Alan

I will add that as a GTS owner its clear that there IS aeration to some degree (perhaps doesn't ever make it to the pick-up) in quite normal (for me anyway) driving that leads to oil ingestion via the breathers and high oil usage.

I don't drive it gently but I'm not at WOT for extended periods - or actually very rarely really... but I hated my oil consumption while configured as stock.

So aeration happens frequently - it just may not be that destructive - if it hurts any bearings it may be more due to pinging... Finding a solution to both that AND catastrophic main bearing oil starvation under high load is nice...but not all need it. DR's Sharkvent config. - which is pretty simple - seems to fix at least the daily driver ingestion issues on stock motors... but I'm guessing not a whole lot more than that - for a street only car that's probably fine for most owners.

Alan

Speedtoys

What was the link to those..Im revisiting this over the winter...

Speedtoys

If I follow this, its not how much oil gets there, it cant -drain-...so it builds up where you dont need it to.

Rob Edwards

Jeff:

Here's Andy's thread:

https://rennlist.com/forums/928-foru...esults-14.html

And my street setup thread:

https://rennlist.com/forums/928-foru...8-engines.html

And the newer street crankcase breather setup:

https://rennlist.com/forums/928-foru...ation-kit.html

Tuomo-

I think it would be cool to outfit an (my?) engine with the pressure sensors you mention on the valve cover outlets and a DataQ. Without having taken the time to RTFM, I see on the pic of the DI-155 thing that it has digital outs- I wonder whether that would be compatible with the auxillary logging channels on the ST2? Or only via the USB out to the DataQ software? Would be nice to be able to look at pressure measurements in concert with rpm, throttle position, etc.

For the questions that can only be asked on a static load dyno (and where the scavenge belt could be taken on and off between runs), I was talking with Greg yesterday and at some point in the next year or so (yes, a ridiculous time window, but that's likely the timeframe, as I'm in a rental house until spring) I will have an engine that will be going on the same dyno at Roger's shop in Fullerton. We'll call it the HPDE engine, since it's time for me to learn how to drive properly. Greg wants to see how high he can spin a 5L engine.

I'll be the first to admit that the scavenging stuff is probably gross overkill for the street, and I'll probably be pulling it off the stroker and swapping it over to the new engine, and putting one of Greg's street setups on the GTS.

In the spirit of good experimental design, I would be interested in your wish list of measurements to make on the HPDE engine being run with and without the scavenge pump. Since being able to _intelligently_ predict what would happen is wayyy above my pay grade, what would be the 'highest yield' information RE: cylinder head and crankcase pressure and under what conditions?

I recall this picture of Dennis K's engine, that had an oil pressure transducer tapped into the oil galley in the girdle, can't recall whether it was at the level of the 2-6 journal (can't find the pic!) but that would be very interesting data. I guess the trick would be measuring without materially affecting flow in the galley. Jim Morton certainly knows how to do it.

Somewhere out there, there must be a powertrain engineer who has some sort of imaging device that can measure the amount of entrained air passing by a fixed point in an oil passage (?) Certainly there must be a physical property of aerated oil that can be measured (index of refraction? Other?)

Speedtoys

Rob: Ya..went lookin on Greg's WWW site..so I had to ask here.



But..read the note "not for boostards"....

Cheburator

With all due respect - Greg Brown has some amazing products and is obviously very good at what he does.... BUT does that mean that we are not allowed to think on the same subjects too? If mankind did not try and re-invent the wheel all the time we would still be stuck in the bronze age at best...

What makes you think that the BMW system is inferior to Greg's? Are you telling me Greg is better than a bunch of guys who made F1 engines? Btw, this system was fitted on the BMW F1 engine too. Tuomo, the pumps only come on for their particular head and are triggered when a 0.8g threshold is exceeded. For the 928 I suggested we also have a rpm/time trigger added as Greg has highlighted that a problem occurs in a straght line at higher rpms too.

Another example - both Louie Ott and Mike S offer ITB systems which are very good, but require extensive mods to the water bridge in order to fit. We developed our own system for our race car, which does not require any mods to the water bridge, and it is a lot cheaper, and utilises the stock ICV system, thus making passing emissions a child' play. We will not sell these as we are not in the business of making 928 Performance parts - it is a ****ty and ungrateful business indeed. Yet, when I dared to suggest that there are alternatives if people are ready to look beyond their nose, I got po-pooed by everyone...

Look at Uwe in Germany and what he has done to a 928 transaxle and a 928 32v engine. Unlike all of you I have actually seen another race car he has prepared for one of his customers. The attention to detail and the skill of execution is amazing. Not only the car looks good, but it is also fast, Aston Martin N24/GT4 fast. So, suddenly there is another race car builder out there who seems to be pretty good, no?

