The Technical Questions Thread

[johnnynumfiv]

Wouldnt they calculate that from the circumference of the pulley rather than the diameter?

Wouldn't they be the same since circumference and diameter are related via pi?

10cm/ 5cm
31.4cm/ 15.7cm

[fpv_gtho]

Next topic: rotaries.

First off, what is the difference between a 2/3/4 rotor rotary engine?

The number of rotors in the casing. Each rotor is equivalent to a piston, but has 3 combustion chambers rather than 1.

Why aren't rotaries used in more racing series due to their superior hp/L rating (and hp/kg rating - a 13B in the RX8 has 1.32 hp/lb while the Enzo's F140 has only 0.01 hp/lb more at 1.33 hp/lb)?

They're banned in alot of series. I guess its also hard to agree on an equivalency formula. A 1.3L rotary isnt equivalent to a 1.3L 4 stroke motor. Its more widely agreed to be equivalent to a 2.6L 4 stroke motor, although they generally dont make as much power as a 2.6L.

Why don't we see any large displacement rotary engines - an example beiing the RENESIS being 1.3L and the Mazda 787b's engine being 2.6L and yet still producing over 700 hp?

I dont really know, but Mazda have been the only ones taking rotaries seriously. The cars theyve been sticking them in have generally been lightweight sports cars, where only a small engine is needed.

Could a racing rotary theoretically rev as high as an F1 engine?

I think they could theoretically rev higher, as theres less moving parts

If rotaries are so good, why don't we see more of them road cars?

They lack development. Mazda are really the only ones giving them serious effort these days, whilst Ford, GM, Toyota, VAG, BMW, Nissan/Renault, DaimlerChrysler all still develop 4 stroke motors. Added to that, theres over 50 years difference between the introduction of the 4 stroke motor and the Wankel Rotary, so Mazda are forever playing catchup.

[Kitdy]

It's quite simple, they're not allowed thanks to rules in several series. They're banned at Le Mans IIRC.

I've read the some of the ACO rules for LMP1 and LMP2 in the ALMS - I think they're the same for Le Mans, and it allows for rotary engines.

In fact - and this was another point I was gonna raise - I don't see anything banning two stroke engines. Someone could just make a two-stroke and have near double the power and smoke everybody. Why does no one do this?

[hightower99]

I've read the some of the ACO rules for LMP1 and LMP2 in the ALMS - I think they're the same for Le Mans, and it allows for rotary engines.

In fact - and this was another point I was gonna raise - I don't see anything banning two stroke engines. Someone could just make a two-stroke and have near double the power and smoke everybody. Why does no one do this?

Rotary engines are banned and so are 2 stroke engines.

And even if rotaries and 2 strokes were not banned nobody would bother using them because even though they make more power in the same package they consume disproportionally more fuel. So you might be alittle faster but you have to pit at least twice as much.


Rotary engines are very fascinating but they have several severe drawbacks. The biggest being that they suffer from low thermal efficiency because of the physical design. That and lubrication problems shared with 2 strokes makes them not suitable for racing (even though mazda did win Le Mans with a 4 rotor NA Wankel engined race car)

[fisetdavid26]

Rotary engines are very fascinating but they have several severe drawbacks. The biggest being that they suffer from low thermal efficiency because of the physical design. That and lubrication problems shared with 2 strokes makes them not suitable for racing (even though mazda did win Le Mans with a 4 rotor NA Wankel engined race car)

...and the fact Mazda mechanics declared the engine capable of running another 24 Hours race at the end of Le Mans '91.

[NSXType-R]

I don't know the rules for Le Mans, but I'm intrigued by the Rotary engine win by Mazda. It's a shame that they didn't let it continue to compete.

[Kitdy]

Rotary engines are banned and so are 2 stroke engines.

Are you sure? I have read some of the rules for the ALMS and there are provisions for rotary engines in the rules so I assume they are legal.

There was also nothing mentioning the banning of two stroke engines that I saw.

[hightower99]

Are you sure? I have read some of the rules for the ALMS and there are provisions for rotary engines in the rules so I assume they are legal.

There was also nothing mentioning the banning of two stroke engines that I saw.

To be honest rotary and 2 stroke engines are not illegal for GT1 and GT2 classes however in order for anyone to run a GT1 or GT2 class car with a rotary or 2 stroke engine they need to make a certain number of homogulation vehicles to be sold like normal cars with those engines.

Rotary and 2 stroke engines are banned from prototype classes.

[Kitdy]

Rotary and 2 stroke engines are banned from prototype classes.

I still gotta disagree with you there. I read the ACO rules for LMP1/LMP2 and there was no indication of either being banned.

There was even a table indicating air-restrictor plates for rotary engines.

Then again, maybe I missed something...

View.

Page 8 for the engine, page 22 for rotary engine restrictors.

[fisetdavid26]

Dude, they are banned. They were banned from Le Mans the year after Mazda won. To be sure you'll understand, I made you a drawing.

[Kitdy]

Dude, they are banned. They were banned from Le Mans the year after Mazda won. To be sure you'll understand, I made you a drawing.

That doesn't mean they weren't reallowed in a different series - the ALMS - not the WSC!

Have you read the rules? I have!

[fisetdavid26]

Have you read the rules? I have!

No, I have to admit I have better things to do than read 36 pages of rules and regulations. I did read page 8 and 22 though.

[hightower99]

That doesn't mean they weren't reallowed in a different series - the ALMS - not the WSC!

Have you read the rules? I have!

It's all a moot point really as the only people who could field a rotary powered car is mazda and they don't want to blow the huge amount of resources it is going to take to make the current wankel engine competitive. It's just not going to happen anytime soon.

[Kitdy]

It's all a moot point really as the only people who could field a rotary powered car is mazda and they don't want to blow the huge amount of resources it is going to take to make the current wankel engine competitive. It's just not going to happen anytime soon.

Why then no two-strokes?

If they really wanted to, Mazda could come in to the ALMS and utterly dominate for a year with a large multi-rotor wankel engine. If they were interested in returning to motorsport, the ALMS/Le Mans would be a great opportunity for them.

[The_Canuck]

Why then no two-strokes?

If they really wanted to, Mazda could come in to the ALMS and utterly dominate for a year with a large multi-rotor wankel engine. If they were interested in returning to motorsport, the ALMS/Le Mans would be a great opportunity for them.

Because Two strokes are innefficiant. The End.