stef12rr
Expert Class
Posts: 144
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posted March 04, 2007 03:54 PM
oil pump VALVE-ASSY-RELIEF
I need some advise about this valve can i put more pressure on the spring to add more pressure on the oil sys.
  
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CrotchRocket
Moderator
Bracket Racing with Betsy
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posted March 04, 2007 05:06 PM
 Edited By: CrotchRocket on 4 Mar 2007 17:06
Dont get crazy with the valve...The valve releases the pressure when it gets to a certain #...
The 12 needs more pressure at low rpm...
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dougmeyer
Needs a job
moderated
Posts: 2713
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posted March 04, 2007 06:18 PM
The relief valve has no effect on low pressure, it only limits the high end of the pressure curve. A 12 with an undamaged pump has all the pressure it needs at low RPM. The only way to get more pressure is to spin the pump faster (not gonna happen). You can increase the FLOW somewhat though, by carefully porting and smoothing all the passages in the pump and the the cases.
Doug
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entropy
Moderator
Posts: 8671
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posted March 05, 2007 02:48 AM
there are soooooooooooo many schools of thought on the 12's oil pressure situation.
I didn't like the low pressure at idle (oil light flickering) so i went to 15-50 syn and jacked up the idle.
Additionally, some experts said that the 12's "rod bearing issue" on stroker race bikes would be helped by shimming the relief valve, elevating pressure to 90-100 at hi revs. So i did that also.
A couple cautions here:
1. with 15-50 syn, and shimmed relief valve, you really gotta warm the oil up before reving or the oil pressure goes way high and may compromise the filter.
2. i lost a motor on the dyno after taking apart the oil relief valve and not seating the lil circlip well enough. be careful...
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stef12rr
Expert Class
Posts: 144
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posted March 05, 2007 04:03 AM
thanks do you know the tickness of the shim 1, 2 ,3 mm
and i took the balancer out that will not add pressure in the système
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entropy
Moderator
Posts: 8671
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posted March 05, 2007 05:50 AM
i used a 1.5mm washer as my shim and that increased the opening pressure from about 60-65# stock to 80-90psi shimmed.
Please be careful, like i said i spent about $7000 to learn my lesson 
(torched a $3700 billet stroker crank, cases, rods, pistons)
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psycho1122
Pro
Posts: 1608
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posted March 05, 2007 08:05 AM
entropy;
I am suprised to hear of only 60-65#.
I have an on board guage connected with a -4 line.
I run Mobil1 15w50.
I have not done any mods to the valve.
However, I have replaced the oil pump rotor assm. twice in the engines life. Keep the screen clean, use Kawi filters, yada,yada,yada....
I see 80# pressure under regular operation (@10 psi every 1,000 rpm's). Under very high temp. operation (Like a trackday) i have only seen it drop maybe 10 psi overall.
Looks like my Pop-off valve lets go at 8,000 or so.
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entropy
Moderator
Posts: 8671
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posted March 05, 2007 08:51 AM
My unshimmed tests = 60#+/-were done on the bench, and that's why i said "about".
the shimmed 90+ numbers come from numerous logs.
I agree about the 8000+/- where the stock one opens. I saw that on the dyno, but i didn't have data logging the.
as usual, we are aligned
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Seth ZX12r UK
Expert Class
Posts: 238
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posted March 05, 2007 06:51 PM
So is shimming the pressure valve a good idea or not?
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osti33
Needs a job
Posts: 2973
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posted March 05, 2007 08:33 PM
quote:
So is shimming the pressure valve a good idea or not?
It's one of those questions that if you ask 10 different people you will get 10 different answers.
I don't have mine shimmed.
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psycho1122
Pro
Posts: 1608
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posted March 05, 2007 08:51 PM
No shim needed.
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stef12rr
Expert Class
Posts: 144
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posted March 06, 2007 03:48 AM
Yesterday i did some valve testing at the shop and measuring, if i put a shimming under the buket, the opening presure is 94psi but i loose some opening of the piston, so i did not like that, i found a smaller spring to put in the big one, like the head valve, and i did test the opening and i have 94psi and the opening are the same.
stock is about 74psi
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Seth ZX12r UK
Expert Class
Posts: 238
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posted March 06, 2007 04:51 AM
quote:
Yesterday i did some valve testing at the shop and measuring, if i put a shimming under the buket, the opening presure is 94psi but i loose some opening of the piston, so i did not like that, i found a smaller spring to put in the big one, like the head valve, and i did test the opening and i have 94psi and the opening are the same.
stock is about 74psi
It would be good if you could post some photo's stef..of the springs, shims, fitted etc.
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stef12rr
Expert Class
Posts: 144
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posted March 07, 2007 02:21 PM
Seth ZX12r UK sorry i have no pic but i used a spring that's is the same lenght as the stock , it's about 4 mm dia and the .7mm wire are pretty close together, after you put it together with a none métal tools compress the valve and check if you have the same opening, i think it is important that the escape oil stay the same at hight rew. and by doing that you adj. only the presure not flow
i wish that my girl was here she better then me in english
i hope that will help
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dougmeyer
Needs a job
moderated
Posts: 2713
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posted March 07, 2007 03:20 PM
Guys,
Please understand that a ball/spring pressure relief valve (PRV) such as the one in the 12 has an inverse effect on rate of flow of oil through the engine. When the valve opens the flow INCREASES. The problem is, of course that the flow isn't going where you want it to go. When the pressure on the ball raises the valve off the seat it will move only enough to equalize the pressure on both sides of the ball, balancing the spring above and the oil below. As soon as the area below is sufficient to reduce the pressure in the engine, the ball stops it's movement and the size of the orfice stabilizes. As the pressure below gets lower the orfice is closed by the spring. (I'm sure that seems obvious), but the oil system is such that with the stock pump it takes very little movement to hold the pressure at the desired 80 psi. The PRV does not divert enough oil to change the flow, which is determined by the pumps ability to move oil (which is very high)
but by reducing the "restriction" caused by the various orfices in the engine which is what creates the pressure. Remember, YOU CAN HAVE PRESSURE WITH ZERO FLOW. you can also have flow with zero pressure. A lighter spring will cause the ball to move SOONER, but it is the AREA of orfice (the size of the ball) that determines how much the ball needs to move to balance the presssure (remember it's pounds per square inch).
The spring rate on the ball will balance the pressure (psi over psi), but it is the "square inch" part that determines how far the ball needs to move to balance the pressure.
Trying to move the oil through the engine at a pressure greater than that which is required for bearing life actually costs you power by driving the pump against a greater "head". I have looked at a lot of data on this on a lot of different engines, both wet and dry sump, and trying to get more than 80 psi (hot) is counterproductive. 80 is plenty for good bearing life and the flow rates through the bearings are engineered for good cooling by the oil FLOW out of the
clearances and gaps. Like I said earlier somewhere, MANY race engines based on production engines actually have reduced size oil pumps so as not to consume power making flowing excess oil against excess restriction.
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stef12rr
Expert Class
Posts: 144
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posted March 09, 2007 02:29 PM
Thank dougmeyer 80 psi is the target ,
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