Ok heres the deal, 2 bbl 500 cfm 360ci chevy V-8, comp roller lifters, forged crank, pistons and rods, comp 4-7 swap cam with stud girdles, brodex spec aluminum heads with Ferrea valves. We race in a winged sprint car class. After break in we switched to Amsoil 20W-50 Series 2000. After appx 13 racers she went pop.....( there was 1 race on the oil in the car this race was to be the 2nd) numerous holes were in the oil pan, and a wrist pin actually left the pan. After tear down the 7-8 rod journal was cooked(#8 rod is the one that failed). Some other rod bearings showed some pitting, but it wasnt real bad, IMO any pitting after 13 races is a worry, oh and some of the mains showed some signs of pitting as well. The only thing that really struck me as odd during the tear down was that the rod bolts were smoked, it took all the driver had to break the bolts loose with a 1/2 drive inch breaker bar. I sent the oil in for sample but have yet to receive the results. I have talked to several major players in the sprint car world, from Boyds in Norman, Ok to Gaerte in Indiana. They are of the same opinion that they doubt that the oil failed or that the thin nature of the full synthetic had any thing to do with it. So my question to you guys is, what might have caused the engine to pop........
Dirt racer's engine goes up in smoke........
- Thread starter Jeff70
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Hard to say from this distance but couple things speak to me:
1) Rod bearings showed pitting and 7-8 was "cooked", #8 failing. Is it possible that these were oil starved?
2) ALL the rod bolts were very tight?
What kind of rod clearance were you shooting for? How did you tighten the rod bolts?
Pitting - and smearing or just pitting? What metal and brand are all the bearings? What did the mains look like?
1) Rod bearings showed pitting and 7-8 was "cooked", #8 failing. Is it possible that these were oil starved?
2) ALL the rod bolts were very tight?
What kind of rod clearance were you shooting for? How did you tighten the rod bolts?
Pitting - and smearing or just pitting? What metal and brand are all the bearings? What did the mains look like?
MolaKule
Staff member
"that the thin nature of the full synthetic had any thing to do with it."
A 20W50 has the same viscosity whether mineral or synthetic, so it does NOT have a "thin nature."
Most engines fail because of lack of lubrication or an internal mechanical deficit, not the oil itself.
A 20W50 has the same viscosity whether mineral or synthetic, so it does NOT have a "thin nature."
Most engines fail because of lack of lubrication or an internal mechanical deficit, not the oil itself.
MolaKule
Staff member
Do you guys use methanol fuel?
You say the 7 and 8th position rod jpurnal was "cooked." I assume you meant it had a purplish/blue or dark color to it.
If so, this a meant lack of lubrication, I.E., the metal didn't get cooled or lubricated.
You say the 7 and 8th position rod jpurnal was "cooked." I assume you meant it had a purplish/blue or dark color to it.
If so, this a meant lack of lubrication, I.E., the metal didn't get cooled or lubricated.
What are the piston tops and plugs like ?
What manifold ?
I've seen detonation pull the sides of the upper bearing shell in, turning it into a scraper...lubrication failure as a result.
Otherwise, too heavy a reciprocating mass (coupled with bulk revs) can do the same to the cap...tight rod bolts may suggest this.
I'd bet (on this little information) that it's a mixture stratification between the front and rear cylinders, causing detonation.
What manifold ?
I've seen detonation pull the sides of the upper bearing shell in, turning it into a scraper...lubrication failure as a result.
Otherwise, too heavy a reciprocating mass (coupled with bulk revs) can do the same to the cap...tight rod bolts may suggest this.
I'd bet (on this little information) that it's a mixture stratification between the front and rear cylinders, causing detonation.
Originally Posted By: Shannow
What are the piston tops and plugs like ?
What manifold ?
I've seen detonation pull the sides of the upper bearing shell in, turning it into a scraper...lubrication failure as a result.
Otherwise, too heavy a reciprocating mass (coupled with bulk revs) can do the same to the cap...tight rod bolts may suggest this.
I'd bet (on this little information) that it's a mixture stratification between the front and rear cylinders, causing detonation.
The pistons and plugs looke ok.
To answer all, yes its methanol, and we use a Victor Jr intake. The engine was built by a supposed profesional builder who didnt even inquire as to the malfunction after the engine went up in smoke at his race track. And I would probaly agree with the too heavy of a rotating assy as he used h-beam rods instead of I beams which are much much lighter, The pistons were fordged mahle, with low tension rings (didnt like these from the start), the crank was a 4340 Scat, and the rods were 4340 Scats as well. I do not know if he torqued the rod bolts, if so this is not the perferred method according to ARP, ARP says to use a stretch guage in lieu of torque. The 7&8 bearings were absolutly trashed and the other bearings were pitted with very little smearing. The engine on average turned 7200 to 8000 rpm during a race. The # 8 rod broke and the wrist pin extixed the motor through the right side of the oil pan.
