GThinkiong ab out pulling pump and all the crap goes with it. Ran vc to headers beofe and never issue and lot less stuff on engine. I know helps issure no or less oil leaks. But that should be fixed other wise.

Two option to replace. Simple puke tank or crank case evac. Both nothing gained power wise but effective pressure control.

I understand that with correct rings their is some power. Question I have is has anyone seen track numbers improve or change with or without vacuum pump?

I had a vac pump lock up and sling the belt at some point during the run and car ran .04 off. I don't know exactly when in the run it did it or if the pump seizing caused part off the loss. 5.0 car. I had a buddy of mine with a 6.10 car slowed down .06 and said it was all vac pump related.
I find it hard to believe a vac pump makes that much difference but that is what I've seen.

Yes, a vacuum pump will make more power and your car faster plus stop oil leaks if it is sealed good. Been there done that. How much difference it makes on your combination? Who knows it depends on how well it is working and how well it is sealed up.

I would not remove the vacuum pump.

I have chucked a belt off in the middle of a dyno run, it was worth 18hp in this case. I can tell you the more vacuum you pull the more hp you make up to about 15 inches. After that the gains are pretty small.

Also people don't run their pumps near fast enough, most times at 1/2 engine speed, nowhere near there max speed. Note the speed limts for the pumps from this PDF

"Q: HOW FAST CAN I DRIVE MY VACUUM PUMP? A: Moroso Vacuum Pumps Part Nos. 22640 and 22641 can turn no more than 6500
RPM shaft speed. Moroso Vacuum Pump Nos. 22642 and 22643 can turn 8000 RPM maximum shaft speed"

https://www.moroso.com/pub/med...VacuumCombo-Info.pdf

quote:

Originally posted by sr4440:
I have chucked a belt off in the middle of a dyno run, it was worth 18hp in this case. I can tell you the more vacuum you pull the more hp you make up to about 15 inches. After that the gains are pretty small.

Also people don't run their pumps near fast enough, most times at 1/2 engine speed, nowhere near there max speed. Note the speed limts for the pumps from this PDF

"Q: HOW FAST CAN I DRIVE MY VACUUM PUMP? A: Moroso Vacuum Pumps Part Nos. 22640 and 22641 can turn no more than 6500
RPM shaft speed. Moroso Vacuum Pump Nos. 22642 and 22643 can turn 8000 RPM maximum shaft speed"

https://www.moroso.com/pub/med...VacuumCombo-Info.pdf

The OD works about same as TA/FC does with blower. They lowered allowed OD so racers went smaller crank and more rpm, Same power. With punmp if you are hitting 7000 max then pump never see over 3500 and if you ar 8000 pumps at 4000 rpm. To get same vacuum gthe lower will need more over drive. I would like to find a max rpm effect of moroso iolder 3 vane pump I have. Guessing it is alose dependant upon windabge created in your combo and how much you are pulling postive out before getting to negative pressure, Probably just overthinking it.

Right now rings are nowhere near optimal for gains from punmp. New engine with bigger higher compression and more optimized ring package might see something from it. RFunning .047 SS dyke upper 1/16 TS secondary and 3/16 low tenion oil rings. New combo thinner rings gas ports and .125 bigger with about 3:1 more compression. Figure better suited and need of vacuum pump.

This message has been edited. Last edited by: wideopen231,

quote:

Originally posted by sr4440:
I have chucked a belt off in the middle of a dyno run, it was worth 18hp in this case. I can tell you the more vacuum you pull the more hp you make up to about 15 inches. After that the gains are pretty small.

