>>
>> > Hi Paul,
>> > I'm enjoying following along with your current threads!!
>> > Hope you don't mind me chiming in here again to ask
another
>> newbie
>> > question:
>> >
>> > I've been slowly acquiring S5 NT ( 9.7 : 1) rotors for my
20B NA
>> project
>> > (much cheaper that RX8 rotors). I had 2, and just
received the
>> 3rd one
>> > today. I've been trying to be careful to make sure I
get
>> rotors with
>> > matching weight code stamps, but the one I got today is
>> different. Can
>> > you help here? I hope you don't mind me including
pictures!! I
>> tried
>> > to make the files small. The first 2 pics are the
rotors I
>> already had,
>> > and they show a "C" along side another weird symbol
(kinda looks
>> like
>> > a 7).
>> >
>> > The next pic is the rotor I got today. It shows a
"C" along
>> side an
>> > "E" :
>> > My question is.......Is it OK to use all these rotors
>> together? Are
>> > these all S5 (9.7 : 1) rotors? Is this last rotor a
weight code
>> "C" or
>> > "E" ? What's the other symbol of Letter mean?
>> >
>> > Thanks again for all your help and knowledge!!
>> > Don
>> >
>> > From what I gather you can't mix and match weight codes.
>> > I think you need to have it balanced by an experienced
>> > rotary engine balancer. The rotors must be balanced
>> > about their center point and matched with all the other
rotors
>> > for weight and then the counter weights adjusted
>> > for the exact weight of the rotors. There is a guy
here in
>> > So Cal that does it.
>> >
>> > Rotor weight codes.
>> > The only thing I can find is this.
>> >
http://www.rx7club.com/showthread.php?p=1309602#post1309602-
>> >
>> > I'll forward this to Jim Mederer. Hopefully he will
have time
>> > to help as he gets the really hard questions :)
>> >
>> > Paul Lamar ...No rotor no motor.
>>
>>
>> Hi Don;
>>
>> These all appear to "C" weight rotors. For a 2-rotor,
letter
>> codes must
>> be adjacent,
>> e.g. B/C, D/E, C/D are OK (A/C, B/D are NOT)
>> The rotors themselves are balanced about their centers
at the
>> factory.
>> I am not sure what the balance requirements are for a
3-rotor.
>> I believe the backwards "E" and other characters are
Japanese -
>> don't
>> know what they mean.
>> Theoretically, the S5 rotors weigh the same as the 20B
rotors,
>> and you
>> "should"?
>> be able to use the 20B front and rear counterweight without
>> rebalancing.
>>
>> I posted some rotor/balance info a few weeks ago.
>> The S5 rotor faces are machined, the S4 have a rough cast
>> appearance.
>> You could also measure the depth of the combustion area.
>> See attached file
>> -> might be worth adding to the website. I don't have any
turbo
>> stuff.
>> A couple of housing comparisons might be useful as well,
I'll see
>> what I
>> can scare up...
>>
>> When mixing and matching parts for higher than stock rpm, a
custom
>> balance is not a bad idea.
>>
>> Cheers
>> Cary
>>
>>
>> Thanks Cary,
>> This is what I have:
>>
>> All are machined faces.
>> Thanks,
>> Don
> Hi Don;
> The S5 NA rotors are at a bit of a premium for racing and higher
> activities :)
> Worth a quick depth check on the rotor recesses to ensure they
are all
> the same.
> Personally, I would run the stock 9.0? 20b rotors in NA mode
for the
> 5-8% HP loss.
> If you have the room under the cowl - you could re-add a
turbo later.
> Just curious, what is your project?
> (Sorry if I've missed it, I don't read all the emails)
>
> Cheers
> Cary
Hi Don;
Also meant to ask if you have removed and replaced the stock 20B
exhaust
sleeve inserts.
I have heard they are quite restrictive and many people replace
them
with 13b turbo inserts.
Although removing them is a good way to break taps...
Cheers
Cary
I haven't removed my exhaust inserts yet, but I've been considering it.
Any tips on how to do this? Why not just port out the ones that are
already there?
Don
Don,
If you take a close look at them, it isn't that simple. They are very
different than the N/A inserts. The EGR passage is quite large so that
cutting out the shelf would result in a big void and undesirable exhaust
flow. Removing the 20B inserts isn't that difficult if you resolve that
the insert will be destroyed in the process. Just take a die grinder to
the spot where the pin is and grind it down until you see the pin from
inside the port. Then drive the pin into the port from the outside with
a drift punch. Remove the old exhaust insert and replace it with a
turbo insert and drive the pin back in from the outside. I'll check
tonight and see if I can snap a picture of one of my old inserts.
Mark S.
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.