Brand New Engine Toast
 

Hey all,

I'm in a situation where a engine was bought and installed by a shop, they ordered it brand new from Mazda. I broke it in for about 2000k miles and the limiter was set at 4.5k the whole time. I brought it back for the final tune. After picking it up from the tuner/ installer, I was able to drive it 45 min before it lost power. The car was on the highway doing 80 in 4th when I accelerated and at 100 it just lost power. I was around maybe 6.5k rpm? I limped it back to the installer and he tore it apart. I'm not super knowledgeable about rotary's. He is saying that the edge of the rotor hit the housing and it needs a new rotor and housing, and that the tune they did or the install had nothing to do with that. He is stating that's common of a missed shift / over rev with the Power FCs. They set the rev limiter to 7.5k, which I don't know if that matters. It has been over 1 year since they ordered the engine so I'm out of luck with Mazda. He is saying he will pay for labor, but I would have to buy the parts. Is this scenario reasonable? I'm reaching out to see if the edge of the rotor hitting the iron is indicative of that. I'm not going to say the shop, they have been accommodating, I'm really looking for knowledge If that is a common cause for a big failure like that.

Let's see pics of the damage.

Will post soon, installer said Monday he can send the pics, as he has already left the shop.

Sorry to hear about the motor.
Care to share what shop?

I won't be sharing the shop as they have been working with me on this build for a while. They've been decent for communication almost every time I call and for the most part fairly transparent with the overall build. I was going to post a positive review of the shop before all this went down. I'm certain that if it was just a blown Apex seal the shop would have taken and just did it for free, I think what's pushing this to this level is the fact of the price of a new rotor and rotor housing, as we know the cost of those items.

What modifications?

Modifications include upgraded fuel pump, fuel system lines were done in the engine pay ,1300 secondary cc's injectors 900 primaries, harness redone by rywire, Power FC, new engine, new turbos. The engine was dropped in as is from Mazda from my understanding. I will say that in the process of the rebuild rather than replace the lines we ended up going with the non-sequential set up for the stock twins. Initially I had a greddy intercooler that fit in place of the stock one and the stock air box which is why it was limited for the break in. When I brought it back to him, we finished by going with a V-Mount set up with custom air intake. The initial build put out 309 to the wheels at 14 lb on the stock twins.

Need more info of course but...Post pics of your setup. Also, How old is that harness? Those harnesses had problems in the past.

Sounds like a bad tune and it sounds like the shop doesnt know what they are doing
how old was the fuel in the car?

the edge of the rotor touched the housing and because of that you need a new rotor and a housing? Wtf … over revved and it is common with the pfc?

these moronic excuses are a huge red flag and it sounds like you got screwed

100% agree w R-R-Rx7

Looking forward to the input on the pics, I should hopefully have them Monday. Harness was ordered and installed somewhere around April 2022.

It would be a shame if that's the case. They have been reasonable with the build on time and prices from the start. Fuel should have been refreshed through driving around. I did not mention earlier that I drove it home from the first tuning session that limited it to 4.5k. the drive was 7 hours and mechanically seemed good. I then proceeded to drive here and there every week or two to make sure the seals were moving and lubricated before I went back down after the funds were raised and he could fit me in for the V-Mount I would say 6 months later. I then drove it back down to the shop. Somewhere along the line the car started to put out a really rich tune. but was drivable none the less.

I'm not super knowledgeable about rotary's and did the homework to get by most of problems I faced. Im looking to your guys knowledge on this front with the way the casualty happened.

I appreciate the reply Howard. Any ideas for the specific corner of the rotor hitting the Housing? Seems to me outside of the bad tune, which could be the case, Would a Manufacture defect cause this?

Unless you rev'ed the engine to 10,000 rpm, rotors should not be hitting housings. This was a new engine? As in, new bearings? Did the shop verify endplay? What kind of oil were you running, and you verified the level was correct?

