drnick

the pump is from a company localy in the uk - pace products - its a two stage scavenger and it spins at half engine speed. alexs tank came from ebay and cost around $100 including postage from the usa - thats much cheaper than anything custom fabricated. if you mount the tank under a fender it is at risk of damage if you have a minor collision, the engine bay would be ideal excepting its quite tight in there already.

FUSE69

Forgive my ignorance.. but whats wrong with the harnesses?

Jim bailey - 928 International

Too low a mount and much too far behind the seat. IF they stayed on the shoulders ( big IF ) there could be extreme spinal compression from the low mounting. The rollbar needs a horizontal bar just behind the seats at a level near the cutouts in the seat which also prevent the seatbacks from breaking should you back it into a wall at 100 MPH . Most racing organizations would have issues with the 2-3 gallons of 250 degree hot oil inside the passenger compartment and would REQUIRE that it be partitioned with a sealed metal bulkhead. Braided stainless lines are allowed to pass through the passenger cabin but not recommended.

Lizard928

Nick, good point about the container not being in the fender due to a wreck.

Although if you are putting a drysump setup into a car, this isnt going to be your standard street car.
So you will have probably pulled alot out already, therefor should have enough room in the engine compartment for it.
Do you also know, or can you find out as to what the displacement of the 2 sections are? (ie. 3cc, 1.7cc)
TIA

And you got a very good deal on that tank, they normally cost around $250+ around my parts.

svp928

Lizard, check on www.daileyengineering.com. They make several versions, and are considered as some of the best for pumps. He also makes an air separator section that would allow a smaller tank to go in a different location. His billet sumps are also very nice...

Lizard928

svp928,

I already have one of Dailey's pumps, a 3 stage billet, with the air oil separator section.
I have 3 1.7cc sections.

I am simply trying to find out as to how many GPM there pumps will pull/push, compaired to mine.
I tried to CC the factory pump, but wasn't that successfull. I did that to try to figure out how many GPM of oil it flowed so as to be able to calculate how much I would need to pump out.
However talking to Bill at Dailey, he said well it doesnt matter if you have too much. The pump I have he told me to run at a 1:1 ratio and at 6500rpm will move 90 gpm.

Jim bailey - 928 International

stock pump 65 liters per minute at 5250 according to the book, Excellence was Expected

Lizard928

Thanks Jim!

looks like I will be sucking alot more than needed.

slate blue

Alex, I am not an expert in this area but I do know a bit about the topic, the vacuum in the crankcase is ''normally'' set by the vacuum valve to limit the amount of vacuum, this is a filtered air valve so that you don't suck in dirt through the seals or through the valve itself. If you run too high a vacuum your seals won't be able to keep the outside air out, so simply you can have too much of a good thing. The reason the Nascar rods are small pin pressure feed is that high vacuums do funny things to wrist pin oiling, that is they don't get enough, Kevin Johnson knows quite a bit about this, he quoted a specific phenomena and cars that don't have the wrist pins force feed if they run high vacuum levels need more clearance in the wrist pin bush, this means more movement and hence quicker wear.

Also like many things the laws of diminishing returns apply, the major gain is at low vacuum levels that don't require these changes. That bit is the good news and is where I will be setting mine. The reason I said "normally" is that if you have low volume pump and turn it slow that will set your vacuum level. The faster you spin your pump and have to let off the excessive vacuum this is just a waste and friction loss plus your pump will wear out quicker.

As to your oil tank, certainly in this country it would be illegal for the street and racing, I think it is highly dangerous but I would be trying to put it in the rear and I hope to fit mine next to the battery box and it will be a in a range of 12" to 15" in height. You certainly don't want ANY pressure in that tank at all. The reason is quite simple, pressurized oil doesn't deaerate nearly as well as oil under no pressure or a vacuum. So one of the your goals will not be met if the tank cannot breathe properly.

What I haven't worked out is how to have a self draining purge tank, I hate the idea of having to keep an eye on that issue, there must be a way.

Best of luck

Greg

Cheburator

Jesus! Why is everyone jumping to conclusions, even before the final word on the subject is said...

1. Jim Bailey - for a change you are wrong! The harnesses were fitted in accordance with the instalation instructions supplied by Schroth. They also meet the Blue Book specifications of the UK MSA and the German DMSB.

