Oil pressure, temperature, starvation for road race duty

[bjhines]

I have a 1964 327 SBC in my road race car. The car has a 3qt Accusump, oil cooler, thermostat/cooler-bypass, Z28 oil pump, Corvette 6qt pan, block hugger headers(no room for kickouts). I am having multiple issues with oiling for this engine combo.

 

 

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First issue; pressure drop when hot.

 

COLD OIL:

35PSI idle

60PSI 3k RPM

 

190 degrees warm:

25PSI idle

40PSI 3k RPM

 

240 degrees HOT:

20PSI idle

30PSI 3k to redline

 

This all seems a little low to me, but It is not so bad that I was worried about it until I saw the HOT oil pressure get so low.

 

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Second issue; HEAT. My oil temp sender is in the oil pan just above the drain plug.

 

My oil temps are only approaching water temps under "normal" driving conditions. ~190 degrees. My problem comes from the fact that the temps rise QUICKLY when I am on track. Once the car is warmed up I will generally see 210 degrees. When I really get on it with sustained 4k+ RPMS the oil temp will climb in just minutes to 240+ and continue to climb until I give it a cooldown lap. I never let it get past 270 this weekend and I watched the temp gauge like a hawk. The water temps NEVER go above 190 and stay VERY STABLE under all conditions.

 

This puzzles me because I have a large, stacked plate cooler with it's own fan. The bypass closes at 165 and the oil cooler fan kicks on at 185 degrees. This should be plenty to cool the oil(unless there is not enough flow through the system to properly cool the oil).

 

 

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Third issue; starvation in high G corners.

 

I have a 3qt Accusump with the 20 PSI EPC valve. This is wired to a light and a buzzer to let me know when it is working. At Carolina motorsports park I get intermitant beeps from the EPC valve on tight corners with hard braking just before turn in(turn 14 at CMP). I do not notice the problem on long sustained corners(like carousel). The pan is a "normal/stock" 6 qt with stock baffle plate, no kickouts, and 3/8" clearance to the pickup.

 

 

 

.....

Edited October 17, 2011 by bjhines

[johnc]

First off, you want to measure oil temps after the cooler. Right now you're seeing worst case temps as the oil drains off the engine into the pan. 270 worst case isn't bad at all.

 

Regarding oil pressure, again, were are you measuring it? Right after the pump is best but I'm SBC ignorant so I don't know where the factory sender is.

 

A flicker on an Accusump under braking isn't a big deal. Almost normal.

[bjhines]

The factory pressure port is on the oil return at the back top of the block right where it feeds to camshaft, crank, and lifter gallerys.

 

The temps just keep climbing as long as i keep my foot in it. I want to run more than 3 laps with relatively stable temps.

[luigi]

The oil temps don't scare me....yet. The oil pressure does. Z28 pump is high pressure, not volume right? What weight/type/brand oil are you using?Do you remember your oil clearances?

The pan is not very well baffled for what you are doing. maybe some additional baffles to keep oil outta the crank.

Also, what is the condition & state of tune of the engine? Blow-by can drive oil temps up. Ignition timing can also. I doubt that's the case for you, but I've missed it on my own car so I gotta put it out there. How much total oil? 5 in pan w/filter +3 for accusump + 1 for cooler & lines? you may try lowering the pan level by 1-1.5 quarts. that may keep it out of the crank. Otherwise its time to pull the pan and start welding & shimming pressure springs. It's not staying in the heads is it? Some of the heads have really poor drain back holes, & some head gaskets get in the way too.

Lewis

Edited October 18, 2011 by luigi

[johnc]

At the next event try temporarily eliminating the the thermostatic oil temp switch. Also, maybe get rid of the fan behind the oil cooler.

[bjhines]

I am using 2 gal., 15-40 Rotella with break in modifier to add zink.

 

The oil level ends up being too high for sure after the accusump discharges and then cannot refill at the higher cold pressures. I could remove a quart and see if that helps reduce foaming.

 

All the bearings have factory clearances with little time on the build. The heads are modified 461s with 1/2" holes for drainback. It may actually have the stock pump. I have a catch can that collects very little oil, mostly vapor from blowby.

 

I was looking at a high volume pump and claimer pan with some kind of windage tray and vertical baffles. I was looking at a welded pickup pump/pan combo like Milodon offers. I could also try 10-30 oil.

Edited October 18, 2011 by bjhines

[z-ya]

The factory pressure port is on the oil return at the back top of the block right where it feeds to camshaft, crank, and lifter gallerys.

 

The temps just keep climbing as long as i keep my foot in it. I want to run more than 3 laps with relatively stable temps.

