Kevin Johnson

I thought we ran the numbers on the hundred plus track days over years and years of racing and it came out to about one typical serious race season in Europe less the practice time. (?)

mark kibort

Yes If it was SCCA racing only, that might be true to a certain extent, but the 7 full race seasons, of over 107 race days on the Holbert engine, is about 110 hours, PLUS the 30,000miles of street driving, also running the car very hard, as far as street driving goes. Its probalby a little more on the race hours measurement, due to the first few years, I was running in several other venues. Usually a cup car engine gets rebuilt after 30 hours.

mk

Leon Speed

So, no bids yet?

GlenL

You didn't do the math but you proposed some numbers so I did the math with those. If the car is accelerating at 0.2g then the pan has to be sloped at 11 degrees to make the oil flow down it. Now I don't think it's doing .2g is 5th but you see the point. That pan is just a few degrees (I measured it but forget!)

Running the pan dry requires knowing how much oil is actually being pumped into the block and not being returned to the pan by the pressure regulator. There's about two gallons to start with. Any guesses? A half-pint a second?

We've talked about this. Driving style and track configuration play a big role in the issue. Driving "hard" isn't quantifiable. Short tracks, like you drive, with more corners and shorter straights have the oil slammed forwards into the sump more often.

I know you bristle at the suggestion that your tracks are easy on the 928, but that's a better explanation than magic, or Amsoil, albeit less fun.

ew928

So has anyone opened up the 'Holbert' Speed Record Speciale motor to see what's inside?

mark kibort

Yes I posted pictures of the disassembly. It was perfect in side. (and real clean)
I didnt touch the bearings, but based on constant oil analysis, coming back with perfect results year after year, i would suspect they are fine. when I pulled the original 170k mile engine, (4.7 liter) the bearings were perfect and it had about 50k of racing and street driving to its credit. If you want to see engine picture, go do a search on the stroker rebuild. I think its there.

mark kibort

yes, its around .2gs actuallly less in 5th but the mid .2gs in 4th.

If the pan would have to be 11degrees, then after a 20 second straight at Road america, never even hitting 5th, wouldnt all the oil be in the back of the engine getting whipped up by the back half of the crank?

Did your numbers take into account the vector force of gravity? (just curious because I really havent done the numbers, just provided actual gs of acceleration in 1st through 5 in a car that could do a high 12 second Quarter Mile.

Thinking out loud, if 1g of acceleration will have the oil at a 45 degee angle, a vector 1g lateral and 1g for gravity straight down, what would the liquid look like if the the lateral G forces are .3g's and you still have gravity at 1g?

all I know is that I ran my car with out the oil cooler attached to the radiator, and the entire oil system went dry after 5-7 seconds at idle speeds. I imagine at 6500rpm, it would be a little bit faster than at 1000rpm.

as far as my tracks? yeah , Laguna, thunderhill a 3 mile track with long straights, and sears, world known for one of the toughest tracks in the world, are real easy on the 928.

watch this video and you tell me that Sears or thunderhill, is easy on the 928.
1.5g loading turn 2, near 10 second redline, 135mph straights, for hours and hours of racing! No issues. I guess its due to the little rabbit foot I keep on my key chain.

http://www.youtube.com/user/zanick2#p/u/7/ddvWNNBDEp4

mark kibort

Thunderhill lap http://www.youtube.com/user/zanick#p/u/7/N3q_Nyv3FBc
Road America lap http://www.youtube.com/user/zanick#p/u/69/T1saqGlm5ok

76FJ55

It is relatively easy to figure out the resultant vector for any given longitudinal or lateral acceleration. it is mearly the arctan(acc/G)= vector angle.
.2G gives 11.3
.3G gives 16.7
.4G gives 21.8
.6G gives 31.0
one thing to consider is as oil piles up at the rear of the engine it increases the effective angle of the pan. A way to envision this is to imagine an oil bottle put at the end of an arm with the lid facing the center of rotation rotating and along the bottom edge, and the edge of the bottle is parallel to the ground. The arm rotates in the horzontal plane. If the arm is rotating to give a lateral acceleration of .2G and you remove the lid oil WILL puor out even though the bottom of the container is flat. The oil will contine to flow until the oil has reached a level when it forms the 11.2 degree ange as dictated by the vector of the combined accel and G force, so even with little to no drain angel most of the oils will pour out.

dprantl

Ok, but how much space is there for the oil to "pile up" before it gets obliterated by the spinning crank?

Dan
'91 928GT S/C 475hp/460lb.ft

ew928

Too bad there's no room to pitch the engine/torque tube assembly forward.
As in drop nose of engine and raise the transmission a little.
Probably not enough forward pitch to help keep more oil in the front deep part of the pool.

blau928

This is just the funniest thread ever, debating the resultant vectors and all these other variables. If you go racing with the car, any car for that matter, why not put in a dry sump and be done with it..?

It would be so easy to plumb in a 3, 4, or 5 stage weaver/Barnes pump and replace the air pump on an S4/GT/GTS, or even take out the AC Compressor in an OB, or S4/GT/GTS, and use that space...

By the time you plumb an Accusump and all the lines, and remote switch, you can fit a DS tank in the spare tire well, with the same lines to and from the motor, and fit the pump in the AC or Airpump slot, put on the belt, and be done with it...

The thread sure is entertaining though..

Ok, back to the regular programming...!

Hilton

No offense guys, but we've had this debate of Kibort vs. whoever in a zillion other threads. How about we keep this one to discussion/findings of the actual baffle, rather than the relative merits of whether an oiling solution is needed for the 928?



Someone at Porsche evidently thought it was needed.. this isn't a cheap part to develop, so lets just leave it at that and see if we can find out where this pan came from, whether it was used in any wheeled vehicles, how many there were, whether its possibly still available, and ultimately (little to zero chance at this end of the wishlist), if someone with a crank case window can test it.

IcemanG17

MK
Everyone is well aware of the success of 928's you have raced and-or built with stock oiling setups....however you are the ONLY ONE.....others have tried to mimic your success on the same tracks you drive and BLOWN ENGINES to prove it...myself (two), Dennis (two), Louie (one) and Don Hanson have all blown engines on the same tracks you drive..... You even drove the last one I blew up...for the longest combined stint.....

There are countless others who have blown track driven 928's engines all over the world... there IS a design flaw.... that I am 100% sure of...... and I will NEVER-EVER run a track driven 928 on the stock oiling system....even the lemons racer has "upgrades"..well more like retrogrades

mark kibort

no one has mimiced what I have done. they always have their own skew of what has been proven to work. You see the videos, you see the track record and its on 4 different engines and the most document racing hours of any 928 in the world! you had an unknown engine that was tracked by who knows who and was probably damaged at Willow springs. your drop in was damaged by the BUILDER, you admitted this! Dennis, who knows, no amsoil and Hanson was beating the heck out of the engines and probably overreved it but was using mobil 1. I personally have seen an unknown engine blow(scots mystery motor) it lasted one day on the track and blew in the race. when we rebuilt it, it was perfect. when we built his 5 liter, it was perfect. when we did my stroker...... the Wisconson boys did it perfect, my old 5 liter euro , perfect.... etc etc. run them with oil, dont over heat them, drive them smart and you get an engine that lasts for as long as you want. we are talking 15 years of racing here, not just a few DEs.

So, I dont believe in tooth fairies, but I do believe in treating the equipment rigth and using stuff that has proved to work, by others before me.

The Lemons racer is stock, you cant count that pan spacer as a mod. maybe the accusump, but on street tires, it aint pulling many gs for sure.

Now, back to the magic oiling fixes for the mysterious problem that no one really understands.