Which is better ?
Does Lotus only offer the Accusump or do they also offer an oil pan?
I have read that quite a lot of people are saying that an oil pan works better than an accusump, but then I can’t understand why Lotus keeps installing the Accusumps in their track cars.
Can someone please enlighten me ? 
The Accusump is a ‘belt and braces’ approach to a problem that only affects 0.0001% of cars and drivers. A baffled sump, such as the Moroso, will do the same job 99.9999% of the time. If you are a track God and corner at sustained high speed/‘g’ loading then I’d fit both, I don’t so went with the Moroso!
I was looking at this and decided I will eventually go the Moroso route with an oil temp and pressure gauge. Right now I’ve only seen the oil light come on a handful of times on track days but with tweaks this year it will hopefully be a lot more often.
I have done a bit of research on this and found a few interesting posts from ads_green, who is a member on SELOC (not sure if he’s around here too), who seems to be quite knowledgeable about this oil issue.
With the Toyota there appears to be two issues - oil moving away from the oil pickup and oil getting trapped in the head.
Dry sump will help with the oil moving away from the pickup but I’ve yet to see a decent setup for the toyota unit that isn’t ���’s. Baffled Sump can help a bit too however neither will help with the second issue of oil getting stuck in the head. If the oil isn’t getting down into the sump then it doesn’t matter if it’s wet or dry it aint gonna get any oil. An accusump can help out a here as it can supply a limited amount of oil independently of the main supply.
and
The accusump can keep supply going - the idea is that the corner finishes before the entire accusump is drained. Unless you are going round and round in circles this will generally happen. As soon as oil is getting back into the sump it’ll start heading back into the accusump before it has chance to pool and get hit by the crank.
Rather have a situtation of a possible transient (but unlikely) overfilled crank than no oil getting to the engine at all!With a baffled sump there is still only so much oil - it will start surging at some point and under significant load whilst much better than the standard sump, I’d wager it’d run into problems before an accusump probably would.
That being said there’s nothing to stop you fitting bother baffled sump and an accusump. They both have advantages and won’t work against each other.
here’s the link to the original posts : SELOC Forums
This is an ineteresting issue, and one I have done a lot of work on.
One of the biggest reasons that oil gets trapped in the head of an engine, is because pressure formed in the crankcase breathes UP the oil return hole from the head. This is because normally the only exits to atmosphere are in the rocker cover (like on a K series) To be honest I can’t picture a Toyota engine in my head and remember where they breath from, but I am pretty sure there isn’t a direct breather to atmosphere from the crank case.
Crankcase pressure is a more regular occurance on forced induction engines as the excess pressure blows past the piston rings and pressurises the crank case. The Audi engine (just using it as an example, the cosworth YB is the same) has a huge breather from the crank case and another one from the rocker cover and this deals with everything nicely. I know I have said it before, but a breather system also needs a return to the sump, in my opinion it is bloody useless without one!!! What is the point of pumping oil out of the engine and just leaving it out of the engine. It isn’t lubricating much, sitting in a catch tank in your boot!!
The other argument is that engines shouldn’t breath. Agreed, they shouldn’t. My wife shouldn’t have 176 pairs of shoes (i’m not exagerating!!) but she does and engines do. So we just have to deal with it. My wife has a walk in shoe cupboard (again I wish i was joking!) and my engine has an internally baffled breather tank bolted to the back of the block (my own design), that takes inputs from the crank case and the head, has a return to the sump (below the oil level) and a vent to atmosphere.
Just my 2p
Sean…
[quote=SeanB]This is an ineteresting issue, and one I have done a lot of work on.
One of the biggest reasons that oil gets trapped in the head of an engine, is because pressure formed in the crankcase breathes UP the oil return hole from the head. This is because normally the only exits to atmosphere are in the rocker cover (like on a K series) To be honest I can’t picture a Toyota engine in my head and remember where they breath from, but I am pretty sure there isn’t a direct breather to atmosphere from the crank case.
Crankcase pressure is a more regular occurance on forced induction engines as the excess pressure blows past the piston rings and pressurises the crank case. The Audi engine (just using it as an example, the cosworth YB is the same) has a huge breather from the crank case and another one from the rocker cover and this deals with everything nicely. I know I have said it before, but a breather system also needs a return to the sump, in my opinion it is bloody useless without one!!! What is the point of pumping oil out of the engine and just leaving it out of the engine. It isn’t lubricating much, sitting in a catch tank in your boot!!
