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Draining Engine Oil

fredeuce
Posts: 62
Joined: Mon Feb 29, 2016 10:56 am
Location: South Australia

Re: Draining Engine Oil

Post by fredeuce »

I finished the fabrication of my spray bar for my camshaft and plumbed it up without fitting it to the tappet chest.

I connected the battery and cranked the engine over to establish what level of delivery was being achieved and the concurrent oil pressure at cranking speeds. Below is a video recording on my phone which shows the oil delivery on the cam and the reading at the gauge which is about 20 psi. Please excuse the quality of the video I'm not Steven Spielberg.

A question for Ozzsp250 : what oil pressure does your engine generate at cranking speeds? That would be useful to know so as to make some comparisons with the modifications done to your engine. I have drilled 17 x 1mm diameter holes in the bar. The bar is 1/4 brass tube . I took the supply from the point where the oil pressure switch and oil pressure gauge are attached on the front right side of the engine block.




Sonus
Posts: 196
Joined: Wed Apr 13, 2016 2:19 pm

Re: Draining Engine Oil

Post by Sonus »

@fredeuce thanks for sharing your progress :)

Ozzsp250
Posts: 217
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Draining Engine Oil

Post by Ozzsp250 »

Sorry for the delay in getting back to you. The engine when on the test stand with a test gauge made around 20 psi -- relaying on memory not always good.

The engine is now in the car but I have not cranked it yet, I have a couple of loose ends to clean up before I fire it up. Due to the garage being attached to the house and the car is on my platform car lift, plus I'm sure it will smell up the place I need to get it in the driveway. The plan is to crank it over and build oil pressure prior to starting it, I'll pay closer attention to cranking rpm and oil pressure.

Dennis

Ozzsp250
Posts: 217
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Draining Engine Oil

Post by Ozzsp250 »

I test cranked the engine in the car yesterday and the cars oil pressure gauge failed to register any pressure and the mechanical tach no speed. I removed the new oil feed line from the back of the oil pressure gauge in the hope to bleed the system and cranked engine catching any oil it in a bucket. The oil pressure gauge has a new stainless flex hose assembly [supplied by Barry and is larger internal diameter than the original plastic one] and the flow was very low and erratic - testing at ambient temperature around 30 C which is a bit disappointing.

Once I start and run the engine which won't be for a couple of days or so, I'll repeat cranking test and add a electrical pulse tach to capture engine cranking rpm, should the car's oil pressure gauge fail to register again I'll add an external test gauge.

Dennis

fredeuce
Posts: 62
Joined: Mon Feb 29, 2016 10:56 am
Location: South Australia

Re: Draining Engine Oil

Post by fredeuce »

Dennis,
I look forward to your further test results when available.
I conducted some further tests on my set up by simply disconnecting the spray bar and cranked it over all else being the same.

This produced a cranking pressure of 40 psi.




My general concern as is yours I believe is to ensure adequate oiling at the camshaft but not at the expense of reduced oiling at the main and big end bearings.
My next step is to insert a needle valve in the line to restrict the flow to the spray bar and see what results I can achieve with oil pressure at cranking speeds and maintaining adequate supply to the cam.

My oil pump by the way has had the small drilling in the relief valve closed off and the relief valve spring packed up slightly. My bench test results were 55 psi to open the relief valve.

Sonus
Posts: 196
Joined: Wed Apr 13, 2016 2:19 pm

Re: Draining Engine Oil

Post by Sonus »

I think you might be able to run the oil pump even harder. I bought an uprated oil pump from Russ and Andrew Carpenter that they testet to 65psi if i remember correctly(?)

Ozzsp250
Posts: 217
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Draining Engine Oil

Post by Ozzsp250 »

I last few days I have been chasing the Phantom of no oil pressure being registered on the cars oil pressure gauge at idle. To recap my issue I had run the engine in my home built test stand and had observed cold oil pressure around 40 psi at idle, this was with feeding the extra camshaft spray bar, with both pick off points being at oil filter assembly. The oil pressure gauge was feed by a 3/8" stainless steel line approximately 12" in length. The oil filter assembly is non-standard converted to spin oil filter. After all the testing I had done in the test stand I had added a permanent feed to the spray bar using 3/16" ni/cu brake line which has an ID of 1/8".

