Oil pressure reduction after track day

[sgernon]

My car typically has 55lbs cold oil pressure at idle, ~75-95lbs cold oil pressure at 1500rpm+ and when it heats up ~35lbs at ilde and ~55-65lbs at 1500 RPM+. Last week I went to a track day at Thunderhill. During last 3 sessions I was running the car fairly hard and shifting and hold the car near 6000+ regularly. After the 3rd track session I noticed I was 1.5 quarts low on oil. I added one quart (all I had) and drove the last 2 sessions. I didn't know any bad oil pressure changes while driving any of the sessions but it was my first track day and I was very focused on driving. After the last session I noticed my oil pressure was ~10lbs lower both at idle and in the upper RPMs. A few days later I checked it again with both an electrical and mechanical autometer guage and when cold the oil was 75lbs+ but warm it was 22lbs at idle and ~45-50lbs at 2000RPM+.

I know the car is still in the decent oil pressure range and it's good it increases with RPM but I'm very curious why the pressure dropped since last weekend so I pulled the engine today. The engine is a 10.8-1 377 SBC with forged Eagle crank, 6" Scat rods, Solid flat tappet cam with ~530 lift and EDM lifters, HV oil pump with high pressure spring, Canton 7 Qtr roadrace oil pan with ~5/16 pickup clearance. I am not sure what the bearing clearance used to be but I just checked them today and the rods are all near ~.0018 and the mains are .002 with the exception of the rear main which is .0025. These all seem fine to me and the engine looks very good internally with the bearings only having a polished finish on them. so I don't know why the difference after last weekend. I'm also running Royal Purple 10W30 HPS oil with AC Delco PF454 filter with the factory oil filter bypass. The oil did not look dirty but I have not cut the filter open. I have not pulled the heads but can see the cam and it looks ok to me with no lobe issues.

I'm thinking that perhaps the oil broke down a little from the track time and extra heat which cased the pressure reduction. Maybe if I add new oil and perhaps change to a 20W50 it will all be fine. I'm posting to see if anyone knows of other possible issues to check for while the engine is out and if the simple oil change solution may be a reasonable thought

[another69]

Wow- I can't believe that you already pulled it apart. Since you already pulled it apart and all the bearing clearances check out, I think it would only leave the pump as being the problem or possibly a small internal leak. You could pull & check the pump (unlikely) and if its good and the bearings are good, maybe there is a loose oil galley plug? The pump does have a relief that may be leaking by when warm, but that is also unlikely. If you don't find anything, you may just want to put on a new pump and plug the factory oil filter bypass. After the hard track day I guess your clearances could have opened up a bit (since you are unsure about the original clearances), leading to the lower oil pressure.

I don't think you need to go to a 20W50, just stick to a good 10W30 like you are using now. You have more than enough pressure now, and although heavier oil will increase pressure more, it may reduce protection.

[sgernon]

I've played with the oil pan in the car before and it gets frustrating. It doesn't take that much more time to pull the whole engine and check it out. I also figured it's free to pull the engine instead of playing with an oil change that costs me near $100. All that and it was getting dirts and needs a little cleaning.

I pulled the pump apart and everything looks ok with it. I did notice some small scratches on the pressure relief valve but they we very small and I could not even feel them with my fingernail so I assume that's not an issue. I'll probably change the pump just to be sure but stick with a HV and high pressure due ot the RPM I pull.

When I first built the engine I did notice a leak from the rear cam plug. With the first install I did not clean the burrs out of the cam plug hole before installing the plug and it was leaking. I pulled the plug, deburred the hole and reinstalled the plug. Since then there have been no issues and that was about 9 months ago. Any opinions if I could have caused cam bearing issue which is causing the pressure decrease? Seem strange after 9 month. I always drive the car hard and figure any shavings would have passed through long ago.

I did notice some oil in the valley of my intake manifold. I read somewhere about someone having a factory distibutor that was not aligned to the oil passage. I have an MSD disti and was thinking to change the o-rings on it to be safe. Anyone think the disti alignment or leak may be an issue?

[Vegas69]

Do you have an oil temp gauge? You likely overheated your oil and caused it to break down. I bet an oil change would've brought the pressure back.

