I am getting about 90-95psi on my newly rebuilt engine per face of the rotor. I was expecting at least 100's. Should this be right? All parts were specked out by Pineapple as above average in reusability. I am using all new seals, apex 2 piece 2mm, oil seals, 1 piece corner seals, and side seals from Atkins. The motor has a street port. The Rotor housings front and rear are used. The side housings all three specked by Pineapple and was told they were close to new condition.

I am having a hell of a time keeping the engine running, or even turning on. It will turn over but eventually try and die off. This of course after the injectors were finally repaired.

I was thinking of trying tranny fluid, or adding some MMO, but didn't want to put anything in there that shouldn't be.

Any suggestions would be greatly appreciated,

 

that's plenty to keep an engine running.

 

thats close to what i was told mine was...I've always had to crank it a bit longer when cold and it runs very shitty till it warms up. I was told that the compresion would go up after breaking..never checked but seems fine so far.
I got about 8k miles on it no problems so far. It pulls very low vaccum(about 12-15 inches @ 900-1100 rpms - yes my idle is all over the place, i need to play with a datalogit!) but street ports are supposed to do that anyways.
Good luck just keep it lit and break it in properly...should be fine!

 

It's enough to keep it running but I would be pissed as hell if I had compression numbers that low on a new rebuild...anyone want to chime in on how much compression increases on a rebuild with all used housings?

 

That is good #'s if some of your parts were reused....

 

Mazda's original worn-engine spec was anything below 100 psi, they later revised this to 85 psi. Hitting only 90-95 psi would NOT make me happy!

How many miles were on the rotor housings?

 

It's fine. Give it time to seat.

 

Michel, how much of an improvement in compression would you expect to see as the engine breaks-in?

 

I thought that it built compression pretty much immediately in the 3rd gens???

 

no, its still a motor.

 

stock compressions is around 120 i think

 

A new rebuild will have low compretion untill break in. a piston motor starts of with good power and compretion and gos down with age but a rotory builds power and comp. after a rebuild and should hold after break in till it wears out. hope that helps.

 

I would expect those numbers with a used housing rebuild, and that is certainly enough to have a smooth running engine. IN 2500 miles expect those numbers to rise to 120-125 with a proper, easy breakin.

What it boils down to, despite the ramblings of others, is that a new housing rebuild will cost you at least $1000 more than an equivalent used housing rebuild. For the first 2500 of those miles, there will be a big compression difference between the 2, and afterwards, it'll be within 5% of each other. IS that extra 20psi compression for 2500 miles worth a grand to you? It isn't to me.

Did you say pineapple did the work? I thought that place refused to use anything but new housings? At least that was the selling point I heard for years (when compared to my own services) before all the bad press came out about a a year or 2 ago.

 

I'm not sure if they will use used parts or not for their Rebuild. But I paid Rob a couple hundred bucks to do me the favor of specking the parts over and he agreed to do so, and to sell me a used housing, also he glass beaded or whatever you call it to the parts. But no I did the rebuild myself.

Anyhow as of yet no real progress on the engine. It will ignite the fuel and attempt to start but won't idle on its own. I had it idling yesterday for about 2 minutes straight and then it just went Kapoop. I'm probably gonna blow the starter out with much more effort. Do you guys think tranny fluid might be a good idea, should it really be this tough to start?

 

if you only had the engine running for 2 mins.... i say you're doin real well with the compression you have... it took me about 400 miles to get my compression to 105 on a ported motor on new seals and housings... i havent checked the compression since

 

You serious...? So how much effort should it take to get the engine going by itself? I've probably cranked it over about 50 times now, thank god the starter is a beast, I'm suprised its still holding up this well. Only a couple times did it run for a couple minutes on its own and then died out. So eventually if I keep trying it should work, crazy..!

 

You shouldnt be having your problem starting...even the older engines with used housings that have much more wear start right up, though they may not idle below 1000 very well.

I'd say change your plugs as they may be fouled from burning off assembly lube. You might also have a fuel delivery issue, but it could be many things at this point. Compression is not your problem, and though a little atf/oil won't hurt, it probably won't solve your problem.

 

i agree... your problem is either spark or fuel not compression

i know from experience... couldnt get my motor to start til dragon sent me a map for his car with a similar setup, cleaned the plugs.. and started at first crank

 

The plugs are pretty new, and clean still guess it wouldn't hurt to get another set. Spark is excellent as I tested each ignition wire and it is ommitting excellent spark. Fuel may be a problem, maybe running to rich from injectors preventing the spark from igniting the fuel properly.

 

I think ATF/MMO is a bad idea --that is to resolve carbon buildup which would be pretty bad to see in a new motor. New motors run rough and have low compression until the apex seals seat. As mentioned the plugs may very well be fouled too from assembly lube, etc...

Also, how is your tuning for that streetport?

Just some ideas,
~Kris

 

Those numbers are fine. Don't let people on here get you worked up over nothing. Starting issue is probably plugs, take them out clean them off, Putting in the ATF wont hurt and can help with compression but I would say clean the plugs first, check fuel, ie pressure. Rob builds good motors I have had tons of motors, 30 or so come through this shop never had a problem, none have come back yet either. So maybe when he hears they are coming here he builds special ones I guess who knows. But They all had new housings that's for sure and that's the only way I'll build them as well.

 

No, no it's not. It's been proven that atf and mmo have almost no carbon dissolving properties. On the other hand, it's well known that to form a good seal and make strong compression, the metal-on-metal contact of seal vs. housing needs a coating of oil. Startup for rotaries means quite rich mixtures (like a choke on a carb'd engine) which can potentially wash the housings of this coating, and, if the engine is shut off during this time, it can lose some compression and have a hard time starting back up. A shot of oil or atf rebuilds this coating and raises compression momentarily.

 

Exactly

 

Okay, that was my misunderstanding of his intended purpose for it then -- that makes sense to me now, thanks for explaining it.

~Kris

 

So brand new plugs can get fouled out that easy. Honestly I can't tell what a fouled plug looks like from a non-fouled plug. A friend of mine told me to clean the plugs you can usually light them up with a lighter, and of course you can use carb cleaner as well. Usually they just have a lot of carbon on them right? These plugs are pretty cleane but the diode is black.

I'm gonna buy a new set just courious about that.