2. The tank is separated from the rest of the car by a clear bulkehad, which was installed after the picture was taken. The compartment where the tank sits is completely sealed from the front of the car and again, the bulkhead meets all relevant FIA, MSA and DMSB regulations.

3. There is no other place to fit the tank. Regulations for some of the racing series where the car is entered do not allow modifications of the dash/bulkhead/engine compartment area. We have explored every nook and cranny of the car and we also have access to welders/fabricators who can make anything. We are not stuppid and are reasonably adept at engineering out problems. For our purposes - 4hrs+ endurance racing, a bigger tank is an advantage, and it can only fit at the back.

4. Too much vacuum is not a good thing - I agree. Once we fitted a vent and a catch tank, all returned to normal. Bear in mind that the original car, which had the same dry sump installed has been running hard for 3 seasons now...

5. Running report - did 300 miles at a steady 90mph. No oil used at all, nothing collected in the catch tank. The engine runs cooler to the tune of 10deg and my butt-o-meter told me that we have liberated a few more ponies just as Patterson and Moroso claim for a decently designed system.

Alex

Jim bailey - 928 International

Just lifted this from a Circle Track Article...."SHOULDER STRAPS
The purpose of the shoulder straps is to anchor the driver's torso against the seat. Although brevity is necessary with all the belts, you especially want to keep the shoulder straps as short as possible because they are the longest pieces of the system. Any safety harness will allow a certain percentage of stretch, so the longer the belt, the more overall stretch it will allow. To minimize shoulder-belt length, the belts should mount to a rollcage bar almost directly behind the driver's seat and approximately level with his or her shoulder blades (or slightly higher).

The height of the shoulder strap mounts is critical because if they are too low they can actually compress the driver's spine in a collision. But if the mounting position is too high, the driver will be allowed to slide up in his or her seat if the car is overturned.

VanGilder says that the location of the shoulder strap mounts depends on the position of the driver. The mounts should be at a 90-degree angle to the line of the driver's spine. That means if the seat is more reclined, the mounts should be lower. But if the seat has the driver sitting up straight, the mounts should be higher. No modifications are necessary depending on whether the driver wears a head-and-neck restraint such as a HANS Device. Remember that these guidelines for properly mounting your seat and belts could be the difference between walking away from a crash and being carried out on a stretcher. ...." The rules may be different in other countries but the laws of physics are Universal . As a Tech Inspector for POC if I were doing an inspection, I would not allow the car to race with the shoulder belts that long and that low.

Cheburator

Shall we get back on the topic of dry sumps and agree to disagree?

Jim bailey - 928 International

Good idea

FlyingDog

subscribing.

Kevin Johnson

The figures that I have heard for the vacuum needed to "activate" low tension oil rings is a steady 5 inches. Many racers run 10 to 12 inches with a dedicated pump. Reports are that at about 15 inches and higher you can begin to run into wrist pin lubrication issues.

As the atmosphere in the sump is reduced more and more the oil ejection patterns from the rods and mains tend more and more to describe discs in three space. This is problematic because the wrist pin typically receives most of its oil from the piston oil scrapers on areas of the cylinder bore orthogonal to these emerging spray patterns.

In cars capable of multiple G levels the patterns become helixes in three space.
This is why compartmentalization is used.

On another forum a recent discussion brought up rod side clearances. With insufficient side clearance the flow of oil is reduced and there can be localized overheating of the bearing/rod.

If you calculate the surface area of the "cylinder" described by the factory side clearance spec multiplied by Pi and the inner diameter of the bearing shells then you can do something useful. Add slots to the side faces of the rods directly facing the underside of the piston with an end surface area of the same size.

This will allow the safe egress of oil even under stacking conditions where the rods push together to one side or another. It will act as a safety valve for side clearances slightly under spec. It will allow for additional cooling of the piston and oiling of the pin.

It is of particular interest with respect to the 928. Porsche tried adding oil squirters to cool the pistons but the increased flow volume of oil was too much due to the existing windage control problems and the squirters had to be withdrawn. If they had used this technique there should have been no problem since the volume of oil released remains within stock specs. BMW uses these slots on the S50 rods if you need an oem example.

It is important to differentiate this technique from the oil squirters as seen in the 924 Audi engine rods which are fed from within the bearing interior clearance volume. This will add additional oil volume over stock specs.

You should not expect this technique to work well if you are running rods with greatly increased side clearance. I do not think this area is being explored by 928 engine builders in any event, however.