I had my first engine mechanical failure and of all things to break, it was the timing chain that let go ....
I was running the car on the Mosport DDT track at an advanced driving school, and I was out on the last run of the day and was coming out of a 90 degree corner in second gear when the motor just up and died. Had to get towed home, which was a 3-1/2 hour trip .
Now before everyone starts panicking and figues the stock chain is crap, I'm going to explain some circumstances that happened leading up to the failure. The stock chain setup is more than adequate for the majority of folks around here.
1. When I did the cam swap last year, I checked the chain and the tensioner and while the tensioner was showing some wear, everything was well within spec.
2. I'm running a short duration cam with a lot of lift with sufficient spring pressures to run the motor to about 6200 or so. During the day yesterday my average shift rpm was around 5400 or so, with only a couple of runs out to 6000. The ramp rates on this cam are fairly aggressive, but I don't think its killer aggressive... but hey I could be wrong.
3. I was running 10% OD on the MPX blower, mainly to keep temperatures down since I couldn't run with alcohol injection, and I don't have enough capacity with the existing setup to lap for 20 minutes anyways. I also adjusted my tune to back timing off to 22 degrees at WOT. The 10% OD also saved me from wiping the car out because the track is short and had a lot of aggressive turns in it. Suffice to say, I still managed to lap quite a few cars on the track anyway .
4. Because of the FMIC I have on the car, the car never bogged down with heat issues which was a good test of it. I am pleased with the style of IC that Dave picked out for my car and yesterday was proof of it. Its not a bar-n-plate setup.
5. Pushing the car on the skid pad, I was told to stop cheating and not use the car's torque to drift through the circle and actually swerve the car hard to break out the backend and "spin" the car.... it was rather unnerving to actually force yourself to wipe out the car. The secret is to bring it back under control though, anyways. The first time I used the steering to break the car loose, 2 360's was the result and that happened so fast (I barely blinked) I was unable to get the clutch in on time and the car rolled backwards in second gear. It was a hard start but she fired up eventually and off to the races.
6. The car performed beautifully all day, even when the temps got up over 30F. Fortunately it wasn't too humid out. On some of the straighter sections I was able to get the car to about 100mph or so before I had to slow to corner.
The result is, I need to pull the front and top of the motor apart because no doubt I have bent valves and I will need to check for bent rods and so on.
Now, I'm throwing this out there because I am curious as to what your thoughts are in this situation ie, what caused the failure and what can be done to prevent a failure like this again other than not driving the car on a road course which is NOT an option for me .
A timing chain failure is rare, and I'm not exactly considered a hi-powered car since I only have an MPX. I also am maticulous with maintenance and checking the car out and monitoring how it is running etc so neglect is not an issue here.
Fraser
I was running the car on the Mosport DDT track at an advanced driving school, and I was out on the last run of the day and was coming out of a 90 degree corner in second gear when the motor just up and died. Had to get towed home, which was a 3-1/2 hour trip .
Now before everyone starts panicking and figues the stock chain is crap, I'm going to explain some circumstances that happened leading up to the failure. The stock chain setup is more than adequate for the majority of folks around here.
1. When I did the cam swap last year, I checked the chain and the tensioner and while the tensioner was showing some wear, everything was well within spec.
2. I'm running a short duration cam with a lot of lift with sufficient spring pressures to run the motor to about 6200 or so. During the day yesterday my average shift rpm was around 5400 or so, with only a couple of runs out to 6000. The ramp rates on this cam are fairly aggressive, but I don't think its killer aggressive... but hey I could be wrong.
3. I was running 10% OD on the MPX blower, mainly to keep temperatures down since I couldn't run with alcohol injection, and I don't have enough capacity with the existing setup to lap for 20 minutes anyways. I also adjusted my tune to back timing off to 22 degrees at WOT. The 10% OD also saved me from wiping the car out because the track is short and had a lot of aggressive turns in it. Suffice to say, I still managed to lap quite a few cars on the track anyway .
4. Because of the FMIC I have on the car, the car never bogged down with heat issues which was a good test of it. I am pleased with the style of IC that Dave picked out for my car and yesterday was proof of it. Its not a bar-n-plate setup.
5. Pushing the car on the skid pad, I was told to stop cheating and not use the car's torque to drift through the circle and actually swerve the car hard to break out the backend and "spin" the car.... it was rather unnerving to actually force yourself to wipe out the car. The secret is to bring it back under control though, anyways. The first time I used the steering to break the car loose, 2 360's was the result and that happened so fast (I barely blinked) I was unable to get the clutch in on time and the car rolled backwards in second gear. It was a hard start but she fired up eventually and off to the races.
6. The car performed beautifully all day, even when the temps got up over 30F. Fortunately it wasn't too humid out. On some of the straighter sections I was able to get the car to about 100mph or so before I had to slow to corner.
The result is, I need to pull the front and top of the motor apart because no doubt I have bent valves and I will need to check for bent rods and so on.
Now, I'm throwing this out there because I am curious as to what your thoughts are in this situation ie, what caused the failure and what can be done to prevent a failure like this again other than not driving the car on a road course which is NOT an option for me .
A timing chain failure is rare, and I'm not exactly considered a hi-powered car since I only have an MPX. I also am maticulous with maintenance and checking the car out and monitoring how it is running etc so neglect is not an issue here.
Fraser