anyone running a vacuum pump in ENDURANCE application like a marine engine, if so, what brand and where did you mount it? recently saw surprising results on a non marine engine I dynoed with/without the vacuum pump. Standard tension rings, 3% leakdown, no evidence of blowby on top during pulls, saw a 18hp increase at peak and power acrossed the board, vacuum pumps always been hocus pocus crap to me IMO that wouldn't do much unless you ran a exotic ring package that freed up hp from less drag then bandaided the ring seal with a vacuum pump, I no longer believe that!
I see out of all the different pumps available, some comments are they wear fast, were never intended for much more than short burst race use. Exploring options for a dyno experiment Im going to do soon, want to purchase something that will last at least a 100 hour rebuild interval at a minumum, Smitty

From what we've seen is that over about 4" of vacuum on the street causes excessive ring, piston & pin wear. On the strip you fire the motor up first time with the pump hose off to let oil get everywhere. Then plug it in and pull 15-20" with no adverse effects. Somewhere between 15 & 20 is where the gains start to diminish on a fresh build. Whatever you do don't break in a motor with a pump hooked up. Run it thru the 15 minutes of warm up program 1500-3000rpm up and down at 60% load just like any other.

I'm running a gz vp104 pump on my twin turbo street car. In my research that's the only one that would survive and not stick the vanes. I have 1200 miles on it so far, no issues. It can be rebuilt for $100 if needed. They claim it can run for 500 hours at 3500rpm(pump speed). I have it set for 12" max. Just tore engine down for other issue. No pin wear at all. Bearings looked great. Breaking refreshed motor in with it on now. Give tom a call at gz. He is very helpful.

We used the gz pumps on a lot of drag race motors, and always took the belt off if running on the street. Machinist and gz said the wrist pins would not get enough oil for any long periods of run time. The pump was never an issue.

Just curious, what is a long period of street time? A ten minute beer run or an hour away car show?

Cruising for 20 minutes or more was pretty much what we went by. These were all 7-9 second cars, 30-40 minutes was the longest they ran otherwise they got trailered.

Back in the old days (1992), I had Stainless Marine weld pan vac bungs in my fully jacketed dry tails for my twin BBC 28 Magnum B class boat.
Would see around 6"-8"@ 6k rpm. 468 w/ zgs rings.
Pretty much zero maintenance.

Hey Smitty, Craig ran one on the WPM (598" NA) for the last few seasons. I am sure he has pics of where it was mounted.

How much vacuum were you running when belt WAS on? was it regulated or? thanks, Smitty

so you ran one on the street and was over 4" vacuum and actually saw advanced wear on the engine? What kind of engine? These boggers whos stuff I dynoed are "play boggers" , not comp boggers so they get drunk/high and hold everything at wot for 20, 30, 60 seconds sometimes so the couple engines Ive done with vacuum pumps recently we regulated them around 10" from what I was told should be a :"safe" number for longer than a drag race but not continuous like a boat or street car, Smitty