Club Cobra Gas - N Exhaust  

Go Back   Club Cobra > Engine Building, Tuning, and Induction > Small Block Talk

MMG Superformance
Nevada Classics
MMG Superformance
Main Menu
Module Jump:
Nevada Classics
Nevada Classics
MMG Superformance
MMG Superformance
Advertise at CC
Banner Ad Rates
MMG Superformance
MMG Superformance
MMG Superformance
Keith Craft Racing
March 2024
S M T W T F S
          1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31            

Kirkham Motorsports

Like Tree6Likes

Reply
 
LinkBack Thread Tools Rate Thread Display Modes
  #1 (permalink)  
Old 01-25-2017, 10:42 PM
Texasdoc's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2012
Location: Keller, TX
Cobra Make, Engine: Lonestar Classics LS427. Self-built 408W, AFR 195 heads, Performer RPM Intake, Quick Fuel 750, 407rwhp, 479rwtq
Posts: 549
Not Ranked     
Default Thoughts on oil pressure vs flow?

I've always wondered what weight of oil would be best in my car. I built my own motor so I can't "just ask the builder what he recommends"...

I've heard some say "Put 10W-30 in everything" and just drive it. That's what I have been using. With my HV pump I get 75 PSI cold idle, 40 PSI hot idle, up to 70 PSI cruise.

I recently came across an article on BITOG that made the remark that no oil at ambient temperatures (anything less that 120 degrees Fahrenheit) is thin enough to flow well - so use the lightest oil made 0W. They also agreed with the 10psi per 1000 rpm rule. So their summary was to use 0W-XX - the XX being whatever weight oil fulfilled the 10per1000 rule with a minimum PSI of 15 at idle when hot. So if I get 70 PSI at 3000 RPM cruise with 0W-40, I should decrease the viscosity to 0W-30 or 0W-20 to get the pressure down. Lower pressure = higher flow. It is the "flow" that provides protection, not the pressure.

Thoughts on this logic?
Reply With Quote
  #2 (permalink)  
Old 01-26-2017, 04:11 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Louisville, KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,389
Send a message via AIM to blykins
Not Ranked     
Default

It's hydrodynamic pressure that provides protection.

Desired oil viscosity is based on a couple things....two of which are:

1. Bearing clearances
2. Your environment

Most of my street engines run about 30 psi at idle and 70 psi going down the road. I use 10W-30.

I've been following your threads and you are way overthinking the oil to the top end deal. The internet can be helpful in a lot of cases. It can also be totally out in outer space in a lot of cases. There are a lot of engine "experts" out there who 1. Have never laid hands on an engine 2. Don't have a stinkin clue about what they're talking about.

IMO, you just got a set of junk heads.
__________________
www.lykinsmotorsports.com
Reply With Quote
  #3 (permalink)  
Old 01-26-2017, 04:22 AM
1795's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2013
Location: Canandaigua, NY
Cobra Make, Engine: SPF MKII Riverside Racer FIA
Posts: 2,471
Not Ranked     
Default

I am interested in hearing what the engine builders have to say on this topic. There was a discussion recently among several vintage race car drivers about flow vs. oil pressure after somebody (not me) burnt their main bearings. Part of the discussion included a recommendation to go with the oil filter that offered the least amount of resistance to flow, as race engines are rebuilt more often than engines that primarily are used on the road and it is more damaging to them to reduce flow than to let some small particles through.

I would not necessarily equate high pressure with high flow volume. While there may be some overlap, I can easily see a situation where due to tight tolerances oil pressure may be high and flow low secondary to restrictions. At the same time very loose tolerances may result in high flow with low pressure.

My guess would be that many factors come into play.
__________________
Reply With Quote
  #4 (permalink)  
Old 01-26-2017, 04:26 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Louisville, KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,389
Send a message via AIM to blykins
Not Ranked     
Default

There are too many variables to make blanket statements and sometimes it's engine specific....i.e. 289/302 vs 351W vs 351C vs FE....

Texasdoc's post stems from some issues he's been having with some AFR cylinder heads.