Please elaborate on the detonation issue, as we had fought magneto problems for a better part of the season, also we found that we had a bad plug wire during a race(not the race when it blew) as that cylinder was running much much cooler (appx 125 degress, which was # 8 cylinder)than the other cylinders. During this time we had a sever popping occuring during the race..........
What are the piston tops and plugs like ?
What manifold ?
I've seen detonation pull the sides of the upper bearing shell in, turning it into a scraper...lubrication failure as a result.
Otherwise, too heavy a reciprocating mass (coupled with bulk revs) can do the same to the cap...tight rod bolts may suggest this.
I'd bet (on this little information) that it's a mixture stratification between the front and rear cylinders, causing detonation.
The pistons and plugs looke ok.
To answer all, yes its methanol, and we use a Victor Jr intake. The engine was built by a supposed profesional builder who didnt even inquire as to the malfunction after the engine went up in smoke at his race track. And I would probaly agree with the too heavy of a rotating assy as he used h-beam rods instead of I beams which are much much lighter, The pistons were fordged mahle, with low tension rings (didnt like these from the start), the crank was a 4340 Scat, and the rods were 4340 Scats as well. I do not know if he torqued the rod bolts, if so this is not the perferred method according to ARP, ARP says to use a stretch guage in lieu of torque. The 7&8 bearings were absolutly trashed and the other bearings were pitted with very little smearing. The engine on average turned 7200 to 8000 rpm during a race. The # 8 rod broke and the wrist pin extixed the motor through the right side of the oil pan.
Please elaborate on the detonation issue, as we had fought magneto problems for a better part of the season, also we found that we had a bad plug wire during a race(not the race when it blew) as that cylinder was running much much cooler (appx 125 degress, which was # 8 cylinder)than the other cylinders. During this time we had a sever popping occuring during the race..........
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Originally Posted By: MolaKule
"that the thin nature of the full synthetic had any thing to do with it."
A 20W50 has the same viscosity whether mineral or synthetic, so it does NOT have a "thin nature."
Most engines fail because of lack of lubrication or an internal mechanical deficit, not the oil itself.
The 20-50 Amsoil is thinner than say valvoline 20-50, you can tell when you pour it that it is thinner. Not saying that the oils arent alike in the fact that they are same viscosity, I have argued this point with fellow racers who feel the oil is too "thin". I agree with everything you said and have tried to convince people of this.
"that the thin nature of the full synthetic had any thing to do with it."
A 20W50 has the same viscosity whether mineral or synthetic, so it does NOT have a "thin nature."
Most engines fail because of lack of lubrication or an internal mechanical deficit, not the oil itself.
The 20-50 Amsoil is thinner than say valvoline 20-50, you can tell when you pour it that it is thinner. Not saying that the oils arent alike in the fact that they are same viscosity, I have argued this point with fellow racers who feel the oil is too "thin". I agree with everything you said and have tried to convince people of this.
Originally Posted By: Jeff70
The 20-50 Amsoil is thinner than say valvoline 20-50, you can tell when you pour it that it is thinner. Not saying that the oils arent alike in the fact that they are same viscosity, I have argued this point with fellow racers who feel the oil is too "thin". I agree with everything you said and have tried to convince people of this.
I doubt that you are imagining that. There is no reason they couldn't be significantly different viscosities. SAE numbers aren't actually viscosities, they represent a range of viscosities. Each SAE number represents a fairly wide range at that.
The 20-50 Amsoil is thinner than say valvoline 20-50, you can tell when you pour it that it is thinner. Not saying that the oils arent alike in the fact that they are same viscosity, I have argued this point with fellow racers who feel the oil is too "thin". I agree with everything you said and have tried to convince people of this.
I doubt that you are imagining that. There is no reason they couldn't be significantly different viscosities. SAE numbers aren't actually viscosities, they represent a range of viscosities. Each SAE number represents a fairly wide range at that.
Jeff,
detonation can flog engines to death in short order. You're running alcohol, so I'd suggest that's (probably) not the issue.
Is there the possibility that with the magneto and lead issues you've been having a crossfire ? (HV leakage starting the fire in the wrong cylinder at the wrong time)
detonation can flog engines to death in short order. You're running alcohol, so I'd suggest that's (probably) not the issue.
Is there the possibility that with the magneto and lead issues you've been having a crossfire ? (HV leakage starting the fire in the wrong cylinder at the wrong time)
MolaKule
Staff member
One other item, in my experience we changed oil every three races since water and methanol can severely thin out an oil.
