Type 4 CB dry sump?

[KarmannRocket]

Hi has anyone fitted a CB performance dry sump to a type 4 motor?
Not needing an expensive dry sump system.

[Steve Arndt]

It has been done. Pile uses one.
https://www.google.com/search?q=site%3A ... +sump+pump

[Piledriver]

I have extensively played with one, but many others have run them extensively, on street as well as race track and rally cars.
Actively working on fabbing up a rear subframe for the square do I can ditch the rear bus support bar and install it...
The 914 it was originally modded to fit was slapped off the road by a semi and I haven't had time for it to date.

The general consensus is they do not work great used as designed//out of the box, but with small mods it works fine.

The two biggest "musts" are installing a much larger (suction) feed fitting to the pressure (outer) stage from the tank, and modifying the cases (or external) pressure relief so bypass oil goes to the DS tank, rather than the sump, as the scavenge side is on the small side, you don't want to have to pump the same oil out repeatedly.

Even with a 21mm pressure stage a motor with reasonable clearances, the pressure relief is still going to bypass most of the oil back to the sump above ~3K unless otherwise directed.

Racer Chris also welded a huge scavenge stage outlet fitting on his SCCA champion E-Production car to reduce restriction, but he also likely runs at 7-9K all day long.

A fellow built a nice historical rally bug replica ran one, had an issue with the case filling up at idle and basically running out of oil in the tank.
(he was idling at something like 550 RPM, which is ridiculously low even for a stocker)
May have been related to a unique plumbing arrangement, he later installed a larger Bugpack or Autocraft pump with enormous scavenge stage.
Issue could have also been the ridiculously low idle speed.

For my T4 motor, I basically made both stages "straight through", inner scavenge stage feeds in/out like a stock pump, but as a T4 is full flow from the factory that means it provides a convenient port for the scavenge outlet.

I plugged the interstage passages, and used an EMPI full flow iron cover to get past the 914s motor mounts for the pressure stage, with a modified mount to allow a large inlet line to same. The cover was reasonably flat, but do lap it to make certain, it is after all modern EMPI quality...

[Clatter]

Pile,

Where/how did you modify to capture the pressure-relief dumped oil?

[Piledriver]

There are two ways to do it using the internal relief, or use an external like a Jaycee or Parker/Swagelok adjustable relief.

At the bottom of the relief bore is a drilling that allows the oil back into the sump, and an external plug to match.
pull plug, drill/tap for small plug, and install a ~10mm setscrew in the return hole.

With the rest of the factory pressure relief, you can put an outlet in through the bottom plug, run a fitting out the bottom, or leave the guts in or out (but bypassed) and run an external. (the external needs that return drilling plugged too)
You can also take the scavenge out of the lower plug hole with the swarf in it via an elbow simplifying the block off adapter.

Packaging/cooling system/exhaust/engine mounts etc may determine how you decide to go.

I bought a naval brass adjustable relief valve from Swagelok, and installed it in a small block I made for the original filter location made of a small bit of ~1"x1" scrap aluminum. The relief was ~$40. Has an internal set screw to adjust pressure.

Scavenge also comes off same block, getting both fittings into the block was interesting but it worked.

I had pics of the mockup... this one shows the block off adapter, and the cb pump modded with the modded 914 engine mounts. The relief would screw into the upper port of the oil filter mount block off on the side, lower is scavenge outlet.
The "full flow" cover gets the outlet around the mount at left.

The elbow at the bottom into the pressure relief plug could be used for pressure in, or you could install one at the usual top port. (the one not filled with metal shavings in the pic)

All fits behind stock cooling with minimal trimming of some ribbing on the back of the fan housing, or easily clears a T1 diameter std pulley for upright use.

setup.jpg

[KarmannRocket]

Thanks guys for the info, yes wasn't sure before.
But can start with that part of project now on motor.

[Piledriver]

I forgot to mention you can also feed pressure back in via an "external oil cooler adapter" on the oil cooler boss.
May make packaging much simpler. Goes straight to the main gallery.

Those cheap adapters can also be drilled in a few seconds turning them into a bypass loop.
If you aren't hanging a stock cooler on that location IMHO that's the best use of those adapters.

A full flow filter and thermostat operated oil cooler bypass is the best setup if going to a large external cooler.
The stock pressure based thermostat will provide ...unintended oil temperature issues with oversize pumps and/or thick oil.
(general info, I know you are probably eliminating that on the DS setup, although it can be kept, will work fine with the smaller pressure stage )

Older Turbo Volvos had a very nice bimetal strip operated thermostatic oil cooler/filter sandwich adapter...
Stick it on a remote filter setup and hang a cooler on the cooler outlets. Requires an extended oil filter tube.

You may want to have the CB pump body oringed, I installed an inner and one just under the flange to preclude external leaks as well.
If its already in the lathe to cut one, cutting the second one only takes seconds.