Oil pressure drop thru 1/4 mile

cturk1010 wrote:how hot do you start run at and temp at shut down

the Coug wrote:do you have a windage tray in this engine?

bruno wrote:just curious on what kind of times are you guys running ?

Derek Wood wrote:

the Coug wrote:do you have a windage tray in this engine?

Yes it is a short louverd tray between the rather large Titan pump and the dual tube pickup. Nice pan, big kickout, lotsa baffles and the pump looks good all round. Any bad experiance with System 1 filters?Thanks for any input. Goin racing Thursday.

mkopmani wrote:Unless the oil has been heated before you run, I might guess that you may be starving a bearing and opening up clearances. Pop a main cap off if it's a chassis car.

Although the screen type filter should be pretty unrestrictive, it's a possibility that you may have a restriction there either from debris (bearings) or from the heavy oil which starves the motor at high rpm.

I like the heavy oil theory, the filter gets regular inpections and hasn't indicated bearings as yet, alittle cast a little lint and some indication of aluminum chips from the incorect clearance on the valve cover flange...although the oil pressure should stay low if it was a filter restriction due to oil weight, but when you factor oil speed through the filter during the run it could definately be a factor.

As the pump is not load sensitive, you might free rev the engine at a speed that's high but safe and see if the pressure drops. This would tell you if it's related to the acceleration.

Going to the track tommorow, made some changes, will post results. I will take some lighter oil and already have a filter replacement in stock, and I will try to get in that free rev, could provide usefull data.

With the difference in temp that you indicate, clearances would not increase that much to result in such a pressure drop.

Are you sure that your system capacity is correct between the pan and Accusump? If not, you might be pumping the pan dry into the Accusump.

And yet another good question. Ive put up to 18 ltrs into the pan so 1 in the filter and approx 2 in the accusump 15 in the pan. At 45psi I get about 2 ltrs from the accusump. at 80-90psi do I get double?


Cheers and thanks for the great perspective.
Derek

rmcomprandy wrote:IF ... rod bearing clearance is not to wide then the oil is not acting correctly in the pan around the pick-up(s) while RPM rises.
Has 1 pickup with 2 tubes Titan pump, Billet fab pan with baffles and balls for decel. Rod bearing clearance is top limit plus a half, aluminum rods. Found a couple of possible causes and am heading to the track tomorrow. Thanks for the great input, Cheers Derek

Figure out that cause and you will most likely fix your problem.

LivermoreDave wrote:

Derek Wood wrote:

the Coug wrote:do you have a windage tray in this engine?

Yes it is a short louverd tray between the rather large Titan pump and the dual tube pickup. Nice pan, big kickout, lotsa baffles and the pump looks good all round. Any bad experiance with System 1 filters?Thanks for any input. Goin racing Thursday.

Could the style of oil pump pickup you incorporate within your engine be the problem? I assume the pickup's intakes are fore and aft. If this is the position of the two, could the fore located pickup become uncovered during acceleration and after being uncovered, become a "leak"? With the oiling system equipment you mention, I can't imagine an oiling problem with delivery or supply during acceleration!

Just another opinion,
Dave.

the Coug wrote:ok Derek remember are your lifters are the link bars to the valley or to the cylinders? and you say it is restricted oil to the top end did you restrict it front? back? or both? what size restrictor holes? are you sure the drain back holes are lined up with the gaskets and block? how much main and rod clearances? what weight oil? how far is the oil pick up from the oil pan?

dave d wrote:Sorry to jump a thread ,but I"ve got kind of same problem, new motor,same oil pump and pan as prior motor I'm only getting 35lbs at 3000rpm down to 20 at idle-----old motor was running 50--70 lbs.I don't have the specs in front of me for clearences and its 10--30 oil..Will this get better with heavier oil and break in time THANKS Dave champered drain backs on block and drilled dist oil hole.any input greatly appreciated

dave d wrote:Forgot to tell you it's a solid roller cam,put 50 weight oil in still 35lbs.of pressure,HOW big of shim on to the spring makes how much more pressure.Thanks -----This is a high volume pump, not high pressure Dave dist hole is to oil cam gear

mkopmani wrote:Derek,
Have you checked the oil pump pickup clearance to the pan? If it's high, you might be pumping the pan dry if it's higher than 5/8" from the bottom of the sump.

Oil recommendation - if you have loose clearances, you'll not want to go to a light oil, but certainly a multi-viscosity oil. Assuming that you're changing because of fuel contamination and don't want to leave synthetic in there, I'd recommend Pennzoil 25w-50 race oil. Don't confuse this with many of the 20w-50 oils, it's specially formulated for race motors. Don't hear much about it, but it also comes in a 70wt that most of the nitro guys use. Dee Keaton (former Dale Pulde, Jack Chrisman, SWC crew chief, turned me onto it. Dee's still sharp as a tack at 76)

Mike

dfree383 wrote:have you tried running less oil, could be a windage problem.

My last motor had issues running capacity in the pan, when we dropped a quart and a half everything stablized. That was a 9 qt system, no accusump.