Rotary engine with a transaxle

hudson Wrote:
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> john vanlandingham Wrote:
> --------------------------------------------------
> -----
> > So the rotary has a NSU connection but you
> haven't
> > said what's wrong with the OEM motor of
> box....why
> > all the searching before saying what's wrong
> with
> > the stock powerplant.
>
> Nothing is wrong with the stock stuff per say.
> Quite light, very compact. You can build them to
> ~100 hp, but that takes $$$ I'd say the one I
> have is probably good for 50 hp (on a good day?).
>
> Mainly, I just like to consider things.. I find it
> fun and before I got stuck into putting $$$$ into
> carbs, gaskets, yadda yadda I wanted to make sure
> I had looked at some options.
>
> To build a mild/warm (say 75-80 hp) NSU motor with
> a locking diff -- I haven't crunched the numbers,
> but I see what stuff goes for -- 2.5 grand feels
> low ball.

Talk more details so i can figure ways to do moar powerz for less bucks.
I AM Mr Cheap fun.
>
> Andrew McNally
> Hamilton, ON
> 29

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

hudson Wrote:
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>
> I need to figure out if the 944 transaxle is
> basically a newer 901 with the right linkage and
> start figuring out bellhousings.
>
>

The non turbo 944 transaxle is an Audi 016, same as you would find in a FWD Audi 5000.

hudson Wrote:
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> Pete Wrote:
> --------------------------------------------------
> -----
>> The
> transaxle I'm looking at now is out of a 1980
> 944.. >

You mean 924? 944's didn't come out until late '82.

> The word on the street is that
> these transaxles are good for V8s.. so should be
> good for stock 4 port renesis and a 1400 lb car
> one would think.
>

Chevy LS1 conversions are popular for the 944 (we did a bunch of work on one in the shop a few months ago) and the tranny will hold up if you don't dump the clutch all the time. The 016 is pretty reliable up to 300 hp. After that you start taking chances. The 944 turbo transmission is stronger.

Do you have an engine management plan for the Renesis idea? All this mechanical shit is easy, making that thing run is the challenge. You either need a whole lotta RX-8 harness or purge your wallet for that formula Mazda deal.

Also, I'm not sure what the formula mazda oiling strategy is. Last time I checked (years ago), they just pre-mixed oil in the fuel and didn't use the stock oil injectors. That won't work on a street car.

Peripheral exhaust port rotaries are pretty tolerant when it comes to oil injection or pre-mixing. If you over-oil, you'll start getting carbon buildup on the rotors, which will eventually flake off and get swept out the exhaust port. No big deal.

Do the same thing on a side exhaust port, though, and the carbon just piles up against the trailing apex seal and never gets to the exhaust port.

If you consistently drive a Renesis hard, like the formula Mazdas, combustion temps will be high enough to burn off the carbon and all will be fine. Puss around too much (which might be impossible to avoid with that crazy power/weight ratio) and you may run into the carbon problem.

Stick with the stock engine management and you have the stock oil injetion mapping, which walks the razor's edge between dry seals and carbon buildup. Lots o wires to figure out, though.

-Dave

eyesoreracing Wrote:
-------------------------------------------------------
> Do you have an engine management plan for the
> Renesis idea? All this mechanical shit is easy,
> making that thing run is the challenge. You either
> need a whole lotta RX-8 harness or purge your
> wallet for that formula Mazda deal.

Standalones have been done on turbo RX-8s.

> Also, I'm not sure what the formula mazda oiling
> strategy is. Last time I checked (years ago), they
> just pre-mixed oil in the fuel and didn't use the
> stock oil injectors. That won't work on a street
> car.

Thanks for the clarification, I've only been doing that since 199-fucking-8 on my street RX-7s.

> Peripheral exhaust port rotaries are pretty
> tolerant when it comes to oil injection or
> pre-mixing. If you over-oil, you'll start getting
> carbon buildup on the rotors, which will
> eventually flake off and get swept out the exhaust
> port. No big deal.
>
> Do the same thing on a side exhaust port, though,
> and the carbon just piles up against the trailing
> apex seal and never gets to the exhaust port.

The carbon problems aren't from the oiling so much as they are from running too rich. Historically speaking, Mazda makes the rotaries run pig rich over X RPM or heavy load to keep the converter from slagging. IIRC the fuel injected ones slam the AFR down to 10:1 any time the engine is over 3800rpm.

> Stick with the stock engine management and you
> have the stock oil injetion mapping, which walks
> the razor's edge between dry seals and carbon
> buildup. Lots o wires to figure out, though.

Except they don't. Pre-2009 engines had insufficient oiling. In 2009 they added another squirter per rotor. Word on the street is to premix with all pre-2009 RX-8 engines if you want it to live.

---

Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

Pete Wrote:

> > stock oil injectors. That won't work on a
> street
> > car.
>
> Thanks for the clarification, I've only been doing
> that since 199-fucking-8 on my street RX-7s.

Yes, and I did it on street 13B powered 510s in 199-fucking-1. Big deal. Neither of us had side exhaust ports. Ever wonder why side exhaust ports didn't appear until the RX-8? It's because the oil injection systems were too crude to find that balance of enough oil without ever having any carbon land on that apex seal. Remember, once it piles up, it's not going anywhere. It will wedge under the apex seal, lift it off the rotor housing and kill compression. (There are ways to flush it out, but they aren't elegant.)


>
> The carbon problems aren't from the oiling so much
> as they are from running too rich. Historically
> speaking, Mazda makes the rotaries run pig rich
> over X RPM or heavy load to keep the converter
> from slagging. IIRC the fuel injected ones slam
> the AFR down to 10:1 any time the engine is over
> 3800rpm.

I think the FD RX-7s actually got to something like 8.4:1 at peak torque. Widebands don't go that high, but I got that number from a guy that ran the test cells in Hiroshima during FD development.

The carbon issues happen primarily on Renesis engines that are never driven hard, though. The low combustion temps aren't enough to burn off the buildup. Renesiseses that are driven hard almost never have issues. Ironically, the under-lubrication issues also happen when they aren't driven hard, because the oil injection is mapped very light in those areas to try and avoid the carbon buildup.

Guys like you and me would never have a problem...


>
> > Stick with the stock engine management and
> you
> > have the stock oil injetion mapping, which
> walks
> > the razor's edge between dry seals and
> carbon
> > buildup. Lots o wires to figure out, though.
>
> Except they don't. Pre-2009 engines had
> insufficient oiling. In 2009 they added another
> squirter per rotor. Word on the street is to
> premix with all pre-2009 RX-8 engines if you want
> it to live.

You're kinda right, but its not quite as simple as that. The third injector was added so that the center of the apex seal could be lubricated at a different rate from the corners. 2009s also got electric oil injection pumps (one for the center injectors, one for the corner injectors) that are better at drooling oil onto the rotor surface rather than spraying it into the combustion chamber. Putting it exactly where it is needed means it does its primary lubrication job better, and is slower to burn, and less likely to cause that buildup. Basically they were widening the razor's edge so it would be easier to walk on.

The oil injection is mapped to throw tons of oil at the engine when its running hot enough to both need it and to burn off any residue. I would go through a quart in one trackday with my RX-8 (2006). I'd recommend the pre-mixing guys re-think their strategy. A redline a day is better medicine.

-Dave