Also people don't run their pumps near fast enough, most times at 1/2 engine speed, nowhere near there max speed. Note the speed limts for the pumps from this PDF

"Q: HOW FAST CAN I DRIVE MY VACUUM PUMP? A: Moroso Vacuum Pumps Part Nos. 22640 and 22641 can turn no more than 6500
RPM shaft speed. Moroso Vacuum Pump Nos. 22642 and 22643 can turn 8000 RPM maximum shaft speed"

https://www.moroso.com/pub/med...VacuumCombo-Info.pdf

Not saying lack of vaccum did not cause loss. I do wonder if butt load of crankcase pressure due to now was out did cause a good amount of it; Just always question the obvious since has bitten me before/

quote:

Originally posted by wideopen231:


Not saying lack of vaccum did not cause loss. I do wonder if butt load of crankcase pressure due to now was out did cause a good amount of it; Just always question the obvious since has bitten me before/

Crankcase pressure was 3 inHg max on that pull. I was testing a bunch of stuff, intakes, camshafts, valve lash, headers and after that run pulley size. It was my engine and when I got done, I had 56 pulls and used a barrel of fuel.

I keep the vacuum limited to 14, been told that beyond that a wet sump can dry out the wrist pins. Not about to test the theory, 14 will do.

Bob

I like my evac now that it’s working properly. Pulls just enough that there is no positive pressure and not enough to collect any oil. Zero maintenance.

I put a VP104 on my old car. SBF 438", made maybe 700hp give or take. 5.90 consistently on methanol, very predictable, before the pump. Threw the pump on it and picked up 0.0 tenths. Oil stayed cleaner but that was the only difference I noticed.

Fast forward a little. I pulled the engine in the winter for a 12 season freshen up. I know, I should have had it apart long before 12 seasons but it is what it is. While apart I did the pistons (exactly the same as the old ones just not worn), reused the rods, new bolts, had the crank magnafluxed, etc (no issues found), same cam, new lifters (identical to old ones), same everything except I was able to source some low drag rings. These were 1.5-1.5-3.0 and they didnnt have anything but low drag 3.0 oil rings, so I picked up 8 of those. I also went to a coil-near-plug setup running off of a megasquirt (but without the FI part of EFI, it ran spark only). Well I realized that my old valve covers weren't the greatest to mount the coils so I bought some fabricated covers and put my own coil brackets on. They hit the rocker shafts on the ends like a lot of the SBF covers do, so I had to clearance them with a hammer (you know the drill). In the process I guess I created a leak because I noticed some oil after the first start. Pulled them back off, fixed the leak, and while I was doing it I decided to smoke test the entire crankcase; finding all kinds of leaks here and there. Oil pan especially, corners where the end seals are mostly and then a dipstick hole (which I plugged but the plug leaked). This was the same pan I had on it for the last 12 years (Moroso). Intake also leaked a little but it was minor. It took a while but I got all that fixed and smoke tested again with zero leaks. Went to the track (ran out of time on the test stand) and immediately figured out that the the pump's valve needed to be adjusted-it was datalogged at 20"/hg. It was a botched run with no real ET or MPH data. I turned it down and got it to 12". Finally got a good run and, combined with averaging runs over the next few race days, came up with exactly .16 improvement and about 1.8mph. 5.90 consistently to 5.72-5.73. I found a little more later on with a change in the intake setup (.03 or so) and then at an old high school buddy rally at the drag strip, ran the best it's run without running nitro, at 5.68/122. Our little group of buddies were trash talking on farse book about who's gonna be the baddest. I stayed out of it (which is unlike me...) and just showed up with the same car I used to street race in the 1980's against those guy's fox bodies camaros etc, clicked off a 5.68 3x in a row and they about kicked me out of the place. 2 1/2 months later I sold the entire operation. Car, parts, trailer, hitch, generator, everything. Just burned out on drag racing, after owning the car for almost 40 years.

I learned that you can't just throw a pump on and expect a huge improvement. The engine has to be "built" for use with the vac pump, and I'm sure I could find more if I'd kept it and played with it some more, but it was time for it go go.

Here is how much you can pull with NO vacuum pump if you get creative!

^^^^^ Being creative might mean having a knowledgeable header designer/ fabricator build an evac header like you purchased to produce the results you posted.

It looks like that vacuum is around 4,000 rpm, what happens at other rpms?

2BKING