However, some of the things he quoted, I don't necessarily agree with.
__________________
www.lykinsmotorsports.com
Reply With Quote
  #5 (permalink)  
Old 01-26-2017, 06:51 AM
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2012
Cobra Make, Engine:
Posts: 61
Not Ranked     
Default

This is the perfect opportunity for me to ask about my problem. I have good pressure at idle and cruising at Highway speeds, but at higher speeds and higher rpm i.e. 4500 over 100 mph the oil pressure drops. I'm using straight 30, but for this problem, I don't think that has anything to do with it. Any input would be appreciated.
Reply With Quote
  #6 (permalink)  
Old 01-26-2017, 06:55 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Louisville, KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,389
Send a message via AIM to blykins
Not Ranked     
Default

If you're losing oil pressure with rpm, it's most likely that you're running out of oil in the pan.

Either you just don't have enough oil in the pan, or your pickup clearance is such that it's either being uncovered or too close to the pan to flow enough oil.

Could be some other causes too....a galley plug missing somewhere which causes an internal bleed, too much oil going to the top end, etc.

It's not uncommon to lose a few psi at the top end, but if you're just getting into the gas above cruise rpm and you're losing pressure, I would lean towards my previous thoughts.
__________________
www.lykinsmotorsports.com
Reply With Quote
  #7 (permalink)  
Old 01-26-2017, 07:10 AM
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2012
Cobra Make, Engine:
Posts: 61
Not Ranked     
Default

Thanks Bill,
I have a Milodon Oil pan and I didn't build the engine. Dipstick shows full, but could it be improperly marked? 351w Just a thought. And no,doesn't drop right after cruising speed,after. 100 and drops below 40!
Reply With Quote
  #8 (permalink)  
Old 01-26-2017, 07:38 AM
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2012
Cobra Make, Engine:
Posts: 61
Not Ranked     
Default

I thought it might be a quick easy fix buy adding a couple of quarts of oil, or maybe it's a blessing in disguise.I have no buisness driving that car over 100 mph.
Reply With Quote
  #9 (permalink)  
Old 01-26-2017, 08:11 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Louisville, KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,389
Send a message via AIM to blykins
Not Ranked     
Default

Matt,

Sounds like you are starting to lose volume in the pan or you're uncovering the pickup on high acceleration/speed.

Without knowing or assuming anything else about how the engine is assembled, your idea about trying an extra quart of oil would be something worth trying.

Also, if you're pulling your oil pressure from the rear of the block, it's not uncommon to see oil pressures like that, since it's getting "residual" pressure after all the bearings/lifters/etc. have been fed.
__________________
www.lykinsmotorsports.com
Reply With Quote
  #10 (permalink)  
Old 01-27-2017, 05:00 AM
Dwight's Avatar
Senior Club Cobra Member
Visit my Photo Gallery

 
Join Date: May 2001
Location: Florence, AL
Cobra Make, Engine: RCR GT 40 & 1966 Fairlane 390 5 speed
Posts: 4,511
Not Ranked     
Smile

I'm not an engine builder

so when I build an engine I get my buddy Eddie who is an engine builder to help me. I watch him and hand him tools and do the dirty work and clean up after he leaves.

I had an engine that would run out of oil in the top of third gear (6000 rpms) 100 mph. Oil pressure gauge would go to zero. Problem was dip stick was marked wrong and the pick up was 5/8" off the bottom of the pan.

Now I clay check all pick up / oil pan clearance.

And through the years I have found several Cobra dip sticks marked incorrect. We assume the factory got it right when they made the dip stick. But they don't know what block, timing chain cover or oil pan we are going to use.

One time I was helping with a 440 and was doing some research for a oil pan. Some would list the pan as a 5 qt and others 4 qt. After a couple of hours I found the pans were the same but some would add the qt for the oil filter. I guess they though it would sell better if it sounded like it held more oil.
So now I find out how much oil a pan holds and add that amount of oil then crank the motor, let it run for a couple of minutes and shut it down. Wait 15 minutes and check the dip stick. Most of the time I have to remark or cut the dip stick. I know it very anal for a street motor but that just a flaw in me.

Dwight
__________________
''Life's tough.....it's even tougher if you're stupid.'' ~ John Wayne
"Happiness Is A Belt-Fed Weapon"
life's goal should be; "to be smarter than inanimate objects"
Reply With Quote
  #11 (permalink)  
Old 01-27-2017, 06:20 AM
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2012
Cobra Make, Engine:
Posts: 61
Not Ranked     
Default

Thanks Dwight
Reply With Quote
  #12 (permalink)  
Old 01-27-2017, 04:42 PM
CC Member
Visit my Photo Gallery

 
Join Date: May 2006
Location: St. Louisville, Oh
Cobra Make, Engine: A&C 67 427 cobra SB
Posts: 2,444
Not Ranked     
Default

First, now days you here a lot of talk about needing to get flow to the top of the engine quickly. This talk is all about overhead cam engines. Some of the engines are aluminum heads and there is no bearing. The head just has a half round cut into it and the caps bolt to it. The only thing between the cam and the aluminum head is oil. If you do not get oil flowing to the cam quickly on a cold start, its a train wreck.

