Register now to get rid of these ads!

Oil Pressure change with new cooler?

Discussion in 'The Hokey Ass Message Board' started by jonny o, Jun 14, 2009.

  1. jonny o
    Joined: Oct 26, 2007
    Posts: 836

    jonny o
    Member

    In general, how will the addition of -10 lines and a good flowing oil cooler change my cruising oil pressure?

    I understand that the cooler oil will add pressure when it's released into the motor. It's a strip 350 that I'm trying to make highway cruisable and I need to get rid of the high volume pump, but if the addition of the cooler will drop it a few pounds, I might try that before swapping pumps.
     
  2. lippy
    Joined: Sep 27, 2006
    Posts: 6,825

    lippy
    Member
    from Ks

    I don't understand what you are trying to do.:confused: Lippy
     
  3. Scorch67
    Joined: Jun 6, 2009
    Posts: 85

    Scorch67
    Member
    from Omaha, Ne

    you could add a hundred miles of lines and the only oilpressure change will be untill the entire sytem is pressurized.

    The walls of the conduit will flex but build tension untill the tension equals the oil pressure then it stops flexing. same as with rubber vs braided stainless brake lines, theres no overall drop in pressure just takes a moment longer to build max pressure.

    if you put a restriction in the system it will cause pressure to build on the pump side but only to the rated pressure of the pump the excess is released by the blowby in the pump so there'd a pressure drop on the other side of the restriction by restricting the flow like you do with the pill in a mechanical fuel injection setup but never from adding dimension to the system.

    Your applying the logic of an open system to a closed system maybe?

    A high volume pump is better than high pressure. high volume has bigger pump gears, high pressure does not and just has a pressure blow-off with a stiffer spring.
    high pressure puts more stress on the pump driveshaft. Anyway the engine builders always recommend installing a high volume not high pressure pump.
    I've read that too much pressure can damage bearings somehow but as to how I can't imagine.
    My pontiacs generally run 60-80 lbs at speed
     
    Last edited: Jun 14, 2009
  4. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,910

    dirty old man
    Member Emeritus

    Try a lower viscosity oil in synthetic. Synthetic doesn't thin out as much as it heats up so they can start out much thinner and not be too thin when heated up. Examples: (1) I have a '94 Lincoln MKviii daily driver that I run on Amsoil 0W-30, it's thin as water when you pour it in, but since it doesn't thin under heat, it is still a 30 wt. when hot. (2) My '03 Chevy Silverado Duramax diesel powered pickup runs a special Amsoil diesel formulated synthetic 5W-30 that again, doesn't thin out under heat.
    I'm citing Amsoil products because I'm an independant dealer for Amsoil and this is what I'm familiar with. I'm sure some of the other brands have similar oils out.
    My under construction 355 SBC for my roadster (also under construction) will have a flat tappet cam and with all the talk and magazine articles on how ZDDP has been cut back in oils approved for new cars (supposedly to reduce catalytic converter clogging), I'm going to run Amsoil 10W-40 "Premium Protection" oil, which has a high level of ZDDP and is not intended for vehicles with cats.
    I'm using a high volume oil pump because I'm using the new Comp Cams lifters (flat tappet) that have a .012" hole in the face of the lifter to bleed oil off onto the cam lobe and lifter face. Comp Cam advised using a high volume pump with that .012" hole in 16 lifters bleeding off oil.
    Is your engine flat tappet or roller?
    Dave
     

  5. jonny o
    Joined: Oct 26, 2007
    Posts: 836

    jonny o
    Member

    Thanks Scorch, It makes sense now that you put that imagery in my head.
    Dirty, It's a hyd flat-tappet cam, with slightly enlarged bleeds for a long duration cam.

    I'm at 50-55psi idling once warmed up, and 70-80 at the top end (6800). It's what the engine builder and I wanted for the strip, but I fear that running at 2700-3000 on the higway for extended periods is going to cavitate and air out my oil... if not fill the valve covers.

    I am adding the cooler for consistency and volume, and hoping that I can run a lighter, and yes, possibly synthetic, oil on a road trip without worrying about that much psi for extended periods.
     
  6. jonny o
    Joined: Oct 26, 2007
    Posts: 836

    jonny o
    Member

    Thanks RR. In my search before I posted, I saw a lot of people pushing no more then 60psi at redline, so thanks for the backup.
    The theory behing changing viscosity was that the same weight oil will run cooler and consequently thicker with an oil cooler, and a lighter weight could be used.

    I guess it's time to hook it all up and see what happens... I really don't want to have to pull the motor, but I also don't want too much air in my oil.
     
  7. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,910

    dirty old man
    Member Emeritus

    My suggestion of using synthetic is to allow an oil of thinner viscosity while the oil is cool, so as to lower cold oil pressure, which is the usual time of trouble with a high volume oil pump in my experience. The pressure relief spring, valve, and passage simply can't bleed off enough oil to keep the pressure down if a thick oil is used.
    At higher temps, a good synthetic won't thin as much as a petro oil that was the same viscosity at low temps. When up to operating temp a synthetic will be much higher in viscosity and film strength than a petro oil thaty was the same viscosity at low temps. Sort of like the best of both worlds, thin at low temps to aid circulation and flow, but still thick enough for bearing protection at high temps.
    Dave
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.