RX...4?

yeah, but wouldn't the (un)reliability of rotaries harken back to the old days of the british sports cars?

Strizzo wrote: yeah, but wouldn't the (un)reliability of rotaries harken back to the old days of the british sports cars?

Come now, the supposed lack of reliability with rotaries is due to unknowing people driving them the same way they would a piston engine.

I've seen one guy pull a 120K+ mile 13b out of a junkyard and put 100k miles on it and still not need a rebuild, and I've seen another guy's g/f kill a perfectly good low mileage motor in < 10k miles. The difference was the first guy drove it like he stole it, she drove it like she would break it at any second.

My 12A has 231xxx miles on it, never been rebuilt, and it's at the races redlining nearly every weekend.

Oh yeah! My 12A blew up!

I heard that they would burn oil. To solve that problem I disconnected the oil pump that injected oil into the combustion chamber. Then it asploded!

Explain that one!

[fishing is good here...grab a hook and some worms on your way in...]

Rotaries are stupid reliable.

The problem is, they run awesome even if they are beat up, worn out junk. And they get beat up and worn out partially due to the factory tuning, which is basically "make it run super rich and then inject air into the exhaust to burn it off" and then everything gets all carbony and bad things happen.

I've done lots of things that people say you simply Should Not Do with a rotary... and they never failed. At least, not until I safely got home, which is the sign of a good engine. Bad engines will leave you stranded 500 miles from home, in the middle of the night, on a holiday weekend, while it is raining.

PS - Peripheral ports rule.

So then, what's a 'street port'?

Would that just be a mild bridge port, suitable for street use?

'Bridge ports' are radical modifications for a race motor. They aren't generally recommended for street use. 'Street porting' usually is a shallow extension of the stock port. Like this:

I've also heard them referred to as 'J-port'.

Here's the thing about porting a rotary: Changing the size and shape of the ports can be compared to changing the lift and duration on a camshaft in a boinker motor, but unlike the camshaft it's pretty hard to undo what's been done if it's not what you need. A PP might make ultimate top end power but around town you might as well do a Fred Flintstone to get the car away from stoplights, etc. A streetport will add some to the mid and top while not taking too much away from the bottom end.

Also, a rotary has a heavy flywheel to smooth out the idle. If you streetport a motor and then hang a light flywheel off the back, it could wind up with a nasty rough idle. Again this may not bother you, but it's worth calling Mazdatrix or Racing Beat, telling them what you want and get their recommendations.

A J port is a bridge port that has the eyebrow so large that it is into the water jacket. It's what you do when the rules don't allow a peripheral port but don't exactly specify what one is - a J port pretty much turns into a side entry peripheral port.

I daily drove a peripheral port for a while. It actually got better fuel economy than my current monster street port. (monster = the ports are at the limits of the castings) Drove a hell of a lot better around town, too. And that idle!

But the problem is, when you have an exhaust quiet enough to drive on the street, a peripheral port or a bridge port simply do not tolerate that much exhaust restriction. That's why I yanked it out and went with a street port, that incidentally makes about 50 more HP on the same exhaust system! (But it doesn't go brap brap brap, it just kinda goes bokitabokitabokita at about 1200rpm)

Very glad to see this thread. Been wanting to do a nasty sounding rotary in a first gen GLC for a while now. The project may get underway when the current time sucker is done.

Mazdatrix has a good porting description: http://mazdatrix.com/s.htm Here's some more: http://www.turborx7.com/portingpictures.htm

I saw some street ports which had a pretty radical extension pointing toward the center of the housing that were described as J ports. It looked a lot like the 'monster port' on the rx7turbo page, but without the secondary port near the water jacket.