Push-rod engines do not apply to all of that talk.

Bottom line, as far as springs and valve guides go, oil flow nor oil pressure is critical in this area. In fact they use to put umbrella type valve stem seals on the valve stem to prevent too much oil from getting on the valve stem and dragging past the old cup type seals. You don't need a lot of oil going to the guides. If fact too much will cause it to burn the excess oil. The springs don't do much rubbing against anything, unless the rpms are so high that they are gyrating all over the place. Well the seat and cap see movement. Again if oil pools up, there is plenty. You just need flow to carry away some heat.

If you are getting oil out of every push rod, odds are you have plenty of oil flow.

I tend to be on the side of thinner oil in most engines. A small block does not need thick oil unless the bearing clearances are looser than I would choose to have. I run 10W 30W oil in my 5.0 / 347 stroker.
Pete Munroe likes this.

Last edited by olddog; 01-27-2017 at 04:45 PM..
Reply With Quote
  #13 (permalink)  
Old 01-27-2017, 09:04 PM
eschaider's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2006
Location: Gilroy, CA
Cobra Make, Engine: SPF 2291, Whipple Blown & Injected 4V ModMotor
Posts: 2,628
Not Ranked     
Default

Quote:
Originally Posted by Texasdoc View Post
So if I get 70 PSI at 3000 RPM cruise with 0W-40, I should decrease the viscosity to 0W-30 or 0W-20 to get the pressure down. Lower pressure = higher flow. It is the "flow" that provides protection, not the pressure.

Thoughts on this logic?
If lower pressure provided more flow then you could reduce your pressure to zero psi and get maximum flow. I have noticed that whenever my oil pressure is at zero the flow is also at zero. I suspect your experiences might be similar.

Dr. Dmitri Kopeliovich is the Director of Research at King Bearings and has been with them in that capacity since 2000. He has published 500 or so papers on Materials Engineering and Materials Engineering related subjects. He is responsible for a significant portion of the original research in the design, development and production of King bearings for both racing and non racing applications.

The following figure is from one of his papers Engine Bearings and How They Work (<= clickable).



Figure 2 above, graphically depicts how the oil is literally pumped into the space between the crank journal and the bearing insert by the rotating journal. Some of Dr. K's words, on the phenomena, which you can read if you choose to download the paper;

"Fig.2 demonstrates a hydrodynamic journal bearing and a journal rotating in a clockwise direction. Journal rotation causes pumping of the lubricant (oil) flowing around the bearing in the rotation direction. If there is no force applied to the journal its position will remain concentric to the bearing position. However a loaded journal displaces from the concentric position and forms a converging gap between the bearing and journal surfaces. The pumping action of the journal forces the oil to squeeze through the wedge shaped gap generating a pressure."

There are a wealth of additional bearing, lubrication and performance related white papers the good Doctor has published that are downloadable from the King Bearing website. I think you will find a very well organized and presented technical emporium of information specific to bearings, lubrication and race / performance engine applications that is factual.

Ford went to progressively heavier oils for their higher powered engines. The low viscosity oils they recommended for their daily driver types of vehicles had to do with CAFE (Corporate Average Fuel Economy) standards the Detroit Car Makers were required to meet.

Ford likes a 5W-50 weight oil for the new GT350 engine. Most Windsors and FE's are assembled with looser clearances which would encourage me to run something more like a 15W-40 or 50 oil if it were my engine.

Here is a pic of Ford's oil change kit for the GT350. Note the oil weight on the bottle;



The little pipsqueak engine I run uses 15W-50 Mobil 1 synthetic. My engine idles at about 900 rpm with 65psi oil pressure after it warms up. When it is cold, at first start, it idles a little north of 110 psi. When I am driving in traffic at 1800 rpm it has a little over 85 psi of oil pressure.

