So, I got around to getting the compression tested at the dealer, got back these numbers:

Rotor 1 ---> 113.39, 118.46, 113.68 @ 276 RPM

Rotor 2 ---> 117.59, 118.46, 117.59 @ 277 RPM

Motor is the original, 51k miles

I was looking at the ways to convert to the 250 RPM standard as per the FSM, it looks as though I just subtract by ~7, right?

Which would give me a lowest reading of 106ish, which from what I've read is not bad considering mileage but the two 113s may indicate a failing apex seal, correct?

What do yall think of these numbers? I hope to get another pretty much gentle 15k out of it, or am I dreaming?

 

those numbers are way better than most with 51k miles.

 

I have to agree. Thats very impressive results.

 

Thats what I was thinking, I'm beginning to believe the prior owner's claims that the car was not driven hard, which more often than not is a lie for this kind of car.

Funny story, the master mechanic at the dealership said when he saw my car pull up he thought to himself 'man I sure hope he's only here for parts', when the sales rep leaned in to check the odo he gave a 'thats-not-stock' look at the boost gauge and asked if it had a turbocharger... , the mechanics had a small chuckle about that.

 

LMAO , I get asked all the time if I'm boosted LOL

but for a mazda mechanic LOL I guess its a testimate to just how rare these cars are lol

 

Yeah those are some really good numbers.

 

Great comp numbers, no indications of a failing apex seal

-Geoff

 

Apex seals typically don't test as "failing", they're either good or not good. If you had a blown apex seal, you'd have a rough idle, low idle vacuum, and 2 of the pulses would be very low, like 30-60psi.

That's a fine motor. Keep it running COOL and you'll have many miles on it.

Dale

 

Thanks, and I recently put in a fluidyne radiator and FC thermoswitch due to concerns, I don't have an accurate measure of temp though but I'm guessing with those two mods I'm pretty good.

Here's the odd thing - from what I've read a healthy engine should pull 16-18 vacuum at 700-900 rpm idle, while mine will hold 14ish if the idle settles there. I usually idle at ~1000 +/- 200 rpm

Little backstory, I did all the vacuum hoses back in winter when I got the car, and in the process I removed alot of the emissions and non-essential mechanisms such as the ACV, Air Pump (no cats anymore, restrictor plated, the pump is still there as an idler pulley for the belt), EGR, and double throttle. I kept the OMP even though I premix w/ idemitsu and the AWS. I don't have a Power FC yet but thats my next big purchase. Could my low vac numbers be due to my stock ecu having trouble with the deleted items? or is my autometer boost / vac gauge faulty? or is that just a normal reading as well?

Oh and I failed to mention I did a steam clean + oil change the day prior and in between I put ~40 miles on it, pretty sure all the water had been cleared out but that may be a factor as well.