Oil Pressure

[Sundance]

Mike,
I asked a question thru Karl this week concerning a Feuling Oil Pump installation and Latus Mtrs. oil pressure relief spring....I was able to get an email answer from Feuling and would like to share it with you, if you don't mind.


Davis, Jerry J wrote:

>I just installed your Feuling Pump in my 2003 Roadglide. I had
>previously installed a different oil bypass spring to increase oil
>pressure about a year ago.
>Now my oil pressure is 30-55 cold and 25-45 warm(I've only run it one
>time for an hour + I live in Seattle). My question: is this an
>abnormal oil pressure for the twin cam and should I go back to the
stock
>spring? I noticed on your earlier pumps on the installation
>intructions that you wanted installers to stretch the length of the
>bypass spring......have you changed the pump since then?
>
>Thank you ,
>
>
>Jerry Davis
>
>
>
>
Jerry,
The by-pass spring does not create oil pressure only the oil pump can
create pressure. The by-pass valve is what it says it is - a by-pass
this is put in the camplate to protect the engine of too much pressure.
When we state to stretch the spring .050" this sets the valve to pop off
at +/- 55 psi this means the engine shouldn't see much more than this
for pressure ever. The pressures you state sounds great - the pump
install gave you 3 H.P & 4 Ft./Lbs of TQ at the rear wheel along with
cooler engine & oil temps. The aftermarket camplates already come with a
stiffer spring and if you get one of our new camplates we set each plate
to pop off at 55 psi. We also just started making a tool to sell to tech
that test the pressure relief valve and camplate.

I hope this answers your ?'s
Thanks,
Luke Leatherman
619-917-6222

Your forum is great, Mike. I live in Seattle and have brought two friends bikes to you for dyno tuning....I would not go anywhere else!

[Mike]

Thank you for the kind words, we hope the forum will just keep getting better with time. Fueling is correct in that the bypass should regulate the pressure as dictated by the spring. Our spring is 15% stiffer than the stock which typically translates into a 5lb increase at cruising speeds. The reason we express our spring in % is to take into account differences in oil pressures from bike to bike, temperature and rpm. For example, if you have 30lbs press at 180 temp/3500 rpm stock, then our spring would increase that to 35lbs at the same temp/rpm (15%). If at idle you have 5lbs, then with the spring you should have about 6lbs. (5.75lbs). The springs we have seen in aftermarket cam plates have the low coil count similar to H-D and straight cut ends. Ours has a high coil count and ends ground as flat as is possible (completely flat is not possible). The engineering that was done to develope the spring indicated that this would provide a more consistant pressure rise, a spring that was less stressed over time (maintaining its design pressure) and overall finer control. This spring was engineered after testing several H-D springs on a profiler. The H-D springs were found to be somewhat inconsistant.
This sounds like a lot of effort just for a spring but oil control in the TC motor is nothing to take lightly. To date we have over 1200 installed with no reported (to us) problems. We have seen several cases where the bypass valve was sticking or stuck fully open in the camplate, so we now recommend that the bypass be removed and lightly polished when the spring is installed.
Regards, Mike