These slightly elevated oil pressures will consume an incrementally small but real portion of your engine's power to maintain. It absolutely guarantees a more than adequate oil delivery to all bearing surfaces in the engine as long as there is oil in the pan and my oil pump is spinning. I have never wanted for that incremental horsepower.

BTW in the FWIW category the relationship between pressure and flow for fluids is a second order relationship where the pressure increase is equal to the square of the volume increase. If you wish to double the volume flow of a fluid thorugh a given orifice then you will need to increase the pressure by a factor of 4. The bearing clearances we run in our engines represents the orifice referred to above.

You should do things for your engine that you think are best for you (and your engine).


Ed



p.s. If you choose to run high volume, high pressure oil pumps you also need a properly baffled, high volume oil pan. If you do not use one, you will pump your pan dry and smoke your engine's bearings which is one of the issues Brent was cautioning you about. Take a look at Fords oil change kit for the GT350 one more time. There are ten quarts of oil ...
olddog and 1795 like this.
__________________


Help them do what they would have done if they had known what they could do.

Last edited by eschaider; 01-27-2017 at 09:13 PM.. Reason: Spelling & Grammar
Reply With Quote
  #14 (permalink)  
Old 01-28-2017, 12:13 AM
xb-60's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2009
Location: Adelaide, SA
Cobra Make, Engine: AP 289FIA 'English' spec.
Posts: 13,139
Not Ranked     
Default

Texasdoc, I agree, yes I think you’re over-thinking it. Even ‘highly-tuned’ engines can get by with less than ideal oiling conditions.

A short story….a few years ago (mid-eighties) Wheels magazine in Australia ran a bog-standard Alfa 2 litre twin cam sedan from Sydney (east coast) to Perth (west coast)….around 4000km / 2500 miles in around 29 hours, start to stop. At Port Augusta (roughly half-way) the Alfa mechanic from Adelaide met them for a quick check-over and they reported zero oil pressure at idle, and around 15psi on the gauge at their 170km/h / 110 mph / 5000rpm cruising speed. The mechanic said “he’s OK” and they continued their blast across to Perth at 15psi on the gauge and with no problems. The cause of the low oil pressure was one of the aluminium slugs that blank off the cross-drillings in the crank having come out. I know this because A. my Alfa has had the same symptoms twice and B. I knew the Alfa mechanic.

Providing your oil is thin enough at cold start-up, you’re OK (almost all the wear occurs at start-up). I could also add that my Alfa is 41years old now (I've had him for 36 years) and has clocked up over 250000 kilometres, and has always run on 20W-50 oil.


Cheers,

Glen
Reply With Quote
  #15 (permalink)  
Old 01-28-2017, 10:06 AM
CC Member
Visit my Photo Gallery

 
Join Date: May 2006
Location: St. Louisville, Oh
Cobra Make, Engine: A&C 67 427 cobra SB
Posts: 2,444
Not Ranked     
Default

Quote:
Originally Posted by eschaider View Post

BTW in the FWIW category the relationship between pressure and flow for fluids is a second order relationship where the pressure increase is equal to the square of the volume increase. If you wish to double the volume flow of a fluid thorugh a given orifice then you will need to increase the pressure by a factor of 4. The bearing clearances we run in our engines represents the orifice referred to above.

You should do things for your engine that you think are best for you (and your engine).
First Ed's post is one of the best posts to this site.

I wanted to clarify and expand a bit further on this paragraph. As a process control engineer (more on that later), I have used orifice plate flow transmitters. For accuracy you have a pipe with a plate clamped between two flanges. The whole in the plate is a smaller diameter than the pipe. The pipe must be straight (no elbows) for a length 10 pipe diameters upstream, and 5 pipe diameters down stream of the orifice plate. Now you measure the delta pressure across the orifice plate. (delta meaning the inlet pressure minus the exit pressure. You take the square root of the delta pressure and that is proportional to the flow.

Flow = K * (delta Pressure)^0.5

where K = a constant

K has to take into count the pipe diameter, the orifice diameter, and the viscosity of the fluid.

If you are pumping fluids like water the viscosity changes very little over its temperature range. The orifice plate flow transmitter is as easy as falling off of a log. It works perfectly.