We were changing the oil about every four races. The oil that was in the motor when it failed was one race old, this night was gonna be the 2nd time the car was ran on this oil change. We use a System One filter, which is a canister type filter, that we took apart and checked in between races. The system one filter has a cleanable stainless steel filter element.
I never liked the crank as it was not the lightweight Scat crank and the rods were not either.
As to the detonation issue please alaborate, I believe that there were times that we were only running on 7 cylinders. As #8 cylinder was running so much cooler than the others. During a race when he would slow down for the corner then get back in the gas for the straight the engine would pop pop pop pop then finally it would clear and reach are target rpm, depending on what gear we were running. We thought we had this fixed as the race weekend b4 the engine blew no popping occured. During hot laps the next week was when the engine blew, and the poppiing returned during the hot lap session. There was so much damage that it was hard to diagnose the problem, but like I mentioned before I did catch some of the oil that was running out of the pan and have sent it away, when i get the results I will post them here and yall can help me read it. Also could the pitting be caused by a poor air filter? Numerous times when we would pull the filter to clean it you could see some dirt deposits in the carbraetor. Any and all thoughts are welcome.....As an Amsoil dealer and this guys sponsor as well as him being my good friend I dont not want him to give up on the oil........
I never liked the crank as it was not the lightweight Scat crank and the rods were not either.
As to the detonation issue please alaborate, I believe that there were times that we were only running on 7 cylinders. As #8 cylinder was running so much cooler than the others. During a race when he would slow down for the corner then get back in the gas for the straight the engine would pop pop pop pop then finally it would clear and reach are target rpm, depending on what gear we were running. We thought we had this fixed as the race weekend b4 the engine blew no popping occured. During hot laps the next week was when the engine blew, and the poppiing returned during the hot lap session. There was so much damage that it was hard to diagnose the problem, but like I mentioned before I did catch some of the oil that was running out of the pan and have sent it away, when i get the results I will post them here and yall can help me read it. Also could the pitting be caused by a poor air filter? Numerous times when we would pull the filter to clean it you could see some dirt deposits in the carbraetor. Any and all thoughts are welcome.....As an Amsoil dealer and this guys sponsor as well as him being my good friend I dont not want him to give up on the oil........
If you had a magneto issue as you stated and #8 was the one burning colder, my guess is that you likely hydro locked that cylinder at some point with fuel and it bent the rod. at that point it was a matter of time before it went boom, but without looking at things close its all speculation.
44H
ps. thats also the one that had the wrist pin ejected out of the engine as well, so it could have been an upper end rod bend at the piston or even cracked the piston also. but as I said before, its all speculation
44H
ps. thats also the one that had the wrist pin ejected out of the engine as well, so it could have been an upper end rod bend at the piston or even cracked the piston also. but as I said before, its all speculation
My best mate is a sprintcar engine builder. Tell me about your oiling system, pan and pump etc. I take it your running dry sump like a Barnes or Peterson? What pan/windage tray are you using?
sprintman has the right idea, need more info. Pictures?
More info on the looks of the rear main bearing. Have you re-routed any of the oil passages? When you measured the journals did you also measure the the ID of the bearing saddles? Is there a pattern of wear from the front main to the rear that increases and are the journals in a straight line and do you have a crank that's straight front to rear? What did the rear main seal look like? Do the con rods measure straight?
In other words there is more info needed. You might be talking an oil problem but that may just be a symptom of the real problem. You can improve the oil system and still get an engine that goes back into the pan on the next race.
More info on the looks of the rear main bearing. Have you re-routed any of the oil passages? When you measured the journals did you also measure the the ID of the bearing saddles? Is there a pattern of wear from the front main to the rear that increases and are the journals in a straight line and do you have a crank that's straight front to rear? What did the rear main seal look like? Do the con rods measure straight?
In other words there is more info needed. You might be talking an oil problem but that may just be a symptom of the real problem. You can improve the oil system and still get an engine that goes back into the pan on the next race.
Which block are you using and how good is the machine shop that prepped it? What about dirt in the oil? My mate is at the final night of Outlaws Downunder (I would be but Fri/Sat rained out so I had to come home) I'll ring him later and get his thoughts.
It ran 13 races.. any issues like that would likely have surfaced long before that.
44H
44H
I'd consider cleaning out the oil passages then. Running parts of the engine without oil is a problem.
If you don't think you've stretched the rear main saddle or done other damage like twisting the crank then just put it back together with new parts and figure out the problem that way. If it's serious it will show up.
If you don't think you've stretched the rear main saddle or done other damage like twisting the crank then just put it back together with new parts and figure out the problem that way. If it's serious it will show up.
I'd bet it was a wet sump and oil starvation was the cause.
I ran the topic by a buddy who still races and builds engines. His first question was "Alky or gas?" His opinion, likely oil cavitation issues and/or oil contamination issues.
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