So I got my compression numbers here and I'm undecided on what to do. From what I've been reading, these numbers seem low but not low enough for a rebuild? Wanted to hear some thoughts before proceeding to invest in the car. I had plans to purchase the LS Ignition Kit from Bennet Built with the spark plugs as well as redoing the radio system cause the wiring is all messed up as well as looking to paint the car and buy new tires. I don't want to start dropping money on it if it's not worth it in the long-run. Thanks guys!

 

drive it until you have issues and save up for a reman from mazda

 

Exactly as stated above!! This is about where my BB 04 is and I drive it often with zero issues. I know what's coming, but I'm going to enjoy the car while the engine is still running well. I have another engine in the garage just in case. For what it's worth, I've been driving around for 4 years and 4k miles with numbers like that and no symptoms of low compression other than lower than normal fuel economy....roughly just over 17mpg.

 

Im actually in the same boat and want to share some of my recent findings. I too thought I neeed to make a decision ASAP on what to do. I found this blurb in the FAQ section of Rotary Resurrection's website (one of the better known engine rebuilders). Maybe it can provide you with some insight also. From the website:

"In my experience most rebuilds utilizing used rotor housings, used irons, etc. and mostly new oem compression seals/springs, will see 90-105psi of compression with an accurate test after break in, with the variation depending on the specific condition of the rotor housing surfaces used in that particular build. In fact a couple years ago I had a customer bring me an all original, well maintained rx8 with 72k miles for rebuild. The housings looked nice with light wear and were in above average condition. The iron housings had very light wear well within spec. All new oem rotor compression seals and springs were used in the rebuild. I recently did a comp test on that engine after 10k miles of break in and driving. The engine shows about 96psi on the front and 91psi in the rear. It starts cold or hot on the first 2 rotations, idles perfectly, makes good power, and runs like it should with no issues. On a dealer test those compression numbers are failing, a "bad engine" in their view. Does that mean the engine is bad? Heck no. In reality a used rotor housing rebuild isn't ever going to get a whole lot better than that."

Your motor isnt too far off from his remarks above. For reference, my engine has scores from the upper 80's to mid 90's. That means our engines are outside of Mazda's new engine spec, but within expectations for a reman or rebuilt engine. Ultimately, whether you decide to spend money on the car at this point is up to you. No one here will be able to tell you how long the motor will last. Drive the car until it dies, then move on or rebuild/replace the engine.

 

mid-80’s is rebuild time, that’s the rebuild point for the older 13B rotary engine that has lower compression rotors even.

the thing to consider with these numbers is they aren’t normalized to 250 rpm. So it’s going to be even lower then. Which the program is telling you that by stating it should be low 93 psi range for the indicated 273 cranking rpm showing there. It’s probably 79-80 psi range when normalized to 250 rpm.

so yeah, you need to start thinking about rebuilding or replacing this engine
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Thanks guys for the responses. I've decided to go ahead and plan for a rebuilt within the following month. I'll be taking it to Kilo Racing here in St. Cloud, Florida. I've spoken with him for a bit on the phone and he told me he will be getting the engine remanufactured from Mazda directly and everything else in terms of the housing, springs, seals, etc will be brand new. He is charging me $5,000 for everything with labor included and he assures me the car will be brand new at that point; engine wise. He also told me he offers 12,000 miles and/or 1-year warranty on the engine itself but from all the jobs he has done in the past, he never had anyone come back with issues

I went ahead and also purchased a BHR Ignition Kit with plugs, BHR clutch pedal, and oem air filter. I'll get all that installed as well. He also told me to go ahead and buy a quart of Klotz Uplon Fuel Lube and to put 3-4 oz every time I fill up for gas

Overall, pretty excited with what is to come, once the engine portion is 100% solid I can go ahead and focus on the cosmetics of the car and get my tints re-done, radio fixed, and paint job

 

I know nothing about Kilo, but some of these things seems off to me. First off, a Mazda reman is a reman. No one can guarantee that the engine or any part of it will be brand new. Word is that a lot of the major parts are now new from Japan, but no one can guarantee that. Also, Mazda offers the same warranty on the engine when they install it, 12K or 1 year. Maybe he somehow has a deal with them? The price seems about on par and not bad if he is installing the engine.

 

Jesus; the guy who runs Kilo told me the engine itself may not be brand new but will be reman. I meant in regards to everything else like the housing, seals, and stuff will be brand new he says; straight from oem. He did mention he says he has a deal with Mazda but I'm not sure entirely how that works with them. The reviews seem excellent from what I've read on Google about him.

 

well many are coming that way and nobody has posted otherwise

he gets wholesale and is just passing on the Mazda warranty, that’s pretty standard.

you’ll pay a lot more getting it hand built and maybe the quality might not be as good because even a lot of rotary shops aren’t as adept with a Renesis as the previous 13B. You really don’t have any other choice except that or just bail out of the car.

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A bit of a repost after no love on the OZ subforum, not much traffic there. I am on a rebuilt engine to OEM specs (no porting) after catastrophic engine failure at 100km/hr. Aparently very good 2nd hand housings used as my very tired ones were toast. Irons were in pretty good condition and were just resurfaced. Most other parts installed were new including OEM seal kit. Compression tested at similar numbers to above from new @300km and again at 1500km with slight improvement in compression normalized for 250 rpm and elevation.

Just wondering if not enough km on car to build the compression yet or otherwise. Thoughts? Will test again in another 1 to 1.5 k. It really is a super smooth engine with no issues and all rotor face readings are within about 3 psi within and between rotors. Could my tester just be reading low? Maybe. Back to back to back tests show only small changes in PSI.
Looking for approximate numbers expected on rebuilt engine and what they are likely to get to thereafter. Approximately how many km to reach full compression? Engine premixed from day 1 with Mobil TTS which is FD rated.