930 rebuild in progress.......I need your help and opinions on the mess inside

[Wayne 962]

Originally posted by CBRacerX
Great point Wayne, I was thinking this was localized damage to a single cam lobe (wait, isn't that what this is?). OK, I stand by my clogged spray bar theory

Did you forget about the scoring on 100% of the cylinders? How about the bearing that looks like it was run with no oil pressure?

-Wayne

[CBRacerX]

Wayne - I'm with you! I was only commenting on the rocker and cam lobe. Unfortunately for Craig, there is plently of damage to go around.

[WERK I]

Sorry, have to disagree with Wayne. The whole ugly affair started with detonation. Matters got worse with elelvated head temps, flaking con/main bearings with over the top loads, a turbo charger with oil temps approaching the surface of the sun.
I'm sure it could be the "chicken or the egg" scenario, but I think the underlying cause of the problem was detonation. Domino effect.

[Craig 930 RS]

Dave gets the prize.....

[Facey]

i dunno...i've seen a detontating engine before.... and the damage wasn't this wide spread... or extreme after such a short period..

i'm with the oil flow guys....

[WERK I]

Originally posted by Craig911
Dave gets the prize.....

Does that mean I get a free "tour" of the trackin the new beast?

[Craig 930 RS]

Sure, it should be ready by what...fall? ;-)

[RoninLB]

This happened at 6.5k in 4th after doing the 1,2,3 till 6.5k.

#5 cylinder

3.4, A/F mix was reading 12:1 at 1 bar. Injectors are 72#/hr

no sign of preignition, no cracked rings, no head damage, or damaged pistons.

It's not my engine but I'm just a bit baffled by this blown out cylinder.

Even a wild guess is ok... thx

[RoninLB]

[Craig 930 RS]

6,500? Why rev a 3.4 so damn high?
Back on track: Anything, anytime can happen with a CIS Turbo....quickly.

[DonE]

Originally posted by WERK-I
Sorry, have to disagree with Wayne. The whole ugly affair started with detonation. Matters got worse with elelvated head temps, flaking con/main bearings with over the top loads, a turbo charger with oil temps approaching the surface of the sun.
I'm sure it could be the "chicken or the egg" scenario, but I think the underlying cause of the problem was detonation. Domino effect.

I think I have to go with Wayne's explanation. With the scoring of the cylinders, spun bearing and rocker shaft discoloration, these point to oiling problems. With lack of proper oil pressure, you add heat. If everything else stays static (timing, fuel delivery, engine speed), the likelyhood of detonation climbs big time with the introduction of heat in an air cooled motor - especially in the cylinder. Just think how hot the rocker arm had to get to be burned like that.

I just logged some data today and noticed that the knock sensor picked up less noise than a couple of weeks ago. Only one thing changed - brand of gas. I've been using Citgo and Racetrac but went back to Chevron (all premiums) this last tank (I've already used about 1/2 tank). Although the Citgo/Racetrac did not cause detonation, the Chevron showed much lower noise levels at same RPM's. At least with my engine/EFI setup, there seems to be a difference.

[DonE]

Originally posted by RoninLB
This happened at 6.5k in 4th after doing the 1,2,3 till 6.5k.

#5 cylinder

3.4, A/F mix was reading 12:1 at 1 bar. Injectors are 72#/hr

no sign of preignition, no cracked rings, no head damage, or damaged pistons.

It's not my engine but I'm just a bit baffled by this blown out cylinder.

Even a wild guess is ok... thx

What boost? What cams and cam timing? There was some hellatious heat and pressure in that cylinder. It almost looks like my cylinders when I went too lean, and the engine oil was not at operating temp.

[Craig 930 RS]

Regarding this thread topic:

I tend to agree with Wayne and his oiling theory. Oil pressure per se may not have been the problem - just lack of oil at certain points. I suppose that indeed does amount to 'oil pressure'...

As far as I have been told, the oil pressure was fine with the previous owner when he owned it for a year after the first rebuild.

I suspect oil flow was compromised in one or more areas via debris, causing the scoring and burning that we see.

Perhaps the crank bearing debris caused it. All I do know at this point is that this is costing a hell of a lot of money for an engine that should have lasted a lot longer - for reasons which we may never know for certain.

Live and (maybe) learn.

[MotoSook]

Originally posted by RoninLB
This happened at 6.5k in 4th after doing the 1,2,3 till 6.5k.

#5 cylinder

3.4, A/F mix was reading 12:1 at 1 bar. Injectors are 72#/hr

no sign of preignition, no cracked rings, no head damage, or damaged pistons.

It's not my engine but I'm just a bit baffled by this blown out cylinder.

Even a wild guess is ok... thx

initial failed ring/head seal and things went to crap from there...would not have happened if the ring groove wasn't on the jug and head.

[gtu935]

Hmmm. so your saying that the initial problem was a defective nirist ring?

[Craig 930 RS]

Hijack.

[MotoSook]

Originally posted by RoninLB

The bottom cylinder in this picture supports my theory. The numbers Ronnie posted with the initial pictures would not lead me to think there was an engine "control" related cause. We've run 1.2 or 1.4 bar with 52lbs injectors...no problem...and AFR has been slightly higher (shame shame ). That's not 100% supportive, but things point toward a "mechanical" cause.

