Lotus Elan and Lotus Elan Plus 2 Forums

Does the Lotus twin cam engine suffer from oil surge (starvation) problems during sprints or hillclimbs? do you have to get the sump baffled or go for a dry sump

Cheers

Doug

yes, common problem. Drysump is great if legal, but have its disadvantages. A good baffling usually does the job.

Dag

Drysump is great if legal, but have its disadvantages.

care to expand on this topic? I'm currently gathering parts quotes to dry sump my engine. would like to hear your thoughts.

fj..

While we're on the subject, any comment on the use of fuel tank sponge in the sump. Supposed to stop surge.

WOW! great idea,why hadn't I thought of this? anyone know pro's and con's of this? maybe try it on customer's car first.
Martin

Just a guess, but the volume of oil pumped through an engine greatly exceeds the volume of fuel pumped. I don't think that the foam matrix could handle the flow. Even if it did, any breakdown in the material would have disasterous effects.

Dry sumps are fairly bullet proof, but are expensive and complex. An Acusump accumulator provides good protection for those who race in the US under rules that do not allow dry sumping of the engine.

Jerry

grat wrote:

Drysump is great if legal, but have its disadvantages.

care to expand on this topic? I'm currently gathering parts quotes to dry sump my engine. would like to hear your thoughts.

fj..

-
-drysumping is the only 100% proof system for maintaining oilpressure/supply at any time. However, it ads weight, takes up space, and two hoses with 100. deg. oil passing through the cabin ( - the oil-tank will have to be situated in the trunk ) has a nasty tendency of turning it into a sauna...... . Besides that, it is not homologated for the Elan S1 & 2 in FIA period F. ( -65) .
A properly done baffling will take care of 99% of your oilsurge-problem, and is so much simpler in any respect. Others may of course think differently....

Dag

QED do a nice baffled sump if you are not too good with the MIG yourself.

-drysumping is the only 100% proof system for maintaining oilpressure/supply at any time. However, it ads weight, takes up space, and two hoses with 100. deg. oil passing through the cabin ( - the oil-tank will have to be situated in the trunk ) has a nasty tendency of turning it into a sauna...... . Besides that, it is not homologated for the Elan S1 & 2 in FIA period F. ( -65) .
A properly done baffling will take care of 99% of your oilsurge-problem, and is so much simpler in any respect. Others may of course think differently....

Dag

Ok, nothing unexpected here. Just wanted to make sure I wasn't missing something.

I'm building out an S4, dry sumping is allowed in all of the racing sactioning bodies that I have the ability to run it. The oil hoses are something to consider but I'm running a DHC so that isn't too big an issue either.

Thanks Dag,
fj..

SADLOTUS wrote:While we're on the subject, any comment on the use of fuel tank sponge in the sump. Supposed to stop surge.

the thought of this wrapped around the crank would be enough for me not to go there. . .

fj..

I know one guy who runs fuel tank foam in his Marcos sump here in historic racing and he claims it solved all his oil surge problems in the 1800 volvo engine. He tested it by heating it in hot oil for many hours to ensure it does not disintegrate. He holds it in the sump with a mesh grill on top. He has used it for several years now without problems.

I would test the particular brand of foam you use before I tried it if you go down that path.

regards
Rohan

I use drysump for the following reason - it extends engine life . A friend of mine running my old car with a wetsump with Accusump ( don't waste your time here ) goes about 20hrs before a teardown - I look into the motor between 40-50 hours . However - things I don't worry about are the fia periods ( I declare mine back dated to 1966 spec with drysump 1600cc listed as an option on the RAC form. BTW , i have log books into the early 70's when the car ran a monster engine and 8-10 inch wheels and figure I am being kind not insisting I can run as it did in period ...

My drysump tank is installed in the passenger foot well and no lines run inside the car, Tank has a oillevel tube mounted on it so the level is checked by looking in the footwell. have not noticed any exsesive heat, but I use to run cars with spaceframes that used the tubes to transport oil and water....

One way keep the heat to a minimum would be to fun alum hardlines with insulators ( aeroquip firesleve ) inside the sills with the sill pannels on and install the tank in the trunk - I don't like the long line runs vs the short ones I have ( have often wondered if leaving the tubes bare and venting the sill would cool the oil ala porsches loop cooler )

Hi
I too run a dry sump for the reasons above.

I have a roadgoing Sprint which I sprint on occaision.

I also use a dry sump tank which lives in the passenger footwell. It runs from the engine bay through the bulkhead to the bottom of the footwell. The engine bay is sealed from the footwell with an ally plate I had welded to the tank about 1/5th of the way down.

I used a rally navigators footrest to keep the passenger's feet away and there's still loads of room.

I had a problem heating the oil so i don't run an oil cooler but a Mocal Laminova water to oil heat exchanger. This has the advantage of heating the oil quicker. I have a caterham radiator to cope with the additional cooling requirement and an electric water pump.

At present, the oil is only reaching around 85 degs with the engine running at between 85 and 90. Am currently trying to work out how to decrease engine temp and increase oil temp with this set up. I think the principle is correct - I just need to tweek.

If I can work out how to attach a photo, I'll have a go - tried but failed. send me an Email me if you want them


Good Luck
Gavin

- if you don't have to worry abt FIA periods, just don't worry.... Not all of us are that lucky! The scruteneers I meet don't care what I declear, they care for the homologation form and my Historicat Technical Passport.....
You lucky guys...!

Dag

Beware of the fuel tank foam solution.
My company tried it with the thought of putting it into production cars.
It works to some extent with hot sloppy oil but not as well as a decently baffled sump.
Problems start when the ambient temperature drops. The old oil pump doesn't like scavenging the thick cold oil through the extra resistance that the foam presents. Not very healthy for cold starts!
I also wonder how much muck hangs onto that foam, staying in the engine even when you do an oil change.
John