The other argument is that engines shouldn’t breath. Agreed, they shouldn’t. My wife shouldn’t have 176 pairs of shoes (i’m not exagerating!!) but she does and engines do. So we just have to deal with it. My wife has a walk in shoe cupboard (again I wish i was joking!) and my engine has an internally baffled breather tank bolted to the back of the block (my own design), that takes inputs from the crank case and the head, has a return to the sump (below the oil level) and a vent to atmosphere.
Just my 2p
Sean… [/quote]
Fook the LSD, I’ll have one of those then…and Fee wants a look in the shoe cupboard 
Sean, is the oil that’s "breathed out " somewhat diluted and compromised anyway ?
What are the benefits of re-using it ,over simply catching and discarding it , replacing the lost level with new oil ?
Cost is one obvious issue …
Anyhow the Yota’s dont use any lol !
Only kidding …
Reading an article on a US web site ( can’t find it now I want it ! ) about the accu-sump. There was concern that while the accu-sump was ‘refilling’ the oil pressure would drop and by default pump less oil to the engine until it ( the accu-sump ) was full again, there by depriving the engine of oil when it needed it most, as you accelerated out of the corner ( or spin off the track ) Not sure if this is a real concern or just worrying about nothing. It all depends on the Toyota oil pump and if it has excess capacity to do both with out reducing the oil flow below the minimum required. ( Which no one seems to know. )
There was a link
http://www.daileyengineering.com/2__zz.htm
to a very nice looking dry-sump system. Looks to good to hide under the engine. Mind you the estimated cost for the dry sump system was about �2500.00 + fitting. For a 10-15 hp gain at the wheels, the gain was quoted after the conversion. As you mention if you are a ‘Driving God’ the �/hp is quite good value, compared to other enhancements. But the other down side is extra weight. Another option would be a larger oil pan with a lower oil pick up with more oil, or an oil pick up that moved as the car cornered. Just a few thoughts.
Graham
If your keeping the oil topped up this shouldn’t really happen? Not meaning to offend but are you sure it’s not the brake reservoir? I had to pull one of the wires off the reservoir to stop that going off.
If your keeping the oil topped up this shouldn’t really happen? Not meaning to offend but are you sure it’s not the brake reservoir? I had to pull one of the wires off the reservoir to stop that going off. [/quote]
Seen the brake light too I’ve only seen the oil light a few times, primarility on a long sweeping bend at Colerne and when I’m spinning (which is too regularly) 
[quote=Neil_C]
If your keeping the oil topped up this shouldn’t really happen?[/quote]
That’s what most people are hoping.
However, I for one can’t imagine, that all those people whose engine broke down, had not checked their oil level prior to going out on track…or ? 
Mines checked before and during, I even stick a bit extra in to be on the safe side.
I continued my research and here are 2 interesting answers from Lotus Sport:
Russel Gibbons:
“The accusump releases more oil into the engine once it detects low oil pressure.The bottom end is not the problem like a lot of owners think, they are junking the accusump and fitting baffled pans which is not a solution
…
For extra peace of mind I have no concern with you fitting a Moroso pan as additional protection but the benefits are minimal over the accusump system.”
and Nick Adams:
“The issue is not just simple oil surge, what happens is the oil gets caught up in the cylinder head and cannot drain back down the the sump quickly enough. This means that the oil level in the sump drops and then oil surge starts to occur when the level gets too low. The accusump works well to overcome this, but making it larger will not necessarily help as it is already as large as it can be without dropping so much oil into the engine that it starts to lead to issues with overfill when the car comes out of the corner. If you want further protection, a larger capacity sump in addition to the standard accusump would be a good idea, preferably with baffles in to reduce surge. The larger capacity gives you longer before the oil level starts to get critical and the accusump has to cut in. Baffles in the standard capacity sump won�t help much as the oil still gets caught up in the head and the baffles won�t have much oil to catch”
The 2ZZ has a crank breather coming up to the cam cover, a breather outlet and PCV valve in the cam cover. The problem with the Toyota 2ZZ is when under high G loads the oil will move from the stock pan pick up and the oil sitting in the head does not drain fast enough to make it back to the pan and will puke out the breather hose on high G right handers… The fix is a baffled pan…
Right, this sets me back at the beginning again. After my previous post, I thought that a baffled pan wasn’t the right solution (see Russel’s answer : [color:#FF0000]a lot of owners are fitting baffled pans which is not a solution[/color]).
Will we ever know for sure who’s right or wrong ?
Well I’m not tryin to sell you anything and I own and drive a stupid high HP Lotus like a madman…without ever having an oil related issue after 48,000 mi.