Edit: Re: Hijack- sorry Craig, but since you're ringing you jugs...it may be of interest to you.

[WERK I]

Originally posted by RoninLB

Sorry to be off topic.....
Is this a twin-plug engine?

[RoninLB]

Originally posted by Craig911
6,500? Why rev a 3.4 so damn high?
Back on track: Anything, anytime can happen with a CIS Turbo....quickly.

------- I just got more info and did some thinking.

It's Haletch EFI. The web evo. cam should allow for greater revs so to my understanding it was just a routine run.

Thanks for showing interest in my bs on your thread. [img]
[http://www.pelicanparts.com/support/smileys/wat6.gif[/img]

Originally posted by DonE
I just logged some data today and noticed that the knock sensor picked up less noise than a couple of weeks ago. Only one thing changed - brand of gas. I've been using Citgo and Racetrac but went back to Chevron (all premiums) this last tank (I've already used about 1/2 tank). Although the Citgo/Racetrac did not cause detonation, the Chevron showed much lower noise levels at same RPM's. At least with my engine/EFI setup, there seems to be a difference.

---------------- "there seems to be a difference".... my bud lives on the same block as a mostly retired 1/4mi drag pro. The guy said the gas sucks no matter what you buy. Since Katrina many big bucks drag engines have been blowing up relative to before Katrina. That's all I know.

Originally posted by DonE
What boost? What cams and cam timing? There was some hellatious heat and pressure in that cylinder. It almost looks like my cylinders when I went too lean, and the engine oil was not at operating temp.

----------- 1bar, 12:1 A/F, Web Evo. cams set to their specs.

I would think when you went lean you caused preignition from hot spots and you did ring, head, damage also? Your EGT's probably went ballistic till it blew?


So "It almost looks like my cylinders" means that you blew out a chunk then maybe the jugs heated and pushed against the head sealing groove. That psi and combustion psi may have caused a leak from a somewhat imperfect flat faced head. The Manual on p E76 allows .15mm [.0059"] surface distortion.

I looked up jug info in the P Workshop Man and only found a crude measuring technique. They only measured once at 30mm from top edge. I'm no pro but I believe there is a few thou jug expansion.. especially in the 600+ hp range. I'm still looking for more info on this.

This engine was running 12:1 A/F and it was the infamous #5 cylinder. That's the mystery.

Originally posted by Souk
initial failed ring/head seal and things went to crap from there...would not have happened if the ring groove wasn't on the jug and head.

---------- been thinking as per above but I didn't see any heat damage at all. The pistons look great. If no high heat the jug shouldn't have expanded enough to push against the head groove edge, I think ?

Then if the jugs were welded to the heads it would not have blown out the jug? I like that fix.

Originally posted by gtu935
Hmmm. so your saying that the initial problem was a defective nirist ring?

------------ What's a nirst ring?

Originally posted by Craig911
Hijack.

[QUOTE]Originally posted by Souk
The bottom cylinder in this picture supports my theory. The numbers Ronnie posted with the initial pictures would not lead me to think there was an engine "control" related cause.
---------- I'll post cyl pics below. All the other parts look great. #5 carbon must have happened after it blew, not before imo.



We've run 1.2 or 1.4 bar with 52lbs injectors...no problem...and AFR has been slightly higher (shame shame ). That's not 100% supportive, but things point toward a "mechanical" cause.
------------- A very experienced racer and wrench ran 12/1 A/F & 1bar. The only thing I can come up with besided jug expansion is high CHT distorted the sealing with the jug. AFAIK and can figure it would take only a itty bitty leak to blow the dam open. I've also read that jugs can be machined to allow for jug expansion. If not machined that way the piston clearance would expand with higher temps. I need to read more research for a better answer.

Anyway it definately seems like "mechanical" failure. But how to modify and avoid this happening again? So far I can only figure CHT instruments more accurate than the spark plug ring probe to monitor. AFAIK the more output power the higher the CHT. For example even my low hp engine gains 25-40F going from 3.5k to 4k in a steady 5th gear for a total around 275-290F. That's a relative number because I'm not sure how the spark plug ring sensor on our engines compares to a more accurate probe placement. It can vary either more or same depending on how the plug is designed to off load its heat. If I assume 400F should be max CHT and allow 25F margin to 375F then CHT becomes marginal when running a very powerful engine [600+hp] at 90% output. Grady did some exotic CHT installs and gave info on one of his threads here.

Let's say CHTs were installed and they showed 400+F CHT. Then the best and safest answer is to lower hp output or install better CHT & jug cooling?

Edit: Re: Hijack- sorry Craig, but since you're ringing you jugs...it may be of interest to you.

--------------




[QUOTE]Originally posted by WERK-I
Sorry to be off topic.....
Is this a twin-plug engine? [/QUOTE[img]
------------ I'll find out. AFAIK there is outlander gas molecules that if not used in combustion can become very unstable and at least mix with next intake charge. I don't know what other problems they may cause. I can dig for more info if you think this is relavant.. especially that the engine was rich at 12:1.







The pistons are 4,5,6. Then 5 & 6