CB PERFORMANCE DRY SUMP PUMP.

[Matt Mariani]

Piledriver, great ideas. I'll read and re-read your posts. I'll start to look at my options and update this thread, -Matt

[Crawdad]

Would it be a bad idea to use a thermostat to control flow to the DS tank? I'd like to run a dry sump on the street, but my worry is that with short hop trips, my oil would never get up to temp. When the thermostat is closed, the only oil flowing would be the oil in the filter and lines. It would get up to temp very quickly. Then the thermostat would open, drawing on the oil in the tank, and the temp would drop, closing the thermostat. I suppose this cycle would repeat a few times until all the oil is heated.

Would it be bad to have such a small amount of oil circulating on initial warm-up?
A further advantage of this arrangement, it seems to me, is that the thermostat would also serve as an anti-drainback valve. Am I missing something obvious?

[SCOTTRODS]

I don't think it would be very drain back preventive when hot... so when you shut down the engine at the end of a drive... it would definitely drain back down... unless it is electrically closed. I guess some clarification of the thermostat would be needed to know how the actual component would work. I cn envision two different ways. one completely thermo/mechanical, the other electro/mechanical.
There could be some other ways as well. Those just come tom mind first.

[blue thunder]

I have a similar setup with the scavenger part of the pump connected to a thermostat. I agree with Scott: it wil not prevent oil flowing back to the case. As mine is a streetcar too, and I did not want to use a valve to prevent all the oil going into the sump, I adjusted the volume and the height of my tank (and the mounting position in the car) in a way that ensures the oil level in the tank will be at aproximately the same level in the sump (max oil level on dipstick) when you park the car for a long time (on a level plane). As soon as you start the car, the larger scavenger stage drains the sump and fills up the tank to max level, while still having enough oil in the tank at startup. Works for me

[Crawdad]

Blue thunder, so that means that when your engine is cold, the only oil circulating is the oil in the filter and lines? So the oil temp must rise up to the set point on the thermostat very quickly, yes? Do you then see the oil temp drop as soon as the thermostat opens and the full tank of oil is bought into play?

[blue thunder]

Hey Craw, that is correct. It still takes some time to warm up the oil (6.5 liters or quarts in the system), but it is only circulated through the oilfilter and lines until it reaches the temperature to open the thermostat. The oil will then circulate through the lines to the front of the car where I have a large oilcooler. The cooler is not as efficient as with a normal setup, as the oil from the scavenger side is aerated. It is sufficient though, as it keeps the oil cool enough for my application (2276cc GT3076R)

[Crawdad]

Do we have a verdict from RHough on the Honda CB 750 oil tank used as a dry sump tank? I have a few of those lying around.

[Matt Mariani]

I've got the car body about ready. Time to revisit all of this DS tech.

I like RHough's idea of using the CB750 oil tank very much.

I made my -12 'trombone' cooler and tested it with compressed air to 140 psi (with soapy water), no leaks. I plan to use one of Earl's oil thermostats as seen in my drawing.

Odd (and maybe dumb) question for you guys;

Has anyone designed a system with the stock oil pump (not DS pump), and into a DS tank (like the small CB750 oil tank) before heading home back to the motor just to remove air from oil ?

Could the CB750 tank be placed so that it remove air from the oil while adding a few extra quarts into the system BUT without the side effect of way overfilling the engines sump during operation?

I don't want to add a deep sump, never liked them and need to add an oil tank as stated no matter what.

[Matt Mariani]

In my opinion after weighing the above information, there is no need to use the CB dry sump pump to build a pseudo dry sump Type 4 motor. It's still not really a dry sump engine..

I did this (see pic)

Once warm up takes place oil will scavenge out the oil filter out port (lower port), go through an Earl's remote filter (with big 9/16" ID fittings and interior) then to my custom trombone cooler(3/4") then into the CB 750 dry sump tank and back into the pressure port (lower port) at the OE oil cooler location.

How is this any different than modding the CB DS pump?

The stock HD VW 30mm pump is likely better than the 21mm scavenge side of the CB pump.

?: I'm now considering the CB 750 DS tank overflow line in terms of

where i should plumb that smaller overflow line? Into a can or into the pressure circuit somewhere using a wye or tee?

The CB tank fits like a glove into the quarter and my vintage Blau oil cap covers the opening.

[Piledriver]

There is nothing "psuedo" about the CB drysump pump, it has just two stages as most of the huge pumps sold for the purpose.(autocraft/bugpack) and even the famous "Salzburg" rally car pump from days of yore.

It could use some mods to work better, but it has the benefit of fitting and clearing a full size crank pulley on a upright-cooled T4 or stock cooling setup with a little effort. I'd prefer it had a little larger scavenge stage, but that would make it harder to fit, and external belt drive pumps can be had and are more flexible if you really need that--- almost no one really does.

