Don't overthink it I say. If its running good, and starts easily, send it :-).

 

^^ … back to the engine builder

no way is that acceptable on a new rebuild unless the owner refused on recommended parts

edit: unless he can show you with his own tester that it is indicating significantly higher than your tester.
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Agree
Another reference point = last Mazda crate motor we installed tested 110 / 113 before break-in.

 

A lot of things here are concerning. The compression #s, the fact it was getting hard to start on the dyno even with the 110 heat index, that doesn't necessarily simulate how hot it would get lapping a road course or a tight mountain road. Concerning cranking speed, mine is much slower than yours was, even pre-banzai starter, with no hot start issues; the hp numbers are not that bad for the weather conditions but pretty low compared to what I've seen your car put down 1st hand. Sounds like Nelson was concerned with this hot starting as well. Is he a member here, have you tried to see if he'd like to view or chime in on this thread? I know Bryan is old school, and not a forum guy, but the more heads we put together the better, this has got to be driving you crazy.

 

When we Dyno'd our cars, we used a Mustang Dyno which is quite different than a Dynojet. My shop warned me their dyno was a "heart breaker" and that is always reads lower than others. Nelson is not a member here that I know of. Bryan is. Nelson suggested I drive the car more and circle back.

as for driving me crazy, yes. I'm on the verge of selling and wiping my hands clean.

 

Talked to Bryan and he said we re-used the springs since the previous build had less than 1000 miles on it. He's concerned with my numbers as well. He said he set the tolerances pretty tight. He said new side housings might make a difference but mine were within acceptable tolerances when he put the motor back together. The only thing new to this rebuild was a used center housing as mine was starting to wear thing around the water seal (see post #507).

 

I am practicly nobody to criticize any engine builder, but when something as bad as what happened to your apex seals , that indicates a lot of heat and could had affected the side seals springs and corner seals springs.
Your case reminds me mine about 3 - 4 summers ago in this Florida heat at the dyno.
The air temps were prety hot without boost juice back then, but we let it cool down. It was hard to get it started after the tuning session. Went home and compression was 60's all the way around. I Found weak corner seals and some of the side seals got stuck.

 

I'm with Rich and Zac, I think you're stressing over nothing. I used the exact same tester on my engine after a couple years of use and with zero starting issues of any kind, hot or cold, and I got roughly the same numbers you got. Granted, I'm at 6k feet altitude, but that was with the correction. Same as yours, you'd never know it was bad if not for the numbers. Several years later and it's still running strong with no starting issues. I think you have PTSD from the last failure lol. Just enjoy the car and don't worry about what the numbers are telling you unless you start seeing some actual issues that indicate low compression.

 

I am on the other side of the fence - take it back to Bryan and let him diagnose and repair. Bryan is a stand up guy, so why not? Put on the miles he has asked for, test, and take back.

If it were me, this would always be in the back of my mind.

 

In no way am I knocking the builder because life happens to us all, but I can’t even begin to entertain the idea of “it’s all good” being proposed. The compression test is the one true indicator that every professional engine builder relies on. To suddenly discount it on a new engine isn’t logical at all. Five years down the road and trying to decide on whether to rebuild or not, the “it starts ok” reason is plausible, but not here imo.
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If I pull the motor and bring it to him, he will diagnose it for free but if I bring him the car, he's going to charge me for labor to pull and reinstall the engine. I don't have the time or tools to pull it myself and I sure as heck and forking over another $1200.

I know there are a two schools of thought going on here. I've talked to people who said if it starts, pulls good vacuum, just drive it. Before rotary compression tools were available to the masses, people rebuilt these motors and had no reliable way to check compression and people still drove them, often for 10's of thousands of miles.

Others have relied on the tool and the numbers as the barometer. Bryan told me he stands by his engine build and told me to put another 800 miles or so on the motor, retest and we can re-evaluate where we go. He said he checked the springs against new ones as part of the build. Had he found them to be bad, he'd have suggested new springs but they had no visible wear, carbon build up, etc and checked out fine. Bryan is definitely old school and has been in business a long time so he's in the camp of does it start easy, does it pull good vacuum...if so, just run it. We agree the numbers may go up, but likley not by much. He said he raced for years without ever checking compression and his motors performed fine.

I talked to another member on this forum who pointed out that compression at low RPM isn't always indicative of compression at high RPM as you have lots of centrifigual force helping to create a seal as the rotors spin. Bad starting compression doesnt always equal bad running compression.

Another thing to factor in is that the engine with the iRotary seals were compression tested (at my request) before I took delivery of the car from Bryan and was over 100 and that didnt seem to matter because the engine went boom on the dyno. This motor, didn't get pushed to 8k RPM on the dyno (but I have done a few pulls on the street) and is still working so honestly I don't what to think these days.

I did replace the master and slave clutch this week (super easy...should have have removed the starter though). I drove the car and it still drove "fine". I did also get back from VIR in the Porsche and frankly, it was sooo much better than the FD. My first session out I turned a ~2:25 lap which is 8 seconds faster than my best FD lap. By the end of the weekend, I was down to ~2:17. Not apples for apples but it def made me think twice about if I really want even track the FD. After a short drive with the FD post cylinder fix, it still puts a big grin on my face.

At this point, I've decided to just drive it more miles, see how it behaves, retest compression after break in miles, and go from there. I'm honestly so tired of worrying about this. I'm just going to drive it and see how it behaves. If it doesnt change, then I'm good. If it shows signs of having problems, it's likley going to go on Bring a Trailer and I'll just move on.

 

Good plan. Enjoy it..

 

I see. I would offer the advice to drive it for the number of miles Bryan wishes and then test the compression. If it is low, then Bryan needs to pull and repair the engine at his cost, not for $1,200. That's crazy and doesn't sound like him as you've already paid him for this work and if the engine is not good, then he needs to return the car to you with a reliable, high compression motor.

