TWIFOSP

I'm trying to get some opinions on my scenario.

What this is: Me trying to get some outside speculation on why my motor went. I know we can't tell until we tear it apart, I just want opinions.

What this is not: Me trying to point the finger at the shop or anyone involved. It's just a car, the motor let go on a rotary... big shock eh?

A local shop was performing a single turbo install for me. I'm not going to say who just yet, but they have a great reputation for rotaries. These guys are definetly not strangers to rotaries. They have built some awesome rx7's in the past as well.

Gt35/40 and pretty much all the other upgrades to support it.
2x1600 injectors, greddy smic, fuel pump (already installed), pulleys, clutch, power fc (already installed) is pretty much the support mod list.

Some background information on my car:

Miles on chassis: ~56k
Motor and turbos replaced 9k miles ago at 47k.
Compression check on motor before install read front 110,110,110, rear 110,110,105

I decided to go single turbo when my twins started to let go and I decided I didn't want them anymore.

Today began the tuning process.

During the baseline run, the motor let go.

The situation as explained to me:

This baseline pull was to establish the boost controller and wasn't even to baseline maps.

During the baseline run the motor let go during a 4th gear partial throttle (~30%) pull. During the pull there was a sudden loss of power and vacuum. Apparently no detonation was heard.

The max boost on the profecB read 1.02k so around 14 psi. Which is something I don't get, 14 psi at 30% throttle at the begining of the run? The af reading at this time was "a little above 12". I'm no tuning expert, but that is way too lean for a properly tuned car let alone a baseline map. They didn't have a log, but they said that the knock never went above 50.

That's pretty much the first set of details as this just happened a couple hours ago.

The initial assumption by the tuner is that since there was no detonation heard, that he suspects carbon build up letting go and dislodging an apex seal. I'm a fair person, I can of course accept this if it is the case, but naturually, I might be a tad skeptical.

My engine only had 8-9k miles on it and I use MMO in almost every tank. It was also driven and started at least 4-5 times a week. Not exactly the most ideal situation for carbon build up I'm assuming. But hey, I don't know...

So... thanks for reading this... any opinions or thoughts will be appreciated. Like I said, I don't expect anyone to know why my engine failed. Nor do I wish to point blame at anyone and start some huge dispute. I just want some opinions of this forum who are obviously no strangers to engine's blowing. If my engine went, it went. What can one do, eh?

Thanks!

rotary-tt

Is it just me or does it seem that dyno'ing an FD is pretty risky? What steps can be done to mitigate the risk? Sounds like his car was setup right. Maybe it's a heat build-up issue. What was the airflow (cfm) from the fans through the rad and oil coolers?

TWIFOSP

It was during like, THE first run. I don't think heat was a factor.

It was done on a mustang dyno with a massive fan simulating wind. These dynos are supposedly good for simulating real world driving conditions? Dunno.

BigIslandSevens

iTrader: (4)

I think shooting for 14 psi for the first run to dial in the BC is a bit foolish. Espeacially if there is not enough fuel present to help the combustion process. I hesitate to blame the engine.( i know you aren't trying to blame) But the tuning sounds questionable, I would want a knock sensor/reading for dyno tuning for sure. And the dyno is where alot of rotaries blow up, detonation is a common culprit. That sucks man, I feel for you!!

2manytickets

I did 26 pulls on the dyno with mine during tuning from 4th gear all the way to redline and never had an issue, we started at 10psi

SleepR1

I'm guessing the shop is Rotary Performance of Garland TX. They are an authorized Apexi Power FC/FC Data Logit tuner. I agree that they probably know what's up.

I'm very sorry to read about the mishap. It is strange to get 14.5 psi (1.02 kg/cm^2) with 30% throttle? I can't imagine the single turbo would even be spooled up yet with only 30% throttle?

The GT35/40 is a ball-bearing turbo, I suppose, but hard to imagine it could make 14.5 psi THAT quickly!!??

pomanferrari

iTrader: (1)

4th gear pull at 30% throttle under load ... 14 psi. THat's awfully high psi at 4th gear and 30% throttle. I would think a baseline pull would be starting much lower and at 2nd or 3rd gear at least. The base line maps should take into account the volumetric efficiency of the engine at various ranges of rpm and throttle so that adequate fuel can be delivered w/o blowing the engine.

It sounds like someone just nailed the throttle with a load on fourth gear w/o determining how much fuel to inject. Was this done with a PFC? If so, was the proper map used as a baseline?

Mister7

Negative. Since he said a local shop, it would appear that it is a shop in Austin.
That sucks about your engine. Is the turbo at least okay or did the engine take that out along with it?

ejmack1

Isn't Austin and Garland relatively close?

TWIFOSP

I don't think they were shooting for 14 psi... they were trying to tune the boost controller.

These are apparently the last power FC entries as "remembered"

Water temp 88c
Intake temp 38c
Knock value 52
Injector duty 65%

Attatched is the comma delimited trace file of the last part of the run where the engine blew

911GT2

The fact that under 14 lbs of boost it had afr's in the high 12's and low 13s is really sketchy. I can't see how any turbo could be making 14 lbs at 30% throttle, but regardless, the afrs should have been a lot lower if it was in the boost at all.

It's not impossible, but unlikely IMO.

rpm_pwr

what plugs are you running?