 

 

So the pressure sensor is on the main oil galley that feeds the crank? I would think you should have around 80-90psi at full load/RPM. At idle 30-60psi should be fine. It's a solid lifter motor? I'd try Bran Penn 20W50, it already has the zinc in it.

 

I would also remove the thermostatic bypass as well. I don't run one on my vintage racer, I just have to give it ample time to get the il up to temperature. Oil temperature stays in the 200F range in the pan.

 

I'm running one of these SW aircraft oil coolers:

 

 

Stupid question, is the fan running in the correct direction? You might get another MPH on the main straight

[saxfiend1967]

the clearance at the distributor could be allowing oil to drain past distributor shaft too. I would run a great oil and filter . k and n or amsoil and I would also run synthetic oil. likely 10 w 40 . I studied in depth on oil about 2 years ago amsoil redline or jgr (royal purple is good too) If you are willing to pay for it. the jgr will be the best oil imo it is also problably 12 dollars a quart. i believe it has zinc too as they use flat tappets in nascar. Oil will make a huge difference. huge , All oil is not equal. most every oil gives way to heat and loses viscosity. the ones mentioned above are the best in that area. you can look at amsoil online at theyre website, they will show you comps on other oil and how viscosity holds up. the rotella 15-40 may only be 0-25 when hot. that would surely cause your problem. I hope this helps. Ps as a matter of fact I am one of the nerds that took 4 weeks to study and understand the difference in oils, I spent 2.5 years studying theory on camshafts and heads and am studying now on how exhaust tuning makes a difference. In a nascar engine teams are claiming to get 75-100 hp from tuning the exhaust. sorry im rambling LOL

[saxfiend1967]

one other thing, cant you also get oil pressure at pump on the bottom of the block where the allen head screw is? you can on fords but not sure about chevy. I know if you pull oil pressure from top of block its not as accurate because it can get air pockets in it there especially if distributor lets oil by it. the msd comes with provisions for o rings to fix this.

[bjhines]

I called Melling, and Moroso about this. The additional cooler, thermostat, filter, accusump, fittings and lines(and the lack of any block mounted bypass) are too much for a stock pump, or a nearly stock Z28 pump. The only thing the Z28 pump has got over stock is a steel drive gear and ~maybe~ a stiffer bypass spring. It was shipped with standard and 10psi higher(purple) spring. They all agreed that I needed a higher volume and a higher pressure pump. The starvation issue and oil overheating are likely because of poor oil control in the pan. Apparently windage can cause a great deal of added heat when the oil is whipped into a froth. This leads to lower pressure as well.

 

I did not realize at first, but the addition of the 3qt accusump requires a larger pan volume to accommodate the added oil it can put into the pan. The factory 4.5qt pan will allow the level to rise into the rotating assembly when the accusump discharges. They suggested an 8 qt pan.

 

 

I chose the Hamburger's performance 1088 7qt pan. It has a large boxed sump with trap doors and comes with a pickup to suit the pan. Hamburger's lists the Melling 10550 pump as well as others to suit the pan/pickup combo. BULLSHIT!!! The Melling HV pump 10550 puts the pickup 1/8" off the bottom of the pan. The pickup is not even level with the bottom of the pan. I knew this would not be that easy, so I cut, and rewelded the pickup to add clearance.

 

Hamburger's instruction manual insists that I must use their crappy paper pan gaskets. I used a nice one piece silicone gasket despite their doomsayer instructions. Frankly I need the extra clearance to reduce the amount of cutting I had to do on the oil pickup. I did not want to reduce the volume of the pickup too much. The pan is notched for stroker clearance which means there is no room for conventional fasteners. It uses allen head cap screws for clearance, which means I had to purchase longer allen screws to accommodate the thicker silicone gasket.

 

The pan is 8" deep where the original was 7.5" deep. I still have enough ground clearance the way the car is set up now.

Edited November 22, 2011 by bjhines

[johnc]

Plumbing the oiling system is often a big pain in the ass. Although I've never pulled the trigger on one, dry sump systems look pretty good when you're having to cut and weld a pan to get what you need.

[bjhines]

The dry sump systems are far more expensive than most people think.

 

The pickup mods were a Sunday afternoon project. I used a sawzall and eyeballed the cut. Then I used the belt sander to get it flat. Total thickness reduced 3/16". I did not braze the pickup to the pump. I only hammered the pickup tube in enough to get the pump-cover bolts on for clearance checks. When I cleaned and reassembled everything I pounded the pickup tube in a little further for a tight fit and bolted it on. It sits dead flat with the pan floor now @ 3/8"

 

 

Aviaid makes entire Dry-Sump systems for the SBC and they list prices for various parts. For fun lets think of just the main parts. 3 stage pump($750), Gilmer drive($225), Oil Pan($350), Oil tank($500), Breather can/vacuum relief/AN fittings/manifolds/brackets/etc($800). That stuff is IN ADDITION to the other things I have already added to the system(minus the accusump).