Once installed in the car the no oil pressure problem reared its head, I checked calibrated the gauge out of the car it is accurate, all the external lines for gauge and spray bar removed cleaned and reinstalled with no issue found. I decided to purchase a small needle valve to place in-line to the spray bar in case I had miscalculated the oil flow, while I awaited the valve pottered around with other small projects, during this time I came across a low oil pressure topic discussed on the forum where the issue was resolved when the author had found the oil pressure gauge instrument light was installed to deep within the gauge preventing the needle movement.

Today I installed the need valve made a new spray bar feed line and connected up --- an absolute bear working above the oil filter and between the engine and fire wall. Once done I opened the needle valve a turn or so and started the engine. A repeat performance again oil pressure not registering --- I closed the needle valve, no change. I them reached behind the dashboard and removed the oil pressure gauge instrument light and holder at which time the oil pressure jumped to 45 psi! I was happy but frustrated for sure, opening the need valve completely resulted in no change in oil pressure at idle.

I'll go through and do the test crank test v oil pressure when I get a bit of time.

Chris_R
Posts: 527
Joined: Wed Feb 10, 2016 12:48 pm
Location: Twickenham

Re: Draining Engine Oil

Post by Chris_R »

This topic seems to have morphed from draining engine oil into camshaft spray bars!
Anyway, I thought it might be useful to put the question of oil flow and oil pressure into some context although I may be stating the obvious.
The pressure you observe is mainly due to the resistance to the the flow of oil out of the crankshaft bearings. Oil is pumped into the bearings, dragged around inside the bearings and then leaks out of the sides of the bearings and the resistance to the flow into the bearings is the pressure reading that you observe. Important to remember that although related it is the flow of oil into the bearings that is important, not the pressure that you observe. The oil pressure you observe is nowhere near enough to support the bearings which impose loads of up to 5 or 6,000psi on the oil when inside the bearings so what is important is to maintain enough flow. A positive pressure, at a minimum of about 10psi per 1,000 rpm should do that. The other point here is that the pump is generally capable of pumping far more oil than the engine can consume and the pressure relief valve balances the capability of the pump to pump with the ability of the engine to consume that pumped oil and to keep a positive pressure to maintain the required flow. A higher pressure will not increase the flow, it simply means there is more work being done in pumping.
When the oil is cold the oil it is far more viscous and resistive to flowing through the bearings than when it is hot. It is also harder to pump. Add to that the grade of oil and a 20W-50 is thicker by an order of several magnitudes than a 5W-40 or even a 5W-50. This graph illustrates this effect.
Viscosity vs Temperature.jpg

fredeuce
Posts: 62
Joined: Mon Feb 29, 2016 10:56 am
Location: South Australia

Re: Draining Engine Oil

Post by fredeuce »

As you know this thread has touched on the issue of engine oil drainage and the related topic of the oil galley and use of spray bars.

tjt77 has mentioned blocks with drain holes from the factory in the cam galley with 12 holes @.125" diam. Unfortunately , however nobody has been able to produce a photograph of such block. That difficulty coupled with an examination of the depth of the water jacket I am concerned about drilling through the block in such a manner.

Fossil has mentioned in discussion on this thread drilling the block on a SP250 block to provide drainage to the front via the timing cover.

Against the background of that discussion I have recently had my block re-bored to take 79mm pistons. Once I received the block back from the machine shop I then had my brother who has a milling machine mill down the tops of the camshaft bearing webs to provide clearance for the spray bar.

Once that task was completed I then set about drilling the block to effect drainage to the front of the block by drilling a two holes longitudinally through all cam bearing webs . I have attached a series of pictures of the procedure thus far. In summary the holes are centered 4" from the top of the block and the centres of the holes are 1 5/8" apart or 13/16" from the vertical centreline of the block. The front wholes are 17/32 as is the first web . The remaining webs are 7/16".
tjt77 mentioned the 12x.125" holes as drainage. This translates to a mere 0.147 squ. in. area in total to deal with all of the oil.The 17/32 holes in total amount to .433 squ. in. or approx 3 time the area. However with the introduction of the spray bar the adequacy of the drainage is moot point.

Having progressed thus far I am now going to pause to reflect on the adequacy of the drainage . Any comments or suggestions always welcomed.


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