some where the exhaust divider was removed.
And btw, many turbo aircraft have had to resort to Inconel exhaust parts per FAA AD. Several turbo twins come to mind-fires and crashes. The 321SS parts did not hold up (flow dividers, clamps, etc). Aircraft operate at constant high power levels constantly at high altitudes on constant boost, completely different than any ‘racer car’ environment, and for longevity and safety must be ‘bulletproof’. And that is with Continental and Lycoming piston engines with much lower exhaust temps. The Wankel has higher exhaust temps and frequency issues. 321SS will last a while, but YMMV!

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#### dwalker

##### Well-Known Member
I beg to differ. I have rebuilt several OEM 13brewtt engines. (93-98 as sold in USA?) and ALL had Inconel studs, nuts, washers and exhaust manifolds to the tts. I know because I ordered OEM replacements. Look it up. Your probably right about the lack of an exhaust divider, however. That I can’t confirm unless I go to my shop next door. I’m getting older.
In general I try not to correct people who are just thinking of something else, but accuracy matters, and people base opinions which become beliefs which in turn factor into thier planning of projects, spending of time and money, and quite possibly- in fact usually- thier health and safety. What I say from here forward is simply to correct potential misunderstandings and to emphasize the facts.

Accuracy matters.

#1 is that ALL, and I mean ALL factory OEM turbo exhaust manifolds fitted to the 12B-T, 13B-T, 13B RE, 13BREW, and 20B (Cosmo) have been CAST IRON. Huge hulking engine killing cast iron heat reservoirs. Not even ONCE has Mazda used an Inconel OEM manifold in any application, including the turbos. If they had the manifolds would not crack, rust, or otherwise turn into worthless scrap and you would not be able to buy them on Ebay.
The EXHAUST PORT SLEEVE, in every 13B Mazda, the Studs (13BREW, 13BRE, and 20B-TT), nuts, and maybe the washers were Inconel. Thats it. Nothing else.

Also, NO, and I mean NO, NONE, ZERO, NOT EVEN ONCE did Mazda install a divided turbo manifold. The 13B-T in the FC RX7 had a single turbo with a very simple cast iron lump of a manifold. NO CENTER DIVIDER. Because the turbo was not twin scroll. Not just in the US cars, but in the entirety of production.

The 13BREW, as OEM in the FD3S, has a CAST IRON manifold and turbo assembly. Also NOT DIVIDED. Not even a little bit. Because twin scroll in turbos of that size with the available exhaust energy is simply ludicrous. Below I have attached pictures taken today of an OEM FD3S exhaust manifold. It is clearly cast iron. It is clearly NOT DIVIDED for a twin-scroll arrangement, but is obviously setup for two small turbos. The one pictured is very low mile, which is why it is not cracked in several places. Following that are pictures of the turbo assembly. You can clearly see the pre-spool valves, etc. that allow the sequential system to function, but it also very obviously CAST IRON and not inconel. The flappers could be inconel, but mot likely not.

I hope this puts this issue to a rest.

ALL of this discussion is academic of course, because the 13BREW OEM turbos are far too small and would die in dramatic fashion if asked to perform at even medium boost levels continuously at altitude. Same with the OEM 13B-T turbo, as the late John Slade documents quite well in his flight logs, they die an early and quick death.

The only real option is to fabricate a proper turbo manifold and use a properly sized and built turbocharger hanging off of it. Since we are not asking much of the turbo in regards to transition etc. even a simple well-made log manifold would work quite well. 321SS is a PROVEN reliable material to build such a system.

I have in fact, run a 500whp turbo 13B on E85 at altitude, from 8000ASL to 14Kft ASL. Engine was in boost- much more boost than I would likely run in an aircraft and 200more HP (thats wheel horsepower, not flywheel horsepower)- than ever needed in the aircraft, and it worked perfectly. In fact, last I heard that engine and manifold is still being beat upon in a drift car based in Vegas, and still making over 500whp.

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#### dwalker

##### Well-Known Member
And btw, many turbo aircraft have had to resort to Inconel exhaust parts per FAA AD. Several turbo twins come to mind-fires and crashes. The 321SS parts did not hold up (flow dividers, clamps, etc). Aircraft operate at constant high power levels constantly at high altitudes on constant boost, completely different than any ‘racer car’ environment, and for longevity and safety must be ‘bulletproof’. And that is with Continental and Lycoming piston engines with much lower exhaust temps. The Wankel has higher exhaust temps and frequency issues. 321SS will last a while, but YMMV!
This is the kind of thing that makes me avoid GA folks.

I actually would like to see the AD's that specified inconel exhaust manifolds to replace SS ones. I once checked out a Foxfire Baron and it had SS exhaust for sure, and was certified with them.

I honestly think you are stretching to make a point that does not need to be made. First you cited all racers as using inconel, now you are saying it does not matter that they do not. I can go along with inconel has its usefulness, but in my application it is an unwarranted expense.

You are welcome to build whatever you want for YOUR aircraft, but your input thus far has not been accurate.

#### Cardmarc

##### Active Member
This is the kind of thing that makes me avoid GA folks.

I actually would like to see the AD's that specified inconel exhaust manifolds to replace SS ones. I once checked out a Foxfire Baron and it had SS exhaust for sure, and was certified with them.

I honestly think you are stretching to make a point that does not need to be made. First you cited all racers as using inconel, now you are saying it does not matter that they do not. I can go along with inconel has its usefulness, but in my application it is an unwarranted expense.

You are welcome to build whatever you want for YOUR aircraft, but your input thus far has not been accurate.

As an aside, I once built an aluminum mid-pipe back exhaust- including muffler- for the Pirelli World Challenge MX5. It would last an entire season, then we threw it into the recycle bin and built a new one. Saved us more weight than the titanium equivalent, and cost a lot, like a WHOLE LOT, less. We checked that exhaust- like everything else on the car- pretty much everytime it came off the track. Never cracked, no holes burned through, pretty much the only issue we ever had was the aluminum tabs we originally used were not up to the various loads put on it by the car zipping around the track, so we re-engineered the mounts to use band clamps instead of tabs. Worked perfectly. I mention this because literally no one would ever endorse doing such a thing, and on a street car it would be absolutely stupid to do so, but on a race car that is checked and rechecked and checked again, each and every time before and after it goes on track, it performed exactly to expectations. And I had no issue throwing the bits in the recycle bin at the end of the season and spending another \$150 in aluminum tubing and bits to make another one.
Posted the AD. Replacement manifolds to comply with this AD are made of Inconel now. Also see https://support.cessna.com/custsupt/contacts/pubs/ourpdf.pdf?as_id=52201

#### undean

##### Member
If I had my all my RX7 parts with me I would use my pictures but sadly I don't. Here is a picture of a stock FC S5 turbo manifold. Notice the divider after the central combined volume. This along with the two-paths that exhaust is encourage to flow along make it a twin-scroll (two path) exducer and thus a twin-scroll turbo. I'm unsure if you're assuming twin-scroll means two easily distinguishable exhaust paths, two exducers, or something else but the 13BT is undeniably a twin-scroll setup.

The 13BREW being a twin-scroll is obvious on the one hand but less so on the other and not something I care to argue right now.

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