Subject: RX8 intake manifold and conversion.
From: Rotary Engine
Date: 10/10/2005, 6:30 AM
To: AA-me



>>
>> Thanks for the update, Rino.  You are definitely doing >> ground-breaking work in our arena.
>>
> snips....
>
>>
>> BTW, did you fabricate your own intake manifold or sub it out?  >> I'll be building one for my Renesis -- haven't decided on using >> aluminum vs.
>> molded CF for the upper manifold yet.  My engine is still at >> Bruce's getting the final touches.
>>
>> Scott Gettings
>>
>> Scott what all are you doing to your Renesis? What are your >> manifold plans?
>>
>> Ken
>>
>
> Ken,
>
> I bought a Renesis with 2K miles on it from a Rx-8 getting a 3-rotor

> conversion.  It is currently in Bruce Turrentine's shop.  He is > doing all the standard internal modifications, such as replacing the

> side seals, doing some porting, adding silicone to dampen the > tension bolts, as well as lightening, etc.  The internal variable > intake tubes will be ported, then set-screwed in place to optimize > about 7K rpm.  They can be adjusted if needed.  Redrive and ECU will
be Tracy's.
>
> I plan on cutting off the  lower intake manifold (exact position not

> yet determined), and weld on 4 elbows to keep the profile much > closer to the engine than stock.  From the elbows, I'll have 4 > runners flow across the block, with injector, a plenum and throttle > body on the cool side (similar to many existing installations).  > This upper manifold will most likely all be carbon fiber and > high-temp epoxy, but I haven't completely ruled out welded aluminum
yet.
>
> Having had considerable composite experience, I'm pretty confident I

> can build plugs, molds and produce a manifold with smooth internal > and external surfaces from carbon fiber.  The plugs will be built > from foam or paraffin wax, 1/2 at a time (upper and lower surfaces.

> The bonding between the upper and lower runner products will be a > flat flange that runs between the tubes.  So the upper side looks
(roughly) like:
> _/\_/\_/\_/\_     The flanges also allow mounting surfaces.
>
> Blending in bell-mouths and the plenum chamber will be a little > tricky, but is not beyond reason.  I might build the plenum chamber > so that one could attach a throttle body on either end, making it > useful for pushers or tractors.  Positioning the injectors on the > side  of the plenum chamber (pointing at the bellmouths) would allow

> a much easier installation than fitting them against the curved
edges of the runners.
>   The latter case is easier in aluminum, but can be done with a > composite version.
>
> The downsides of epoxy/CF are that it needs to be strong enough to > withstand a backfire (anyone want to estimate a psi from a > backfire?), it is a little difficult to integrate metal components, > and it is eventually capable of burning (but so is the cowling).  > I'll have multiple temperature sensors and a fire-suppression system

> to mitigate the latter.  Regarding a backfire, the weakest area of > the manifold would be the bonding flanges, which could 'peel' apart > long before the tension of the carbon fiber was exceeded.  If I have

> a optional position for the throttle body, this (unused) end of the > plenum could be capped with blow-off capability at a certain > pressure.  Some secondary CF tapes placed at the bond line inside > the runners might also be possible (at least in some areas), or a > secondary internal flange that spans the bond line also seems
possible.
>
> Pending issues:
> 1. Exhaust:  probably three, 321 pipes to a tangential muffler, > exhausting at the prop hub area.
>
> 2. Thermostat:  Bruce wasn't certain if I should use a restrictor > plate, keep the thermostat, or modify it to accept no restrictions > at all.  I haven't seen the internals on the RX-8 pump yet
>
> 3. Cooling: using Paul's concepts, with internal ducting.  Large, > thin main radiator up front and the oil cooler below the engine.  > There should be more than enough frontal intake area to handle the > main radiator, oil cooler, intake, and exhaust tube.  This will have

> to follow the engine installation.  I'll probably be able to shrink > the original cowling once everything is optimized.
>
> This will keep me busy for a long time!
>
> Scott Gettings
>
> If you are exhausting to the rear (flywheel) of the engine, why > don't you just use the stock exhaust manifold?  It only weighs 15 > lbs and will need about a foot of pipe on the end to reach out of > the cowl.  How much weight can you save by building your own and how

> much will that wt savings cost?
>
> Bill Bradburry


Bill,

That is definitely an option.  I (will) have a stock exhaust  manifold

with my Renesis, I just don't have it yet.

Scott

Hi Scott,   I have the stock exhaust manifold for the Renesis, I am not
going to use it.  If and when you decide to use one, tell me.

Rino Lacombe



Scott,
Did you get the  Renesis Idler Pully Assembly with your engine? I need
one to support my supercharger installation. My crate engine did not
have one. If you do and are not planning to use it would you consider
selling it?

Thanks,

Bobby Hughes


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