Cavitating oil pump = utter horsepucky

What is up with you guys?
If you disagree at least be polite about it. I have recived tons of help from this forum, and to be honest I would not have kept the car if it were not for you people. Thank you for that :) I am no expert, only a regular guy who has spent way too many hours studying this and I sincerely believe a new pan will be a massive improvment.

Whether the pump cavitates or not is not the main reason for this oil pan. (I still believe it does and I have offered the reasons why). This sump will be to improve windage control, cut down on foaming, increase the available volume of oil and increase HP at high RPM (compared to an engine without scrapers) regardless of whether the pump cavitates or not. It wil, however, be of even greater benefit if the pump is actually cavitating.

Let's bring this back on track. Please let me know if you would be interested in an improved oil pan design.

Only for a good price

Thanks for letting me know :) I'll come back with a price if I there is enough interest to make it feasible to to go ahead with this.

I recently installed a Longacre stepper motor oil pressure gauge and while the stock pressure gauges does not move very much, the Longacre gauge DOES move around quite a bit with pressures ranging from 85 to 60psi, oil temp dependent. This fluctuation is pronounced at idle, but pretty damn steady under load.

This could be due to error or location of install, but it is interesting.

One thing I know for sure though- my oil pressure is a lot better since I change oils. The previous oil I used did not have enough anti-frothing ingredients and under heavy load, pressure dropped to dangerously low levels. With the current oil, it holds very steady throughout a 30 minute track stint and the rest of the track weekend. I burn no oil now, either.

SO... the question I keep asking myself is, how much of this #2 bearing issue is due to improper oil?

That is interesting. Where is the sender located?

The pressure fluctuations, are they before or after you changed oils?

Like you say I would imagine this is due to bubbles in the oil. The 928 crowd has been discussing this for a while. Take a look at this very interesting thread which has images of how the bubbles affect the oil passages of the 928 and the flow to the different bearings. the 928 suffers from similar problems with #2/6 rod bearings, although for not all the same reasons.

I would think improper oil (to thin) could be behind many of these failures. Proper clearances, proper oil level and correct viscosity should be enough for the majority of owners. your findings with anti-frothing oil are very interesting and go a long way to prove my argument. A redesigned oil pan should minimize this frothing. Like you say, if the anti frothing agents are good they may be a good enough fix for many? Personally I would like to do both for a variety of reasons.

This oil pan thing is really for racers, high power engined cars, and owners who like to drive their cars hard and for many laps when at the track, or for those considering a windage tray to gain a few high RPM HPs.

Not trying to be impolite, just stating that the issues that are concerning you can be easily and inexpensively addressed without redesigning the whole oil pan.

Remember that hundreds of 2.5 race cars are on the track every weekend using the stock pan.

Let's leave it at this then: Some very knowledgeable people, like yourself, think this is not neeeded, and are happy to run the stock pan. Other knowleadgeable people think it would be really beneficial.

When studying the block and sump I found several areas that, to be honest, are incredibly crude and can be massively improved to real benefit. Does that mean that a new pan is necassary? Absolutely not, but it will provide added protection for the engine and a much simpler and better windage control system which will give some small performance gains.

Now the next question is; can it be done at reasonable cost? That remains to be seen, but remember a windage tray from IJ is $500. This will provide a windage control system and a new pan in one package, and much easier to install. One of the interested manufacturers price their pans from $300 to $500. This will likely be more, because of the low numbers, though.

Erm, doesn't the stock pan have windage? Aren't you really talking about a $100 IJ crank scraper?

No, I'm talking about a windage tray integrated into the pan, like the one in the picture in post #1, but hopefully closer fitting.

More than $500? The stuff from LR is a lot less expensive

Also, to clarify. . .I am participating in this thread to ask questions about your idea. That is how I learn about stuff!

Thanks Rasta. I realize that, I just didn't think you contributed much at first. You are contributing now though :)

The LR baffle is much less expencive because it does a lot less. It will still improve things though, and may be right for you.

