13.65 psi, 11.7 AFR, bye bye front rotor
06-11-2006, 09:04 PM
#1
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Join Date: Nov 2002
Posts: 3,108
Well was in 3rd gear between turn 7 and 8 at shannonville motorsports park, 6400 rpms aprox. Chasing down a black M roadtster, 100% throttle, Huge stutter, lift gas pedal. No power. AFR was around 11.7, New plugs, two crane Hi-6 Ignition boxes, two LX92 coils, new plug wires.
History:
Dyno'd the car at 231 rear wheel horsepower,
AFR was in the high 10s, low 11s
hit 11 psi on the dyno.
Noticed: Car was hesitating/sugring/flat spots on the dyno as she made her runs, took some fuel out, it got better, not as pronounced. I thought it was a flakey FCD and I was hitting fuel cut. I checked the FCD later and found it clamped at 8 psi voltage exactly. Didn't think much of it.
Took the car to the 1st time trial race of the season. Air temp was cold... started to boost high all the time. The surging/flat spots came back big time. I would lift to 3/4 throttle from 100% thorttle whenever I felt that surge and I was able to drive through it. Kept on doing that all saturday. Same thing happned at warm up laps today, did about 1 hour of practice laps. Noticed it was hesitating not surging now. Took a gander at the AFR gauge whe I was running max boost 13.65 at 6500 rpms in 3rd, the AFR was between 11.5 to 11.7. Thought all was ok
Then the motor went a couple of laps later.
Pulled the plug from each rotor and listened. No comression on front. I thought the rear blew because Fuel cut due to over boost would normally cut the fuel to the rear rotor no?
The car still idled at 500 to 600 rpm with --54 mmHG vac or basically no vac at all. I managed to limp the car about 60 kms on the free way doing 60 mph before it wouldn't hold 60 moh and I had to get towed home. The car would buck/hestiate at around 4000 to 4500 rpm, and again at 6000 at anything more than 3/4 throttle. AFR would jump to 18 to 20 AFR during this buck when it was running on one rotor.
What caused the motor to fail? was it too much timing on the stock ECU for 13.5 psi? Too lean? Electronics problem with the TPS/ECU/other sensors?
Motor had 132,000 miles on it.
MOds related to engine:
2X Crane Hi-6
2X Crane Lx92 coils
680cc secondaries
Apex-i SAFC
Aprx-i AVCR
Paul Stokes DIY FCD
History:
Dyno'd the car at 231 rear wheel horsepower,
AFR was in the high 10s, low 11s
hit 11 psi on the dyno.
Noticed: Car was hesitating/sugring/flat spots on the dyno as she made her runs, took some fuel out, it got better, not as pronounced. I thought it was a flakey FCD and I was hitting fuel cut. I checked the FCD later and found it clamped at 8 psi voltage exactly. Didn't think much of it.
Took the car to the 1st time trial race of the season. Air temp was cold... started to boost high all the time. The surging/flat spots came back big time. I would lift to 3/4 throttle from 100% thorttle whenever I felt that surge and I was able to drive through it. Kept on doing that all saturday. Same thing happned at warm up laps today, did about 1 hour of practice laps. Noticed it was hesitating not surging now. Took a gander at the AFR gauge whe I was running max boost 13.65 at 6500 rpms in 3rd, the AFR was between 11.5 to 11.7. Thought all was ok
Then the motor went a couple of laps later.
Pulled the plug from each rotor and listened. No comression on front. I thought the rear blew because Fuel cut due to over boost would normally cut the fuel to the rear rotor no?
The car still idled at 500 to 600 rpm with --54 mmHG vac or basically no vac at all. I managed to limp the car about 60 kms on the free way doing 60 mph before it wouldn't hold 60 moh and I had to get towed home. The car would buck/hestiate at around 4000 to 4500 rpm, and again at 6000 at anything more than 3/4 throttle. AFR would jump to 18 to 20 AFR during this buck when it was running on one rotor.
What caused the motor to fail? was it too much timing on the stock ECU for 13.5 psi? Too lean? Electronics problem with the TPS/ECU/other sensors?
