Engine teardown - 300+ hp with highish miles
03-10-2013, 08:39 PM
#1
Engine teardown - 300+ hp with highish miles
Just pulled apart my old engine that I just replaced .
Why i pulled it out :
*was hardish to start and was running low vacuum at idle
*Every now and then under boost I would hear this knocking sound . After hearing this - it would cease running on one rotor altogether and run like **** . I would let it cool down and then restart it and it would run fine again. We dubbed it the "healermotor" because of this weird behaviour .
Conditions of use :
*Had 60,000 kms of hard running with an upgraded Greddy turbo at 11 psi of boost 320whp peak power and around 260lb/ft torque.
*Ran on 5w40 synth oil changed every 8000kms or sooner
*Set OMP to 1/2 normal useage
*Ran Castrol 2T premix at the rate of 250-300mls every 50Litres (200:1 minimum)
A little bit about the engine :
*This was a rebuilt engine with mostly second hand parts used .
*We installed Esmeril apex seals - which are softer than stock . They seem to be unscathed.
*We did some mild porting of the exhaust ports and a bit of a cleanup of the runners.
Pics and failure analysis to come ...........
Why i pulled it out :
*was hardish to start and was running low vacuum at idle
*Every now and then under boost I would hear this knocking sound . After hearing this - it would cease running on one rotor altogether and run like **** . I would let it cool down and then restart it and it would run fine again. We dubbed it the "healermotor" because of this weird behaviour .
Conditions of use :
*Had 60,000 kms of hard running with an upgraded Greddy turbo at 11 psi of boost 320whp peak power and around 260lb/ft torque.
*Ran on 5w40 synth oil changed every 8000kms or sooner
*Set OMP to 1/2 normal useage
*Ran Castrol 2T premix at the rate of 250-300mls every 50Litres (200:1 minimum)
A little bit about the engine :
*This was a rebuilt engine with mostly second hand parts used .
*We installed Esmeril apex seals - which are softer than stock . They seem to be unscathed.
*We did some mild porting of the exhaust ports and a bit of a cleanup of the runners.
Pics and failure analysis to come ...........
Last edited by Brettus; 03-10-2013 at 10:07 PM.
03-10-2013, 08:49 PM
#3
Front iron - note gouge at side of exhaust port . This was by far the worst damage - 1mm deep at it's deepest point.
Rear iron- same gouge , not quite as bad
Centre Iron - same gouge , just started to form .
Front Bearing - down to copper in one spot
Rear bearing - even worse.
Rear iron- same gouge , not quite as bad
Centre Iron - same gouge , just started to form .
Front Bearing - down to copper in one spot
Rear bearing - even worse.
Last edited by Brettus; 03-10-2013 at 10:03 PM.
03-10-2013, 09:46 PM
#6
Failure and wear points and points of interest:
*No signs of any overheating
*Cracks around sparkplug holes
*small grooves around circumference of housings in centre
*Wear at point where split apex runs
*Gouges in all but one exhaust port (rear centre) as shown
*Chaffing of irons where housings have been moving during compression cycle
*Front and rear bearing wear
*Esmeril Apex seals seem unscathed apart from some wear on the side where it slides on the rotor.
Main failure mode is the gouging of the exhaust ports . This could have been the knocking noise I was hearing as the corner seals were knocking in and out of the gouge.
I think I know why the gouges happened but would welcome any theories .
*No signs of any overheating
*Cracks around sparkplug holes
*small grooves around circumference of housings in centre
*Wear at point where split apex runs
*Gouges in all but one exhaust port (rear centre) as shown
*Chaffing of irons where housings have been moving during compression cycle
*Front and rear bearing wear
*Esmeril Apex seals seem unscathed apart from some wear on the side where it slides on the rotor.
Main failure mode is the gouging of the exhaust ports . This could have been the knocking noise I was hearing as the corner seals were knocking in and out of the gouge.
I think I know why the gouges happened but would welcome any theories .
Last edited by Brettus; 03-10-2013 at 11:28 PM.
03-10-2013, 09:55 PM
#7
My first guess was apex corner piece, but it's a common mode failure on all the housings. Dunno how it was ported, but maybe the side seal was dropping in the port. Eventually it shattered and was carried around in the grove gouging the housing the whole way. Your right this one is interesting!
I'd like to hear some more educated guesses.
I'd like to hear some more educated guesses.
03-10-2013, 10:13 PM
#9
Here is my theory :
There was minor port work done on the two outer exhaust ports and both of these are badly worn . There was no porting done on the centre exhaust port . One centre port is damaged but not anywhere near as bad as the outers. The other is unscathed.
I think the slight reduction in land width (on the outer ports) at the point the corner seal is over the port had a huge influence on the occurrence of this damage .
There was minor port work done on the two outer exhaust ports and both of these are badly worn . There was no porting done on the centre exhaust port . One centre port is damaged but not anywhere near as bad as the outers. The other is unscathed.
I think the slight reduction in land width (on the outer ports) at the point the corner seal is over the port had a huge influence on the occurrence of this damage .
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rob babicki (06-17-2021)
03-10-2013, 10:31 PM
#13
The fact that the ported ports fared far worse than the unported , points more towards the land size being the issue to me . That and perhaps the increased loading from higher combustion pressures.
03-10-2013, 10:34 PM
#14
Unless your seeing a different eye pattern I don't see how a corner seal could have cause it. Corner seals always follow the outside of the housing they never cross over. The eye pattern does correspond to the approximate center of the side seal though, or maybe part of the scraper ring.
03-10-2013, 10:38 PM
#15
Unless your seeing a different eye pattern I don't see how a corner seal could have cause it. Corner seals always follow the outside of the housing they never cross over. The eye pattern does correspond to the approximate center of the side seal though, or maybe part of the scraper ring.
brain fade - yes of course . I was thrown off by the way the pattern follows on from the gouges .
03-10-2013, 10:56 PM
#16
No sign of overheating around the ports - which is what Pettit were saying was the cause.....
The fact that the ported ports fared far worse than the unported , points more towards the land size being the issue to me . That and perhaps the increased loading from higher combustion pressures.
The fact that the ported ports fared far worse than the unported , points more towards the land size being the issue to me . That and perhaps the increased loading from higher combustion pressures.
that's what I was saying about porting the exhaust being a double edged sword, you can try and reduce/compensate for the flairing, but then that's more thermal loading on less material plus the issue with porting increasing side seal abuse