All I am trying to say is that we are collectively better off if we discuss things and share, rather than just say - oh, we have GB's ideas/products, they work, let's just sit on our laurels.

P.S. I work in the financial industry and I have no commercial interest in 928s whatsoever. Actually I don't know why I keep bothering with 928 for the last 10yrs - a GT3 Cup car or a M3 GT4 make soo much more financial sense from the ease of use perspective...

AO

This is a great discussion! I really like the idea of data logging some of these parameters to develop an intelligent system that is based on evidence and not conjecture. But let's conject... Because its fun.

The BMW pumps sound like a reasonable solution, but I'm a little concerned with coming up with the controller for such a unit. But I would imagine we could come up with something at a reasonable cost, no? further, I assume, as previously suggested, these could be located somewhat remotely - say where the air pump would go or on the side of the oil pan if packaging allows. Then it would be a matter of developing a "pickup" that ties into the cam covers that could suck up any "excess" oil in the heads.

P.S. I do not work in the financial services industry nor am I an investment banker (but I do have an MBA in Finance). Instead, I've chosen the highly lucrative startup path... Actually, it's paying okay, which is better than 80% of the startups out there.

ptuomov

The benefit from having them on the ST2 log is that everything is in the same file. The cost is that especially at higher rpms, the datums on ST2 log records don't synchronize very well. This is because the computers start getting busy at high rpms. So if you are not holding the engine in a steady state, then maybe you want to access the data logger separately. I have not used DI-155 UBS, but if it works the way I think it does one can log the spark pulse with it (with an MSD pickup or the like) to rpm. Then, separately log the LH and EZK rpm fields as well, and split the ST2 data log file to two. Finally, synchronize the three data files using the three rpm fields.

(By the way, before I start sounding too much like an expert, let me disclose that I wasn't even able to hook up that MSD pickup on my own...)

Sounds like an interesting effort. I have toyed with the high-rpm 5.0L idea as well, but the turbos make it pretty pointless...

My personal opinion (and recall that I am just a guy with an internet access, so there's no authority whatsoever behind this opinion) is that the smartest way to do this is the following. Take a close to stock S4 with a close to stock 5.0L engine. Hook up all your pressure pickups wherever you think they need to go. Then find a Dynapack dyno that bolts on to the rear axles and can hold the load like an engine dyno. Then start logging and try figuring out what the hell is going on with the oiling and breather systems at higher rpms. Only after you've exhausted the stock S4 as a source of information I would start putting together an expensive engine with custom crankshaft etc.

My intuitive reaction to that system is that "I felt a great disturbance in the Force... as if millions of voices suddenly cried out in terror and were suddenly silenced." ;-) The reason for that is that my (uneducated) thinking on oil system draining is that one always wants to align the acceleration forces (such as gravity and cornering loads) with the pressure forces (such as head-crankcase pressure differential and active scavenging vacuum from pumps), both pointing towards the oil pickup. Now, I understand that sometimes the conventional wisdom such as the above doesn't work as well as out of the box thinking. The reason why I've been getting under peoples' skins nagging about the underlying physics is that it is an unusual arrangement and I'd like to understand whether it's an inefficient system or whether it's a brilliant new design and my current thinking about oil and gas evacuation is as wrong as my thinking was two years ago.

It may be a good idea to get Jim Morton's opinion on what should be logged, although he's moved on to the BMW world here.

I am working on my own wish list for pressure measurements and once I've got something that I believe in I'll post it to you and others to critique.

John Kuhn has some thoughts on boosted crankcase evacuation. Tim Murphy and Todd Tremel as well. All three would probably be good sources for how to either make a system from scratch or modify Greg Brown's system for boost once the design is fully understood. Advice is good, but I would still rely on one's own understanding of what is happening.

I also found these kinds of suggestions in this thread and other threads that have been written during my two-year absence utterly absurd. This thread was about a person in Strasbourg performing an experiment that delivered fairly conclusive results about air-oil separation in the girdle oil passages. I thought the experiment was highly informative. To my dismay, the response from a significant fraction of the forum was that

"Why are you wasting your and our time thinking about this, Greg Brown has a $4000 active scavenging system which will solve all problems and by definition can't be improved upon by anyone else but Greg Brown. We'd love to tell you how it works, but then we'd have to kill you, so shut up and drive."

Since I am at least as interested in understanding the car as driving it, this absolutely does not float my boat. This is not a criticism of Greg, since I absolute understand he has to put food on the table doing this for living and can't run a pure charity. It's more of a criticism of the fan-boy contingent... and not even them individually, since they are all reasonable people on their own. It's the fan-boy pack in collective that rubs me wrong.

