Quote:
Nice work. Shame about the bottom end problem but at least that's sorted now.
You're using a different sump than standard...just wondering, 5000rpm, obviously accelerating fairly hard, what looks like a loss of oil supply....
Where is the pick up in that sump and was it well baffled? Also, did you check the clearance between the pickup and the bottom of the sump?
Just thinking out loud...you don't want it happening again. Or did you find the cause?
Thanks for the comments.
I have had the same feedback from 4 different sources now referring to loss of oil supply. SBD quoted this straight away and indicated you get it on conrod number 1 1st which is where I had my failure. (By the way I have to say the help I got from SBD was exceptional, they were more than happy to discuss problems and clearly have a vast experience to draw upon - very professional) So my initial approach has been to ensure the oil system is functioning correctly by doing the following
1. New oil pump
2. New oil filter
3. Clean out sump, block and head - sump was full of shades of bearing!
4. Clean out pick up pipe, again full of shades of bearing. Don't belive it actually became blocked though.
5. Fit oil pressure gauge
6. Fit oil temp gauge with sensor in sump plug
7. Check clearance of pick up pipe to sump bottom. It had about 12mm which I have increase to 20mm. Also checked for any pin hole leaks in the pick up pipe as it was modified to suit the front bowl sump - it's sound, no holes found.
8. Refit crank and conrods, new ARP bolts (these did not fail), torque bolts as per spec with calibrated torque wrench.
With all this done the oil system appears to be functioning fine, 5 bar cold, 4 bar hot 2-3 bar hot idle. Operating temperature seems to be around 50 degree C.
Also water temperature seems fine with the needle on the sprint temp gauge reading between 1/2 - 3/4 without the need for the kenlowe to kick in. Opening temp of thermostat is 92 degree C for the redtop whilst the Sprint opens at 82 degree C. I have read that the redtop happily sits at 100 degree water temp so my gauge reading between 1/2 - 3/4 seems fine.
With the above in mind I am still concious that a root cause hasn't been established. So your note has prompted me to capture possible causes below. First here are the symptoms as I recall them.
1. Bang heard at highish rpm (between 4-5000 rpm) but not under significant load. Suspect this was the initial bearing failure when it first spun.
2. 30 seconds later at around 3000 rpm knock heard from block
3. When engine next went to idle, oil light switch came on and would only go out above around 1500 rpm.
4. Engine shut down.
5. Inspection of conrod bearing clearly indicates loss of oil wedge to spin it. But only on number 1.
Possible causes
1. Oil pump failure - inspected this and it seemed fine. Replaced with new.
2. Oil filter blocked - possibility but I will never know, i clearly had oil pressure when the initial failure occurred as the oil light only came on afterwards
3. Oil relief valve stuck open - unlikely as I would have seen low oil pressure before the bang.
4. Incorrect torque setting of ARP conrod bolts - unlikely, I was maticulous on the original engine rebuild and when I dismantled the bottom end I used a torque wrench to estimate the breaking torque of the bolts and they were all the same.
5. Loss of oil wedge on bearing - this obviously happened but why?
So my thoughts now are moving away from the oil system being the root cause.
Other area of interest -
ignition timing.
I am running MEGAJOLT mappable ignition with a conservative initial map.
Following the recent rebuild I believe I am getting
pinking at rpm's above 4500rpm. It's difficult to determine with the induction noise present as well but there is something there that doesn't seem right. I also haven't been above 4500 rpm much. Power and torque from idle to 4500 is very impressive though.
The engine itself has high compression pistons with deeper valve cut outs, 276 degree sports cams. So I have done a compression test and got 230 psi on each cylinder. Obviously high, so I compared with my track BMW M635csi which runs at 220 psi so given gauge inaccuracies it's pretty close to the BMW engine and not wildly excessive.
I don't know much about pinking but given it will stress the conrod and bearing it's got to be considered as a possible cause of oil wedge depletion and hence the failure.
I can't think of any other root cause that I haven't already taken action on.
So next thing to do is to feed the motor with some super dooper high octane juice and retard the iginition above 4500 rpm to see if I can eradicate it and then progressively increase iginition advance to get the power back. I am tempted to start off at a low 10-15 degree setting above 4500 to be on the safe side. Timing at idle has been confirmed at 10 degree as per the MEGAJOLT requirement.
Thoughts welcomed on all the above.
Thanks
Ian