BC

The throttle body sits there, but on 2V engines, it sits high enough I think. 32V may not use the center hole, but surely the two threaded holes at either end (long way) would be clear I think.

Vilhuer

On 32V engines center hole is not used but two others have knock sensors I believe.

Carl Fausett

I have the 16v CIS system on a 32v Block - there isn't much room between the bottom of the CIUS shoe and the block at that point - maybe 1/4" or less.

A large venting port has been provided at the front top of the motor - I do not think we will find a better one - even with the fact that vent is directly over the top of the counterweight slinging oil up into it.

I think Tony is the only owner I have seen who has welded up a descending pickup into that hole in an effort to get clean air. He says it works well on the street and I have no doubt of it. It is not tested on racing, tho. I do like the looks of it.

Mark Anderson purchased one of my thinner oil pan gaskets - wonder if he installed it and can report that he sees more windage problems or not in his racing this summer. He is also dry-sumped, which takes him out of these problems in another direction.

Carl Fausett

BTW: I spent some internet search time on "Oil Separator With Boost" this weekend. It was not hard to find lots of forums having the same "What to do?" discussion. The Supercharged Mustang forums have threads about it, the Supercharged Toyota MR2 have threads about it, the Supercharged 996 mention it but will not divulge what they do to correct it... just to name a few.

My point is: Boost will increase crankcase pressure, and overpower stock PCV systems. It happens everywhere with other motors too.

Several of us have improved oil control systems that work on the street with boost. Even my own had no problems with my engine on street trials. I went to 6000 rpm on occasion as I broke in the motor, but did not sustain it nor did I do a lot of engine braking. The oil control system we ship with out kits does a nice job - there have been no complaints about it from our installs.

But - under racing conditions... we see the limits of our current oil control system. This is where we are working... and whatever we figure out will be applied backwards to street driven supercharged 928's and help them out as well.

BC

Well, I have a complete block, but I do not have the intake on, or the heads for that matter.

mark kibort

near redline in 3rd gear at the exit.(probably near 110mph, just as fast as many of the back of pack cup cars. Certainly as fast as Fan or JP on that hot humid weekend day. We were running 2:34s but the tires were proved to be 2 seconds slower than my usual RA1s that i use today. (the used hoosier issues) the carocel at Sears point (infinion) raceway has a high g loading 180 turn, where we run 3 seconds faster than Mark Anderson's 1st time there with speedvision in 2000 with his car at near 420rwhp and BFG DOT slicks . (ie 1:52.2 vs 1:49.2 for the holbert car) now of course, Mark is runnng 1:40.xx but also has more tricks, real slicks, more time there and 485rwhp!

so, we know the car is running fast, certainly as fast as any sub 375rwhp 928 there is. I just came from thunderhill with its 80mph constant radius turn carocel with just a little dip under 5 bar, and thats it.

no accusump,, scraper , vent, catch can , nothing. 5 full seasons of racing, Ive lost track of the number of races now. drain plug clean, oil filter elements clean, no sign of any unsual wear. dyno with in 10hp of its best run 5 years ago, etc etc.

scots running the same stock type set up with his euro 4.7 US conversion.
he ran a 2:05.0. anyone that knows thunderhill, knows that is not slow.
Im running in the 2:02 range with 50more hp and a better suspension.
Scot is not seeing more than just slightly below 5 bar around the carrocel there at Thunderhill either.

MK

mark kibort

I dont know, but i tend to lean to the oil. maybe the anti foaming characteristics of Amzoil and redline reduce the exposure of the 2/6 bearing to oil starvation. maybe there is a better film layed down , who knows. However, i have to believe that driving style is part of it. I havent seen a lot of incar from 928 owners that have lost engines, but the ones i have seen looked like rev limiters were used as tachometers. wonder if that plays a part.

everyone used to jab me about short shifting at 6,000rpm. well, in races over the last few years, and especially in those SpeedGT races, i run well past 6000rpm to 6500 or so, but rarely trip the revlimiter. (maybe 4 times in the 5 years ive raced the Holbert car) I can say, i run the car right up to some turns at near redline, am off the gas, and fethering around high g turns. (thats where ive had time to see the slightly lower presure, but we are talking 4.5bar min. On the otherside of the coin, my old '79 stock racer running mobile 1, would get near 2 bar and the oil light would come on on slow corners with lower rpms when it was hot. this has never happened to scot, my car or my old 84 5 liter part euro with the use of redline or amzoil.

my 84 block had 170,000miles on it, the 5 liter block had 2 race seasons on it and the Holbert car has 5 race seasons on it. these are full race seasons of 8-10 races per season, where every lap is all out , with no let ups. the only problem ive had was the defective replacement water pump. Its the only time the car saw a trailer from the track!