If you are pumping a polymer like Polystyrene, the viscosity changes with temperature exponentially. That could be compensated for, but it gets worse. Polymers' viscosity also thins (lower viscosity), when it is put into a sheer plane. As polymer flows through a pipe the velocity of the molecules at the wall approach zero. Each layer of molecules further from the wall is traveling faster than the previous layer (closer to the wall), and the flow is greatest at the center of the pipe. This causes a shearing action between each layer of molecules. The velocity change between the layers is not all the same, therefore the viscosity change due to shear thinning is different at every layer and therefore the viscosity of the polymer is not constant across the pipe. The point to this paragraph is to explain that an orifice plate flow transmitter will not work, with a polymer flowing through a pipe. Although with a large finite element computer algorithm and a lot variables not mentioned, we can estimate pressures for design purposes, but there are so many variables that the errors in each measurement adds up to me using the words "estimate the pressure."

Ok Rick so why did you waste my time telling me about polymers when we are talking about oil? Well because the way they get oil to behave like a straight 5 wt oil at a low temp and also behave like a 50 wt oil at a high temp is that they attach molecules into chains that intertwine like a plate of sphegetty. "Attaching molecules into chains that intertwine like a plate of sphegetty" is the definition of how a polymer is made. Multi-viscosity oil is partially polymerized oil. So, it does not behave like water at all. It behaves similar to a polymer, but not nearly as extreme.

The further the spread of the viscosity numbers, on a can of oil, the more they had to polymerize the oil to accomplish that spread. A can of 5-20W oil is not as polymerized as 5-50W oil. They need longer chains of molecules linked together in the 5-50W oil, to get the 50W behavior at high temperature, because it is a 5W base oil.

So what does all this mean? Well it explains why oil pressure readings are often talked about, and there are as many opinions as there are people talking about it. You are looking at a reading that does not precisely tell you a damn thing (other than the pressure at one spot). Because there are so many other variables that you do not know, you could not possibly tell me how much oil is flowing based on that one pressure measurement.

So why does one person run 5-30W oil in his engine and another person run 5-50W in essentially the same engine and neither one of them has ever had a failure? Both emphatically states they are running the best oil. They cannot both be right. Right? Well maybe.

Because of the sheer thinning property of polymers, the oil kind of self adjusts or automatically compensates to some degree. If you put a high viscosity oil into your engine, the oil will flow slower, therefore it will stay in the bearing longer. The longer it says in the bearing, the longer is will get shear thinned, and the more heat that will put into the oil. The thinner the oil gets, the faster it will flow. Hence it somewhat finds it own temp, flow, and viscosity. So at 8000 rpm the behavior of a 5-30W oil in a bearing may not be all that different than a 5-50W oil. The temperature of the 5-30W will be less than the temperature of 5-50W oil when it exits the bearing. The shear thinning has a greater affect in the 5-50W because it is more polymerized. The viscosity of the two oils while in the bearing is much more close than you would think, given what they act like when you pour them out of a bottle.

One last point to make. Don't think, based on what I said, that you cannot put too thick of an oil into an engine, because it will just get heated and thinned more and self adjust to the right thickness in the bearing. I did not say that. The oil passages (pipes if you will) that the oil is pumped through to get to the bearings, has little shear thinning and heat affects on the oil. A high viscosity oil will only flow through the block to the bearing so fast. It is possible for a high viscosity oil to stay in the bearing so long, that the viscosity of the oil, while in the bearing, is much lower than what it would be, if a lower viscosity oil was used. Let me state that again. It is possible for a high viscosity oil to actually be thinner, and therefore less protection, while in the bearing, than a lower viscosity oil.

So from this there is a fairly large range of oils you can put into an engine, without issues. The higher viscosity oils require more hp to pump (think the shaft driving the pump getting twisted off), and they will run hotter. The oil only has to keep the metal parts from touching, beyond that you are wasting power and energy. It's a lot cheaper to waste some energy to be on the safe side than destroy an engine. However if you twist off your shaft to the oil pump and are not looking at the pressure gauge you can equally destroy an engine.

So for push-rod engines, I personally wouldn't go less than 5-30W oil nor more than 20-50W oil. I would take into count the typical oil pressure range for the engine in question and if that engine has issues with twisting off oil pump shafts or bearing failures. Generally speaking I stay away from heavy oils unless the engine runs low pressure or it is going to be pushed to the limits of holding together, such as racing. The heavier the oil the more care needed in letting the engine come up to operating temp. That said we are not talking an exact science and there is room for error and many opinions. In this range, it likely doesn't matter a whole bunch.

