Clutch Death

[Gus 5]

i think my clutch is dying....change in bit point and slipping when changing into 2nd at

high rpm? sound about right? just checking its that and nothing else....bit of a bugger but

taking car apart when i get brake hoses so that would be a good time to do it.....and

what a good time to lighten flywheel!

[325GRANT 0]

what a good time to lighten flywheel!

how light are you going?

[Gus 5]

prob as light as i can

although with the cam, will make it even more of a bitch to drive round town...meh

[325GRANT 0]

mine was down to 12 pounds and it was to light!!!

standard one back in. so be careful. if you want to try my 12 pound one before you do yours you can... just need to get it up to you

[Gus 5]

you dont want to get rid of your 12lb? why did you get the standard one back in?

[Carl 3]

you dont want to get rid of your 12lb? why did you get the standard one back in?

I read that he said it was too lite...opens up a can of worms

[325GRANT 0]

way to lite!

had it in on the way up to taupo and to keep up with dan i had to live in 5ooormp+ land. had nothing at all down low.

only plus was it did rev fast so it might go back in when turbo's on.

[Carl 3]

way to lite!

had it in on the way up to taupo and to keep up with dan i had to live in 5ooormp+ land. had nothing at all down low.

only plus was it did rev fast so it might go back in when turbo's on.

Perhaps only lightening it a little may be the key???

Something to consider

[325GRANT 0]

Perhaps only lightening it a little may be the key???

thats it but the question is how lite to go!

i was just going by the old mazda / datsun / etc rule of thumb... go as light as you can. not so with bmw's

standard flyweel is 28 pounds i think (correct me if im wrong) and we took off more then half the weight! ...

the moral of the story ...

theres a big difference between a bmw 2.5 and a 13b rotary.

[BMW POWER 2]

the moral of the story ...

theres a big difference between a bmw 2.5 and a 13b rotary.

Is the reason why rotarys are so fast is because they have really good power to weight ratios?

Cos i know they are only like 1.3 or something....

[bravo 35]

It's because of the way that a rotary generates power. they produce more hp per litre of engine capacity, but there are other negatives which is why they are still not being widely used by anyone other than Mazda, and even then only in selected models.

Try Google for more answers.

P.S. mazda uses engine capacity as part of its engine coding 12A, 12B are 1.2L, 13A, 13B are 1.3L and so on.

Edit: may I suggest no more rotary discussion in this thread - remember that my explanation was just a simple one to give Emma a rough answer to her question. No need to go further off topic with pro-rotary or anti-rotary arguments. :thumb:

Edited March 21, 2005 by bravomikewhiskey

[m325i 711]

technically the capacity is 1.3, but you cant look at it like that. a 13b will use gas more like a 5 litre V8.

[m325i 711]

The Motorkhana must have done wonders for your clutch?

[325GRANT 0]

Is the reason why rotarys are so fast is because they have really good power to weight ratios?

Cos i know they are only like 1.3 or something....

theres a bit more to it then that ... from what i understand each cylinder equivalent

(there is 2 in a 12a or 13b) is equal to a 1300 (ish) so a a 13b is = to a 2.5 /2.6

im sure someone can explain this better then me but its getting off topic and sic will shut it down soon haha

maybe someone that knows more about it could start a new "off topic" about it.

[Carl 3]

Sic won't shut it down if you relate it...see below

A single rotor rotary matches a 4 cylinder 4-stroke engine for having 1 combustion occuring at any given point. Double the rotors and you get a V8, triple rotor and you get a V12 equivalent...

To go on, the beauty is that the output shaft is rotating at 3x the actual rotation of the rotors unlike the 1 to 1 crankshaft in a 4 stroke. Power output is smoother and more constant and there's bugger all moving parts...a rotor and an output shaft...

But as stated before the downside is the rotary sucks at thermodynamics so they use alot of fuel...much like a 750i or any american vehicle for that matter

How this relates is because the lighter the flywheel the easier it is for an engine to accelerate...however, there are so many factors which reduce this it's not funny.

E: The 1992 13B twin rotor from the RX7 produces 255bhp @ 6500rpm, capacity is 654cc x 2 = 1308cc.

