crankcase evac

[69trk]

I was thinking about going to local salvage yard and finding an electric vacuum pump to use for an evac system. What do you guys think? I was told if i run full exhaust not to plumb into headers because of back pressure. And i have march surpentine pulleys and can't run a vacuum pump with my set up, plus the pumps are pretty expensive. Just trying to make a little more power, and i think this will help some.

[Super73]

Any idea how much vacum a evac pump creates?

[LONGHAIR]

From what I understand there really isn't an electric pump that can make enough vacuum to do anything. The Corvette pump will only pull about 1.5" and there is a Pontiac version that will pull around 3". That is not nearly enough to do anything. The regular header evac systems pull roughly twice that and even they don't gain that much power.
You need to pull quite a bit more vacuum to really see the benefit and justify the expense. Even then you can still only hope to gain about 5%. That is 25-30 in a 500+ HP engine. It is essentially "free" power after the parts money, but how much is 25HP worth when you are at 500+ already? If you are not making that much power, the gain is even less.
Unless you are competitively racing, I just don't see it. Plus you have to deal with sealing everything up to keep the vacuum in, and to get the maximum benefit, you should really have built the engine with this in mind in the first place. Low tension or even gapless rings help produce more power.
A weekend racer could probably see more gain by looking into traction/chassis tuning, especially in a pick-up truck.

[nxtruck]

Guys,
I'm in the process of doing just this to my truck. I'm using a pump from a '00 Camaro SS. I mounted and wired the pump this past weekend and am waiting on the breather tank and oil cap. From what I've heard, you can expect anywhere from around 2" all the way to 8" of vacuum from one of these pumps. I think the 8" quote might be a little optimistic, but we'll see. I've got a vacuum gauge that will be plumbed inline, so I should be able to monitor how much vacuum it's pulling.
It's been my experience that the header-mounted evac tubes do little, if any, on a vehicle with any sort of exhaust system. On an open-headered race car, they can be made to pull around 4 or 5"s of vacuum, but only if the evac tubes are positioned perfectly in the collectors.
My main concern is pump life. I street-drive my truck quite a bit, and don't want any reliability problems from this setup. Time will tell, I guess.
One more thing to consider: even if these pumps will only pull 3-4"s of vacuum, that's 3-4"s more than you had using just v/c breathers. As far as power is concerned, it's all dependant on how efficient your pump is and how well your engine is sealed up; internally, that is. An efficient vacuum pump will help with any oil leaks you may have, and will also help to control windage in the lower end.
I'll let you guys know how this works once I get some miles on it.

[Super73]

If your only concerned with the vacum at WOT, wire it in to a relay on a WOT switch..

[nxtruck]

Super73,
I have thought about that. Either using a WOT switch or an rpm-activated switch. I'm going to try running it continuously first and see how well it holds up. If the pump dies, I'll end up wiring it to one of the two previously mentioned switches.

[Rodms]

Originally Posted by nxtruck

Super73,
I have thought about that. Either using a WOT switch or an rpm-activated switch. I'm going to try running it continuously first and see how well it holds up. If the pump dies, I'll end up wiring it to one of the two previously mentioned switches.

What kind of gear do you run we can't get that much mph out of mine but we should be in same et mine only 87 mph with 513 gears and th350, 12 bolt?

[Marv D]

Originally Posted by LONGHAIR

From what I understand there really isn't an electric pump that can make enough vacuum to do anything. The Corvette pump will only pull about 1.5" and there is a Pontiac version that will pull around 3". That is not nearly enough to do anything. The regular header evac systems pull roughly twice that ........

I was reading about that 1.5" and 3" and was thinking that exact thought. My header evac will pull 5" with a 1300rpm idle, open exhaust and LONGtube headers. On a street truck through legal exhaust it's going to be lower, but just as effective as a 3" electric pump. I'd think,, and as long as you throw those junk MrGasket push-in breathers away, and replace them with good Mopar breathers (that don't leak like a sieve like the MrGasket junk). Your going to make enough vacuum to keep the seals and all nice and dry anyways. Maybe not enough to help ring seal that much, but every bit helps. ANY vacuum in the crankcase is better than pressurizing the crankcase IMO.

I put a Aerospace vacuum pump on the Nova and pull 10-12" from 6000rpm up (shift at 6800 and trap at 7200). And to be honest, haven't seen any significant increases in power / ET. Mind you the pump went on just as things got stinking HOT around here, but ET's this summer are no better than last summer in like air. My machinist said he sees roughly 30-40HP on a 800HP wetsump motor, and 40-60HP on a drysump high vacuum motor. But dyno HP and what I'm seeing on the track doesn't seem to jive. One big problem you run into with high vacuum is piston pin gaulling. Not sure the dynamics of what all goes on, but the piston pins take a real beating from what everyone tells me. So be carefull in what you ask for,, too much vacuum can cause more headaches than too little. Know of one high RPM motor that was making BIG vacuum and he sucked the Steffs aluminum pan up against the oil pickup,, NASTY results!!!