[sgernon]

I have a guage with the sending unit by the pressure port but it doesn't seem to be working. I think you are right about overheating it and this another reason to pull the engine is to fix the sending unit issue. I might also be adding an oil cooler this week

[another69]

An oil cooler is a good idea, just make sure you plumb it right and add a t-stat to avoid over cooling the oil. My 406 SBC is similar to yours and when I would really hammer on it, the oil temp would go above 250F which is bad for mineral oil. Adding a small Mocal cooler and relocating the front spoiler to direct more air to the new cooler did wonders- now my oil temp rarely gets above 215F. BTW- how do you like the Royal Purple HPS oil? I'm looking for a good performance oil to use with my flat tappet motor until I swap to a roller cam.

[Flash68]

Yep. Been there. Oil cooler is a good idea esp with summer coming.

Before I overheated/overdetonated my 377, I tried a few different oils... 10w30, 40 wt, 50 wt.

Oil changes for sure after each track day.

How high do you rev yours?

[sgernon]

I usually shift near 6200-6500 but at the track I might have been touching 7k+ so I didn't have to shift as much at the end of the straights

[sik68]

+1 On an oil temperature gauge as said above...on your next track day you will likely see your motor is getting hot hot hot. The lot of us has since learned (some easier than others) that a good oil cooler is pretty much mandatory for track day duty.

Sgernon, you going to join us in Buttonwillow in September?

[sgernon]

I'm ordering the cooler and relocating the sending unit this weeek. Hopefully i get it all done by Friday. I'm going to plan on Buttonwillow assuming no new weddings pop up this summer. My checking account is getting beat up with all the travel I have to do for friends and family getting married.

Dave

Did you see any differences with all the oils you tried? Any hold pressure/temp better than others? What are you currently running in your car?

[sik68]

Friends' weddings eh? You're going to get :nopity: from Todd & Dave on that.

FWIW I use Redline 40WT "Racing Oil" which has a couple features (viscosity profiles, higher temps, LOTS of zinc, etc) that "street" oils don't really offer. Gibbs & Amsoil have racing oils that also seem to be popular.

From what I know, street oils are compromised in a race environment because they are designed to be easy on catalytic converters. That's why you may see disclaimers about not using race oils in street cars, because they are more "corrosive" to the cats.

[sgernon]

Thanks for the info. I was using the Royal Purple HPS oil becase it is a decent price sythetic that also has the extra Zinc for my flat tappet cam. Does anyone have any good or bad feedback for the RP HPS line of oil?

[Flash68]

I'm ordering the cooler and relocating the sending unit this weeek. Hopefully i get it all done by Friday. I'm going to plan on Buttonwillow assuming no new weddings pop up this summer. My checking account is getting beat up with all the travel I have to do for friends and family getting married.

Dave

Did you see any differences with all the oils you tried? Any hold pressure/temp better than others? What are you currently running in your car?

Man you tore right into that thing. Nice work.

I had chewed up a dist gear and one of the theories was too much oil pressure. Was running VR1 30 or 40WT at that time and I believe we saw 45psi @ idle and 70ish @ rpm. Eventually decided to go back to 10W30 VR1 and had been running that until RTTC ended the 377's life. On 10W30 I saw 15psi @ idle and 45ish @ rpm. So yeah we saw big differences.

VR1 is high in zinc as well. My new motor I am not sure what oil I will run. Will get that recommendation from the engine builder and go from there, but if I had to choose I would also go to 40WT like Steven.


Friends' weddings eh? You're going to get :nopity: from Todd & Dave on that.



Ha yeah you need to be scheduling all weddings AROUND the car activities. LOL

[sgernon]

First off they are not my weddings, unlike some of you I'm not crazy, so I can't scehdule them. Only good part is I have to spend Memorial weekend in Vegas with my college buddys. I'm hoping I make it through alive.....

Funny you mention the disti gear. When I pulled the disti I found the roll pin as sticking out ~30% from one side. Luckily I see no damage to anything. If I would have just changed the oil I might have a similar story as you. I expanded the pin with a punch, reinstalled and used the punch to collapse the hole in the gear a little on the edges so hopefully it stays this time. Anyone else and any ideas to make sure the pin stays in place?

