When things go wrong at 9000rpm

[BlackDC2]

This is the 3rd motor i have heard of in the last two months that has let go because of incorrectly stretched rod bolts.

Makes me think how important specs are on Honda engines

Do you believe it is incorrect build practices or poor performance/engineering in aftermarket parts for the failures you have witnessed?


I will not take offense in your response as I am the builder of this engine

[felixR]

wow.. i would cry if that happened to me!

all the best with it Jase!

[kavehman]

Do you believe it is incorrect build practices or poor performance/engineering in aftermarket parts for the failures you have witnessed?


I will not take offense in your response as I am the builder of this engine

I personally would think it is incorrect build practice, I myself am not an engine builder never have built an engine and have never cracked open a block. So experience wise I am no expert.

I really would think that incorrect build practice is a high possibility here, from what I have read from other engine builders correct bolt stretch is extremely important.

Reza on honda-tech had a motor that did the exact same thing, he used stock bolts.

http://www.honda-tech.com/zerothread?id=2119505

http://www.honda-tech.com/zerothread?id=2122519

Somewhere in those two threads is a link on correct stretch procedures.

So my question to you is did you use the special calibration tool when building this engine ?

I mean this forum is for learning isn't it ? so lets try and figure this one out.

[tinkerbell]

my guess is that any incorrect assembly practices would have already taken their toll, i.e. in the first 1000km of hard driving, not 49'000km later...

and FYI - since we are all learning...

i installed ARP rod bolts on my B20VTEC, and it is not really rocket science to do the "correct installation proceedure"

apply moly lube on non threaded surfaces
torque to 40 ft lbs
break loose
torque to 40 ft lbs again
break them loose again
torque to 40 ft lbs for the final time

http://www.arp-bolts.com/Tech/T1_Ins...etention3.html

do you think i should pull my engine appart at 50'000km and recheck the torque to prevent a rod letting go?

just because i didnt use a stretch gauge?

[DLO01]

Yowzers!

Thanks for sharing though.

Good luck for future build.

[kavehman]

do you think i should pull my engine appart at 50'000km and recheck the torque to prevent a rod letting go?

just because i didnt use a stretch gauge?

Couldn't hurt, could it.

I mean I guess that would be the ultimate test of if a stretch gauge needs to be used or not. If after 50,000K its still the same then I guess a stretch gauge is not needed.

Like I said I'm no expert on the matter, just found it coincidental that someone else went through the same thing.

I mean overtightening and undertightening could lead to failure.

Anyways I may be wrong.

[tinkerbell]

I mean overtightening and undertightening could lead to failure.

no, over tightening or undertightening WILL lead to almost immediate failure.

doing it correctly will lead to a long life, as is the case in this situation...

[BlackDC2]

plus, may i just reiterate that since i purchased the rods, eagle have started using larger rod bolts.

maybe it was just an under engineered bolt to begin with?

[tinkerbell]

yes, they are now moving towards 3/8 bolts over the 5/16 ones too FYI...

[STOCK]

Unlucky Jase, whats the new plan?

My eagle rods came with 3/8 arp bolts, however i didnt use a rod bolt stretch gauge =/ as one was one was not available at the time of my DIY build. I followed arp's alternate recomendation of basically what tinka just pointed out.

[tinkerbell]

STOCK - i think forced induction applications are much more gentle on rod bolts than NA engines...

[STOCK]

In my application - yes i stayed with stock rev limit =)

[freakie]

Jase,

Ive got a spare vtir motor if it helps get you out of trouble mate, give us a yell if you need it.

Sorry to see, but hey, thats racing

[Page]

Ouch. I guess 50,000 race kms is pretty good??

[OZ-227]

I wouldn't retension rod bolts. Sounds like that's asking for trouble.
Replace with the better ARP bolts, yes, OK. But retensioning No Way.

Apart from that, I agree with everything else said.

Just my 2c.

If your engine is going to blow, That's the time it'll happen. When you get off the GAS. For the reasons Tinks already mentioned. But changing the way you get off throttle won't matter much. If it's gonna happen, it will.

Good luck Jase.