Tore my engine down for a rod knock and found number five rod bearing was squished out the side with hardly any damage to the crank,a nodular, then pulled the girdle to find number two and four mains spun. This the first time I’ve ever seen this and at first I blamed the vac pump for sucking oil off them at high speed,but not sure. What do you guys think. It’s iron block,Peterson oil pump mods, moroso pro mod vac pump,464”
The vacuum pump would pull the oil from the wrist pins long b4 I effect the bearings. Are the pins stuck or stinky....if not I would doubt the vacuum pump. How much vacuum where you running
I had a issue with my moroso pump i installed for the last race 2 years ago. I was only running 7 inches of vacuum. After 4 passes it took out number 5 also. Slowed down every pass. Installed a previous freshened engine and it was doing the same on 2 passes before I removed the vacuum pump. I had the relief valve on the passenger side valve cover. Pump on drivers side. I want to get a fitting to mount the relief valve on the pump. Im thinking its pulling the oil off the floor,uncovering the pickup. Starving the bearings.
I never was cognizant enough to watch the vac gauge but it runs up to 5 unloaded free revving. Another piece of info: I noticed the rings were stuck on all pistons along with a silvery substance in the chambers, the valves were also allowing air to pass by them (did a leak down).
So how much of the giggle gas are we spraying? and how sure of you on the tune? Everything you've said so far can be attributed to overloading. Wiped out main bearings, "squished" rod bearings, collapsed ring lands. Likely from excessive N20 use, or Detonation, or some combo of both. I can't recall who first said it, but boosted induction is not all the same... where Supercharging or turbo charging increases cylinder pressure, but it does it across as much as 30* of crank rotation.. Chemical supercharging (N2O) produces a very distinct spike in cylinder pressure, over a very narrow range of crank rotation degrees. You could say that the affect on the engine with supercharging or turbo charging is a strong push, with N2O it's like hitting the piston tops with a sledgehammer. And most likely why your seeing what you are. JW
I'll share an odd experience with my vacuum pump on my engine 11to1 compression I run on 94 pump fuel ..never heard or felt any detonation ever ...put the pump on and the odd time I can feel it tip into detonation if I'm not careful .. My theory is the low tension oil rings and thinner metric rings are now sealing up tight and creating more cylinder pressure ..the car actually felt stronger with the pump which was surprising to me ... That being said I would say no way a pump would cause bearing failure. pressure of oil coming through bearings wouldn't be affected by vacuum. Even the piston pin thing is getting debunked lately from what I've seen..I'm with Jim detonation would be my guess
I hear that the relief on the pump is a much safer way than drawing through the engine like that also
Many motors with loud exhaust or open headers can detonate and you won't really know it....if you can tell then it's extra bad. It doesn't take much to pound out rod bearings. Like a sledge hammer hitting pistons. A guy I know ran nitrous on BBB and was melting spark plugs and eating up bearings. Setup was wrong. Needed to pull more timing out on big end. Would always smoke some thru traps...detonation rattling the rings. Ended up putting BBC in..... Usually rod bearings go first then debris takes out mains. Happened on my original 70 GSX motor. The guy was hauling rocks cross country with it....no lie.
Sorry to hear this , but before you throw stuff out could you post up some pictures of the split open Rods Bearing area without the bearings in on some of the Rods that did not spin there bearings?
It was 28n32f fogger 5.5 psi fuel 950 bp Timing was 38 taking out 11. Footbraking Plugs were decent looking
No idea whether it was the cause, but have you tried pulling more timing? I think 28n32f translates to a "240HP" shot but I bet you'll see a torque increase if you take out more timing than that. -BC
Well 11 for 250ish is close to base rule of 2* for 50hp. But I think starting at 38 is up there......I've never had a bbb that liked that much. What was the clearances when built. How did the main caps fit??? I lost the center 3 main in 2 1/8mile passes from missing the center caps didn't have enough fit into block. Even after all the trash the rods all basiclly looked like the 1 posted. Things can go south fast, my first clue was idle oil pressure down 15psi, I bet the next pass would had been a very different result though
I’ve beat on these things pretty hard thru the years and I really didn’t consider the out of the box jetting anything dangerous. Yeah the timing is kinda high,but the plugs and pistons didn’t show anything scary. The car did sit for long periods of time,but I kept it up. It showed some signs of being tired with the valves leaking air and the rings being stuck. I’m taking it to the machine shop and make sure all is well with all the hard parts and hopefully proceed with new rings and bearings. Thanks for the responses. Fish
Going to replace the crank, one rod and line bore it. The cam got some damage too, custom Scott brown one too
Got cracks in the main webs even though I’d run the ta full girdle. Dropped off two blocks to see if they’re good, if so they will get the oil feed hogged out for the finish line perf oil pump, and then fitted for the girdle. Fun,fun
If you have every watched any of Darin Morgans video's on wet flow, there is one in peticular where he clearly states that even with aftermarket heads and the better chambers they have over iron heads that there is a certain level of NOS usage/ hp level production PER CYLINDER where a specific chamber shape is needed to stop detonation from taking place. Your cracked block is a sure sign that your in the middle of that detonating ocean, and everything you have shown in pictures that failed and talked is detonation problem related! Just consider yourself very lucky that you did not drive over your own oil and loose control of the car, or send a pistion or two up into a chamber in the head and distroy those also.
The tune up is just flat wrong period.28n32f is way to fat.I would switch the jets run 32n28f but honestly you will most likely end up with a 26 on the fuel side around 4.5 to 5 psi of flowing fuel pressure.To much fuel kills nitrous motors.The old adage I run it rich so it's safe wrong wrong wrong.Na turbo blower you can do it and all it does it cost you hp. Now time for chemistry class.The air we breath is 21% oxygen buy weight.Nitrous adds 33.3% oxygen buy weight.In an na turbo blower deal no matter what you have 21% oxygen but under boost pressure.So now let's get to why fuel kills a nitrous motor.Fuel builds heat no fuel no heat assuming timing is correct.When you run a nitrous deal fat you leave fuel and latent heat in the chamber.When the intake valve opens and you introduce 33.3% oxygen and fresh fuel to the chamber now you have detonation.The left over fuel will stay in the quench areas and above the top ring.This is why you will see the side of the piston nuked.You stack the ring lands and pinch the rings once that happens the excess oil is no longer removed from the cylinder wall (oil has zero octane)and you burn the side of the piston off.I can promise you your rings have no tension left and the 2nd ring probably doesn't move very good in the ring land. Now timing you really don't need a ton of timing when the tune is right.On your jetting I would start at 18 deg total get the fuel tune up right then add timing till it doesn't pick up et or mph and back it off 1 deg. The plug in the picture is 44n32f with 6.5 psi flowing.This is what I look for.I wish I took a pic of it cut apart. For afr you want to be 11.8 or above that is where I start.On kill you will be 12.8 but unless you are looking for every little hp 11.8-12.0 is perfect.If you are 11.0 or below you will hurt parts.Not if just when. We have had a ground wire break for the fuel solenoids while on the dyno.It lost 300 hp and went to 17to1 afr.It didn't hurt anything.We fixed the ground and it went back to where it was and finished the season with no issues.Hence no fuel no heat and my timing is responsible.
No problem.I hate to see guys tear **** up.I have killed alot of parts.Someone took me aside and set me straight.If you ever have questions dm me and I will do what I can.
