) so the oil circulates rather than accumulates 
Cheers
Alex
Simple question, but I've only ever dealt with 3 dry sumped engines, and certainly no bike engines with dry sumps!
On the new grasser, I plan to run 1 7 or 8 litre oil tank to feed the two dry sumped engines........
What stops the head of oil filling the crankcases of the engines up when they are not running? I'm just worried that while it is stood for some
time, I could end up with a serious problem if a crankcase full of oil on both engines!!!
Any thoughts, or anybody got a dry sump bike engine and tell me what happens on theirs?
edit to add the "when not running bit" !!!!!
[Edited on 18/12/06 by NS Dev]
The return feed sucks (literally ) so the oil circulates rather than accumulates
Cheers
Alex
I know that!!!!
I meant when the engine is stood and not running, I'm guessing the only seal between tank and crankcase is the pump rotor, in which case there
will be some leakage, which over time will surely fill the crankcase?
is there not an anti syphon valve fitted in the oil line
I know a couple of people with old brit bikes who fit a tap in the pipe at the bottom of the tank so it doesn't drain back into the sump.
The tricky bit is remembering to turn the tap back on before starting the engine.!
Also some have fitted a one way valve (simple ball bearing and a light spring type thingy) for the same reason. Some don't trust this in case the
valve sticks and so they go with the tap method above.
Cheers
Mark
Ooops 
LOL
Well I only know them from harleys, and the oil pickup from the tank is higher than the oil level in the tank (if that makes sense) so you get whats
in the pipe running back to the crackcase/sump if left lying for any time, I think the oil is too thick for much more than that to draw by
syphoning.
Hope thats more helpful than my last
Cheers
Alex
Just read that back and realised it doesn't make sense (not having a good day!) but I meant that the pickup goes in higher but obviously is then
piped to the bottom (or near) for collecting the oil.
Does that sound better or should I just give up now 
[Edited on 18/12/06 by ecosse]
quote:
Originally posted by mookaloid
I know a couple of people with old brit bikes who fit a tap in the pipe at the bottom of the tank so it doesn't drain back into the sump.
The tricky bit is remembering to turn the tap back on before starting the engine.!
Also some have fitted a one way valve (simple ball bearing and a light spring type thingy) for the same reason. Some don't trust this in case the valve sticks and so they go with the tap method above.
Cheers
Mark
I ran a dry sumped hayabusa and the oil does drain from the tank to the sump until they are both at the same level (like a hydrometer).
When starting the engine after standing, remove the plugs first and prime the system with the starter motor until the oil light goes out / gauge
registers pressure. Then crack it up.
Whilst the engine is cold it will appear that there is very little oil in the tank as the viscosity makes it slower to return, the level will however
return to normal as the oil warms up. Install a sight gauge in the tank to keep and eye on the levels. I made mine from John Guest push fit plastic
fittings for 8mm nylon pipe.
[Edited on 18/12/06 by Nick Skidmore]
quote:
Originally posted by ecosse
Ooops
Well I only know them from harleys, and the oil pickup from the tank is higher than the oil level in the tank (if that makes sense) so you get whats in the pipe running back to the crackcase/sump if left lying for any time, I think the oil is too thick for much more than that to draw by syphoning.
Hope thats more helpful than my last
Cheers
Alex
Just read that back and realised it doesn't make sense (not having a good day!) but I meant that the pickup goes in higher but obviously is then piped to the bottom (or near) for collecting the oil.
Does that sound better or should I just give up now
[Edited on 18/12/06 by ecosse]
Nat,
Aren't you better off running seperate dry sump tanks for each engine? If one engine goes bang and contaminates the oil or you lose a
hose/fitting on one engine you risk rogering both engines surely?
Ned.
Just make sure that the outlet from the tank isn't too high as all that can happen then is that you will have the same level in sump as you do in
the tank.
It takes about a week for the oil to drain level sump to tank
quote:
Originally posted by ned
Nat,
Aren't you better off running seperate dry sump tanks for each engine? If one engine goes bang and contaminates the oil or you lose a hose/fitting on one engine you risk rogering both engines surely?
