1.9 Mi16 And Semi-slicks

[James_R 3]

Yeah I've looked over the thread, the glaring oversight made was that you set the pressure in the accsump when charged and from reading it it was set at 75-80psi, which means it dumps it's oil anything below that.

 

When set properly, 25-30psi it will only discharge the oil in it below that pressure.

 

So no I don't rate that "informative" thread.

[Rob Thomson 6]

When set properly, 25-30psi it will only discharge the oil in it below that pressure.

That simply is not how the Accusump works.

 

You actually set the surcharge, which is the pressure above which the Accusump starts to fill and below which it'll be completely empty. The 75-80 psi is the maximum pressure when it's full, which just happens to be the peak oil pressure.

 

God knows how long ago I tested that Accusump on Antoni's car and wrote that article... three or four years? The laws of physics haven't changed since then but I have read about lots of people saying the Accusump does help and I'm prepared to believe them because something is always better than nothing. It might even help enough to make a XU9J4 last for a sensible number of trackdays, but Antoni's still suffered from shocking surge and IMHO he was absolutely correct to ditch it and get a dry-sump.

[Dino 3]

Nothing changes as time rolls by I see!

 

These oil surge discussions are similar to the ones we were having 5 - 6 years ago!!!!! Although I'm not sure if it was available or we knew about Accusump back then.

[James_R 3]

With out wanting to come across as completely dumb, it was set up so it was discharging at idle

 

they way I've been explained it by people that use them is you set the full charged pressure to the pressure you want it to realse at say 2 bar, so when the engine's oil pressure drops sub 2 bar the accusump suppliments the pressure, it's just a hydrolic accumulator effectively?

 

Or have I missed something?

 

I know there's the electronic valve thing aswell which means you can set a threashold pressure for it to fill so it doesn't "rob" pressure when it starts to recharge and only realises below a certain amount (at the advantage of a higher pressure)

 

But still I can't see hwo it can work properly set to discharge at idle :s

 

Again not saying they cure oil surge due to accumulation in the head but they can keep you going, which really is the outcome anyones after :s With a PTS baffle in on my Mi and fairly std sus I only found oil pressure loss an issue on prolonged tight swtich backs like M11north/A14east junction, various trackdays no hassle, but maybe I drive like a granny.

[C_W 3 1 Cars]

The PTS baffle was one of the first things I tried to combat surge around 2000 - with no baffles I was getting the oil light on at most circuits. With the PTS baffle it wasn't hugely better and was a waste of money IMO - complex looking but not of any real use.

 

With my own baffle setup since 2001-ish it's satisfactory (engine has done 50-60 trackdays!) which consists of a centre baffle across the sump with only a small gap under it around 2" long, an oil pump baffle from peugeot parts, and a top plate welded onto the top of the sump that just clears the stiffener brace. The gauge still moves but a red light occurance is saved only for Island bend at Oulton Park.

 

I briefly ran cut slicks - although they were well past their prime - and it didn't seem any worse at Cadwell (only slight fluctuation on the oil pressure gauge).

[Rob Thomson 6]

With out wanting to come across as completely dumb, it was set up so it was discharging at idle

 

they way I've been explained it by people that use them is you set the full charged pressure to the pressure you want it to realse at say 2 bar, so when the engine's oil pressure drops sub 2 bar the accusump suppliments the pressure, it's just a hydrolic accumulator effectively?

 

Or have I missed something?

Sorry, you've been misinformed.

 

Antoni's surcharge was set to 7psi, which was what Accusump (or possibly PTS) recommended to him. But that doesn't mean it discharges at idle...

 

An Accusump is indeed a hydraulic accumilator. You basically have a cylinder with a piston in it. One side of that piston is connected to the engine oil gallery. The other is filled with air set to a chosen pressure, which acts as the spring. That's just about all there is to them, they're dead simple. If you pump up the 'air' end the piston will move to the 'oil' end unless there's something to resist it. The only thing that can resist is oil, but that oil has to be at a higher pressure than the air. In other words, unless oil pressure is higher than the surcharge pressure the Accusump will be empty. The surcharge pressure is the pressure at which the Accusump starts to fill with oil. And conversely, when the Accusump discharges it's at the surcharge pressure that all its oil has been expelled.

 

At the other end of the scale, the Accusump is only ever 'full' when the engine's at its maximum oil pressure, although a good proportion of its volume is still filled with compressed air. As soon as that oil pressure drops the Accusump expells oil until the air pressure is equal to the new oil pressure. And so on and so on. It doesn't matter what surcharge pressure you set, the Accusump will discharge as soon as the oil pressure fluctuates (unless you have some clever electronic valving).

[James_R 3]

Ok so it's dyanmic and will flucuate, but with the maxiumum pressure of 75-80psi means it will have emptied 2/3rds'ish at idle, which was some 4L or something :s

 

If you reduce the peak pressure then it over comes this, I follow the surcharge i.e when it's empty will change but it's the inital discharge that matters, if its emptied by the the time you're at the low presure bit it can't help, so wil stil have issues.

 

Anyways it's all acedemic, it's not a cure but helps as people running them will tell you.

 

 

Some surge more than others just try it out

 

Certainly for lapping at the ring there's not really anywhere to have issues bar the right hand hairpin at the top of the hill the rest is wide open.

[welshpug 1,636]

could always slap the 6 head on the 1.9 bottom end

[James_R 3]

That's the future

[Alan_M 66 1 Cars]

could always slap the 6 head on the 1.9 bottom end

 

Is it a bolt on job, or are mods required?

[James_R 3]

yeah use XU7 headgasket and bolts,

 

custom bits;

 

downpipe

breathers

ecu

 

you see about 11.2ish:1

 

A friends just running his in on emerald mapping next thursday, drives like a 6 lump too, way more torque than a Mi has. but yet to see if it helps

 

The head will still fill up with oil, the fact it can't drain back to the sump coupled with the head filling up means it might just com eout the breather system, not entirely sure it's the head filling up that's at fault.

 

A bath not draining fast enough won't drain faster for a smaller bath being put in with the same drain on if it's filled as fast? still a very light engine unit, power will be interesting too

[VisaGTi16v 1]

From what I remember with posts on here the GTi6 head has a second drain which the Mi doesnt. Surely its quite a simple job to tap a hole in the head and run a pipe but where to, top of the sump at the front? I seem to recall Paul/pddc(sp!?) did something like that on his race turbo 205 he was building before selling it

[Alan_M 66 1 Cars]

I've got a scrap Mi head in my garage, might look into this extra oil drain on my nightshifts this weekend.

[welshpug 1,636]

I thought it wasn't so much that the oil cant drain fast enough, but that cornering forces make the oil pool away from the drain channels.

 

Either way I'd be interested to see the results of that alloy Mi/gti6 hybrid.