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Peek-a-boo racing block, enjoy!


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8500 is a lot! I don’t know what cam, valves, and carburetors you are running  but to get a 2 liter M10 to actually make power past 8000 rpm is a good trick. Did you have it on a dyno? I’ve seen a lot

Meh. Spackel some JB-Weld on it.    Back to the races!

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From this past weekend at Pacific Raceways.  Last race, 2 laps to go, running 3rd, fastest lap ever for this car.

Felt fine coming out of T8, a little soft coming out of T9, and destroyed up coming out of T10.

A quick glance coming out of 9 when it felt soft I had 50psi at the back of the head and below 180F water.

Fought ignition issues all weekend, but when it was on the track it was very competitive and pulling hard to 8500.

 

Somehow #3main got a little starved although the passages are clear now.  I think the other light bearing might not mean much since the motor did quite a few revs with a bent crank and block.

 

First time with the knifed crank.  Damn it felt wonderful..very free-reving motor like a sportbike:) but I was warned that knifed cranks can lead to strange bearing failures.  Anyone else?

 

About as little damage as you could hope for with a thrown rod.  The piston went up and stayed out of the way while all the drama was happening in the basement so the head and valvetrain survived.  BTW first time out with the KM rockers..no cam damage and they held their adjustment.

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Yikes ! 
 

Ignition problem could have damaged the rod bearing causing failure.  Any signs of detonation on that piston ?

 

I agree with you that the damage is fairly contained, are you going to do another knife edged crank ? 

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Lorin, good thought, but no signs of #2 detonation or running any different than the others..plugs all looked the same, carbon pattern an the piston tops identical.   Ignition issue seems to have been a bad coil (cracked maybe?) that was intermitently working great.

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Just put'n it out there, but maybe the knife edge on the crank is not allowing enough oil to splash onto the cylinder walls. That rod sure looks like it broke from being stretched, but my first thought if the piston froze it would pull the pin outta the piston, but who knows. The rod damage could be caused by the stretched rod putting enough pressure on the bearing to override the oil lubrication.

Edited by Son of Marty
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Piston was left very near TDC and 3 was at TDC so oddly enough when the head came off  everything looked pretty normal upstairs.

 

First thing I did was push the piston down the bore a bit with my fingers to see that it wasnt stuck.  Skirts and cylinder walls looked too good for any seizure IMO.   Well, the lower region of #2 cyl got beat up by shrapnel.  BTW, that pic of 2 black globs..those are the #2 rod bearings.

 

 

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I've never seen a rod fail by stretching, it's odd. I have marinetex (a fortified epoxy) up a bigger hole than that one on a v12 Allison because there were no replacements available, it lasted quite a while too, not that that has anything to do with this. 

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2 hours ago, Deilke53 said:

 

... Last race, 2 laps to go, running 3rd, fastest lap ever for this car... 

 


When I have to go, that’s how I want to go: at the top of my game! 🙌

 

Sorry to see the aftermath, but perhaps it promises successes down the road...

 

Regards,

 

Steve

 

 

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1 hour ago, tzei said:

Which rods & bolts? How does other rod bearings look like?

Those are the Chinese 144mm sintered rods from TEP, I think they might be the same ones IE sells? Used them since 2017 with no problem even despite my tendency to ignore the tach when I'm in a good battle.   Real ARP bolts purchased separately.   The other rod bearings look perfect and there is no discoloration of the other rods.  That's the mystery, as we know 3&4 are oiled from the same main so the're more likely to be the first to go.

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The failure was the rod bearing.  The bearing basically welded itself to the crank and the rotating crank tried to twist the big end of the rod,  with the piston still in the bore something had to give (the rod). 

 

I know you said there was still oil pressure when you looked but have you ever noticed oil pressure drop under hard breaking (into Turn 3a or 3b) or under long cornering to the left (Turn 2 or 8)?  The damage quite possibly could have happened at lower engine speeds and/or when you had more pressing things to pay attention to than the oil pressure gauge. 

 

What oil pan are you running?  Are you running an Accusump?   

Edited by Preyupy
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23 minutes ago, Preyupy said:

The failure was the rod bearing.  The bearing basically welded itself to the crank and the rotating crank tried to twist the big end of the rod,  with the piston still in the bore something had to give (the rod). 

 

 


I agree 100%.  

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