Ned.
You need to run a tank for each engine to secure each has a known quantity of oil. On my GSXR engined racer the oil drains from the tank into the
engine overnight. I always remove the belt from the scavenge pump and manually turn the pump to refill the tank before the engine is turned to get
oil pressure up before firing.
Scavenge pumps are obviously designed to shift oil and air mixed back to the tank. If you start the engine cold with it full of oil, the scavenge pump
drive mechanism is put under tremendous load trying to move large quantities of thick cold oil, and can fail in extreme circumstances. You may have
noticed drivers of big single seaters at hillclimbs rev the engine hard for a few second before switching off. This is to empty the sump of oil for
this very reason.
ATB
Phil
Ok, so it sounds like my concern was founded, and like a tap will prevent the startup hassle (as long as I don't forget to open it!!!!! )
I had hoped to run one bigger tank rather than two smaller ones to save weight and complication etc.........is this not wise, and why not?
I get the blowup point Ned, and I suppose that alone probably makes a good case for one tank per engine.
In terms of "enough oil for each engine", I know the size of the original tanks as fitted by aprilia, and I was going to just double
that.
Any further comments (all being taken on board even if it doesn't sound that way, as I've never run two engines in one car either before! )
Accususump make an electrically controlled oil valve for their devices. could put it in line and wire it to the ignition. Ignition off, valve
closes.
Only concern, then, is wiring failure to the valve while engine is running!!!
dave
quote:
You may have noticed drivers of big single seaters at hillclimbs rev the engine hard for a few second before switching off. This is to empty the sump of oil for this very reason.
very good point Stu, only worry then is that I assumed the feed side of the pump liked to see some pressure head form the oil in the tank? Maybe not I suppose as you don't get much from the tank in the boot of a mk2 escort rally car when its piped all the way to the front! ?
Iwas trying to make two points. The first is that scavenge pump drivest under a lot of load when pumping just cold oil and not an oil and air mix. The
second is that your pressure pump will run out of oil before the scavenge pump can replenish the empty tank unless you prime it in ome way. To keep
the weight down on my car my tank has a running capacity of about 3 litres, the whole oil system comprises about 6 litres (Two oil coolers and big
pipework). That 3 litres in the tank is almost all retained in the engine when it is cold because of the viscocity,it tends to 'stick'
inside the engine onthe walls, the head, gearbox,clutch etc, so I find it important to get the tank as full as possible before the engine is started.
Once the engine is warm that 3 litres is all returned to the tank when running.
Assuming that the oil pumps in both engines are well balanced, and there is a lot of spare capacity in the dry sump tank, it is probably okay to run
just the one tank, albeit at the expense of some possible extra weight and the risk of damaging both engines should one of them get damaged and the
oil system gets contaminated.
ATB
Phil
quote:
Originally posted by NS Dev
very good point Stu, only worry then is that I assumed the feed side of the pump liked to see some pressure head form the oil in the tank? Maybe not I suppose as you don't get much from the tank in the boot of a mk2 escort rally car when its piped all the way to the front! ?
Does the scavenge pump return unfiltered oil to the tank? If both engines are same they should both take a similar amount from the tank and only have what they need in circulation at any time shouldn't they?
Pete,
typical/generic Pace 3 stage dry sump setup/connections (albeit on a vauxhall engine) here:
http://www.sbdev.co.uk/Info_sheets/Oil_systems/Connections%20for%20the%20SBD%20dry%20sump%20system%202.0L.htm
Ned.
[Edited on 19/12/06 by ned]
On the aprilia its a very simple setup, there are two connections on the engine, one that returns "used" oil to the tank via the cooler, and
one that supplies the internal oil pump from the tank. The filter housing is integral with the engine case and withdraws via two allen screws and is a
cartridge type paper filter.
My only concern was overfilling the crankcase with oil from the tank when the car was stood, bearing in mind I will have a taller tank (thus more
static oil head over the pump inlet) than that used on the bike.
