We were running an LS/VTEC car at the dragstrip tonight, and I happened to mis-shift second gear one time, turned it 10,000 RPM. Finished the run, came back to the pits parked it, checked over it. Car ran fine. Went to make another run, ran a decent time. Still within our range throughout the night. Next run I made I went to second gear and took it to 4500 RPMs, and the motor lets go. #2 cylinder rod bolts fail. Parts of the block, and half of the rod come through the bottom of the block, interestingly the cylinder head wasnt damaged (We pulled the head off before the tow truck came) I am guessing that #2 cylinders valves are slightly bent, but the combustion chamber had no signs of damage.

Had anyone had this happen to them after a mis-shift? If so please explain.

 

10000RPM is normal for this motor BTW.

 

you sure about that???

 

I'm assuming that they aren't stock rod bolts, correct? and if they are, you've got your answer.

If they are aftermarket (arp probably) i can't see why a misshift to an rpm range where you normally shift to would blow up the motor.
Yes, no-load revving is bad for a motor, i know this, but if it's already built for 10K, and you misshifted to 10K, maybe somethying internally was already stressed to begin with.

 

yeah. the motor was fully built. aftermarket everything. when we looked at it. the rod bols look twisted.

 

We just finished removing the engine from the car and dissassembling the block. All of the sleeves, rods, and pistons are useless. Crank has severe rod journal damage. Pics should be up soon. I think that the 10 K mis-shift, caused the rod bolts to stretch, and after the next two runs it stretched them more and snapped them. There is lots of heat markings around the crank end of the rod from where it was running loosly (stretched) after the 10 K mis-shift

 

So play this by me again, you were at 10k, THEN mishifted? (Meaning it climbed past 10k)? It just doesn't seem like it should have stretched the rod bolt if you were shifting them at 10k already.

 

No I mis-shifted @ 8900 1st to 2nd gear and turned it to 10,000 RPM, made two more runs and the car then let go @ 4000 RPM in second gear

 

what the heck,
cant you set your fuel cuttoff for something SAFE?!!

thats what I would do if I had something like that goin on..

 

was everything torqued to the right specs?

 

what kind of rods and bolts are you using?

edit: wasn't thinking and reading correctly. reply deleted


Modified by Stock@$$GSR at 1:58 AM 4/17/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SIlent92EG &raquo;</TD></TR><TR><TD CLASS="quote">was everything torqued to the right specs?</TD></TR></TABLE>

Everything was torqued to spec.

We were using ARP rod bolts, and Eagle H-beam rods.

Engine came out today and everything is useless in the shortblock

My question is has this happened to anyone else from a mis-shift?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by v-attack &raquo;</TD></TR><TR><TD CLASS="quote">

Everything was torqued to spec.

We were using ARP rod bolts, and Eagle H-beam rods.

Engine came out today and everything is useless in the shortblock

My question is has this happened to anyone else from a mis-shift?</TD></TR></TABLE>

I dont think its your rods I run eagles to 10,500 all the time
Usally if a bolt fails there isnt any signs of heat on the rod or crank just broken parts .. Sounds like to me you had some oil starvation somewhere
I would check your oil pump Thats pretty common break oil and then destroy engine

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MAX_CFM &raquo;</TD></TR><TR><TD CLASS="quote">

I dont think its your rods I run eagles to 10,500 all the time
Usally if a bolt fails there isnt any signs of heat on the rod or crank just broken parts .. Sounds like to me you had some oil starvation somewhere
I would check your oil pump Thats pretty common break oil and then destroy engine </TD></TR></TABLE>

Hey Brad this is Robert, I came into your shop in Concord last year to have you look at my JDM ITR head with the busted combustion chamber.

The rod bolts seemed to have sheared right at the point where the cap bolts onto the rod. The bearings for that cylinder are extremely thinned, ( I am guessing from either oil starvation or when I stretched them with the mis-shift, and made two more runs with it) There really isnt anyway for the bearings to get nearly paper then in less than two more runs through the quarter mile after mis-shifting is what I am thinking. I am going to look at the oil pump tommorow and disassemble it. On one side of the rod where the it faces the crankshaft counter weight there is heat checking ( or what I would call lots of multi-colored marks in the metal)

What gets me and is probably why the head is still good is why the engine let go two runs later and at the low 4000-5000 rpm?

Pics soon hopefully.

 

EDIT here are pics, engine had less than 10K miles on it

https://honda-tech.com/zeropost?cmd=tshow&id=835634

 

SO you where at 8900 in 1st and tried to shift to 2nd, but missed the gear and it overrevved?? If that is the case, your fuel cut should have stopped the overrev because you didn't actually mechanically force an overrev from shifting to a wrong gear liek say 8900 in 3rd to 2nd instead of 4th.

 

we have the hondata setup, (not exactly sure if there is a fuel cuttof on hondata or if one was set)

 

Yes second gear was missed and the engine was revved to 10k. Made two more runs and in second gear of last run engine let go @ 4000-5000 RPM

 

So you didn't have any sort of rev-limiter on your high dollar engine? That is what it sounds like.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mikestypes &raquo;</TD></TR><TR><TD CLASS="quote">So you didn't have any sort of rev-limiter on your high dollar engine? That is what it sounds like.</TD></TR></TABLE>

nosir no limiter. that was a mistake on my part. but also, i would of set it pretty high, in the 9000 range. so even with a limiter, and mis-shift, im sure it would of put stress on it the same way.

people learn from their mistakes. ive had this motor for 10K miles. not a single problem or anything really, didnt think there was a need for rev limiter, but we all learn from out mistakes, and some mistakes are really expensive.

lesson learned.

 

Next time put a rev limit on after you hit the dyno so you can stop the rev where you shift at. Maybe it spun past 10000 but your guage tach only reads to about 10000.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mchuang &raquo;</TD></TR><TR><TD CLASS="quote">Next time put a rev limit on after you hit the dyno so you can stop the rev where you shift at. Maybe it spun past 10000 but your guage tach only reads to about 10000. </TD></TR></TABLE>
i thought about that. i was going to ask if the tach needle goes past 10000, but from what i remember, i think the needle will go past. im not 100%

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mchuang &raquo;</TD></TR><TR><TD CLASS="quote">Next time put a rev limit on after you hit the dyno so you can stop the rev where you shift at. Maybe it spun past 10000 but your guage tach only reads to about 10000. </TD></TR></TABLE>

I remember clearly it going right to 10K, but as we all know the factory tachometer is not always calibrated right to that RPM. The ITR cluster in my car is ~ 200 RPM off.