I have not posted much on the forum since I completed my 68 C3 project completion in October of 2019. Very briefly, the project included complete driveline and suspension upgrades, with a BPE 632 with Holley Super Snirper, Monster 4l80e, and 3,500 stall converter, complete Be Cool radiator and dual fan system, custom built exhaust system, Duntov Corvette built center section, 1/2 shafts and inboard/outboard spindles. Suspension was upgraded to the complete Ridetech system with coil over shocks and Willwood 4 wheel disks. Many other supporting components, like wheels, tires, steering, trans brake, line lock, etc.
The car was built to perform on and off track, with AC, power steering - a pump gas cruiser.
Since completion I have put about 2,000 miles on the car and have ran the Texas mile 3 times with a best speed of 194.7 mph and a best 1/4 mile ET of 9.70. Needless to say, I have been very pleased with the outcome of this effort.
The car is now tuned for E85 and we installed a nitrous system in the intake manifold. The speed/et stated above were motor only figures, the nitrous was not added at this time. We had the car on the dyno earlier this year and made 730 rwhp on motor and 915 rwhp with the nitrous shot.
Late March we were registered to participate in the Texas mile event. We teched the car in on Thursday to begin passes on Friday morning. I made two “shake down” passes Friday morning in the 192 mph range. The weather was to change on Saturday, so Friday afternoon was probably going to be our best run of the event. I reviewed the data from the last two runs to confirm that AFR, timing, shift points, etc., were good and loaded the “moon tune” to potentially break the illusive 200 mph mark. After about 2 1/2 hours of making our way through the starting grid, it’s go time. There is a final safety check prior to moving to the starting line and an opportunity for a very short burnout. I passed safety and engaged the line lock for the burnout. As the tires began to spin, I heard what I believed to be a bottom end knock in the engine. I tapped the throttle again to confirm and I was unfortunately correct. I aborted the run and drove back to our pit area. We removed the valve covers to eliminate a valve train issue. No suck luck and back on the trailer.
After removing the oil pan it was obvious that we had a bearing issue. #6 rod bearing had failed, which also took out #5. The crankshaft was damaged beyond repair and #6 rod had some damage, but beyond that all seemed good. We completely disassembled the motor and inspected all components. All still appeared to be fine. I somehow remembered that BPE has a 3 yr warranty. I found my original purchase paperwork from BPE and had 11 days remaining on my warranty. I contacted BPE and they began a claim. The following day a warranty specialist contacted me and we discussed the issues. He immediately offered to ship the motor back to BPE and completely rebuild at their expense. In lieu of this I requested to have the components sent to me directly and we would rebuild the motor. This was for 2 reasons, one, I wanted to control the build and two, we wanted to make some changes also. With 7 days BPE furnished a new crankshaft, rods, rings, bearings, gaskets, timing chain and gears. Probably missing a few items, but these are truly first class people at BPE!
We wanted to bump the compression to about 12.25 to 12.5:1 (safe on E85), and go to a solid roller camshaft to allow for around 7,800 rpm shifts. Currently the camshaft has been ground, diamond pistons have arrived, rotating assembly is now balanced and short block is built. While the heads were off, we polished the runners and combustion chambers and port matched the heads to the intake. New valves, springs and retainers were installed. We are waiting on the lifters, which are scheduled to arrive on Tuesday, to complete the engine.
It’s been almost a 3 month process and I am getting pretty anxious. The engine builder feels like we will see gains of between 100 and 150 rwhp. Hopefully we will have the car on the dyno some time in July. Fingers crossed!

 

Great write-up. Do you have a few photos you can post?

 

Here are some photos of the motor tear down. Rod bearings (#5 & 6) are in pretty bad shape. Damage to #6 rod cap and crankshaft. Cylinder heads showed no signs of damage.
Should have the motor back from the machine shop next week.

 

Heartbreaking , ain't it?

 

Never a good thing!

 

Hey Neighbor, that is an impressive machine you have there! I fired mine up last night after it being apart for a month. We need to cruise to Kemah when you are back up and running!

 

Any idea of what caused the damage?? Could there be some issue with lube passages, blockage, etc? You surely don't want to go thru this again. There must be some viable cause for the first failure.

 

Picking the motor up from the machine shop this week. Should be on the road by later this month. Kemah is definitely in the near future!

 

Everyone is scratching their head over this. We have the failure narrowed down to two possibilities. Either we had a flaw in the crankshaft at the #6 rod journal or there was an oiling issue. I race the car in mile events and there is some question weather 7 qts of oil is enough during shut down. Aggressive breaking at near 200 mph pushes any oil in the pan away from the pickup, and couple this with a near 40 second run of over 7,000 rpm and there is very large quantity of oil in the top end of the motor. To be safe we are trying to get an oil pan to support at least 9 qts of oil. We may have to custom fabricate a pan due to the large crankshaft throw and tight quarters of the 68 Vette.