I did find an interesting thing tonight that may have caused a small internal leak. I'm not sure if you can see in the picture but the oil pump was resting on the main stud at the rear cap. It was enough to make an indention in the pump itself so I assume the seal at the cap was leaking even just slightly which may have caused an issue. Either way I'm definately using the die grinder to create a little room. I've been building engines for ~15 years and never even thought about the clearance to the bolts, although I also typically used bolts and not studs.

http://i52.photobucket.com/albums/g15/sgernon/IMG_0712.jpg

http://i52.photobucket.com/albums/g15/sgernon/IMG_0711.jpg

[sgernon]

I finally have the car back together and the oil pressure is back to normal. ~40lbs idle and ~60-65lbs at speed hot with 40wt Redline race oil. I went ahead and installed an earls sandwich oil thermo with -10 lines to feed a 19 row earls oil cooler at the from of the car. I also went ahead and moved my oil temp sender away from the pressure port at the top of the block. I installed it in the pressure point by they oil filter and think that might have been a mistake. Now with the engine barely up to temp I'm gettting oil temps 200+ and with the engine hot it's reading ~240-245. Do these readings seem right for using this temp sender location?

[sgernon]

Nevermind that last question. Summit sold me the wrong sending unit. Swapped it out and temps are now near ~150.

[Vegas69]

I was going to say, if you have temps in the 250 range you better be road racing or have a major engine issue. Glad to hear you have it figured out.

[Flash68]

double post

[Flash68]

Nice job. Post some pics of your setup. I believe from everything I've read that an approx 40* spread between coolant and oil is normal and good (180 water temp, 220 oil). And this what I've seen on my setup on the street since install and up to temp.

BTW - I was at Thunderhill today and man are they cracking down on sound. A pretty quiet Mustang with mufflers and dual exits before rear tires (supposedly hit 107db) was black flagged. And he's run that same car out there many times before without incident.

[sgernon]

I almost wanted to ask how much sound my car was making but I figure that would be a bad idea. I'm planning to head back on May 19th, I hope the next time goes as well as the first time for me but I also bought some of the auger style inserts just in case I need them.



I'm not good at taking pics during the install but here are some of the complete oil cooler in the car.

https://static1.pt-content.com/images/pt/2012/05/HPIM1165-1.jpg

https://static1.pt-content.com/images/pt/2012/05/HPIM1163-1.jpg

https://static1.pt-content.com/images/pt/2012/05/HPIM1162-1.jpg

https://static1.pt-content.com/images/pt/2012/05/HPIM1161-1.jpg

https://static1.pt-content.com/images/pt/2012/05/HPIM1159-1.jpg

https://static1.pt-content.com/images/pt/2012/05/HPIM1158-1.jpg

[Flash68]

Looks good man. Nice clean install.

I kinda wish I went with -12AN lines for the oil cooler in hindsight over the -10.... no real scientific reason why but most everyone else I see in cars like ours run -12.. what made you go with -10?

[sgernon]

Thanks

I figured that the output of the oil pump isn't even as large as the -10 line so it shouldn't be a huge restriction. The cooler also came with the -10 fittings on it so I assume Earl's knows more than me. Last thought was since I'm using the sandwich thermostat I figure if the cooler has a blockage then the adapter may bypass the cooler and continue into the engine.

[Flash68]

Yeah I hear you there. But then why did all those Trans Am guys use -12 on everything, and every other small block chevy use -12? I haven't found the answer yet... and like you we had an Earl's cooler at the shop with -10 sizes so we just used it.

[sgernon]

Hard to say why. Maybe just to get a little more capacity in the overall system.

According to the catalogs the -10 is 9/16 and -12 is 11/16. 9/16 alone sounds huge to me let alone 11/16. I would have to defer to one of the crazy smart and overly technical engineers to better explain the potential for volume and pressure loss assocaited with the cooler and length of the lines. Hopefully someone will chime in and help you sleep better at night, I can tell this is eating you up.

Since I just finished my install I am interested to know but even if someone proves -12 to be best I really want to stick with denial for a little while. Last thing I want to do is change out the lines imediately after completion.

[Flash68]

Exactly.... I really want to be happy and content with my -10 lines. And I think I am. I just keep seeing -12 on everything of decent size and power (SBC) and now I'm adding cubes and hp it got me thinking again. I think you're right about pressure being the issue and I don't have a grasp enough of it nor have been able to find any relevant tech on the subject. So we will just continue with our puny -10 lines and be happy. :)