Anti-cav tank

[Nick]

Has anyone fitted one of these to a K and did you think it worthwhile for trackday use?

 

I'm considering it as it's cheaper than the full jobby of a dry sump, and on some tracks I worry about oil surge. Round Gerrards on ACB10s I couldn't go flat out without the oil pressure needle hitting the red. I normally use A032Rs but don't want to kill my engine.

 

Thanks, Nick

[Tim Seipel]

Nick

 

I thought the same. Mine lasted about 3 years of sprint and hillclimb - er notice the past tense! You could try the tappet feed blanks and mods to baffles in the sump (only if using mechanical tappets of course). Oil Airation tank will not solve problem of no oil around the pick up pipe. It only sorts most problems when the oil is airated due it being wipped up into a frenzy! Especially on hydraulic tappet engines.

 

My experience is either fit less grippy tyres for track days. Defeats the object rather! OR start saving!!!

 

Tim

[Tim Seipel]

Sorry I did mean oil DE-airation tank. Nick named the 'steam boiler' in certain circles.

[Nick]

Hmm, so the good news is I don't need to spend a few hundred pounds on an anti cavitation tank; the bad news is....I need to spend much more on a dry sump?

 

sad.gif

 

[Mike Bees]

This has been covered on the sevens list in the past. Peter Carmichael has data logs of oil pressure before/after fitting the the air/oil separator tank, it can't and doesn't eliminate the effects of surge but it does reduce them - when the pickup is sucking air you still get a supply of oil from the tank albeit at less pressure than before.

 

Mike

[Nick]

Thanks Mike, I always appreciate your advice. I do sometimes check the list but I can only connect to it very slowly and it takes an age.

 

That's the trouble with two forums as well I guess.

 

So, it would seem to help a bit but maybe not enough...

[Andy Checkley]

I've been using an Anti Cav tank on my K series VVC, and have now done 8 or so trackdays with it, and I can't detect any nasty sounds or other problems, in fact the engine seems to run very well. However, I have had the same worries and concerns. The only problem is that even if I wanted to dry sump the car, I don't believe Caterham support dry sumping on the VVC. Does anyone know why? Is it to do with the physical installation of the Caterham system or is it to do with the hydraulic oil operation of the variable valve timming gear?

 

The engine has now done 15,000 miles and I was going to have it rebuilt at the end of the summer. One of the reasons was to try and gauge how succesful the Anti Cav tank has been. I will post the outcome for those who are interested. Incidentally, I use A032's as well.

 

Apart from the details Mike has given above. I would be interested if anyone else has any thoughts about the effectiveness of Anti Cav tanks.

[Nick]

Andy

 

Peter Carmichael's data log can be seen at http://www.se7ens.net/pub7/data/PC_oil_surge.gif

From this it looks as though the Apollo tank is effective enough. I gather Peter Carmichael is not a slow driver (as the log time shows) so I think I may go for it.

 

I've heard that the VVC cannot be dry sumped as well but don't know why.

 

I'd be interested in your engine analysis when it's done.

 

[old captain slow]

Andy,

 

Does the engine really need a rebuild after 15k? My 1600 supersport has done about 20k and seems just about loosened up.

[Andy Checkley]

David,

 

I suspect that the engine doesn't need rebuilding, but this question of oil supply has been bothering me for some time, and if it turns out that the bearings and engine wear generally look good, then I will have a lot more confidence in the Anti Cav tank approach, as I will have done a number of other trackdays by then.

 

Nick, thanks for the link.

 

 

[Andy Checkley]

Nick,

 

I've just looked at the log and I think I agree with you. (Is this log definitely from a K with Anti Cav tank?) If it is, it seems that at no point does the pressure drop below 35psi, (approx 2bar), with a lateral G of just over -1. I haven't got the advantage of a data logger, but I suspect that your average 7 with reasonably sticky tyres wouldn't pull much more than this. (Anyone out there know what your average 7 with A032's pulls max?).

 

Also, what is regarded as a safe minimum pressure, and not knowing Cadwell Park are any of the corners long and sustained?

 

Thanks everyone for your input.

 

[Nick]

Thank Mike Bees for the link!

 

The log is for a 1.6K Superlight on ACB10s (stickier than A032Rs). I gather Peter Carmichael is a fast driver and from I remember of Cadwell times, the log confirms this. Therefore, on A032Rs, you are unlikely to 'surge' the oil as much as Mr C.

 

Apparently Roger King advises that 42psi is good so a quick dip to 32psi should be OK.

 

Cadwell has a glorious mixture of corners, including Charlies which is a long right hander - it is the one at the top of the circuit diagram on the log page. Looking at the log though, the biggest drops in pressure seem to be at slower corners, where the car is more violently 'flicked' perhaps.

 

 

Edited by - Nick on 4 Jul 2000 20:49:47

[Tim Seipel]

I mostly suffer oil pressure problems only on right hand corners that are slower. Ie you can really chuck the car into it. Something like Curborough hairpin is the worst. Trouble is I enter it at about 8500 rpm stand hard on brakes and turn in. Halfway round start applying power again at the same time pressure drops drastically As pressure tries to recover the engine revs are rising drastically back up to 8500 ish. The engine will not last forever under these circumstances!!