Another engine down the tubes...
by JoeB » Mon Nov 01, 2004 2:21 pm
Well, I figured it was a matter of time as hard as I pushed it. Those of you who know me also know I've put plenty of money into the car keeping it tuned right and monitoring it as I carefully pushed higher and higher with the boost. I can't really say when it went (what boost level) unfortunately. The problem is, the car still runs pretty strong. I took it to the track a few weeks ago and it's still running 14.2 1/4 miles consistantly. The thing that was bugging me is I KNOW it should have been in the 13s easily.
The only thing I could think of that would keep it from knocking is if the compression was lower (due to damage - rings/pistons). Well Sunday I checked the compression on the front 3 cylinders. Since the fuel delivery was weaker to the front rail and it is MUCH easier to check the front 3, I decided it would be a good indication only checking them. I checked #6 first, 190psi, looking perfect! Plug looked very good too. Moving to #4, I got 120psi. Surely I didn't have it in tight enough so I backed it out and put it back in again a little tighter, 120psi it is
. Next I moved to #2, here is the real trouble, the plug has oil all over it and it tests to 110psi. So at least 2 bad cylinders. Now I can DEFINITELY say 8psi is too much maybe/probably 7psi is too much. I think it actually happened at 7psi.
The problem is simple our $46 pistons are WAY too weak for the pressure. Knock is just an instant killer when the pressure is that high but I don't know that it even needed knock. Without building the bottom end, I would not go over 6psi. Someone else gave us a calculated maximum of 5.5psi as a theoretical max at sea level. If you read this and are curious about what to do to get it to handle more, I'll post a thread in the Forced Induction Forum. -JoeB
The only thing I could think of that would keep it from knocking is if the compression was lower (due to damage - rings/pistons). Well Sunday I checked the compression on the front 3 cylinders. Since the fuel delivery was weaker to the front rail and it is MUCH easier to check the front 3, I decided it would be a good indication only checking them. I checked #6 first, 190psi, looking perfect! Plug looked very good too. Moving to #4, I got 120psi. Surely I didn't have it in tight enough so I backed it out and put it back in again a little tighter, 120psi it is
. Next I moved to #2, here is the real trouble, the plug has oil all over it and it tests to 110psi. So at least 2 bad cylinders. Now I can DEFINITELY say 8psi is too much maybe/probably 7psi is too much. I think it actually happened at 7psi.
The problem is simple our $46 pistons are WAY too weak for the pressure. Knock is just an instant killer when the pressure is that high but I don't know that it even needed knock. Without building the bottom end, I would not go over 6psi. Someone else gave us a calculated maximum of 5.5psi as a theoretical max at sea level. If you read this and are curious about what to do to get it to handle more, I'll post a thread in the Forced Induction Forum. -JoeB
- JoeB
- SolaraGuy Street Racer
- Posts: 1166
- Joined: Wed Apr 24, 2002 6:58 pm
- Location: Myersville, MD
Sorry to hear that JoeB. I know you have a plan 
