Greg,

Is the pump you are using able to withstand sucking in lots of air when the engine is operating under street driving conditions?

FWIW I have seen lots of engines fill or overfill their catch cans connected to the valve cover vents at the track. On the 18th I saw a 951 overfill a large catch can and oil two corners. I don't think the car was out there more than 20-30 minutes. My Vett fills a small catch can in 20 minutes with a new engine! It seems to me ALL engines fill the heads under track conditions.

Tony

 

I've got about 2000 miles on mine since installation of the scavenge pump, so far so good. It's being used as a school bus this morning.

 

Good post. I noticed my heads filling with oil on a dry sumped engine but didn't realise the signifacance. Greg is really breaking new ground here and it seems bizarre to have such effort go into whatever the long counterpoint posts have been about.
I've noticed other types of cars have signs of the heads filling with oil but it's not wideley recognised as a problem that requires a specific solution, at least not understood by everyone.

BTW, if I had to guess on the street life of the pump with no oil I'd say it's fine. I assume he's using the Daily pump that has timed rotors that don't need lubrication. A pump that was two spur gears with one driving the other would require some oil but not this style.

 

www.norcal928.org/928cup/928Club94Letter.pdf

Ok, so that is 17 years the issue has been widely recognized for the 928.

I picked a reference you should be aware of. There are many others.

 

and ive got near as many as well under my belt, and all on the race track. My question was what are you doing to qualify beating the car or engine? as far as I know, there is no more "beating" i can put on the engine, except for over reving the engine on downshifts i imagine!

Greg, i appreciate the complements on what im doing, as far as driving or style. Because the "used " tires i use, as much as i make fun of them, they are always in great shape. My times near as fast as Joe Fans, , not only on tires that have less "stick" (im using old R compound and he is running slicks. 1:36.1 at laguna for example vs his best time of 1:35ish). Im also doing it with a LOT less of YOUR Greg Brown HP too! 520rwhp vs my paltry 370rwhp. Hmmm, what does that mean?? it means i have to be braking and cornering harder, right? i still peg the rev limiter or near it on every shift, and while Id like to think i drive smooth, i dont think that is the reason. probably more to do with the tracks, and maybe even more to do with some subtle driving techniques. (gear selection, shift timing, etc) heck, maybe it is the oil. I dont know. Im no expert, but i do have a condition and situation where i dont have seen any issue, so i think this would make you curious as to what is different to those situations to where the 928s have blown up and spewed parts all over the planet!

my point is this, i understand exactly what you are saying that you have seen a problem under WOT and sustained high rpm (which i understand to be 5500rpm and greater for over 1 min). this i suspect is the issue. BUT, in our world, it does a world of good to look at situations that are not failing and understanding why they are not failing its not luck. there is a reason why im not pucking oil at the track or on the street. there is a reason why im not blowing up motors from '79s, 82s, 84s, 87s and all of them with all sorts of mods and changes. (but nothing to the oiling system or breather systems)
Sure, scots has been burning some oil and smokes on the exits after left turns.
But, this is the old style engine. but the engine still runs and is in good health after a bunch of years of racing. my engine has had no issues both the stroker and the stock 5 liter

hey, you are the one that qualified that you shouldnt pop-off, unless you race for extended periods of time at willow spring or road america. I just tossed out Joes fan's car, Ive raced at willow, he has raced it more than a few times at willow and has done ENDUROS up to 4hours long, at willow to boot! he has also raced at road america a few times as well with it. Sure, it has an accusump, but does it really need it? i dont see any fluctuations in oil pressure, so i suspect he woudnt either. But again, what do I know. just reporting what ive seen.
i do understand that the breathers can put oil in the intake. this i know. i have done something with making the "loops" a little higher so that the oil condensation can happen and flow back to the heads and not go into the intake. i dont know if this is a solution,but i dont seem to have any major issue with oil flowing into the intake to cause massive oil burn or smoking. my rear view camera video shows this.

anyway, i do believe that there is a weakness in the 928 system that can effect some applications of how it is raced or pushed. maybe the design is perfect for how im using it. (just road racing) i dont know. But, keep up the good work, as long as it doesnt hurt anything or create more risk, its all good for the 928 racers!

 

Kevin:

There can be no doubt that Porsche tested these engines......and they had to be aware of the "issues".

You are a very smart guy, that knows details about a whole bunch of different engines. I just know a whole bunch about a few engines....and the 928 engine is perhaps the engine I know the most about.

It would be "remiss" to not accept the fact that the 928 engine has had a history of failures when run at high rpms, for extended periods of time.....many, many people have had these engines fail, under these conditions.

It is my belief that the Porsche factory's stance on not racing these engines and these vehicles was directly due to these problems. There's a rather lengthy story about Alan Johnson (San Diego) wanting to prepare a 928 for competition use....which the Porsche factory "shut down" with some vigor.

I believe that the absurdly "long gears" that Porsche installed into these cars we designed to keep the engine out of the rpm ranges that cause the problems. (Note that the first signs we had of problems were 60 seconds into a 5,000 rpm test.....loss of oil pressure did not occur until 60 seconds into a 5,500rpm test.

I'm not going to "banter" back and forth with you (or Mark Kibort) with each of us trying to prove our point. I feel that my testing and my findings are very valid and explain volumes about the engine failures on these engines.

You can do it your way.

I'm going to do it my way.

Easy.

However:

I think that if you took the time (and money) to actually "test" your pieces on an engine, like I have done. you would find that even with your considerable windage system, the heads would fill with oil, at high rpm use for extended periods of time.

I'm so confident of this that I'm willing to "test" this, on the current engine we are building, which is also going onto an engine dyno.