For racing the coefficient is a 1.8x multiplier so the 1308 is effectively a 2.3, the turbo coefficient is 1.7, not sure if that makes the 13B turbo a 4.0 or not, but they use as much gas as one

E2: Actually, the reason why there is a 1.8x coefficient multiplier is that each rotor chamber actually contains 3 separate chambers (piston-like) so a 654cc rotor has the equivalent capacity of 1962cc (assuming capacity is the measurement of a full piston intake). Makes sense then that a 13B twin rotor has equiv capacity of 654x2x3 = 3924cc...probably why it uses so much gas

Edited March 21, 2005 by ///Carl

[bravo 35]

How stuff works.

[BMW POWER 2]

but there are other negatives which is why they are still not being widely used by anyone other than Mazda, and even then only in selected models.

Thats what my Dad told me when i asked him about them a while back.

He said the can't be too "sh*t hot" if only Mazda is using them.

Edited March 21, 2005 by BMW POWER

[CaM 0]

Thats what my Dad told me when i asked him about them a while back.

He said the can't be too "sh*t hot" if only Mazda is using them.

Funny his name is Graham-Rex but he's just called Rex.

.

relevance????

technically the capacity is 1.3, but you cant look at it like that. a 13b will use gas more like a 5 litre V8.

i fail to see the truth in that....my 13b turbs s4 gtr used to use less than my mini.... how's that figure???

oh, and rotaries are only a 1200/1300, thats it, motorsport have a multiplying constant which penalises them to a higher theorectical capacity.... due to their power advantage blah blah blah...

[BMW POWER 2]

Thats what my Dad told me when i asked him about them a while back.

He said the can't be too "sh*t hot" if only Mazda is using them.

Funny his name is Graham-Rex but he's just called Rex.

.

relevance????

i fail to see the truth in that....my 13b turbs s4 gtr used to use less than my mini.... how's that figure???

oh, and rotaries are only a 1200/1300, thats it, motorsport have a multiplying constant which penalises them to a higher theorectical capacity.... due to their power advantage blah blah blah...

Relevance.. Bravomikewhsikey's name is Graham........

And plus everyong else was talking about Mazdas... so i thought it would be a good chance to ask about the engines.

[318is 0]

Hopefully on topic now this is on rotangs...

I build years ( 14 ) ago a 13B stage 2 engine, and put it into a Chevron Kit car I build. ALL my mates were V8 freaks ( so was I to tell teh truth ), but if you've looked under a Chevron bonnet, its damn small. Anyway - none of my mates could beat my Chevron, and some had big block badass chevvys.

The ones I took for a drive all said it was the fastest thing they ever been in. Power to weight ratio is awesum, if you dont mind the sound they make

They are amazing engines, basically go together like a ruddy big club sandwich

[CaM 0]

word.... done right they're reliable and perform awesomely.... done wrong they suck mega pills.... excessive fuel consumption, poor running, need tow starting everytime etc, much like almost every shitkick in NZ that has one in their phat wags yo!

[BMW POWER 2]

much like almost every shitkick in NZ that has one in their phat wags yo!

:mosh:

[Gus 5]

how bad was it having it that light? like really really bad? i really want fast revving haha

hmmm..clutch time..so much non fun

motorkhana loved my clutch. really.

and as for rotors...targa adds 1.8 (or 1.7, one of the two) to a rotor to get its engine class

so 13b= ~3L

and back to me me me.....stick your rotor topic else where before i mod you all

bitches

[Carl 3]

how bad was it having it that light? like really really bad? i really want fast revving haha

Fast reving comes at the price of torque

Too lite and you get no acceleration up an incline, which is what Grant was talking about when he said he had trouble keeping up with Dan in his auto up the biggest damn mountain on SH1 just north of Mangaweka. Even I was keeping up with Grant's 325 up that hill so that's saying something

I think 12lbs was too much, makes it very easy to stall aswell if you uprate the pressure plate and clutch in tandem.

I'm going to lighten up my flywheel but was thinking more towards only a few pounds, poor B20 may not like a super lite flywheel but fast reving is badassnessextremeness

[CaM 0]

dude extra flywheel weight isnt a torque creator...... mac it on a dyno before and after and on paper the torque wont drop.... it's more about momentum.

mangaweka deviation owns, hills like that level every vehicle out. gearing and driving style etc play a huge part in that. I've been over that in so many different vehicles, and the best bet to goin over it quickly is in a diesel i reckon, if you know what you're doing (van holds 100mph over there, closed road of course).