I understand "back in the day" we may just have gone off of vacuum, but now we have better ways to measure the sealing capacity of a rotary engine. Compression is the de facto standard I think we can all agree.

The issue with your BAT plan if it comes to that is that the bidders are going to want compression numbers and you will take a hit for the low numbers. That should not be your problem. So, one way or the other, Bryan needs to fix his work if indeed the motor is low on compression.

 

FD is a drivers car, so people like you and I are going to be faster in the Porsche which is built to be fast with the people that can afford to buy it driving as opposed to people who spend all their time learnimg how to tune a car and drive instead of earning $.)

Basis of this statement.
fastest stock 911 GT3 at Tsukuba is 1:00.20.
stock twins 200utqg street tireRe Amemiya FD in 59s.
FC was under 59s on DOT tires in 2001when it inspired me to build my FC

Fastest naturally aspirated Porsche just barely beat fastest naturally aspirated FD this year at Tsukuba.

Fastest FD is 53 seconds.

Fastest porshe is hard to find. Help me out? I found a 57sec RWB.

Porsche has made this semi trailing arm rear strut front car (what we call shitboxes affectionately) fast from the factory like R35 GTR, butt hard to tune to be faster.

Its ofc not fair against Porsche that I choose Tsukuba times since it is a course that rewards good handling cars that dont understeer (light tune na rx-8 on Federal tires 1:02 is faster than most porsches on their DOT-R stock tires).

My point is FD is tuner's and driver's car (which we arent).

But, what do we aspire to?

So, Im keepin my baby...

 

I don't disagree, but then I see this thing sell for $47k. I think I have a better overall build minus salvage title my car had (now it's got a clean title) when I got it. But I guess we'l see where my head is at in a few months since that probably how long it will take me to put 700+ miles on given I have zero commute and very little free time with the kids.

https://bringatrailer.com/listing/1994-mazda-rx-7-63/

 

Salvage title, even if somehow is cleared, is a major hit on a site like BAT. Doesn't matter how your build compares to that one. You'll get 20 people that aren't even interested in buying start picking it apart and many potential buyers will then just wait for the next one.

 

I can certainly sympathize with the OP’s frustration

It was sort of understandable that the first engine compression issue could be handled that way with the apex seal choice not being so familiar, but rebuilt attempt #2 now brings their reputation into possible dispute. It seems like they would be doing more to protect their good name given the circumstances.

Because their position on #2 as was presented doesn’t seem very reasonable under the circumstances. Not that I was considering them for such work any way and had previously only heard/thought good about their company. However it seems as if that’s just as much in question now as two motors in a row with compression issues right out of the fresh rebuild gate.

if anything it seems like they’re taking a lax approach based on not receiving much pushback on it. Which is just my feeling and not based on any actual knowledge, but occasionally it takes getting in someone’s face to get them to do the right thing when they might otherwise try to avoid it. It’s not like it’s just slightly off the expected numbers.

That’s not going to correct itself to the appropriate compression values with more mileage. It’s just not. They might be wishing or hoping otherwise, but someone with as much experience as that has to know better in their heart.
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Have you managed to get a second, or even third opinion on the actual compression numbers? I'd be wanting to double, and triple check the numbers you have reflect reality. Not too hard to make up an adaptor to a 1/8NPT thread using an old sparkplug with the ceramic removed. Then use a common 150psi sensor, and look at the raw voltage output on the scope, convert it back into pressure. I've not used one of the compression testers that seem to have flooded the market, but I'd certainly double check its numbers.

 

my offer to send the latest RCT version only used a time or two since new still stands.

I also have the old computerized RcT tester as well that spits out full rotation pressure trace graphs. The newer testers are cheap and make wise the simple, but the devil is in the details and they fall short in that regard. The full trace graphs can often reveal a lot about what’s going on internally.

Funny enough, this is right out of the manual for it:



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^ I have the same tester, bought it more than 10 years ago, did they make an updated version?

 

nope, they just quit the business
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For some reason I never did get notifications that people had replied to this post so apologies for the late response. I ended up getting my own RCT (finally back in stock a few weeks ago). I haven't had much time to drive the FD due to family and travel for work. My numbers didn't get much better.

Front: 69 74 73
Rear: 67 64 65

These are warm and "corrected" with RCT. @TeamRX8 , if you think the computerized tester you have will give me more insight, I'll happily test it. But if it tells me the same thing, I'm not sure my options are any different other than to pitch a fit with Bryan at Rotorsports and demand he make it right and that I won't pay $1200 again for the labor to pull and put the motor back. At the same time, he can tell me to pound sand. I really don't want to get into a pissing match with Bryan ... and I'm usually one who has ZERO issues getting into it with vendors when I need to. He's always been helpful to when I called. I think he genuinely takes pride in his work and has been doing this long before tools were available. The car continue to starts cold no problem. When hot it takes a little longer but with the new starter, its not like it struggles to the point where I think it won't start. But I do feel like I always worry when the other "shoe is going to drop". I'm also at a point where I'm done putting money into the car. Do I think it's street worthy, yes. Do I think it's track worthy? No.

 

Hang in there, buddy. You're fighting the good fight.

 

Personally, I think you should sell everything and buy the new GT3RS.

 

I was only intending to send another RTC unit just as a double-check. The computerized one requires a Windoze7 configuration and is complicated to setup with all the necessary support files and downloads. It won’t be feasible to send it imo.

regardless of their reputation, the results speak for themselves. Unless they can pinpoint something you did wrong or recommendation you didn’t do then it’s entirely on them and their reputation. There’s no way that’s getting better to an acceptable level. It’s simply either delusional or dishonest to claim otherwise.
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