A show on Motortrend called Engine Masters just did an episode testing the oil pressure and power of different stages of oil pumps for a GM LS engine. For an engine making
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Engine Masters Tests LS Oil Pumps
- Thread starter RDY4WAR
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I remember that, the How to hot rod small block and big block Chevrolet engines books in the early 1970's would say the HV and HP oil pumps would take more HP to run and that the most of the savvy pro engine builders would keep the standard volume oil pumps.
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It has to, but it isn't by much. So it's still a waste.
Engine Masters is awesome. I get it on my cable as channel 426 and record every epoisode. I have to catch up!
The pressure curve on the gen 4 pump was weird.
The pressure relief bypass opened.
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There was mention the other day about the current LSx having a vane pump, not a PD pump, but I could not find anything on that on the web when I briefly searched. Would that be a Gen V pump? Sorry, I don't keep track of GM's smallblock evolutions.
Funny you mentioned those. I have them all as well as a few other books that are my bathroom reading material.
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The vane pump started with the Gen 5 LT1 engines.
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Excellent, thanks for the confirmation. Do we have any details on this pump? It seems like a bizarre detour on an engine family that has been GM's staple for over 20 years.
I don't know hardly anything about it. I haven't kept up with the Gen 5 engines.
Yeah i get that was the conclusion. It is still weird and I can't see that pressure being desirable. don't understand why Melling would build a pump that would keep the relief open at higher RPM.
Of course I also don't understand why they shipped a bunch of FE pumps with a hole in the relief valve plug...
I like the show, but some parts do annoy me. I've heard them state known myths on there before. I've also heard them try to describe why something made more or less power that's not actually correct and they're misunderstanding what's going on. I know there's times they try to simplify what they're doing for the average joe, but that sometimes causes misconceptions and leaves things open to misinterpretation. This episode is an example of that as people might think oil pressure is what's robbing most of the power. It is a contributor, but the real power robber is oil volume. The Gen III pump moves 0.96 in^3 per revolution while the Gen IV moves 1.28 in^3 and the HV Gen III is somewhere in the middle. Slinging that higher volume every revolution is what's killing the power regardless if it's being bled off downstream or not. If you were to bypass the Gen IV pump at 75-77 psi like the standard Gen III, you'd likely still see a similar power loss.
I'm waiting for them to do an episode on oil viscosity. Take that same LS engine that'll run forever on a decent 5W-30 and put in a 10W-40 and 20W-50 to see the difference in power to viscous losses.
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On one episode they used 87 , 90 something, 106 Racing gas, and E 85.
They adjusted the timing for the best power with each.
Their conclusion was if a engine was tuned for max power, which in the case of the gasolines turned out to be 29 degrees all in, upping the octane then trying to advance the timing did not actually result in more horsepower.
The E85 turned out to make the most horsepower and responded to more advance. Rather than me going further with that, check out the episode.
They adjusted the timing for the best power with each.
Their conclusion was if a engine was tuned for max power, which in the case of the gasolines turned out to be 29 degrees all in, upping the octane then trying to advance the timing did not actually result in more horsepower.
The E85 turned out to make the most horsepower and responded to more advance. Rather than me going further with that, check out the episode.
It's because the Gen V pumps are variable displacement. A vane pump is much easier to make variable displacement because you can slide the the core of the pump one way or another to change the displacement, thus pressure and drag.
Most transmissions oil pumps are variable displacement vane pumps and have been for many years, They're still reliable and can make a ton of pressure.
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