You "loan" me one of your windage systems (I'll return it, after the dyno testing) and I'll install it and pay to run it, on the dyno, and we can see if this engine suffers from the same problems that all the rest of the 928 engines have suffered from, when run very hard. Of course, you would have to pay for any damages that occurred to the engine, from this testing....but since you are so confident that your stuff "solves" the 928 oiling issues....this should be a moot point.

Seems like this would be a very small investment, for you to make.....and would be a sort of "put your money where your mouth is", kind of thing.

 

I don't like the idea of adding a restrictor to keep oil from getting to the heads. It is an easy mod for a dedicatd race car but not ideal and not something for a street car. I've seen 928 engine failures that were from oil starved camshafts. If you did that mod on a street car it could be a disaster.

 

Interesting.

Could this explain why the 944 16V engine suffers from cam chain / tensioner failures while the S4 motors do not (or at least as often) with the exact same parts in both engines??

Something to think about as I put my 944S back together.

 

The idea is to regulate the pressure; the side effect is to lower the volume of oil in the heads. The 928 street engine already has restrictors. Edit: I should have written that the bedplate passages are themselves restricted by cross section. Erkka color coded a nice chart.

 

Greg,

If you want a 928 system for dyno testing you can have one at no charge. There is no need to return it.

I will certainly not be responsible for damage; be careful installing it and building the engine. Be sure to check that matched serial number caps are not mismatched from the factory.

I feel honored. The last person I pissed off this bad was Darrell *** and who made a similar offer. He was quite upset that I felt his pickup tube should have a screening element and not be inches off the pan floor. Silly me.

Let me know.

Kevin

 

I dont want to banter. this is just a discussion and you know this.
but, when you say things like porsche putting long gears in and running the car at 5500 for over a min, what are you pointing too as far as racing? no track around in this country has you running at over 5500rpm for longer than 30seconds. in fact, the longest straight at road america, (all three straights) only have you WOT for a total of 15 seconds each! AND, during that time, you are going through only 2 gear changes. in fact, my 2.2 will have the highest RPM of any gear box set up at the end of these straights with my power or the power anderson had back in the day. (420rwhp)


so, when you see what you have seen emperically, i believe you. it all points to issues if you are going to run a 928 engine over 45 seconds or so at WOT, and over 5500rpm. this also means you are strictly talking about land speed record runs, or running at the "Ring", or autobahn. race tracks dont EVER have you over 5500rpm for more than a few seconds with-out a lift and brake or a shift. its the way it is! AND, if that is the way it is, the problem really is not in the average of RPM of near 5500rpm while racing, its about the actual RPM being above 5500rpm, which clearly doesnt point to road racing in this country, anywhere!

 

Mark:

Are you seriously totally ignorant of the number of 928 engines that have blown up on race tracks or are you just babbling to hear yourself babble?

 

Hello All

I have stated this before , my project car which can be seen of the url at the base of this message , has the head restrictors and the I and J windage system in place . In my Dyno ( MY DYNO ) at 6000 rpm the heads fill with oil instantly , filling the catch can and overflowing , to help me finish the tune in the dyno I put the overflow line ( which incidently was considering to vacuum source this ) into another reservoir on the floor .
A frightening prospect for this to happen on the track , any wonder they grenade , GBs system will allow the heads to be kept clear and oil in the sump although to seriously track this engine, as I will be with the next project , I will be dry sumping it . As I will be running it over 7000 rpm to which I believe they can easily perform to.
Interesting that the GT cams were designed to run up 6800 rpm , particularly when they must have known that they were suspect up to this speed .

I have been sitting on the sidelines watching this thread , I am never ceased to be amazed at some people who want to argue black is white and visa versa , oh well if you want to band aid the system you will install put a windage system in , if you study the oil system in detail in the 928 you will see that heads have no pressure feed system back to the sump reservoir , the space in the heads allows for much more then the volume of the sump to accumulate oil . As it is only fed by gravity and is being fed by to 10 bar , simple application of mathematics accompanied by observation in my case ,the dyno cell , it all becomes a mute point .
After watching Rennlist for a while now , I would forward my opinion that to discount GBs experience and assertions would be the height of ignorance . I for one am glad that he regularly posts and forwards his opinions, remember that this is free , his experience here has been accumulated from years of ecperience and trial and error.
His development and observations of this problem has cost hundreds if not thousands of hours , and offers a solution to a problem that the factory walked away from .

 

The 1994 Letter about the head restrictors was sent to Kim Crumb. His GT experienced TWO engine failures , after that date as I recall.

 

You are mistaken...I'm not even close to being pissed off.

I'm just not going to argue about something that I have proved to my own satisfaction.

Thus the "testing trumps theory" comment.

You can sit in front of your computer, all you want, debating what happened on the dyno, but the reality is....oil did "pack" into the heads....in large volumes....leaving very little oil left over, in the pan, for the pick-up. I don't see that your "windage" system is going to keep this from happening....it may "help" or "slow" the process, but the heads are going to fill with oil and the pick-up is going to get "uncovered".

I'd agree that there are a few engines that have Accusumps on them that have survived...but this simply "masks" the issue. I'd also agree that Kibort has developed a driving style that makes the engines live....combined with used tires that have very little "stick" left in them.

However, I can't train everyone that uses one of my engines to drive like KIbort....and I don't like "masking" problems. I want to "fix" the problem...so I don't ever have to think about it, when one of my engines leaves my shop.

Everyone else is free to do whatever they want....

BTW....did I notice that Carlhole equipped his engine with both one of your windage trays and a system to remove the oil from the heads? Why would he do this, if your system "cured" the problem?