The SCCA E Prod championship was won on a modified CB dry sump pump (same pump flow path mods) that's where I got the idea, I just worked out how to get similar flow results w/o welding on the pump.

The scavenge stage is 26mm, pressure is 21mm.

The stock t4 pump is 26mm, not 30.
The 21mm pressure stage has proven itself to be sufficient sucking on a steady flow of deareated oil.

I would want at least 6 quarts in the system, that requires an 8 quart tank absolute minimum.
The cb750 tank is a neat idea though.

[FJCamper]

Hi Matt,

External oil tanks and semi-dry sump systems are intriguing. I've tried to design a couple myself. Then, we started using the CB pumps and I learned something.

The difference between your idea and the CB system is the CB in/out pump flow and volume balance is already figured out and actually very precise and well regulated.

On a Type 1 engine with a CB pump, the in/out volume and pressure ratio is such that no matter the RPM, there is usually no more than enough oil in the case to just register less than 10mm on the dipstick.

In short, you've got to guarantee you have enough oil-in to balance your oil-out, or you'll quickly have trouble.

We once suffered a really stupid our-fault oiling problem. We had a stainless steel scrubbing pad ingested by our engine. It might have been in our oil tank after a welding party to improve slosh baffels and flaps. Anyway, the pad was sucked out of the tank, to the intake pump, crushed, impacted, and shredded, and made it to the case oil-out pickup which had a small screen.

That plugged part of the oil pickup, restricting oil to the filter, cooler, but not volume from the oil-in fie, The case quickly filled with oil and it came out of the carburetors!

Your oil tank size and volume is important. You have to get as much out as you put in,

Good luck,

FJC

[Matt Mariani]

Thanks Piledriver and FJC,

When i said pseudo dry sump engine, i meant, its a pseudo dry sump engine bc it has a sump still..
It's not a true dry sump engine as oil fills back into it's sump to the pick up tube as before.

My only concern is getting the amount of oil in the system just right and it not ending up having too much in the sump once warm.

I still installed a windage tray in this motor but hope to keep the oil in the sump at the right level while cooling and degassing the oil with the CB 750 tank (which is race proven). It's a nice tank, i'll replace the cap O ring anyway prior to use to make a great sealing system.

Anyway, the thinking (or not thinking) is;

If i fill the sump to the correct level before start up (3.5L) and fill the CB tank (3L), and run it at idle for a minute (with light weight oil) and stop to check oil level in sump. I can get an idea as to how it's working. If it's working as planned once the relief valve opens bc of the extra volume of the empty cooler lines, the sump level should be low and i can add some oil. I have to be careful as oil expands when hot. Once I carefully figure out the exact system volume needed I think the system will work fine. Your opinions are appreciated.

I hope too much oil doesn't end up in the sump with my approach.

My brain tells me; one pump so pressure out and pressure in the same, oil level will remain the same in the sump.

If i can get the oil amount just right, it would work just like the CB pumped motors (with just the right amount of degassed oil in the sump).

Am i missing something?

[Piledriver]

You do realize a cb750 has an 8 or 9mm pump, right?
(I seem to remember looking it up previously)
Even the "tiny" 21mm pressure stage in a CB pump is going to empty that race proven (on a totally different application) tank in seconds at cruising rpm...

It would be truly awesome if it worked, but the laws of physics are likely to hit back violently...
I'm a really horrible optimist and it still fails my sniff test.

If you could stretch it ~4x the size it might work, but a simple, cleanable tank would be easier.

[Matt Mariani]

I never wrote the 21mm side was "tiny" look above. Simply that the stock pump is likely better as they make a lot of pressure.

As quickly as the tank empties, it fills. I don't understand your concern. it's a closed system.
The entire system will easily hold 8 quarts; 3.5 + 3 tank) + lines..
The CB tank holds about the same amount of oil as the engine's sump. That seems a good feature to me. If you calculate volume of the lines from the tank to the inlet of the engine it's about 3.5 quarts or exactly the same amount as the engine's sump.

Everything going out quickly is coming in quickly and at the same rate.

If you,re correct Piledriver, my remote oil filter would create an issue because it empties in seconds. There is no difference between the two, oil goes in, oil goes out.

The CB tank is just a place the oil gets degassed on its way back into my engine. It also is easily drained and cleaned.

[Piledriver]

Degassing requires time, and needs the tank no more than ~ 3/4 full.
The tank needs to hold enough oil reserve to allow for the oil that's being blown around and has not been scavenged and returned to the tank yet... the rocker boxes/valve covers can hold over a quart each...I severely doubt the CB tank is large enough at any reasonable RPM.

A T4 sump holds 5 quarts easily, 4.7 is spec, but 914 drivers frequently run 5 quarts or even a little more esp for AX.

I'll cross my fingers for you, good luck.