Motor had 132,000 miles on it.
MOds related to engine:
2X Crane Hi-6
2X Crane Lx92 coils
680cc secondaries
Apex-i SAFC
Aprx-i AVCR
Paul Stokes DIY FCD
06-11-2006, 09:44 PM
#2
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Join Date: May 2005
Posts: 959
Sorry to hear that man... are you running NASA events, jw?
Either way, I would blame the stock ECU.. I wouldn't think it could handle 13.5 as far as timing goes... the crane units only provide a more powerful spark correct? They don't do much for adjustment of timing, which is what you would probably have needed at 12+ psi at over 6K RPM..... sounds like it's time for a standalone on your next motor....
I think you had enough fuel... the larger secondaries w/ the s-afc should have been enough.. i would really lean towards ignition timing...
Either way, I would blame the stock ECU.. I wouldn't think it could handle 13.5 as far as timing goes... the crane units only provide a more powerful spark correct? They don't do much for adjustment of timing, which is what you would probably have needed at 12+ psi at over 6K RPM..... sounds like it's time for a standalone on your next motor....
I think you had enough fuel... the larger secondaries w/ the s-afc should have been enough.. i would really lean towards ignition timing...
06-11-2006, 11:11 PM
#5
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Join Date: Nov 2002
Posts: 3,108
Originally Posted by RONIN FC' post='823652' date='Jun 11 2006, 11:17 PM
132000 and 13psi, im not surprised you broke a seal. Not to mention the stock ecu thinks your running 8psi.
Did you dial back the CAS/timing any?
That would be a big N O.
=(
I hate to admit this, but for 5 years I've owned the car I've been running stock boost. I thought I could squeeze some more juice from the engine by adding a Cone filter and 3" aluminum bent pipe for TID. I got too greedy with not enough time to play around with the car before the 1st event. I'm going to admit that I'm a pretty newb when it comes to engine and power stuff. I only really understand suspension, brakes and tires.
And yes I do run a form of NASA event, but with the CASC (which is the equivalanet of SCCA for Canadians). The timed competitions are called Solo1 racing. 6 cars equally spaced trying to set the fastest time in your class.
06-12-2006, 06:57 AM
#7
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Join Date: Nov 2002
Posts: 3,108
Originally Posted by kahren' post='823661' date='Jun 12 2006, 12:57 AM
is there a front mount? or are using a stock ic?
Stock IC.
and it was the original engine and turbo that came with the car 17 years ago and 132,000 miles ago.
06-12-2006, 10:29 AM
#8
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Join Date: May 2002
Location: California
Posts: 22,465
i think you're running too much boost, which with the teeny turbo and so so ic = high intake temps; add a little lean and its boom!
keeping the motor together is a balancing act, if you keep the water and oil temps down, lean is ok. the factory setup lets temps go (as you're not gonna be on it that long, right?) and runs it rich.
keeping the motor together is a balancing act, if you keep the water and oil temps down, lean is ok. the factory setup lets temps go (as you're not gonna be on it that long, right?) and runs it rich.
06-13-2006, 08:06 PM
#9
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Join Date: Aug 2005
Location: Freeport FL
Posts: 381
Yea this motor was not built with the supporting mods. Your probably had lower compression over boosting the stock turbo and way over heating the capability’s of the TMIC without proper tuning setup.
The stock ignition is good for 500whp upgrading it is wasted effort.
Try it again just be more intuit to your tuning equipment and supporting mods. go fast and cutting corners will always yield a popped motor.
The stock ignition is good for 500whp upgrading it is wasted effort.
Try it again just be more intuit to your tuning equipment and supporting mods. go fast and cutting corners will always yield a popped motor.
06-14-2006, 12:56 AM
#10
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Join Date: Oct 2003
Location: WA, Renton
Posts: 714
yeah id say it wasnt that big of suprize it let go, especiall running that high of boost on the stock IC, being on the track your running it hard for extened periods intake temps can get real high on that lil IC... not to mention at 132K miles being close to 20 yrs old its no wonder it let go.... it was prolly close to its time to go anyway.