Well, in my own defense, I still do find it highly unlike that motor oil could cavitate inside the oil pump of a 2.5. The pumps are quite robust, and the tolerances quite tight.

928's have an even greater problem with 2 and 6 rod bearings. Race engines have been blowing up for years probably at an even greater rate than the 944's. Scrappers, drilling cranks like Chevy's, dry sumping have all had limited success. Around a year ago they found the real cause. Doc Brown considered by most in the 928 community to be the best 928 stroker engine builder had one of his engines on an engine dyno and was spinning it over 6K for an extended period. Suddenly it was gushing oil out the breathers on the cam covers and lost oil pressure. To make a long story shorter what was happening is the upper end of the engine was filling up with oil and then the oil pump cavitated and oil pressure was lost. Each cylinder head was filling with over 2qts of oil! 928's have an even worse pan than the 944's. Oil was being churned and thrashed by the crank and was unable to drain back into the pan. A lot of solutions were tried and the only thing that worked was to dry sump the cylinder heads. If interested you should go over on the Rennlist 928 forum for some very interesting reading. A lot of the issues raised on the original post here are true. Whether the pan can solve the issues on a 944 will have to be seen.

Who runs their engines at 6K for extended periods of time? I shift at 6000-6200 and the car is only in that range for a moment before dropping RPM's. I'm quite sure that whatever would cause that 928's issue would be solved with an up-shift! Stroking the engine may have something to do with it, too. The car was designed a certain way- change one thing and the parameters change for a host of other things. I imagine if one wanted to stroke an engine and keep it near redline for a long time, one may want to switch to a dry sump!

While I have added a baffle and extended the oil pick-up on my track car, and there is good logic and solid evidence that the #2 oil passage is an issue, I still think the #2 bearing issue is largely solved with good oil selection and watching your oil level. Frothing is the key. Solving the frothing with the right oil and the starvation issue is (once again, LARGELY) solved.

Bebbetufs, I think you may be on to something, but the question is, what's it worth compared to what it costs? Sometimes simple solutions work best and the rest is just overkill. I think there may be a market for your oil pan design if you can throw everything into one package. Not saying I am a buyer, but I know more than a few people that are firm believers in overkill. Good Luck!

:D Thank you.
While I do not think there is a mass market for something like this, I do believe some people want things done "the right way", and that is what I would like to try to do.

One word on the block/girdle mounted crank scrapers. If you take a very close look at how they are mounted you will discover that the oil drains from the top are above it on the upstroke side of the pan. This means that all the oil returning from the head lands on the wrong side of the scraper. The scraper actually only scrapes off the relatively small amount of oil which can accumulate between the cast scraper in the pan, and the upstroke scraper, about 90 degrees of rotation. What is worse, the oil scraped off has nowhere to go as there are no drains in that part of the pan. This has led me to scrap the upstroke scraper. I will improve the downstroke scraper instead, as this is where oil can actually be scraped off and drained into the sump.

With a pan mounted up-stroke scraper and a kick-out drain channel below it the oil can be scraped off and returned to the sump much more efficiently.

I understand why you would say this, but cavitation is actually made worse from tight tolerances. The tight tolerances are needed for the pump to be able to suck oil at low speed. When speed increases the oil is unable to flow into the space between the teeth on the gears quickly enough and cavitation occurs when the molecules in the oil are ripped apart and turned into oil vapour. The problem gets worse the further the pump has to suck the oil before it enters the gears as it is already at a very low pressure. This is why front mounted pumps like ours are more prone to cavitation than in-sump pumps. Check out this article for an interesting read on cavitation in some Chevy engines.

Once again, the issue of cavitation is largely solved by an oil with a higher amount of anti-foaming ingredients. My understanding is cavitation is caused by air bubbles in the oil, created during an oil's movement from high and low pressure areas, sloshing, etc. Foamed or frothed oil damages pumps and starves moving parts of viscous oil. Of course there are other elements involved that can be solved with scrapers and such, but it starts with the oil.

FYI- for anyone out there that sees their oil pressure drop down to the #2 bar on their dash, you want to change your oil brand first...