I know I’ve been talking to a few of you guys, but for those who don’t know, I’ve had a failure on cyl #2 again (same as last year) within 20-25km of start-up, during transport for some street tuning.
I’ve been talking with a few people trying to wrap my head around it, and I really don’t know what went wrong for sure. The engine was started with the same tune as last year, I set all of my timing settings to zero on the AEM to check base/CAS timing and it checked out fine on the light, then I loaded the tune back on. This is what my tuner suggested when I spoke with him originally.
I didn’t think a “bad tune” would cause failure this early, so I had kind of ruled that out at first. I’ve also had a few people check over my tune, and they said it was fine…although the tuner I paid to do it said it was dangerous. A friend of mine said that if a lot of fuel was being added to compensate for an aggressive timing and boost table, this actually makes it worse. I guess adding extra fuel gives you increased “retarded level” cylinder temperatures, and you still get the advanced timing, so you run really hot.
At this point, both engines are in pieces in the garage, and I don’t know when I’ll attempt to put them back together. It looks like I can use the head from the new engine with the re-bored block from the old engine, but I still need to get rebuild parts and deck/clean up the new head.
I think I’d like to send my injectors out to get flow tested. I don’t know if it could be the problem or not, but it’s always been cylinder #2 and #3, so having the peace of mind is almost worth it. I need to find a place for this I guess.
The damage was as follows:
- Piston #2 actually melted through the top and side
- Piston #3 cracked ring land
- Cylinder #2 aluminum build up and scoring on the wall
Compression test:
#1 - 133.5
#2 - 0.0
#3 - 91.5
#4 - 136.0
The only good thing to come out of this is the non-damaged head. The bad part is that I’ve spent way too much money on this car already this winter, and I’m hesitant to spend another pile of money with the potential to be in the same position right away. I paid a tuner to build me a tune, and it didn’t even start the car. I can’t work with him right now, as I have no engine to try another tune with.
Here are the pics.
Shots still in the car.
Head.
Pulled out.
And the money shots.
Note that after it failed, I was stranded about 10km from my house, so I decided to limp it home as is, as I knew that it was catastrophic (White smoke, no power, blown out dip stick). The piston is probably more mangled from the limp home than it was when it broke, but you get the idea.
#2
#3
These are shots from both sides of each cylinder.
#1
#2
#3
#4
“Old” Head.
