Why is Peripheral Porting banned? - Brindabella Motor Sport Club

Daveee · 27-10-2004, 04:48 PM

Just curious, does anyone know peripheral porting of rotaries is banned under PRC regs?

fro · 27-10-2004, 05:12 PM

No idea why...

For those who don't know, the section of the rules Daveee is referring to is:

Quote:

CAMS Manual 2004
(xxix) For normally aspirated two-wheel drive vehicles, the model of which was manufactured prior to 1 January 1986, freedom will be granted in relation to:

(f) The ports of rotary engines, provided that this does not result in: (a) peripheral port, and/or (b) the port does not extend past the original water jacket and seals.

Saru · 27-10-2004, 05:20 PM

You're stuffed if you want to race an NSU Ro80, then.

(factory peripheral intake ports (but they're tiny, tiny things)).

Seriously, I don't know *why* but the usual conspiracy theory is that "CAMS hates rotors".

Are you allowed to re-route the intake (or exhaust) ports on a reciprocating engine? If not, that may be the answer.

rowdytoot · 27-10-2004, 05:42 PM

Doesn't it stem from the banning of peripheral ports in the ATCC when Moffat was running around in the RX-7?? The reason for that escapes me too..

Rowds

Bede · 27-10-2004, 06:09 PM

Surely running a peripheral port on a rotary engine is the equivalent of running a completely different head on a piston motor (by this I mean a completely different port path than that of the original)? Porting the original end plates and centre plate is like porting the original head, but a peripheral port would be like me putting a head I made out of a piece of billet aluminium with completely different ports on my L-series (I wish)...

Besides isn't BP is hard enough to keep quiet ...

Spac · 27-10-2004, 06:14 PM

Because they're too fast...

The really stupid part of it, is that to make a PP meet the noise regs, you'd kill the HP, so they'd be 'self-limiting' anyhow...

Having been (making myself unpopular) on the IPRA forums, there's still quite a deep vein of anti-rotarism out there... I think rally types are relatively tolerant because they can't use their power to weight advantage, so they're not as dominant as they are on tar... But CAMS is all about tarmac motorsport, and they only tolerate us dirt types, so we cop the rules that work for circuit racing.

I'm waiting for someone to build a IPRA type BP (more power than a PP) and put it in a rally car - preferably one that stops and handles...like a S4 RX-7 for example...

Bah - if the rules made any sense, you could put a big-block 12A (that's a 13B) into a R100, RX-2 or RX-3... I mean, you can make a 1600 be significantly over 2000cc*, but taking an RX-3 from 1146cc to 1308cc is not even considered...

*1600cc to 2100cc is a 31% increase. 1146 to 1308 is less than half of that at 14%.... and the car remains in the same class...

Tweety · 27-10-2004, 06:15 PM

Quote:

Originally Posted by Bede

Besides isn't BP is hard enough to keep quiet ...

I was thinking that perhaps Dave is looking for more power at the expense of reliability*

, but he probably is just curious, as he said already.

* given we all saw how much he enjoyed DNFing at the Bay this year

Daveee · 27-10-2004, 06:48 PM

I am just curious

I'd like to avoid as much Bay style DNF pain as I can

Bede, I think what you said might be the reason. But that said, we are comparing apples and oranges here.

Also, anyone know how CAMS determined the effictive capacity multiplication factor for rotaries?

EDIT: Also where would the fact you can get factory PP housing fit into this?

Spac · 27-10-2004, 06:58 PM

Simple - they inserted one digit into their own rectum, then anther digit, then they pinched the two digits together, and pulled.

I honestly doen't know... Rego goes with (Mazda capacity x 2), FIA apparently uses (mazda capacity x1.0) , and CAMS goes it alone with (Mazda capactity x 1.8).

The FIA progressively dropped their "rotary equivilance factors" over the years until they ended up with 1.0 - possibly the last time CAMS put any thought into it, the FIA was still using 1.8...

Spac · 27-10-2004, 07:01 PM

Factory PP housings don't do you any good, because the rules specifically prohibit PPs.

If you wanted to run a NSU RO80, you could possibly put a submission into ARCom and ask for it to be changed... But apart from anything else, you'd have a hard time proving that they were Aust delivered (unless they're FIA homologated).

Bede · 28-10-2004, 09:53 AM

Quote:

Originally Posted by Daveee

... Bede, I think what you said might be the reason. But that said, we are comparing apples and oranges here.
...
EDIT: Also where would the fact you can get factory PP housing fit into this?

So what!!! There is a 'Factory' FIA recognised twin cam crossflow head for L-series engines, but they are banned too.

The reality is a good BP 12A will make more power than any over 2-litre L-18 engine so what is the problem... do you guys want even more power so that you can still get beaten by piston engine drivers*...

* Brad F, Kari in the 1600, Brad G in his 1600, Pete, Marco, etc and in no way does that include me. 8)

Bede · 28-10-2004, 10:13 AM

Spac, stop pretending that rotary engine drivers are so hard done by. As I pointed out there are things that are banned for other engines too.

I am sure that if rotary engines cars were made even more competitive (relatively speaking) we would all swap to rotary engine cars and then you would get beaten by even more people.

Of all the rallycars I have owned, my rotary engine one had the most power by far! Give it a rest.

Tweety · 28-10-2004, 10:41 AM

Quote:

Originally Posted by Bede

Spac, stop pretending that rotary engine drivers are so hard done by. As I pointed out there are things that are banned for other engines too.

I don't think Spac's gripe is with the PP thing. It's with the fact that you can't run a 13B in an R1, RX-2 or RX-3, while you can bore your 1600 out to 1800 etc.

Do you really think that's fair?

No, wait. I get it. You think we should be grateful just to be allowed to compete!

Bede · 28-10-2004, 10:49 AM

Like I said, the 12A's will make more power than the L18's ever will, so why do you care? Do you want even more power so you have even less excuses when you get beaten...

I don't care if R100's are allowed to get 13B's... They would still get beaten by Dave K in the 200B. Then what are you going to complain about? Not being allowed to have Jet engines in Mazda's...

Daveee · 28-10-2004, 10:58 AM

Fair enough about the heads, I was just throwing it in

I wouldn't agree that a good 12a BP is going to make more power than an over 2l L18. In the Volvo thread it was said that Brad F's 1600 has 105kw ATW (140hp). I'd be pretty happy if our new bridgeport managed that!

Wasn't Jennys 12a BP making around 110hp ATW? What about Simey's RX3? What did your's and Sam's make?

Anyway, given the great class rules 12a's are thrown in with 2.4L Stanzas... Doesn't Pete's make around 160hp ATW? Once again I'd be pretty happy with that! (Although I guess the Stanza weighs a bit more!)

What about if they dropped the multiplication factor so that 12a's were under 2l but 13b's were over 2l. (I think ~1.7 is the magic number). Then allow the swap for 13b's for 12a's. Simple.