connecting rod problem after ignition install

[denisst99]

i installed a dynotek ARC2 on my car to replace the bosh igniters i had on my car (one was a bosh the other a HUGO,they need to be the dwell type for my SMC)
car ran fine a bit better then before

comfirmed that timing still was the same at idle, 3000rpm and 6000 rpm
did a few pulls to comfirm everthing was fine

the #2 rod broke on my way back to the shop leaving from a stop sign
i got the engine appart and the #3 is bent..
no coolant leak,no water on that day so hydrolock is out of question

could the timing be different of those 2 cylinders or did i just reach the limit of those stock rods (hyundai 2.0 engine with evo 8 turbo pushing about 18 psi)

trying to figure out what happened...

[supercharged88]

On the conrod that broke, did the rod bolts fail or did the actual conrod break.
In the cylinder with the bent rod, is the cylinder wall holed (ventillated).
Ignition timing issues NORMALLY take out head gaskets or destroy pistons not conrods.
Can you post up some photos.

[denisst99]

cylinders are fine,
headgasket shows no sign of leak
the broken rod snapped about 1cm below the wrist pin and in the middle( 3 parts now)
the bent rod still slides nicely on the wrist pin and the crank pin

in both case bearings are fine and wrist pin bushing are fine

in my mind i'd say that all 4 should show some sign of damage
but only the two middle (companion) ones leads me to think something else went bad...

[Ian]

...the #2 rod broke on my way back to the shop leaving from a stop sign...

Were you just driving away sedately or doing a Fast & the Furious launch? Can you put up a pic of the bent rod? How much power did the engine have?

[denisst99]

10 minutes before the stop sign i did a good pass 3-4 pass to get a good log (wich turned out to be safe A/F wise)

i left the stop a bit fast, but without spinning the tires so it wasn't a F&F style driving

rods must have been hit when i did the pass then failed whenever then wanted to after that..

i'll get a pic of what's left of the broken rod and the bent one (it's bent sideways in a S shape)

engine must have about 300-325whp ( i have 550cc injectors and i`m maxing them out)

[denisst99]

here`s the pic of the dammage..

http://guuzu.com/denisst99/image/5206/large.jpg

[supercharged88]

Looks as though you have exceeded the HP rating of these cast rods.

[denisst99]

their forged...
but i think the same thing
lots of low end torque found the rods weakest point..
the bent rod is still actually "straight" if you check the axis of both end
it`s just a bit offsetted ;-)

[supercharged88]

Forged rods, sorry my mistake,
They sure do look like factory type cast rods to me.

[MRMRacing]

I have bent a rod on a Volvo 850 Turbo just like your rod in the picture. It bent just under 300 hp and did make a pinging sound when it hit the engine block. Just replacing it with new and no other fault.

On the Volvo it is when you have a lot of torque on low rpms it bends, so only alowing full boost at higher rpm´s will do it for the 850.

[denisst99]

it`s the reason why i hooked up the boost controler to the smc
worked fine but i guess 18psi @ 4000 rpm was pushing the limits a bit...

[pilsner]

I did the same thing to a Mazda MX5 engine on 18PSI
http://carco.com.au/images/rod1.jpg
http://carco.com.au/images/rod3.jpg
http://carco.com.au/images/rod2.jpg


http://carco.com.au/images/rod4.jpg

Happen at about 4000 rev coming on the main straight at oran park

[denisst99]

I think that the rods were bent before the failure
And that at one time it gave once it saw a bit too
Much load

[StiWagon]

The rods do not look up to much being honest

This is a forged rod from my subaru

http://i77.photobucket.com/albums/j42/crazyep82/Image463.jpg

[witnessyy]

Made supports, sorry my error,They sure do look like manufacturer kind thrown supports to me.