Region: NWR / Oregon
Car #: 88
Year : 95 Posts: 2000
Status: Offline
posted
I pulled apart what was left of the bottom end after Rose Cup and the damage was impressive. The whole #4 piston and connecting rod literally exploded. It's not like 3 or 4 pieces. It's shards of metal with some recognizable chunks left.
At first I didn't think I'd be able to figure out what broke first considering how mangled everything is but I found a clue. I found one of the bolts that hold the connecting rod to the crankshaft in the debris. Bent but not broken and all the threads are intact. Then I found the nut that goes with it. The first two threads are stripped. It looks like the bolt loosened up, then ripped out the last two threads, then the piston exploded.
What could be the really bad news is that it looks like the piston hit the combustion chamber, denting the aluminum all around the edges, there's shiny spots on the valves of #4 so they probably got hit, and there are shards of metal in 1-3 also so the big bang may have destroyed my shiny new head too.
Steve...if you want to sell that motor I borrowed, give some thought to how much. Right now I don't have a number in my head myself.
-------------------- Keith Novak (Will work for tires)
Region: NWR/Oregon
Car #: #26
Year : 1991 Posts: 334
Status: Offline
posted
Sorry to hear about your motor Keith. Just out of curiosity, how many miles on the motor and were there any tell tale signs of impending doom? As the owner of a 122k motor, I am wondering as to the likely hood of its' similar demise...or is it just simply a crap shoot? And is there anything you might have been able to do more in the way of a preventative nature having seen the internals?
Bill
-------------------- William Bonsell SCCA/ICSCC #26 SM/ITA
Region: SF Nor Cal
Car #: #39
Year : 1990 Posts: 457
Status: Offline
posted
Keith if it helps i lost my engine at Infineon this week. I dont know what happen just yet but sounds like i lost the lower end also. I have a Sunbelt going in. I was going to save it for the next Rose Cup but i need to finish the season. I have been showing the new motor my Rose Cup videos and it feels it will have no problems taking you guys. I have about 4 other friends that want to race the Rose Cup next year so far but expect more. I was surprised to hear that you had that much damage when you were only going a blistering 30mph. A
-------------------- Al Angulo Auto Instructor Ford Senior Master Tech ASE Master Tech
Region: NWR / Oregon
Car #: 88
Year : 95 Posts: 2000
Status: Offline
posted
It'll be good to have you up again Al. Good times. Sorry to hear about your motor too. I know how it goes. I need to find a time to head down there and try out some of your tracks too.
Bill- your motor is probably fine. I think mine was built late on a Friday afternoon. I found several parts that didn't seem to have been torqued down so I'm thinking the connecting rod was another one that was missed. There were less than 20 hrs on the bottom end. At 120+ miles, if something was loose in the engine you'd know it by now.
No warning signs really. Ask anyone who talked to me that weekend and I was really happy with the bunny stomping, baby seal clubbing power (for a Miata at least). The only sign was when we went full yellow I dropped the RPMs, it coughed a couple times then popped. Temp was fine, oil pressure fine, then flat line.
I changed the oil, filter and plugs after every race, changed the oil cooler after my replacement head died (spendy part), broke the engine in properly. What I probably should have done while I had the engine out was tear down the bottom end, inspect and reassemble everything. When you have the motor already out and mostly disassembled it's really pretty easy and much cheaper than a new engine.
I wouldn't worry about yours doing something similar. You could do a leak down test and try talking you son into refreshing the bottom end but otherwise drive it like you stole it. I think Pat's motor had many more miles than that on it when he bought it and the thing just goes faster.
-------------------- Keith Novak (Will work for tires)
Region: SF Nor Cal
Car #: #39
Year : 1990 Posts: 457
Status: Offline
posted
Seems to me when i built one of these engines i had to look twice at the rod torque spec. i think it was around 18-20 lbs seem low to me. But i went with it. Any time you guys want to come down just drop me a line, you can stay with us. We are 1.5hrs from Thunder Hill and Infineon but 4hrs to Laguna.
-------------------- Al Angulo Auto Instructor Ford Senior Master Tech ASE Master Tech
Region: San Francisco
Car #: 72
Year : 90 Posts: 17
Status: Offline
posted
After one of my buddys blew up his air race motor he said you could check the oil with your fist now. There are parts in there that should be in the dark. Windowed the block. Big dollars in the game. Jerry
Region: North West
Car #: 386
Year : 1994, 1991 Posts: 257
Status: Offline
posted
Check out the pictures on Facebook... There is a sleve welded inside the frame, and then it's boxed in all the way around... Not Will nor Bruce could brake the car there!
Region: Oregon
Car #: 68
Year : 91 Posts: 2359
Status: Offline
posted
With that new motor, you just might hit 95mph in T10
-bw
-------------------- Bruce Wilson 2010 Oregon Region Champ 2010 Monte Shelton Driver of the Year 2010 25 Hours of Thunderhill E3 and Under 2 liter Overall Champion Oregon Region SM Class Advisor
Region: Oregon Region
Car #: 92
Year : 1990 Posts: 9
Status: Offline
posted
My dif that blew up at the rose cup isnt that bad but theres a hole in it.
-------------------- 2010 Howard Allen Novice Driver of the Year 7 Time Karting Champion Amsoil/Mayor Apparel/KKR Products/Spy Optics/Fluid Muscle Recovery
Region: NWR / Oregon
Car #: 88
Year : 95 Posts: 2000
Status: Offline
posted
I sort of wondered what happened when I saw the smoke coming out.
Amusing conversation in the paddock but I don't remember between whom... (Driver 1) "Anyone know what happened?" (Driver 2) "He blew his diff." (Driver 1) "No. I don't think it was the diff." (Driver 2) "Well when I looked it had a big hole in it so I'm pretty sure it was."
-------------------- Keith Novak (Will work for tires)
Region: NWR
Car #: #78 sorry Terrell
Year : 1992 Posts: 270
Status: Offline
posted
Yeah.. I pulled behind Thomas in the draft and as I was pulling out to pass was sprayed with diff oil and parts. Remarkably, Thomas' car then sped up. Apparently there is some windage in the diff