Any have experience with vacuum pump scavenging?

[mrfab]

The engine I am going to be running in our lakester came out of an NHRA Super Comp dragster. It is a wet sump BBC, 565 inches and presently has a Moroso vacuum pump for crankcase scavenging. Anyone had any good or bad luck running one of these type systems? My main concern is that the pump can't keep up with the pressure on a (hopefully) long course run. Any help would be greatly appreciated.

[interested bystander]

A great question.

Yrs truly is involved with a handful of Top Dragsters and Super Comp diggers and also an advisor (?) to a few current Landspeed racers with similar engine but with dry sump combinations.

My gut feeling is for Elmo /Maxton/Lorin/Texas mile/Mojave mile, no problem, but for the salt, more pan capacity or add an oil cooler to the system.

[jimmy six]

I've been running one for over 14 years. First one was a converted "smog" pump like Stefs but I was to cheap to buy one of his at the time. Learned about them from econo dragster guys. Converted smog pump vanes don't like oil vapor a lot.

Moved to an Aerospace Industries model a few years back with success. With a wet sump system I doubt you would have any problem. The key to wet sump system is a really well designed pan which helps control oil getting to the top of your engine. I know of a few BBC's that have external oil return lines from their valve covers to the pan.

I have a vacuum gauge on the pan and can see 7" to 9"; I usually glance at it one or two times on a run if I can. A good dry sump system also pulls a vacuum and adding a pump to it just makes it better. I have heard that too much will pull oil off of bearings but I have not had this happen to me. I've found clear condensate water in the catch can after a run also. I help a friend with a Blown BBC and he has a dry sump and a vacuum pump and has run over 250 without oiling problems.

ProStockers all have dry sumps and pumps but only go a 1/4 mile so I don't compare what they do to us. Not sure on pump to engine speed you may need to make and adjusment in that area...........Good Luck

[Rex Schimmer]

Just remember on a wet sump engine you are reducing the pressure on the inlet to the oil pump and there is a minimum inlet pressure below which the pump will cavitate and pump air bubbles thru your engine. Keep the pan deep and plenty of oil around the pump inlet. On a dry sump engine the case pressure makes no difference to the pressure pump inlet so lowering engine case pressure large amounts will not damage the engine and will make hps.

Rex

[Blue]

I've heard a lot of debate on this in the last few years.  There seems to be a lot of debate about the windage losses vs. case vacuum vs. piston spray cooling vs. scavenge trays vs. sump shape. JM2c, it seems that properly shaped wet sumps are as effective at limiting windage loss as dry sumps in straight line applications.  I have a significant disagreement with a top engine builder about the windage loss vs. piston cooling issue.

[racergeo]

    However there is no debate as to whether or not NASCAR is trying to develop every last HP they can find (ceramic cylinder liners anyone?) on an around the clock basis. They now make a reliable 930HP and there drysumps pull 20" of vacuum and require a relief valve in the valley to limit it so cyld. walls don't run dry. They don't run a vacuum pump but do run 6 stage oil pumps. There system address' windage, piston spray cooling and just about anything else you can think of. They are limited to 14 to 1 comp ratio and use a 830 cfm Holley carb.  2.6 HP per C.I. with an endurance engine. Do what there doing and you won't be to far off.

[Blue]

OK, I'll come down on the side of sucking and spraying.  Several engine builders I know disagree.  Certainly dry sumps with pickups on all four corners are needed for road courses.  Aerobatic aircraft are worse off and could benefit from road course experience.

[SPARKY]

I run piston squirters, EDM rods, 5 stage dry sump, on a 565 that we shift at 8200 and have turned 7850 out the back  ---I feel I am on the ragged edge---as we keep blowing up stuff we address that problem--working on eng plates and fly wheels now

[Rex Schimmer]

NASCAR engine builder are following the F1 engine builders in dividing the V8 engine into 4 separate compartments each with its own very large, and specially designed, scavenger pump to get the case pressure very low and this has a major affect on the windage in each section. F1 has been doing this for years and since a number of F1 engine people are now with NASCAR teams they have brought this technology with them. Lower pressure makes for less density and therefore lower windage drag which makes for more horse power.

As a note on windage reduction large power generation stations use hydrogen inside the generators to reduce windage and increase the efficiency of the generator. Try that with an engine.

Rex

[maguromic]

Rex, You are giving all the secrets away.    On my XO-GMC, I am running a six stage pump with 5 scavenge sections for this exact reason.  As Rex mentioned the pan also has to be deigned to wok in conjunction.  Tony

[hotrod]

You might want to touch base with Peterson Fluids Systems.
They have some tech info and frequently asked questions pages on their web site, and are very helpful folks.

http://www.petersonfluidsys.com/

They are doing active research in new pump designs and supply systems to some of the top race teams in the business including NASCAR,

Larry

[mrfab]

Thanks for all the help guys. I'll take a look at the pan real close and make sure it will do what it is supposed to. I'm thinking of doing a lug curve on the dyno and hold it at 6500 for a minute or so and verify that the pump is keeping up. Thanks again for all the input.

[jimmy six]

Every Power Plant I have ever worked at used hydrogen as part of the cooling system for their large generators. For maintenance the H2 is displaced by CO2 and the CO2 is diplaced by air prior to opening...Been part of my electricians job for over 43 years. There are also either horizonal or vertical coolers inside the generators using tubing like a heat exchanger; bearing cooling water is the medium. The addition of higher pressure will allow more megawatts to be attained. Normally the boiler is the limiting factor.

I've serviced generators with as low as 5 psi (1945) to 60 psi.............................JD

[1 fast evo 2]

Has anyone heard of the oil being drawn out and problems with the piston pins due to high crank case vacuum?

[tedgram]

I think that would only be a problem if vacuum was higher than oil pressure.