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Re: [Tigers] Oil Pressure

To: Dave Munroe <dave@munroe.ca>
Subject: Re: [Tigers] Oil Pressure
From: drmayf <drmayf@mayfco.com>
Date: Sat, 30 Aug 2008 07:36:33 -0700
Dave, all...
I am by no means an expert on small block fords, however, I do have some 
knowledge. The very last paragraph below caught my eye regards how to 
modify an engine to get high oil pressures..

Lets look at the oil pathway first. Oil comes from the pickup in th epan 
to the oil pump via a suction into a gerotor pump. The oil is then fed 
to the filter and then into the oil galleries. It goes into the lifter 
gallery to the cam bearing gallery and to the main bearing gallery. Oil 
fed into th emains bearing gallery further goes into the crank to supply 
the rod bearings. Oil that feeeds the lifters travels up the push rods 
to the rocker and then onto the springs to cool them.  Oil is always 
seeeking atmospheric pressure and so at each of the bearings it leaks 
out returning to the pan to be recycled. So where are the places to 
modify the engine? Well if you have tighter bearing clearances you will 
get a higher pressure...also more heat.  The place that is usually 
modified, by the manufacturer, is the oil pump.  Th eoil pump has a 
relief spring inside it which is preset to recirculate the oil when the 
pressure dictated by all the stuff I mentioned above is met. So if you 
have a low presure situation then most likely you have worn bearings, 
particualrly the cam bearings. These see a near constant downward load 
from the valve springs and that tends to wear the cam bearings on the 
crank shaft side.  The oil pump willput as much oil into the system as 
it can handle witin the limits of the relief spring. I  have a melling 
blue printed high volume pump on my race car because I needed more 
capacity to feed the turbo. The relief spring on the pump  can be 
adjusted by the user to have what ever pressure he desires.   And of 
course, if you go to a dry sump system you can set the pump pressure to 
just about anything you want by changing the rpm of the pump.  It is 
interesting to note that a lot of the heat in an engine comes from the 
pump because it recirculates the bypass oil. I am looking at using a 
system that eliminates the relief spring in the pump and puts a regulaor 
on the output side to dump bypass oil back into the pan eliminating the 
continous heating of the oil.  Still an dall, what pressures do I have? 
Well on the race car, I use a pump that is set to 75 psig, I use 20W50 
Valvoline racing oil, a large Fram HP1 racing filter. At the end of a 3 
mile run pressur eat idle has dropped to around 50 psig.

Hope this helps to understand a bit more on oiling.. It can and I can 
get deeper if need be.

mayf


Dave Munroe wrote:

>Thanks Tony;
>
>snip
>  
>

>60 psi and up seems to be uncharacteristically high for a "normal" street 
>SBF engine, and there does not appear to be a lot of info on how to modify 
>an engine to produce these high pressures.
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