oil accumulator

[andy wright]

A couple of months ago, I posted a question about the Moroso oil accumulater I had fitted to my Integrale. Specifically the problem appeared to be connected with the electrically operated valve that can be fitted. Anyway, the problem was sorted once I had fixed my schoolboy error. The valve is controlled via relay which, in turn, is powered by the ignition. That is, once the ignition is'on, the valve is open and oil can flow both in and out of the accumulator. Ideal for a track day or (very) spirited driving elsewhere. However, the drawback is that one of the real advantages of the system is compromised as , on switch-off, oil pressure is likely to be low(tickover and hot) Thus, on the next start-up, the priming feature will not be very effective. Here comes the cunning plan which works. Visit AES (auto electrical supplies) and buy one of their 12V 20A 15sec relays. This neat relay, once activated, will hold its load contacts closed for 15 sec and then open . The effect is that the oil stored in the accumulator is, in effect, at the highest pressure produced by the engine on its previous run. On start-up, the relay opens the valve, priming the engine with about 1.5 litres of oil at 60+psi. 15 seconds later, the valve closes, allowing oil to flow one way, into the accumulator, until the next ignition of/on. For track days, I have fitted an overide switch on the dash to hold the valve open when needed
Andy

[miro-1980]

Andy,

I have the Moroso oil accumulator installed on my 131. The difficult part to actually make sure all works OK was to read the literature over and over again. Doing so I finally realized there is a counter-intuitive element of this electro-valve operation The tricky part is to understand that the valve "on" or "off" pertains to release oil from the accumulator (not drawing oil into the accumulator ). If all the piping is connected ( but the valve is electrically not connected at all IT WILL STILL DRAW OIL INTO THE ACCUMULATOR !!!

TO STATE IT AGAIN : IF YOU TOTALLY DISCONNECT ALL WIRES FROM THE VALVE THE MOROSO ACCUMULATOR WILL STILL DRAW OIL FROM THE ENGINE. BUT ONLY IN THE "ON" POSITION IT WILL RELEASE OIL BACK INTO THE ENGINE.

My experience is this: When I turn the ignition "on" the oil accumulated in the accumulator primes the engine. I keep the ignition on for few moments before actually engaging the starter (to get the fuel pressure worked up by the electric fuel pump and to make sure the he is enough fuel level in the carburetor). During this time the oil from the accumulator primes the engine with oil. When I engage the starter - there is already idle RPM oil pressure in the engine.

You say :

... the drawback is that one of the real advantages of the system is compromised as , on switch-off, oil pressure is likely to be low (tickover and hot) Thus, on the next start-up, the priming feature will not be very effective.

I would think this could happen when the oil pressure produced by the oil pump is too low and/or if you use oil with too low viscosity. (As my car is used exclusively for sports - I use racing oil MOTUL Le Mans 20W60) I have two oil pressure gauges: one: standard oil pressure gauge connected to the oil system and one: connected to the air side of the accumulator piston. With the two gauges I see immediate pressure flow from the accumulator to the engine when I turn the ignition on. I start the engine up when the pressure has equalized. I see no benefit in a relay plus an override switch. I actually see drawbacks : 15 seconds delay in priming the engine.

I am not sure I understand what you are saying. Normally at idle speed the 1.5 litre of oil is in the accumulator. When you turn the ignition on, the oil pressure in the accumulator ( maintained by the air pressure on the other side of the piston in the accumulator ) and in the crankcase is equalized. As there is no pressure in the engine the oil flows to the engine priming it (creasing oil pressure in the engine).

You say : "This neat relay, once activated, will hold its load contacts closed for 15 sec and then open . The effect is that the oil stored in the accumulator is, in effect, at the highest pressure produced by the engine on its previous run ." This looks good is on the shut down, but on start up it takes 15 seconds before the relay starts releasing oil to the engine.

The same can be achieved (if required) by revving the engine a up prior to turning the ignition off.

What oil do you use? Is your oil pump uprated ?


Miro

[andy wright]

Evening,
Thanks for your post. I agree entirely with your analysis of how the valve works. My point is as follows; If the electric valve is activated from the point of ignition 'on' until the engine is next stopped, then the accumulator will indeed prime the engine before start-up (assuming one is patient enough to pause for a few seconds) and will then allow oil to flow to and from the accumulator to retian an equalized pressure during running. dead handy if, on hard cornering, oil surge caused a brief drop in oil pressure; accumulator springs to the rescue by providing a reservoir of oil at a high pressure... enough for a few seconds anyway. All well and good, except that my car will spend some time on the road with me behaving myself. Under these circumstances, oil surge is not a problem. Hence I do not need the electric valve to be open, which means, when 'off' oil will flow to the accumulator, but not back again. On start-up, it would be nice to have an accumulator full of oil at as high a pressure as possible for priming. By using a 15 sec timed relay, on switch on, the engine is primed with the stored oil, then the engine is started. A few seconds later, the valve closes, so oil only flows into the accumulator; the accumulator therefore filling but not being emptied. I do not need to rev the engine just before switch-off to get the oil pressure up(hot at tickover, the pressure is not that high) If I am having some serious fun, or it is a track day, I use the override switch to hold the valve open to allow the two -way flow. I think that, in essence, we are agreeing with each other. Your application is for race only, so a timer relay is of no advantage. For normal road use, I maintain that it is.
Andy

[andy wright]

P.S Forgot to answer your questions. I do not have an uprated pump and I use 20-60 oil, often Motul .
Andy

[miro-1980]

Andy,

I believe we are in complete agreement. The relay installation redefines application of the accumulator, coming up with a different ingenious function of the system. For road use it seems interesting , but for my race use it would be too complicated to use. On a stage I am totally concentrated on the road and I do not even look at the REV mater . I just notice the shift because it is bright and centrally located. The only elements I respond to on a stage: are unusual loud engine noise, shift light , alternator light and low oil pressure light. I bet you I would forget about the override and once off it would remain off, until I killed the engine .... of the low oil pressure light would go on.



From between the lines I read that you have an oil pressure problem ( especially when the engine is hot). ( Is you compression OK and rings tight ?) If yes I would suggest that you uprate your oil pump. It is so easy to do (once the engine is out and/or sump is taken off) and really does a great job keeping the oil pressure high ! ( all you need is a thick washer under the spring !)

M

[Guy Croft]

1. "I do not even look at the REV meter"

You better fit a rev limiter then.

2. Uprated oil pump

AW's engine is an Integrale with crank nose driven pump. There is no need to pack up the relief valve spring on those.

G

[miro-1980]

Guy,


Re: Rev limiter

I really hardly look at the RPM meter . I just look (or rather keep in my eyesight) a rev warning light. It is set at 7000 RPM.

But I will install a rev limiter anyway. I have seen several engines ruined in seconds ( i.e. by gas pedal getting stuck) and the engine revving out of control before the guy activated a kill switch.

M

PS : thanks for explanation of the Ingegrale pump.

M