Oil Pressure

[Jim T.]

Re: Oil Pressure

Using the high pressure/high volume pump also uses more engine horsepower to operate. Read an article in Chevy High Performance magazine, don't remember all the engine specifics, but on the dyno a SB Chevy engine picked up about 7hp on another engine dyno run when the high pressure/high volume pump was replaced with a stock unit.

[Duke W.]

Re: Oil Pressure

Interesting piece of data. I've never seen it quantified.

A "high volume" pump on a road engine with normal clearances will short circuit most of the oil back to the inlet once the relief spring opens, but it takes power to pump the bypassed oil, and this power is converted to heat added to the oil. The pump is just using power to churn up the oil.

High volume/high pressure pumps were the norm decades ago for high revving loose clearanced racing engines, but nowadays the most competitive classes like Sprint Cup use the minimum oil flow/pressure that will allow the engine to live for the length of the race in recognition that eliminating internal parasitic power losses can mean the difference between winning a race and finishing 20th.

Most "engine builders" haven't gotten the word, so they keep up with the same old saw. The fact remains that the OE oiling systems are very reliable and no more than a reputable brand OE replacement pump is necessary for any vintage engine for normal road use and even "light" racing - like occasional drag racing, autocross, and even a day at a real road racing track.

Duke

[Tom O.]

Re: Oil Pressure

[quote=Mark Hontz (44808);341592]I've just rebuilt my 65 SB and have very high oil pressure during the 1st hr or so of break in (over the dash board's gage of 60 psi). I was afraid of blowing the gage, so I disconnected it from the block and plugged it.

I have a '67 427/390. The man who rebuilt it and whom I bought the car from put in a high pressure pump. I've had the car five years and it has pegged the 0-60 psi gage every time on start up. The former owner/restorer also used 10W/30 Mobil 1 in it, so I did also. But it had numerous oil leaks. I mentioned the leak problem to my Corvette expert, friend, and master mechanic. This is after almost all seals were replaced including the rear main. He told me to use 20W-50. And that the seals on our old engines do not seal synthetic oil well. I had never used that heavy an oil but after a year the leaks have all but gone, the gage still pegs until after the oil has warmed up, approximetely ten minutes, and the pressure at cruise is still around 40-45.

I am no expert but my friend is.

[Terry R.]

Re: Oil Pressure

Mark when I was trying to get my oil pressure right and took the pan off several times I found it easiest to remove pan bolts, let drop a little, reach inside and remove bolt for pump then it would all drop right down. You can still torque bolt back on reassembly. This was on a '62 though. Good Luck