Mk

Carl Fausett

Mark Kibort - how is this helping? I'm delighted that your all-stock car never drops oil pressure and does not use oil.... but how is this helping us? I guess I do not see your point.

mark kibort

I am a distributor for Amzoil. ha ha. actually, its helping to understand how you are improving the system vs the stock set up and where the trade offs are, if any. As you know, im a firm believer in not going too crazy in a race type design in a street component machine. what if much of the lubrication of the pistons is from the oil whipping around?? if so, you may induce other points of failure. I dont know enough about what you guys are doing. what i do kow is that by keeping the cars in the 6000rpm range and using Amzoil, (and keeping the oil tapped off) you probably dont need much of any changes in the oiling system. I think the only help im providing is that if someone was on the fence, he could rest at night knowing ive raced and beaten up on 928s for years following some simple techniques.

Ill go away now

Mk

PorKen

Could you add-on or make a custom oil pan that is wider, to hold (8+) liters at the (6) liter level?

Louie928

Ken,
There's too much stuff in the way to widen the sump enough to make much difference if you want to keep the stock oil filter, oil pressure sensor, A/C compressor, and alternator. When I was working on my engine I wondered about sort of a half dry sump system. Have an electric scavenge pump with the inlet at about the 6 qt. level as close to the lateral center of the sump as is practical. Maybe multiple pickups at that level. That pump would dump into an external oil tank where the oil would have time to de-aereate. Another pump (electric) would continuously pump the oil back into the sump. When/if the sump got fuller than the 6 qt level and covered the scavenge pickups, the scavenge pump would dump it back to the holding tank. This would insure that there was always oil to the 6 qt level so the pickup wouldn't get uncovered, and also insure the oil level never got too high. I didn't try it, but it is on the way far back back burner for when I run out of other projects.

Carl Fausett

I have been an out-spoken proponant of keeping the 928 below the manufacturer's red-line too.... I have said it many times. Shift at 6 or less and there is no con rod bearing failure.

But - this discussion is not about the con rod failure caused by over-revving. I do not think Glen is over-revving his car, and can tell you damn sure I am not. I have a 6000 RPM pill in my supercharged shift light, and I shift before it comes on, the moment I feel the power curve (acceleration) fall off, I hunt up the next gear. I treat the rev light not as a "shift now light" but as a "Oh ****" light. I'm old school, I know.

We are trying to labor the blowby/oil aeration/ and windage issues. Similar, but not the same.

Still, thanks for your input, Mark.

Mark Anderson

I guess that means you are going too slow.

SwayBar

Very interesting; so your crankcase ventilation still vents into the intake?

SwayBar

Alright, so we now have identical behavior from two different cars, Carl's and Sterling.

One would have to reason that the 928 engine was designed knowing that it would have at least two quarts of oil in suspension on the crank and rods like a big ball of oil-taffy. Since that two quarts is up in suspension, that means the height of the oil in the pan has dropped to a point where the reciprocating mass misses the oil in the pan completely.

Now, with the introduction of a crank scraper, that oil which was once in suspension, is now scraped off into the sump, over-filling it to the point where the reciprocating mass slams through it, sending oil droplets/mist everywhere, continuously.

The first time at WOT, there will be no vacuum to draw the oil droplets/mist into the intake. However, during a shift when the throttle-plate slams shut when previously at WOT will create high vacuum, drawing the oil-mist into the intake, some of which will precipitate out and settle onto the floor of the intake. Once at WOT again, the pooled oil on the floor of the intake will be drawn up and ushered by the intake charge into the combustion chamber and subsequently burned.

IF that's what really happening, then lowering the oil-level when equipped with a scraper as Kevin suggests definitely makes sense, and would make for an interesting experiment.