That Uwe's car is so fast that it could very well be the fastest track 928 in the world. Yet, the response on this forum for very modest commentary by Uwe is "It doesn't work, and we've been doing this for 20 years, so bugger off with your dysfunctional idler pulley."

Agreed there.

Yes, the point at least for me is for this to be fun, learning experience. Yet I am reading two years worth of angry rants back and forth about whatever, and data from replicable experiments and logic applied to those data have been sucked out from this forum. I have to try to google translate French to get some actual new data collected from a replicable experiment about 928.

I guess I've now descended to the ranting level myself. Time for a personal RL time out for a couple of days.

Alan

I too like that the discussion on this continues - It is rare that Game Over happens due to one person's efforts... and as much as I respect what Greg has done and shared - it is still too expensive & disruptive of an install for most typical owners.

Only when a solution is incredibly cheap and totally effective & reliable is the invention game truly over
(apart from those who will never stop anyway - we all know who we are... ).

I think we have left unsolved the reasons why the heads pack with oil and what options may improve that - maybe the head flow is just too high, maybe the breathing config is all wrong, also needing investigation are the oiling passage changes that would better equalize flow even with some mild aeration to add guard-band...

While active head scavenging may be needed for a track car - maybe it wouldn't be for a street car if the root cause can be addressed sufficiently well. To me there is lots of room for continued theory, analysis and proofs.

But if you need a solution now Greg has one - which is great! I do understand why the game is over for Greg - he's completed a solution that works, that he's confident in, has acceptable costs for his clients and is actually fairly easy for him to add to an engine build in progress.

However even that system (as best we understand it) could be evolved as discussed - electric pumps, control systems...etc So would this be 'for sure' better/cheaper? more flexible? - we won't find out the answer until someone tries to make that work...

Alan

andy-gts

I always agree that there are many ways to "skin a cat" (sorry for my midwestern colloquialism (sp?))

It would be way cool to collect data points and see what the heck is real time going on...Sounds like Rob is going to do just that..

BC

Greg's active systems solve many problems, and work great. I have seen it personally, and as expected everything is machined and fitted very professionally.

I do believe that there is another piece to some of these puzzles. Detonation.

Detonation creates crank case pressure. CC pressure will push out somewhere.

Some feel (around the center north part of the midwest) that with a complete or nearly complete reduction in any blow by created by detonation and pre-ignition - that the windage and oil movement is improved remarkably.

UncleMaz

Tuomo, I am a GB "fanboy", but I truly enjoy reading these discussions, even though much of it is beyond me. My post was meant as a light hearted poke. I certainly did not mean to end any discussion on the matter. My apologies nonetheless.

GregBBRD

I've never had a DR system in my hands, but I was lead to believe that it vented to the open atmosphere. The last time that was remotely allowable, on a US street vehicle, was on a 1957 Chevy. (In 1958, the requirement was closed crankcase.) This was the very first attempt to "control" gross pollution from engines and was deemed the "most important" step.

People ripping off their convertors to get a few extra horsepower is terrible, but to "step back" to pre 1958 standards is absurd. You might as well be dumping your used oil directly onto the highways....a few drips at a time. Think about what our country would look like, if everyone did this! I don't "follow" the supercharger kit variants much, but I've also seen these "kits" dumping crankcase gasses/oil to the atmosphere/ground, which just turns my stomach.

My pieces are closed crankcase. I put "California" cats on everything I build. All my testing and dyno numbers are through these cats. I raise the efficiency on one of my stroker engines so much that the tailpipe emissions are virtually zero, all the way across the board. While I do live in California, that is not why I do this...it's one of the things that is very importnat to me, personally.

Apples are apples. Oranges are oranges. They are separated in the supermarket, why not here?

Speedtoys

I remember what the highways looked like in the early 70s..still stained.

Alan

DR indeed showed open Sharkvent systems - However even with that basic setup plumbing the output back to the stock PCV is fairly easy.

The effectiveness of the seperator part isn't influenced much by where the separated air goes (unless there isn't enough PCV intake capacity), in fact it probably works better with some part time vacuum on the output.

I didn't particularly like DR's Sharkvent breather configuration or the open venting - so although I use some of DR's components I don't use them in his configuration and mine is also a closed system. However those that do have the simple configuration say it too helps oil consumption dramatically - that was the point - I too recommend strongly against any open system.

There are two issues here - oil consumption and bearing oiling issues. A Provent based seperator set-up - hopefully well implemented and in a closed system - can solve the oil consumption issues today (for a street car). We already know your scavenging system can solve the other one - for any usage.

Alan