> > >>>>> Paul,
> > >>>>> Interesting conversation I recently had with the local engine
> > >> builder on RX8 Parts and their interchangeability with the RX7.
> > >>>>>
> > >>>>> He recently built a RX7 racing engine with RX8 rotors - I thought
> > >> the RX8 rotors were quite a bit wider ?
> > >>>>> I also thought the bearing sizes were different - but apparently
> > >> not !
> > >>>>> Anyhow all went well until he got to 10,000 RPM when the rotors
> > >> were binding on the endhousings, so they shaved (just a little) off the
> > >> sides of
> > >>>> the rotors.
> > >>>>>
> > >>>>> He also noted that the rotor side seals were much shorter( in
> > >> length) that RX7 side seals. He was concerned about too muck leakage but
> > >> they worked
> > >>>> OK he can
> > >>>>> only put down the extra gap in the side seal ( to the apex side
> > >> seals) as needed because the side seals were exposed to greater heat of the
> > >> side
> > >>>> exhaust and
> > >>>>> therefore expanded more! Apparently some people put in bigger
> > >> apex side seals to make up the difference in gap.
> > >>>>>
> > >>>>> Also the apex seals were shorter in height so they cut the slot
> > >> deeper and put in Hurley apex seals.
> > >>>>>
> > >>>>> Speaking of Hurley apparently they have a 2 piece side seals (
> > >> very thin) which are very flexible and tough.
> > >>>>> I suggested using a bi-metal hacksaw blade and grind it down to
> > >> size as they are very flexible and tough - the new hacksaw blades out now
> > >> don't
> > >>>> break at all.
> > >>>>>
> > >>>>> Cheap side seal idea if anyone wishes to try it.
> > >>>>> George (down under)
> > >>>
> > >>> -> "Powell, Ken" wrote:
> > >
> > >
> > >>>> George, great info. I have wondered if you could use the rx8 rotors in
> > >> an earlier 13b. The lighter rotors would allow us to turn higher rpm
> > >> safely. If you
> > >>>> are using a PP intake port this sounds like a less expensive route than
> > >> a new rx8 engine. Looks like you would need rx8 rotors, seals, and
> > >> front/rear
> > >>>> counterweights to make this work. Maybe the 86 - 91 counterweightes can
> > >> be used if the rotating assembly is balanced. Does anyone know if weight
> > >> would have
> > >>>> to be added or removed from the counterweights to work with the new
> > >> rotors (seems like the weight would need to be removed from the
> > >> counterweights to balance
> > >>>> lighter rotors but sometimes things don't work like it would appear at
> > >> first)?
> > >>>>
> > >>>> Ken Powell-
> > >
> > >
> > >>> Dave Atkins had a 1993 3rd gen and an RX8 rotor at OSH. They appear to be
> > >> the same weight.
> > >
> > >
> > >> Ken,
> > >> I think Paul is correct with that assessment, I don't think you need to
> > >> lighten the counter weights with lightened balanced rotors. It's something I
> > >> didn't think of and will put that question to the 'boys at the shop' when I
> > >> speak to them next.
> > >> George ( down under)
> > >
> > > Subtle distinction here George. If in fact the rotors are lighter you do
> > > indeed
> > > need to change the balance weights.
> > >
> > > Paul Lamar
>
> -Douglas Fir wrote:
> >
> > Hi George,
> >
> > The Rotary Engine Press paper I sent you mentioned the Renesis rotors are
> > lighter and illustration should less material in the inner metal walls.
> > However it might amount to only a few grams. Can anyone out there weigh one
> > for us to confirm it?
> >
> > Doug in Japan
>
> I can't tell you how many grams but it was about only an ounce or two.
> Something less than a 1/4 of a pound. A regular rotor is about 9 pounds.
>
> Paul Lamar
>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
> Here is a listing from the Maztrix site of rotor weights. I also found a RX8 rotor weight of 8.2 pounds on RX8.com. I'm not sure that I
trust this
> 8.2 lb weight- I thought that the new rotors were 8.7 lbs. In any event this is a very significant weight saving.
>
> Ken Powell
>
> Rotor Weight and Compression Chart
>
>
----------------------------------------------------------------------------------------------------------------------------------------------------
>
> This chart is included in our Website and Catalog for reference purposes. The weights listed are for production, unmodified rotors.
>
> Engine Year Compression Weight (Grams) Weight (Pounds)
>
> 12A 76-82 9.4 4603 10.15
>
> 12A 83-85 9.4 4353 9.60
>
> 13B 74-78 9.2 5253 11.58
>
> 13B 84-85 9.4 5253 11.58
>
> 13B N/T 86-88 9.4 4553 10.04
>
> 13B Turbo 86-88 8.5 4553 10.04
>
> 13B N/T 89-92 9.7 4328 9.54
>
> 13B Turbo 89-92 9.0 4328 9.54
>
> 13B T/T 93-95 9.0 4328 9.54
>
> NOTE: Weights are approximate, and include rotor bearing, but do not include any seals or springs.
Ken are you using a Mac or something weird like that? Your computer makes hash
out of messages :)
Paul Lamar
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
I use Microsoft Outlook. Does it always cuase issues or just this time? I 'pasted' the above table (which would have been HTML format) so maybe
that is why it didn't come across correctly. Ken Powell
It adds a bunch of spaces at the begging of lines that causes problems.
Paul Lamar
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