Accusump

[craig_007 1]

After doing first track session with my MI powered 205 I destroyed my engine but it wasn't the death rattle I got,The piston looks to have dragged on the liner and the rings melted to the piston,There was a lot of scorch marks down 1 side of the piston,The small end also had alot of wear (through to the copper) The other 3 were perfect,The big end on that conrod was also showing a little more wear than the other 3 but not as bad as I was expecting.

 

What would have been the likely cause of this ? I put it down to oil surge but would have expected to run the big ends/crank before melting piston rings !!!

 

Anyway the car is now rebuilt,When I stripped the car the previous owner fitted a S16 sump with trap door but he left the spacer bar on and did not extend the pick up,I assume the deeper sump with spacer and standard oil pick up could have aided in the death of my old engine ? I have now extended the pick up !!

 

Anyway to my point...

 

I'm thinking of buying a 6 pint accusump with manual valve,I have no knowledge of these(I know the principle of them)

 

I'm wondering as to how I would set the discharge pressure on the vessel as surely I wouldn't want it pumping the extra oil into the engine until the oil pressure dropped low enough while cornering/braking(I'm thinking something like 20PSI)

 

Is it even possible to set the discharge pressure on these ??

 

If anyone has any knowledge on these then feel free to pass it on,I've cheked some past posts etc but nothing really gives me much information on them !!

 

Thanks Craig

[Batfink 201]

Have a look at Camerons car build. Fit a Gti-6 head and forget the accusump

[craig_007 1]

Haha,I did read last night about the problems with the head,I'm a little to late now as I have the old MI head fitted again.

 

Thanks for the info though.

[boombang 2]

Make sure the accusump is full of oil before you open the valve with the engine running!

[Galifrey 1]

Have a look at Camerons car build. Fit a Gti-6 head and forget the accusump

 

Installed one in my friends 800bhp Skyline which kept blowing bearings due to surge. We used the electronic valve, and it was pretty much plug and play once setup.

 

IIRC you have to pressurise the system to start with, then depressurise to about 10 psi, once the engine is started the pressure gauge on the tank should show the same as your oil pressure, and the Accusump fills.

 

In the event of loss of oil pressure the Accusump provides around 10-20 seconds of oil and then refils once there is sufficient pressure.

 

The larger the Accusump, the longer it will provide oil for.

 

The main thing I would say is make sure the oil pump is in good condition itself and working well, as otherwise the Accusump will not do its job properly.

 

Many of the BEC (Bike Engined Cars) guys use them in the cars instead of dry sumping, and they have had good results.

 

One question I would ask is: Can you fit an oil return from the cam cover to the sump? From what I read, the MI seems to hold a lot of oil in the head once running, is that correct?q

[Batfink 201]

Haha,I did read last night about the problems with the head,I'm a little to late now as I have the old MI head fitted again.

 

Thanks for the info though.

 

Well the other thing I would do is to improve the drainage from the head to the sump but thats a head off job too as you would need two threaded holes in the head.

I'd rather use methods to solve the issue rather than mask it by pumping masses of oil into the system.

[Batfink 201]

Installed one in my friends 800bhp Skyline which kept blowing bearings due to surge. We used the electronic valve, and it was pretty much plug and play once setup.

 

IIRC you have to pressurise the system to start with, then depressurise to about 10 psi, once the engine is started the pressure gauge on the tank should show the same as your oil pressure, and the Accusump fills.

 

In the event of loss of oil pressure the Accusump provides around 10-20 seconds of oil and then refils once there is sufficient pressure.

 

The larger the Accusump, the longer it will provide oil for.

 

The main thing I would say is make sure the oil pump is in good condition itself and working well, as otherwise the Accusump will not do its job properly.

 

Many of the BEC (Bike Engined Cars) guys use them in the cars instead of dry sumping, and they have had good results.

 

One question I would ask is: Can you fit an oil return from the cam cover to the sump? From what I read, the MI seems to hold a lot of oil in the head once running, is that correct?q

 

It sounds like the electronic valve is better than the mechanical version as I've never seen good results with them.

[Galifrey 1]

Make sure the accusump is full of oil before you open the valve with the engine running!

 

Hmm, I think most people open the Accusump valve just before starting the engine, as a pre-oiler. If you use the electronic valve, this is actually automatically what it does.