[johnc]

Yup. About $2,500 for a dry sump system for a SBC. ARE, Aviad, and others make systems. The big expense is the lines and fittings.

[luigi]

Glad to see you've got it sorted. Are you running the EPC valve on your accumulator?

Also, since you've good some good documentation on your oil pressure before, please let us know how does with the upgrades.

lastly, I recently bought a 3qt accusump myself. My system is a bit different but not much. When I looked at the check valve for the accusump (brass 1/2" NPT), it seemed pretty restrictive. I asked a few of the vintage racer guys that use them and they all said they lost some pressure when using the canton/moroso check valve. They recomended an Earl's hinge style. I finaly found one at Hoerr racing. It hasn't made it here yet. When it does I'll take it apart and get pictures. Otherwise I'm trying to put the oil from the accusump directly into the oil galley. Thinking of teeing outlet to rear by distributor and at the front.

That melling 10550 is a great pump. I've used the 10552 and really like it.

Really nice car

keep us posted

Edited November 23, 2011 by luigi

[bjhines]

I am using the EPC valve with a 25 psi switch. For those who do not know, the EPC valve is activated only when the pressure drops to the the switch activation pressure. You can purchase several different pressure switches. The valve will always allow the accusump to refill slowly through a restriction. The inline/external check valve is to keep the accusump discharge from flowing backwards to the oil pump.

 

I think the next best place to teturn oil is the plugged galley hole above the filter mounting pad. You would need to remove the plug and tap the hole. The small passage leading to the top rear near the distributor is too small.

[bjhines]

Well... The track event had it's ups and downs.

 

The upside is that oil pressure is a steady 55psi(Warm) at speed and the temps climb slowly to ~200 and pretty much stop climbing for 6 laps or so. Yaaayyyyyyy!!!!!!!!!!!!!

 

The DOWNER is a bad leak at the front of the pan that would lead to oil buildup under the car/exhaust and smoking after braking zones.

 

My hypothesis is:

The oil pan gasket needs a THICK front seal which apparently is NOT what I have with the blue silicone gasket I purchased. It is so hard to tell what the heck to use.. The seal is indeed "thick", but I think it is due to the extra thickness of the side rails and ends up loose in front with the pan bolted on.

 

Does anyone know what years the Chevy engines changed from Thick to Thin front sections???, and is the Eldlebrock 2 piece timing cover a "thick or thin" lower section???

 

What a pain in the butt... but I am making brutally slow progress. I still had fun at the event considering my student had a E63 AMG supersedan. Good freaking lord... what a car! Yeeeeeeee... Haaawwwwwww... all that Lux and weight and is still accelerates like my HybridZ Race car. $$$$$$ you can get something functional and entertaining for 6 figures.

[jt1]

John, there's no change in the blocks themselves regarding the front seal. What makes the difference is the pan and timing cover. Some pans and covers are made for thin seals, others for thick, and then you get tolerances thrown in the mix. Felpro makes numerous versions of the blue gaskets for thin, thick, and different dipstick configurations. I went thru several with my comp cover/canton pan setup. The most frustrating part is that it won't leak until you actually get it on track and run it hard.

 

A call to hamburger may help.

 

Edit; Also, if a block was line bored, you sometimes have to fine tune the dowel holes in the cover to get the front seal centered on the damper. that detail is overlooked lots of times and can cause problems.

 

jt

Edited November 30, 2011 by jt1

[bjhines]

Needless to say, my undercarriage is well oiled. I am really tired of washing oil off the back of my new car.

 

I put an emissions smoke leak detector in the oil dipstick tube and turned up the flow enough to pressurize the crankcase. The front seal is TOO THICK. The front corners of the oil pan are not mating to the block.

Also... The distributor adjustable collar leaks profusely at the split in the split collar. I will seal that as well.

[jt1]

Sell the split collar dist and buy a standard type, shim it if you need to. They are a drag race only item and not suitable for track use. BTDT and almost saw a nice engine blown because of it, the only thing saved it was the driver was on his toes..( I wasn't the driver !!!).

 

jt

[bjhines]

jt1... Please explain the distributor problem.

 

I am not using the oil O-rings, I made sure there is a little play in the intermediate shaft with the oil pump and dist torqued down. The dist gear shows no wear. The collar seems very tight and secure??? There is an adjustable cam button with specd end play.