has anyone every tested the return valve spring on the oil pump with compressed air, to see at what pressure it opens (actually at the pump) and what effect adding the shims does to this pressure.
some people stretch the spring, others add washers, but what if we got an uprated spring made, with different characteristics?
eg: http://www.testedspring.co.uk/home.asp
i have jacked the pump on both my clio and gt now both motors hold 5 bar but that is brake off pressure can't see it makes much differnce at low rpms
or this place-
http://www.assocspring.co.uk/
Perhaps I'm in the minority, but I've never felt the need, nor seen the reason, nor ever carried out, increasing the oil pressure?
I think you'd be wasting your time testing with compressed air, it's just a bit too runny to learn anything.
I'm sure I read on one of the manuals, possibly a T2 one?, about adding a washer, if it's good enough for renault it's good enough.
if you read four stroke performance tuning, it states that for every 1000rpm another 10psi is needed. most gtt's get 45-50psi at 3-4k revs, but dont produce any more pressure after that.... if you rev your car to 7k or beyond, then i reckon that you need 70psi or more.Originally Posted by Mart
also, i'd put money on the biggest engine failure that R5 gtt's suffer from in recent years is bottom end failure due to oil starvation.
Isnt the volumetric displacement of the GTT mechanical pp fixed proportional to engine speed as it is a displacement pp (please correct me if i am wrong)?
If so you would be trading off pressure for flow rate, (Bernoulli's principle) and as i understand it the bearings (big little and main) require a set minimum pressure to float but also a high flow to keep the oil wedge, especially at high RPM?
Unless (and i cant remember the details of the pp and spring) by shimming you get more work done out of the pp but the same displacement then you are entering this trade off dilemma? If you want to be sure it might be worth looking at a bigger Pp - but as Mart says whats the point, are you still eating cranks / bearings?
Sparkie - you type too fast
Or that the pump rotors have worn, hence a natural reduction in oil pressure.
Going on your previous comment, does that mean the vtec boys are running 90psi then? Did the Cup cars run a higher oil pressure?
Pressure is restriction to flow, and given that that pressure is dictated (in the majority) by the bottom-end bearings/tolerances, all you're doing is backing up the oil at that point in the circuit even more so, no?
I always ran/run o.e oil pressure, and have not once suffered a bottom-end failure of any sort. What can't speak, can't lie...
ive funked more than a few bottom ends....
what do the cup cars rev too? - how often were the engines rebuilt?
standard Vtec engines dont usually have a turbo to drain oil away from the bottom end.
-its the equivalent of looking at the standard campus engine and noticing why renault fitted a different oil pump.
ive also managed to wear out the top and bottom of the liner so it went like a 'sand timer' - due to revs and lack of lubrication. - obviously thats oil flicking up the bores, but with more oil pressure there is more oil leaking out of the sides of the bearings to flick up the bores....
here i go on one of me weard thinkinkings
get a hose/pipe put one end in a bucket of water .then make sure the hose is full of water then swing the other end of the hose around you will find that water pours out of the swung end
now apply the same thinking to a spinning crank . i think you will find that a spinning Crank will suck up it's own oil.
I think you would maybe increase the oil pressure if you had a larger pressure drop around the oil feed circuit ie if you had a bank of oil injectors firing at the piston bases. You would need to measure the oil feed circuit (all diameters), find out the flow rate required, the pressure drop through the system and then look at the circuit bottle necks, adjust the diameters and then adjust the pump pressure. Not sure its possible really unless someone cuts a block up.
apparently they do run about 80psi, cos when the VTEC kicks in, the oil pressure drops due to the oil operated switch that kicks in the VTEC system
Commonly referred to as the 'Fail Valve'
yeah ive seen alot of posts on the net about it...
All i did to raise the pump pressure was to put a 6mm spring washer behind the spring in the cap which is held in place by the split pin
So what exactly has to be changed to increase pressure?
nothing
apparently alegedly masking tape works
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