> George I think you are right. With the bell mouths the
runners are
> 15.75
> inches long. We will be running on an un instrumented test stand
> first, so
> this is our first attempt. If we can get @200hp out of our RX-8
> engine, we
> will be delighted. Heck, we do not know if the engine will
even run
> yet,
> lots of work ahead of us. Milo
>
> 15.75 inches is too short for 6500 to 7000 RPM Milo.
> What you need is 25 to 28 inches.
>
> I don't think you will see anything near 200 HP at 6500 to
7000 RPM.
>
> However if you want to test it on a dyno the Mazdatrix dyno is
> set up for rotaries. You just bolt them in and run them.
>
> As far as I know the Mazdatrix and the Racing Beat dyno are
the only
> ones set up for rotary engines in the US. Most other rotary
shops use
> chassis dyno's. I could be wrong but I have yet to hear of one.
> If anybody knows of other engine dynos set up for rotaries
please let
> me know and I will pass the info on the next time the subject
comes
> up.
> Power Sport had one but I don't know what happened to it.
>
> Paul Lamar ...No rotor no motor.
>
>
>
> Milo,
>
> Nice work on that RX8 engine. Hope it runs well for you.
>
> About the horsepower, I just ran a few figures throgh my
Turbochart
> spreadsheet. I don't know what the exact volumetric efficiency of
> the six-port RX-8 is, but I would guess it is no less than 100
> percent. So using that value, the spreadsheet shows 226 hp at
7000
> rpm and a best power air-fuel ratio of 12.5 at standard
atmosphere
> an no intake restrictions.
>
> Another figure for VE that I've heard mentioned is 94 percent
-- but
> I believe that is for the 13B engine. If we use that figure, the
> calculator shows 212 hp at 7000 rpm.
>
> I think this spreadsheet is a little conservative, if
anything. It
> jibes pretty well with real-world hp data I got from Paul and
Doug
> Fir on several different engines.
>
>
> Regards,
>
> Gordon.
>
> That 100% figure is for an optimized intake manifold length.
> Nobody so far has built an RX8 intake manifold near optimized
> length to my knowledge.
>
> Racing Beat put the stock RX8 high power engine with the complex
stock
> manifold on their dyno and got only 232 HP at 8500 RPM. Probably
around
> 190 HP at 7000 RPM. Mazda is now claiming 238 HP at 8500 RPM.
>
> The first attachment is what is involved with the stock manifold.
>
> I think your simulation is too optimistic Gordon.
>
> Here are our dyno curves for the Weber equipped P-port
> second gen engine. Best BSFC occurs at the torque peaks.
>
> I am building an RX8 engine version
> as we speak. We will test it on the Mazdatrix dyno.
>
> Jim Poole is building a special cutter to cut the cost.
> We hope to get the cost below $100 each for the two inch P-port bores
> in each housing.
>
> Paul Lamar ...No rotor no motor.
Milo and Gordon,
I believe Paul will be proven to be right, as the complexity of the
manifold
is what makes the difference in the RX8 power output.
A lot of research and testing went into that manifold, pity we
didn't have
the source data.
George (down under)
We're probably not communicating clearly here, but I don't think the
complexity of the manifold is what makes the difference in RX8 power
output. It's that they rate the peak horsepower at such a high RPM.
The manifold allows for better driveability at lower RPM. Said another
way, if you p-port a Renesis engine, it will probably make something
like 270hp at 8500rpm - better than the 6 runner manifold. But, it
probably won't idle as well (who cares)..
Matt-
Matt, I am going to let you take over when I die :)
Paul Lamar
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