I know I’m a bit of a broken record here but there are engine builders who for decades have built race car and track engines. If you don’t want them to build you an engine, I would at least pay them a consulting fee, if they are willing, to help you solve your reliability issues. A similar issue happened to a friend of mine (3 blown track engines) and then Peter Dawe built him his 4th engine that has gone the distance and more. When I asked Peter about what happened, he reeled off a number of issues with the previous built engines that would lead to failure on the track. When I asked another member on this site with a couple thousand engines under his belt, many of them race engines, he told me, “my engines don’t blow up”. He wasn’t boasting, it’s just a fact. There are guys who have this stuff figured out. I would seek them out.

I appreciate the advice toward one deciding not to limit his efforts by relying just on ones own depth in such matters as there are resources out there with far more knowledge and experience than what I bring to the table. I will throw out the net and see what I can learn. Thanks for all that contributed council to my dilemma. Bob

To your point about baffling in the tank, I think a good possibility to look into. I am not familiar with the baffling in stock tanks, but surely someone on the forum is. Perhaps you can post in the Tech forum and ask that targeted question?

To your point about starvation under braking, I would hope the baffling is designed to keep oil in the right place 100% of the time. There isn't really an acceptable circumstance for oil not being available to the engine, but maybe turning the tank in the opposite orientation caused some unintended consequence.

http://forums.pelicanparts.com/uploa...1600458016.jpgCustom '72 tank.

If you search for Jack Olsen's BB11 he is using a modified .72 tank. Here is a stock '72 tank cut open. http://forums.pelicanparts.com/uploa...1600458409.jpg

Bob, if this was my thread it would be “14 months, 4 motors, and 2 wives”.

No technical help here but I feel your pain. Subscribed

From a quick comparison of the innards of a 72 tank and an 86 tank, one quick observation is that the pickup for both is more rearward. Possibly to emphasize oil supply when the engine is under power and oil would tend to slosh rearward in the tank? Would this mean the pickup is compromised if you took a non-72 tank and flipped it to sit in the 72 position?

Thread showing inside an 86 tank => http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/778690-oil-tank-question-2.html#post7736735

Thanks for the oil tank pics. Yes, the oil pick up for the pressure side of the engine is in a similar location on both the 72 and 86 tank. The difference is that the 86 oil feed line is directed forward and the 72 oil line is directed rearward. I am just thinking about what happens during braking. Braking being much more severe than acceleration...at least in my car.

Do you data log oil pressure?

No data log, stock oil sender and gauge. Had planned to use the go pro to monitor the gauge esp when I am not looking at it, turns and braking. Not sure the stock gauge and sender are sensitive enough to monitor quick fluctuations in oil pressure. More things to ponder.

This may be a redundent question, but what rpm are you turning, what rods are you using and what brand rod bolts and are you reusing rod bolts?

Shifting at 7500. Had Pauter and Carrillo rods. Weary of blowing those up so the last motor had SC rods with ARP bolts. All bolts new. On the last motor, #4 rod bearing had failed. #2,3,&5 bearings were intact, but had lost their grip inside the rod. #1 &6 bearings still were tight inside the rods. All rods except 4 still measured correctly. The state of the rod bearings indicates to me that I was losing oil pressure everywhere, and #4 was the first to go. #4 is at the end of the oil galley and thinking #4 and #3 get fed first and your #2 &5 were the more vulnerable. Needs rethinking

From engine to front oil cooler and back, minimum line size should be -20.
Its all about the flow.

I wonder if you are having problems with the oil feed line from tank to engine collapsing at high rpm? It might not happen all the time, but it would only have to happen a few times to hurt the bearings. And unless you happened to see it right when it happened, you would not be any the wiser as the rubber hose would just open back up with ever shift and consequent reduction in flow.
Even though oil lines should be large enough so as not to put an undue amount of back pressure against the scavenge pump section, that should not have an effect on oil pressure, if plumbed on scavenge side. But if the scavenge side were actually that restricted, you would be able to see that on the oil level gauge and your engine would be full of oil and not performing properly.
Of course I am just theorizing out loud here, but it might be food for thought.

14 mos 4 motors
 

Yes the collapsing feed line was a thought as I had heard stories. This is a pic of the line that went from the tank (72 position)to the engine, with the standard line as a comparison. Don't know if it was collapsing, but as I am retreating some what and am installing a conventional tank in the conventional position, am up sizing to -16 and for the tank to engine I will fab a steel line. Would like to have it ready for the Road Atlanta HSR in a week, but will be a stretch. Once up and running will post the results. Thanks for the support. Bobhttp://forums.pelicanparts.com/uploa...1601560925.jpg

If it were me, I'd want to avoid sharp 90 degree bends in any fluid line, especially the feed line.

I also see you have a check valve in there. I've never heard of one blocking flow, but if I were experiencing a possible oil starvation problem, I'd look at everything.

Re: flex lines collapsing, I've heard that with up to -16 it's not an issue. With a -20 feed line, it's recommended to put an internal spring to resist collapsing.

Yes the 90* corner looks bad. Its replacement will have a 45* or I will acquire a tubing bender. The car was a street rod at first and I would make adjustments off and on and test it on the city streets. If it sat for a week or two, would smoke up the neighborhood, hence the check valve, but it will be deleted. One less thing to ponder.

engine blow
 

How are your chain sprockets doing? any excessive wear?

Probably the reason you keep blowing up engines. Never in my life have I seen a right angle in the oil line that directly feeds the engine. And it's not only a right angle, but the tubing has a smaller ID than the stock S-hose. So the oil not only has to completely change direction, but get past a bottleneck. All on an engine being revved to 7500 on the track! Sort of hard to believe.

It is these types of stories that have me convinced to NEVER do my own engine build. Why? I could never do enough of them to gain the experience to do it right. Odds are I would make some kind of mistake that cost me more than the labor to have a professional do it. On top of that, I think a professionally built engine will be better performing and last longer.