It sounds like these guys were being lazy. I've never heard of a baseline that lean. I've had my motor tuned a heaps of different places but they always use the same trick - start off VERY rich and pull fuel out of it as they go. You don't start in "goodbye motor" territory and hope it hold together long enough for them to start dialling fuel back into it!

Unless you had damn cold plugs I can't see the motor surviving 1bar+ with AFR's that high! 30% throttle? Bullshit.

-pete

artguy

ok...prob number one.....you dont just throw the car on a dyno and push it to fourteen psi....you have to inch your way there....when i tuned my car on the datalogit i used maps from xs to start....they were a mess...so i deletedt them....next i did readings at low low boost...fd racer and i drove around taking readings barely hitting into boost....we made adjustments to the appropriate cels in the maps...then we went out and did it again...hitting the boost a little harder...baby steps...inching our way through it...more adjustments....we did not push into fourteen pounds til at least the fourth run ...baby steps...we could have been more patien than that as well.

you can not just put it on the dyno and run it through the gears without tuning for fuel first in the lower boost ranges. you can not trust anyone elses maps. EVER. you need to take readings...and make small adjustments...you have to be very careful. they obviously were not.

that is most likely why you lost your motor....they hurried it seems.

I am in austin...could you let me know who did this so i dont take my car there? Hopefully i wont have to. I will take the drive to gotham unless it is a minor issue.

rule number one....if you are in texas...dont let anyone tune your car when steve kan is just a short haul away. right?

how come i havent heard of this "reputable rotary shop?"


j


jason

artguy

i agree with the statement above....where it was stated that you start rich and move lean....you dont just throw it on the dyno and see where it is it in high boost....

lazy or stupid...which one are they?

how are the timing maps??? conservative? what do the timing maps look like? is there negative split?


j

TWIFOSP

ngk race

TWIFOSP

Artguy - I'm trying to remain objective here and the last thing I want to do is badmouth someone or an entire shop when all the facts aren't available.

I agree with all the points here, which is why I'm trying to get more information.

This wasn't a baseline pull evidently. It was a "car simulation" to get the boost controller locked down at 14-15 psi.

I guess my question now will be should it have been running at a 12.5% af/r at 5k rpm in first gear under 30% throttle.

artguy

i realize that....ive been through all this stuff myself...tuning is NOT rocket science now that the software is available to log it all well...including which cels are lean on the entire rpm boost map. you dont plug a boost controller in and gun it to fourteen psi.....you can see spikes happen if you are easing into the readings and boost. if they hit fourteen lbs it is because of a lead foot. feathering the throttle is possible


that is how you ease through the cels and get readings...feathering the throttle.....you dont even have to push all the way thru the rpm band to start...get readings til four thousand rpms at low boost...fix those areas....inch forward....that way you can see if you are beginning to lean out.

honestly...it sounds to me like they fukked up. had i not gone with my 3mm ianettis I would have lost my motor to a similar situation when i used those junk mail order maps that xs and srmotorsports sell. I trusted those maps and gunned it...only to get nasty detonation. thankfully those ceramics are worth every penny they cost.


j

911GT2

Thats just raising all sorts of red flags for me. Theres no way you can get 14 psi at 30% throttle. I think the shop F'd up, no matter who they are, and is trying to talk their way out of it.

And while I'm far from a tuning expert, I know enough not to start with a baseline map that has AFR's of 13! My car is currently tuned for low, very low 11's. Thats just dumb. They screwed up, they should be putting your next motor in for free and kissing your *** for not badmouthing them.

xchaos

Nope, Garland is in the Dallas area. He must be talking about a shop in the Austin area. It's not RP unless he took it to Dallas.

Pretty easy to figure out which shop if they are rotary respected in Austin. Not many to choose from...

artguy

after looking at the last half of your trace.txt file above ...i really feel like they did exactly as I figured....why did they even attempt to do a complete run...your maps are obviously a mess...your afr's were as lean as i have seen. why did they not tune the lower half of the maps first? set the boost as low as possible and inch up....no guessing.

they did not do baby steps through your tuning session.

that is not your fault.


j

books

iTrader: (8)

that data file needs to be put in a better format...if I am reading it correctly...your 1st 20 or so AFRs range from 12.0-23.1... 2 readings are in the 12s... 2 in the 13s...and the rest are 15 and up....

draw your own conclusions

It would be interesting to know your timing...please post your maps

TWIFOSP

Another thing I'm thinking of... which I can't figure out....

The last hp readings read 215. At 30% throttle at a 65% injector cycle at 5200 rpm, in 4th gear....

One of those figures is wrong. I'm sorry, at 30% throttle in 4th gear, there is no way the engine is capable of producing 215 rwhp on 14-15 psi of boost is there?

I need to figure out how to do to math to solve for an estimate HP under those conditions... one of those variables seems like it wouldn't match up.

books

iTrader: (8)

you MAY be able to correlate those the hp numbers and duty cycles using Max Cooper's fuel site

TWIFOSP

I have the datalogit file, but I don't have any software to open or read it where I am.

Can you (or someone) check it out?

edit: crap can't post .dat files... hrm...

clayne

Why would they calibrate the boost controller on a car that isn't even tuned correctly yet?

That's like taking a lap around the track trying to determine if the wheel/tire combo you chose is correct and then planning to tighten the lugnuts afterwards.