Thanks for all the help, and particularly nick skidmore who has made some suggestions via u2u, including the obvious but clever point that I can make
a "double" tank which will still save most of the weight of a second tank, whilst keeping the oil seperate, which as ned pointed out is a
good idea if one engine lets go.
so just make a single tank with dual inlets/outlets with a large baffle/divider down the middle inside?
Effectively a single tank installation/situation/weight with seperate oil systems then?
Ned.
Exactly, funny how the obvious doesn't spring to mind when you are doing it yourself!
quote:
Originally posted by NS Dev
Exactly, funny how the obvious doesn't spring to mind when you are doing it yourself!
my 2p worth.
as has been said (I didnlt say it as it weemed obvious) is to have separate oil for tanks for the engines; my concern would be if one engine allowed
more oil into it o in worst case the oil for 2 engines ends up in 1 engine with the crank/psitons being immersed in oil = bye bye engine most
likely.
The positioning - I'd would say you want the level of the catch tank to be at such a level so when the oil does flow, it will not drain
completell out of the tank and avoid the above 'immersedd crank' scenario - I can ask my mate who has dry sumped his caterham since
he'll know for sure = also the web must addres this somewhere?
I don't think valves are a good idea.
Yes - I tank with baffle to keep the 2 engine oils sepearte ist he way to go IMO.
regarding the drainage problem, (the oil in the tank leveling out to the engine during standstil)
You could, mount an electric mocal pump in an extra line inbetween the sump and the tank, wire it up inbetween the ignition and an oil level switch
(any renault megane sump)
so when you turn on the ignition the pump goes sucking the sump dry, and on the break contact on the level switch run the wire to the starter motor
and Ignition feed so, when the pump is running you cannot cranck/start the engine,
when the level in tank is high enough the mocal pump stops (there's a 1 way valve init so it won't drain back) and you can start the engine,
it should only take a few seconds for the pump to drain the sump.
then you'd have 2 advantages, you won't have to do the whole take plugs out and look at the tankglas thingy, just turn the key into pos#1
and wait for the pump to stop
and when under any circumstances the drysump pumps fail or you're losing oil, the ignition systems stops working and the engine stalls. to be
very sure about things you can also mount a oilpresure switch in the ignition feed wire.
just a thought. surley you'd need 2 mocal pumps and level switches for twin engine twin tank arrangment
grtz Thomas
a very good idea, for road use very good indeed. I think the extra complication on the grasser would prob not be worthwhile but an extremely good idea nontheless!
you could do without the pump system offcourse,
but the level and presure switches wired to the ignition would still be a good idea, considering there's twice as many money to Blow-Up. have it
on the 20v after the 16v died because of little oilpresure.
grtz thomas
I've never done anything with dry sumps..... but a couple of points occurred to me during this thread;
1) you'd need 2 electric(?) scavenge pumps to take oil from each sump to the big tank - After a long stand, won't these empty the sumps for
you - no bother with taps or anything, just leave the engine on the ignition for 30secs before starting!!
2) if you have a 'shared oil' system & one of the 2 scavenge pumps dies (twice as likely as a single failure) then its engine will fill
up with ALL the oil - it will be damaged and the other will be ruined 'cos it has no oil!! sounds like you definately want independent systems to
me!
Bob
No electric pumps Bob, the engine is dry sumped as std and has mechanical scavenge and pressure stages built in as std, it pumps to a seperate tank on the bike in the normal installation, one of the reasons I went for this engine, funnily enough!
@ bob,
the electric pumps are only to scavange the engines after a long duration standstill. during run normal mechanical scavange pumps are used.
the TWIN seperate system was what we where talking about, 2 tanks + 2 engines hence 2 electric pumps for the way described above.
but Nes isn't going to use it as it'a race car, a road car in which you wanto be able to quickly drive of should beniefit from that
system
grtz Thomas
[Edited on 20/12/06 by thomas4age]
Cheers Fellas ;^)
Bob