I was accelerating out of a highway on-ramp and hit the rev limit then suddenly the engine stopped running properly like it wasn't getting enough petrol.
so i pulled over on the side of the highway, and turned the car off, but then it never started again. what do you think it could have been?

 

Did it make a funny noise? Start sounding "uneven"?

If it's not blown, fuel pump is the likely culprit. The fact that it happened at redline doesn't seem promising though.

I would do a compression test and depending on that check the fuel pump.

 

revs just fell all the way to zero as soon as soon as i hit rev limit and then when i tried to accelerate it just made it sputter more. i think the car may have been shaking more than usual yeah, cause there was more rattling coming from the exhaust and lots of smoke.

 

The first thing I would recommend is a compression test with a rotary compression tester. It won't be a perfect test since the engine isn't at normal operating temperature but it will give you a rough idea if one of the faces has very low to zero compression. Its possible that you experienced apex or side seal failure.

 

I just had a compression test done and there's no compression. They quoted me $10k minimum for a rebuild. Does that sound reasonable?

 

No. $10k is not a reasonable minimum for a stock rebuild.

I usually don't comment on what a "fair" price is since it depends on location and the parts that need replacing (all seals at a minimum, sometimes housings and irons). However, this feels like the sort of price a shop gives you when they really don't want your business. Usually this is because they often build race engines / do custom work that earns a lot more money, so they are quoting a lot more for a "small" job since it has to be very lucrative to be worth their time. They're pricing in their opportunity cost.

I'd try shopping around at other rotary shops near you. They aren't very plentiful, but it's worth a shot. Otherwise you could always rebuild it yourself if you're patient and methodical, although the cost of the required measuring tools (good brand micrometers and dial indicator ) can quickly make it a more expensive job than you'd think. Especially if you also need housings and irons.

 

Price out all the internal seals/springs.

good sources:
pineapple racing
rotary aviation
atkins racing
goopy performance
mazdatrix

now look at the fsm to get familiar with the internal parts inspection process.

understand that not everything in your engine can be reusable due to normal wear, or especially if blown apex seals damaged the internals. Another wear item would be the crank bearings.

Possibly start pricing out used internals: irons, rotors, housings.

Then you’ll understand how much a rebuild should cost, accounting for someone’s expertise and labor.

 

I could be wrong, but would it be less expensive to just order a new engine?

 

You’re not wrong.