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-   -   Major Concern (https://www.rx7club.com/general-rotary-tech-support-11/major-concern-572430/)

azturboII 08-27-06 05:45 AM

Major Concern
 
hey guys, im new to the rotary thing so just keep that in mind before you start flaming. i was wondering if the rotary engine in my 89 turbo II has a timing belt. i was also wondering if it were to snap, would my engine get messed up or if it would be ok. i know on my supra its non interfering so i dont really worry to much about the belt braking. this was just a major concern i had about the car. is the rotary motor non interfering.

trochoid 08-27-06 06:39 AM

No timing belts or chains in a rotary. There is a chain, but it drives the oil pump. They rarely break and I have not seen one break myself. Since there are no pistons, push rods, valves or cams, you cannot have a catastrophic failure like interference engines can.

RX3SP 08-28-06 09:42 PM

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No catastrophic failures...er uum, I've had a few of those! LOL
Here's a picture of a stationary gear that broke in one of my engines a few years ago. The rotor jammed in the housing and pretty much destroyed everything in the back half of the engine. The rotor housing, the rear and intermediate irons all broke along with the intake manifold. Those stock stationary gears don't like a steady diet of 10k rpm runs!

trochoid 08-28-06 10:41 PM

Yeah, I'll bet the rest of the internals were f'ed up real good. Nice job. I was refering to interference piston engines when valves meet pistons in a violent manner when the timing belt breaks. We don't have that worry. Stationary gears on the other hand, well, that's another matter. Staying under 8k rpm, they aren't an issue.

RX3SP 08-29-06 06:41 AM

I've never been able to keep a rotary under 8k for very long! My right foot has a bad habit of getting uncontrollable spasms.

trochoid 08-29-06 08:55 AM

Then it might pay for you to do the internal mods for the higher rpms, along with intake and exhaust to make use of the 8k+. I like to run above 8k on my 12A, but the extra power isn't there to be of any real benefit, let alone risking the engine.

Sorry to hear about your spasms. :)

RX3SP 08-29-06 09:08 AM

As you can see from the picture, I learned my lesson well about the stock stationary gears. That happened years ago before I understood that there was a limit to what they would take. These days, I run the hardened gears with the 3 window bearing in the rear one.
I think those spasms are a genetic defect!

RX3SP 08-29-06 10:46 AM

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If you like gory pictures, here's a picture of another interesting failure that happened to one of my 12a engines(also years ago). I considered it catastrophic, but it wasn't nearly as bad as the gear coming apart. Under high rpm, high load, the casting around the upper dowel severely cracked and came off. I still to this day think it was a bad casting, but they wouldn't cover it under warranty!


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