Keep snapping conrods.....

[darrenjlobb]

Hey guys,

Im having real problems with my IDI build, in that, ive just smashed up my conrods for the second time....

But whats odd, is it just broke out of no where, had just fired up, was quietly driving home from being out, no boost, no engine load at all, around 2krpm, and a rod just let go, for no reason at all?

Am i right in thinking its just pure luck, and it was weakend from before, and just let go today?

The engine is rolling roaded at 213hp at the flywheels, with a big injector pump / turbo, with intercooler.... Might also we worth noting its a pretry revvy little engine, all the power is between 4-6krpm....could this be an influence?

If its just general power being to much, what can i do to stop this happening? Is there somewhere that stocks custom conrods?....anything else i can do?

Thanks....

[MJF]

1,6 or 1,9? What con rod bolts?

[R.O.R-2.0]

i think he runs a 1.9 XUD?? iirc..

[darrenjlobb]

1.9 XUD.....with HDI(dw10) conrods and stock bolts....but the bolts dont let go....

[darrenjlobb]

Cam had also snapped....in 3 places...think from pistons smashing valves home wen there open but what caused the initial snap?

All bearings were fine, except the one pictured...which is the one from the offending rods big end...?

[Mark(The Miser)UK]

So,
What's your problem? Engine looks fine to me

Seriously, what was the other half of the shell bearing like? It does looks a little overheated, but I don't see a smearing of the metal like a true seizure.
Was it possible to see the timing of the remaining piece of cam, the #1 lobe, to see if that was still related to TDC correctly? If so, then it would have been the con rod that let go first and hit the correctly timed valves which thumped the cam, rather than the slipped cam that thumped the valves into the pistons... or will we never know.
For the latter I guess it would be a crank pulley to blame. ...
Well that's my stab at it...