 

Or maybe I am misunderstanding what you are saying?

[Galifrey 1]

It sounds like the electronic valve is better than the mechanical version as I've never seen good results with them.

 

I wouldn't even bother with a mechanical valve on a road car, it's just too much hassle.

[Sandy 191]

Craig, that sounds like overheating or inadequate piston/liner clearance if it's around the middle, possible lean mixture/det promoted if it's at the top. It would not be oil surge. Pics would help.

[craig_007 1]

Sandy,

 

It was around the middle,The the piston rings were melted to the piston really quite badly,The side of the piston was badly burnt and scored and had dragged on the liner ! The other 3 pistons had not a mark on them ?

 

To be honest I never gave a thought to piston/liner clearnace or overheating,I just put it down to lack of oil !!

 

As I say,I now have the car running again,I honed the liner as it wasn't to badly damaged,I stuck another piston and rod in.

 

The piston that came out had C stamped on the crown and the piston that went back in had B stamped on it,So this will be giving a little more clearance on the liner !! Is this a good thing or bad ??

 

 

Craig

[GilesW 41]

Hum.

 

To me that sounds so unlikley to be oil starvation you simply MUST find out the cause and address it before driving the car (anywhere in my opinion).

Oil surge (starvation) would effect everything (to a greater or lesser extent), yet you are clearly saying all bar one component was fine.

 

As Sandy has said that really does sound like over heating.

 

Maybe the fuel injector not working (plug look lean, or indeed melted??), det marks on piston?, inlet gasket ok? Wiring to injector fine?

 

I think a good starting point would be to get all your injectors cleaned and tested (and a report given to you) so you know if they are working. WIll cost you about £40.

[craig_007 1]

Forgot to mention,

 

I'm sure I threw the other piston away in digust !!

 

I still have the existing conrod witht the wear on the small end but I'm thinking that won't give much of a clue to what went wrong.

 

Forgot to mention,

 

I'm sure I threw the other piston away in digust !!

 

I still have the existing conrod witht the wear on the small end but I'm thinking that won't give much of a clue to what went wrong.

[craig_007 1]

The car is running 40mm motorbike carbs,They were set up before I bought it by Bogg Bros.The crown of the piston looked the same as the other 3,When I lifted the head off there was no real signs of damage from up above,It only became apparant when I removed the piston from the liner.The spark plug was also undamaged !!

 

When the engine let go I had 10mins left of a 2 hour track session,I wasn't on track for the full duration but I did spend the majority of it on track,Could it be possible that the oil temp got excessivly high and started to break down causing the over heating on that cylinder/liner ??

 

Thats just a stab in the dark and is mostly probably a million miles away from what happened !!!

[Cloverleaf 1]

When the engine let go I had 10mins left of a 2 hour track session,I wasn't on track for the full duration but I did spend the majority of it on track

 

I never tend to spend more than 20 minutes on track without a cool down including a warm up lap or two and a cool down lap. I think it's asking for trouble...

 

But as others said, oil surge wont cause your rings to melt to the piston! I'd go with what Sandy has said.

[Galifrey 1]

Is it possible a carb flooded and washed the bore?

[Sandy 191]

If you're confident the liner/piston clearance was ok, or somewhere near, then it sounds like straight forward overheating. If it was mixture/spark related, it would have started above the top ring.

[craig_007 1]

I'm as confident as I can be that the liner/piston clearance is in the right region.I had ruled out fueling/spark also as I was aware this kills the top of the piston and all was good there.

 

When you say over heating,Would this likely be oil or the coolant side or a combination of both ??

 

To be fair that does make sense,From what I recall the scorch marks were evident on the piston,Why would this cause the small end to become marked(lose it's coating and rub through to the copper)

 

On the Accusump,

 

I recieved an email from accusump,

 

To get the oil accumulator to discharge it's quantity of oil at a certain PSI I would require the electric EPC valve.There is a choice of a few different release pressures.

 

20/25 PSI

35/40 PSI

 

The list goes on,I'm thinking of going for the 20/25 PSI valve with a 6 pint accumulator !!

[Sandy 191]

Coolant overheating or big time air in the system. The resulting piston distortion could cause small end damage.

[mmt 15]

Hi Craig,

 

Did you get the accusump? How did it work? What´s your experience so far?

 

Where did you get it from?

 

Thanks