That makes more sense to me. I watch people really put the 13b to work and have not heard about a rotor hitting the housing. Mainly a seals issue which is interesting. Good questions, and I can ask the shop themselves for the endplay. The engine was new shipped from Japan from what I understand. Not fully aware of the specifics on that. He stated a brand new or at least we paid around $5800 at the time in AUG 2021 for it. He instructed me 20w 50 oil and I have ran that from the start. The level was correct but here is the catch. Due to the excessively rich fuel tune , which I will ad was not that way when i drove away from the shop, the car was having pretty agressive F.O.D. I could smell fuel in the oil. I did some research and from what I understand this is common to a degree, although it seemed mainly from hard driving on the track. I never took it to the track as it was limited. The oil level was good. Oil metering pump was still in place. I dont think thats a factor but I will add it just incase. I ended up changing the oil once after it returned home. I was not comfortable with the level of FOD after driving it for awhile and changed the oil at some point during those 6 months again. I then changed the oil right before the drive down. Mainly for my comfort and my recognition that the tune was too rich.

Do you have a wideband o2 so that you can quantify how rich the car was running?

I've torn down many reman and new Mazda engines over the years for street porting and other performance work and the side seal to corner seal clearance is typically too loose, which will lead to excessive fuel dilution in the oil.

Thanks for the help Goodfella.The setup is still factory for the O2 sensors as far I know. Interesting information with the fuel oil dilution. That would make sense for the dilution, I can say the even the installer stated the tune was "Too Rich". He claimed it sounded like it had a bridgeport, with the way it was running.

Rich
thats an issue for the long run. Not blow up the engine 45 minutes later.
and since this is brought up i have over revved my engine way past the 11k-12k rpm and I haven’t had this “common outcome” even with the power fc. (Glorious moneyshifts during my more active track/racing years lol).
i have been lucky i am not going to deny that. i am not saying that it can’t happen but i have seen these results with a simple case a bad tune and with a slight benefit of the doubt, with old fuel in the car but the engine was broken in for 2k miles so its not that

This is a classic case of detonation where the tuner is probably a piston engine tuner and possibly inexperienced with tuning of the rotary engine. I havent even seen the tune but i am willing to bet that given the information from the OP thats what it is

Great information and that sounds like what I was seeing around the forums.

Understandable guess given the information I provided. I can say that the shop I'm referring too only works on rotarys. Something I did not mention earlier was that the shop did not tune the car themselves, but had a remote tuner, who has a great history tuning these cars.

The motor should be easily broken in well before a few hundred miles, let alone 2K miles. For future reference: You also don't want long periods of time cruising at a given rpm. You want to always vary the load from accelerating and declarating.

It sounds more like you found a spot in the map that wasn't tuned right, i.e. a condition of load/rpm/boost that hadn't been encountered and addressed during whatever tuning they did, or a hickup in fuel pressure, and pop goes the weasle.

The new rotor and housing is for the damage a broken seal caused, and covering the labor intended to keep you from asking too many questions or talking about it.

This ^^.


Also, when you purchase a brand new shortblock from mazda they come with a 1 year / 12k miles warranty. I verified this with my account at Mazda. Not sure why the shop tore it down rather than just simply getting a replacement sent ( I understand they were on backorder forever ). If I were you I would see about a replacement under their warranty and find another shop that is rotary specific tuning.

~ GW.

Hey all,

Thanks for the guidance on this situation. I was able to get the pics by the builder/installer. It seems valid on what I see but I would love you all to let me know what you have seen after a failure like this.

Here are pics below:


https://cimg9.ibsrv.net/gimg/www.rx7...3dcdc6910e.jpg
https://cimg0.ibsrv.net/gimg/www.rx7...4326891424.jpg
https://cimg1.ibsrv.net/gimg/www.rx7...b5a0721e1d.jpg
https://cimg2.ibsrv.net/gimg/www.rx7...613b73a343.jpg

They broke an apex seal tuning it and handed ot back to you where it came apart enough to slow you down 45 min later.

When it ran rich and sounded like a bridgeport the engine was already blown, just didnt have the collateral damage of running a blown engine yet.

Proof is in the pics.

Are those dents in the rotor face right next to the pocket?