Not everything I have stated is 100% technically correct. I tried to put this into terms that most gear heads would grasp, so I left the crap that would put you to sleep out. I may have failed at that. I am by no means an expert on this subject, but I have some experience that applies. I just wanted to share in an attempt to reduce some of the misconceptions I read from time to time.

Disclosure: I worked for one of the largest Chemical Companies for 38 years. I started as a operator and worked 7 years as a control room operator. I went to college part time to get an electrical engineer degree. I was promoted into a job that was essentially an engineer position. I did not complete getting the EE degree. I have written process control programs that run a variety of easy to complex processes. Among many things, I worked on improving polymer pump designs, which uses the polymer that is being pumped as the lubricant that flows through the bearings. The last 8 years I have been full time in a process control engineer position. The company, I worked for, sold the plant that I work at to a new company, and I continue to work in that role, for the new company.
eschaider, RET_COP and 1795 like this.

Last edited by olddog; 01-28-2017 at 10:49 AM..
Reply With Quote
  #16 (permalink)  
Old 01-28-2017, 12:20 PM
eschaider's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2006
Location: Gilroy, CA
Cobra Make, Engine: SPF 2291, Whipple Blown & Injected 4V ModMotor
Posts: 2,628
Not Ranked     
Default

Very impressive tour de force on polymer fluid flow and properties Olddog (apologies I forgot your first name). You nicely fleshed out the stuff (in English) I couldn't.

The whole lubrication subject for our type of engines, sadly is sometimes permeated with urban legend and internet science. Your explanation adds substantially to the real knowledge base out here. Thanks for weighing in!


Ed
__________________


Help them do what they would have done if they had known what they could do.
Reply With Quote
  #17 (permalink)  
Old 01-28-2017, 02:21 PM
1795's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2013
Location: Canandaigua, NY
Cobra Make, Engine: SPF MKII Riverside Racer FIA
Posts: 2,471
Not Ranked     
Default

Amazing discussion and expertise! Luckily I have enough basic scientific knowledge to follow the discussion. Thanks to Olddog and Ed!
__________________
Reply With Quote
  #18 (permalink)  
Old 01-29-2017, 02:27 AM
RET_COP's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jul 2009
Location: Westerly, RI
Cobra Make, Engine: Fordstroker 408w custom solid roller-Craft ported Brodix 17*heads-CFM ported Vic Jr. intake-1 3/4 primaries- 575hp-TKO-600RR Liberty upgrade- -Moser 8.8 trutrac-McLeod Street Extreme--QA-1-Wilwood brakes, Classic Chambered 3" Cobrapacks, Avon's
Posts: 645
Not Ranked     
Default

All of the oil viscosity discussion had been about flow and bearings. Would having hydraulic lifters vs solid lifters change anything. I read a lot about air being trapped in the oil with higher viscosity oil vs. better lifter stability at higher rpms with higher viscosity oil. any thoughts?
__________________
Lou
Reply With Quote
  #19 (permalink)  
Old 01-29-2017, 04:01 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Louisville, KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,389
Send a message via AIM to blykins
Not Ranked     
Default

I have seen trouble with Morel hydraulic roller lifters not being able to meter higher viscosity oils. Going from a 20W-50 to a 10W-30 made a world of difference.
__________________
www.lykinsmotorsports.com
Reply With Quote
  #20 (permalink)  
Old 01-29-2017, 04:12 AM
DanEC's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Apr 2009
Location: Little Rock area, AR
Cobra Make, Engine: ERA Street Roadster #782 with 459 cu in FE KC engine, toploader, 3.31
Posts: 4,480
Not Ranked     
Default

Quote:
Originally Posted by Marc Wulf View Post
This is the perfect opportunity for me to ask about my problem. I have good pressure at idle and cruising at Highway speeds, but at higher speeds and higher rpm i.e. 4500 over 100 mph the oil pressure drops. I'm using straight 30, but for this problem, I don't think that has anything to do with it. Any input would be appreciated.
There is another possibility for losing pressure at higher engine speed and that's an over-filled sump and the crankshaft frothing the oil (aeration). I experienced this in a Pontiac I once put too much oil in by accident and it was fine until I settled in on the highway and then it would start to lose pressure and the pressure would fluctuate.
__________________
ERA 782 Running
https://www.youtube.com/watch?v=Cfge...b1-77fqwFRu7c]
Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 03:14 PM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: CC Policy
Links monetized by VigLink