Oh yeah no Accusump.
here’s another interesting thread from a moderator (TimMullen) on Lotustalk explaining the Accusump:
In reality, when the Accusump “discharges”, it’s not a big “whoosh” and all the oil is suddenly used up. The oil system itself is rather restrictive, that’s what gives you oil pressure in the first place - the pump trying to force oil through the various passages. When the pump “runs dry” the oil is simply sourced from the Accusump - they can provide pressure for several seconds depending on the size. Although an Accusump can be configured so that it doesn’t open until the pressure drops below a pre-set point, usually they are “open” - they are always part of the oil system, with oil capacity (and pressure) fluctuating with the regular oil pressure of the engine. Basically they act as a large buffer.
When the Accusump has supplied oil to the engine when the pump runs “dry” the oil is not getting down to the engine’s pan, while you are cornering (the reason the pump went dry). As the Accusump supplies the oil, yes, the total internal volume of oil in the engine has gone up, but only by the amount the Accusump has discharged. That oil now has to travel back into the pan, along with the existing oil in the engine. That will, again, take some time - it doesn’t all just go “whoosh” and suddenly get to the pan. Once the pump is “wet” it can start pumping oil again, and supply the oil flow and indirectly, the pressure. As the oil is pumped, pressure builds - some of the oil flow is into the engine’s oil passages, and some into the Accusump - but the pressure is balanced. The Accusump is not suddenly filled back up with oil, it “bleeds in” with the raise in the oil pressure - that same oil pressure that the engine internals sees. The biggest difference in the oil system operation will be that the oil pump pressure bypass will not have to open as soon during high RPM operation as the pump will be filling a larger volume (the engine and the Accusump), but still at the normal operating pressure.
As an example, your engine is pumping 50 PSI of oil pressure. The Accusump also holds 50 PSI of pressure (and a volume of oil). Now you hit a corner - the pump is making 50 PSI and no flow is coming in or out of the Accusump. As the corner continues the pump goes “dry” and the oil pressure starts to drop. At this point, the oil is supplied from the Accusump at the “current” 50 PSI. As the oil slowly flows out of the Accusump, it provides 49, 48, 47… 20 PSI. The oil will flow from the Accusump until the pressure in the Accusump reaches the same level as the engine. Hopefully before it gets too low, you are done with the corner, and the pump is “wet”. It’s now picking up oil from the sump and the oil pressure is raising - it gets to 25, 30, 35… 50 PSI. While the pressure was raising, the oil was flowing throughout the engine and also back into the Accusump. Also while that oil pressure was raising, the oil was flowing back into the sump, so by the time the pressure is back up to normal, the volume in the sump, and the volume in the Accusump are back to normal too. It will be highly unlikely that there will ever be too much volume of oil in the sump (if there was, the pump would have been able to pump it out quicker and build up pressure faster, which in turn would have filled the Accusump faster).It’s not like all the oil is diverted to the Accusump once the pump starts pumping again - the oil goes to the engine and the Accusump in balance.
Although pretty much everyone will agree that a dry sump is probably a better deal, an Accusump is far from a band-aide. They are a proven design and have been used in racing from many years. An Accusump also provides one thing that a dry sump cannot - pre-oiling. An Accusump can “dump” oil just prior to starting the car, such that you always start the car with oil pressure already in the engine (and turbo if equipped).
Although I don’t expect to need either a pan or an Accusump, I believe I’d opt for the Accusump first.
Finally, you can always add a pressure warning buzzer to the Accusump that “tells” you when it’s being used - something that you can’t do with a pan. In the case of the Accusump, if you are dropping pressure/“running on reserve” the buzzer can let you know. With a pan, when you run out of reserve, it’s too late…
Here’s the link : (2ZZ) dry sump? | Page 2 | The Lotus Cars Community
Yeah that’s great info from a guy that will never make more power or drive his car hard on track or canyon.
Seriously if you are worried about an oiling issue talk to guys that beat on their cars and see what they use. I know of two guys with a cup and 211 that have both had engine failure with an Accusump system installed…
They now run baffled pans
[quote=frank]Yeah that’s great info from a guy that will never make more power or drive his car hard on track or canyon.
Seriously if you are worried about an oiling issue talk to guys that beat on their cars and see what they use. I know of two guys with a cup and 211 that have both had engine failure with an Accusump system installed…
They now run baffled pans [/quote]
frank, which baffled pan would you suggest then?
The Moroso is what I’ve been using since day one…and I’ve heard of no oil related failures with this pan so far… A increase in oil volume also…6qt. in pan