Quote:
Originally Posted by DA VINCI
Thierry, How is this new setup going?.
I am very interested in this evolution, because I am planning to optimize my K-jetted 965 as well. I have some questions about this engine and your experiences:
Have you maintaned the dilivar head studs or you went to uprated ones?. Could you tell us a bit more about the minor leaks you had on the cylinder to head union before the 2011 set up?. From what power/torque/boost do you recommend the flame ring on a standard 3.3 engine to be fitted?
Congratulations for your methodical work, it's really inspiring for a lot of us.  |
Hello
Thank you very much for your kind words. It is my pleasure to share and to learn on this board.
I use the dilavar head studs on my engine. But these studs have been installed 3 year ago and from what I understood, this was a new generation of dilavar. ( With very old stuff, I think it is risky to increase boost & max TQ point since these parts can fail quickly and without any prior notice )
So 3 years ago, we did the complete rebuild but my mechanic thought it was not necessary to resurface the head & top of cylinder.
( We just put the new stock head gaskets ) This was a mistake ! At that time I also didn't make the flame ringing. As soon as the engine was re-assembly it made some minor leaks (even at regular 0.8b of boost & quiet driving during the break-in period ).... whatever the boost pressure , the leaks were the same. I mean I didn't get more leak with higher boost pressure (even with 1.5 !) It was never a problem to increase torque & power....just a little upset to see some minor oil leaks on a new engine but not a huge issue.
This year, while we did the new setup, we did a nice head re-surfacing + machining for flame ringing. Until now ( about 5000 km since ) it seems there is no more oil leak !
Just my 2 cents:
If you are about to rebuild your engine and add some torque& power (even low medium setup) , I recommend you to re surface your head & cylinder top and to go with flame rings. Somewhere, the flame rings itself won't prevent the oil leak. But the way to do it will ! The idea is to have a total groove height which is very lightly inferior to the ring height. Thus the contact between the ring and head is lightly compressed after torquing ( while the regular head /cylinder surfaces are perfectly in contact each other too) As you can understand, the success of this assembly rely on high accuracy re-surfacing job with a perfect ring matching & machining accuracy and a perfect torquing. Of course, new dilavar head studs is a must do.