Bad times Bill. I'm sure the stripdown will reveal more (valve springs?), but my two-penneth is either valves or revs. There seems to be some distinction between single and triple collet Supertech valves, with one rumoured to be suffering failures (singles?). A deeper collet on a 6/7mm? valve stem doesn't leave much. I know the previous motor somehow got away with a fair rev beating, but maybe it needs solid tappets after all, just for an additional safety margin?
previous valves were tripple groove on oe collets - the valves were fine, and only a few damaged from plug ceramic, but the single loc ones are supposed to be stronger for higher revs, hence they were what I got and used, along with all new springs and retainers, as I considered the previous ones as "lifed" for my use.. Its when I spend a lot of on renewing things to life them, to find the new replacements fail, which REALLY pi55es me off - Big time the revs I used up to now on this motor are not unreasonable at all.. revs are not the issue, nor hydro top end.. you say safety, but relative to what? and ensured by how?? there is no "safety" - theres luck, bad and worse..
By safety, I mean gut feel. ~9k to me is a lot on hydros - but then again I know they're small hydros. <shrugs due to inconclusiveness> IMO, a few reference points are needed. I personally would want to find out what the Irishman put in Snoeck's 20v N/A 1600. If that came back as solid lifters - I suspect it does - then I'd be personally erring in that direction for peace of mind. On the valves, if the head is off and the collet intact, I'd say hydro. If the top is snapped off (and the head), possibly questions in Supertech's direction also.
I will see tonight which part failed and where. mid to high 7krpms is all its seen.. the DTA's histogram of usage shows less than a total 2 seconds over 8000rpm in its 20 hours life - thats not a hard life. My previous head went for 4 years and a lot of sat on its 8200rpm limiter without any such problems from its tripple groove valves Ferrea dont offer single groove I notice. Only heard of Supertech single groove valves failing, when matched to OE springs/retainers, which was their "wriggle" on it being their fault.. No where to hide on this build as its all new, all supertech supplied parts. I hear you on solid lifter, but that means different cams to me also... and I just dont have the budget for all this right now... Seriously bad timing, when I am commited to buy a rolling road this month. I could cry and kill someone at the same time presently
That combination of single collet / OE retainer issues matches near enough to what I'd heard, so perhaps that suspicion can be crossed off, subject to strip down. Snoeck's collet groove count also would be a nice to have. After that, it's springs, and lift, but I assume turbo lifts aren't at any risk of being coilbound (though I've no idea what cams you're running).
Really glad i actually made it to the track to see you race, sorry to hear the news tho mister - fingers crossed its not too many 's
Well the heads off.. and its not supertech valve problem.. but build problem/cam timing/valve float perhaps centre valve on #3 has lost its head (later found wedged in the port on inlet cyl#4 all 4 cylinders on centre valve show imprint marks on piston crown, so there has been a clearance issue.. the engine is the original Elton built one from 2005, just reworked to recover the damage incurred from the denso plugs from last Junes head lift, gasket failure.. little did I expect there must have been near to no clearance on the valve to piston.. such that the thinner head gasket I now run for the 83mm bore, 0.4mm thinner was all the clearance I could have had! bad news since these cams were fitted back in 2006. i had skimmed the pistons 0.4mm off their crown and 0.3mm out of their bowl, but not touched the relief cut for centre valve, as I never imagined they were close.. pockets are just over 2mm deep, and cam spec on lift at tdc is only 0.3mm, but visually, thats just not the case from the impacts. all centre valves have been pinging off the piston crowns. Amazing they lasted that long. (2 corners more would have been nice of course - lol) so.. new motor it is.. nothing to recover from this one, aside from the new bushed rods perhaps, but for the new motor I already have 83mm pistons, rifle drilled rods, and now need to get a largeport head and some new valves to replace the centre's on all of them.. the rest I hope will be ok. not sure I am going to make the next race meeting, but never say never I guess.
Well, really positive in the sense you know what the cause is. Nothing worse than wondering if it's this, or that etc etc. The head and block being scrap seems sadly unavoidable when valves go west [:^(] I'm amazed at the valve to piston clearance being so tight in the first place - I'd assumed a low compression motor would have a bit more leeway by definition So there was enough static room, but the valves are somehow hitting. Could it be touching off TDC?
its either timing related vs tdc.. and or combined with some float which may or may not have been a factor... I dunno how you could distinguish.. With supertech springs being used, I would hope there is no float. original build tolerances I dont know.. I did'nt build it, but it did'nt run these cams in 2005. they were added during 2006 along with the then newly available supertech springs.. (which I still have in a box) this new head is all new valvetrain, but same cams.. same bottom end, same pistons (skimmed) BUt different 83mm head gasket which is 0.4mm thinner than the std 1.8t one just as well I had'nt got round yet to trying vvt tricks and playing about with cam timing.... seems there was zero margin in there. new motor build, finally comes to have to be. I will class the 2005 one officially retired now - lol
What was the highest rpm registered during the 2 second peak phase? Just enough to clip the pistons on float, who knows? Is there the slightest possibilty of the valve ramping onto/off the piston, approaching/leaving TDC? Just enough for the small skim to create interference? Or is the piston well away by then?
high 7's chris.. like i said, revs were not the issue here either way, 0.4mm thinner head gasket was sufficient to cause interferance.. and indicates to me the motor has always been marginal (way too marginal) on clearance. i have;nt adjusted cams or swung them on a vernier yet, but was going to when i get my RR, so i can dial it all in better.. also vvt not yet employed which is something i will run.. but it would never have had sufficient clearances i dont think, seeing whats happened here. a full dry buld of th new motor is guaranteed... i aint going thru this **** again
while looking on the castle combe forum i found this great pic of you bill finding the limits i think!!!