[69trk]

buddy of mine just put two on his with a guage and some kind of regulator, but he says on his guage that each pump is making 5" of vacuum. He's taking his car to dyno and to the track sometime this month to see what kind of numbers his car will make with and with out the pumps. He's a mustang nut and i guess the mustang guys are doing this. His car ran in the low 9's before he built this new motor. I'll post some numbers as soon as i get them from him.

[nxtruck]

Originally Posted by Rodms

What kind of gear do you run we can't get that much mph out of mine but we should be in same et mine only 87 mph with 513 gears and th350, 12 bolt?

I run 4.88s with a 31" tall tire on mine.

[nxtruck]

Originally Posted by Marv D

I was reading about that 1.5" and 3" and was thinking that exact thought. My header evac will pull 5" with a 1300rpm idle, open exhaust and LONGtube headers. On a street truck through legal exhaust it's going to be lower, but just as effective as a 3" electric pump. I'd think,, and as long as you throw those junk MrGasket push-in breathers away, and replace them with good Mopar breathers (that don't leak like a sieve like the MrGasket junk). Your going to make enough vacuum to keep the seals and all nice and dry anyways. Maybe not enough to help ring seal that much, but every bit helps. ANY vacuum in the crankcase is better than pressurizing the crankcase IMO.

I put a Aerospace vacuum pump on the Nova and pull 10-12" from 6000rpm up (shift at 6800 and trap at 7200). And to be honest, haven't seen any significant increases in power / ET. Mind you the pump went on just as things got stinking HOT around here, but ET's this summer are no better than last summer in like air. My machinist said he sees roughly 30-40HP on a 800HP wetsump motor, and 40-60HP on a drysump high vacuum motor. But dyno HP and what I'm seeing on the track doesn't seem to jive. One big problem you run into with high vacuum is piston pin gaulling. Not sure the dynamics of what all goes on, but the piston pins take a real beating from what everyone tells me. So be carefull in what you ask for,, too much vacuum can cause more headaches than too little. Know of one high RPM motor that was making BIG vacuum and he sucked the Steffs aluminum pan up against the oil pickup,, NASTY results!!!

Marv,
I've tried the header evac setup several times, both on different engines and with two different sets of headers. Mind you, I always ran an exhaust system of some kind, but I never could get any satisfactory results with them. On one set of headers, I even tried the evac tubes in a couple different spots and different angles. Now, I never tried them without any mufflers, and they may have worked had I done so. I have a friend that races a '69 Camaro in SS/JA and he has always had good luck with his evac setup. They aren't allowed to run vacuum pumps of any kind, so the evac tubes were his only option.
You are absolutely correct about having too much vacuum: most guys run between 10"-15" and it seems like anything over about 15"-16" will start pulling oil away from wrist pins, among other things.
Who knows; if this vacuum pump setup that I'm about to try doesn't pan out, I may revisit the evac tube setup and relocate them further downstream, past the mufflers, and see if I can make them work with an exhaust system. My exhaust system isn't much; about 2 ft. of 3 1/2" pipe into Dynomax Race Magnum mufflers and about 8" of tailpipe after that. Apparently, the evac tubes have to have NO backpressure in order to function correctly.
BTW, Congrats on your PINKS showing!! Way to represent the 60'-66' Chevy trucks!!

[Rodms]

When I fired up the first time it blew dipstick out and oiled up everything real good no rust starting under the hood

[regan wilson]

Last time I dynoed my motor we set mine at 10" . It's hard to pull too much vacuum unless you are using a 4 vane pump . I have been running the same three vane moroso pump for 8 years . I have a rebuild kit on the shelf . Guess I need to use it while I have mine down for a freshen up . The first pump I had was a Ford smog pump that I adapted to a vacuum pump . It just didnt pull enough . It was also ugly as hell .

[nxtruck]

Well, I tested my electric vacuum pump this evening. Now, I don't have a breather tank or an accumulator tank on it yet, but I used some hoses that I had laying around and tied a vacuum gauge inline with them and this pump held right at 5" of vacuum. I'll be happy with that, as long as the pump doesn't burn up with little street time on it.

[nxtruck]

I guess I jumped the gun by posting what I had found last night. I tested this pump out this afternoon, and within about 10 minutes of running time in my shop, the motor on this pump started smoking. The rubber boot that covers the motor was very warm, along with the exhaust hose coming from the pump. I added some holes in the rubber boot, thinking that they would help keep the motor cool, but evidently not.
I plan on trying the exhaust pan-evac setup again, this time possibly locating the welded nipples after the mufflers. We'll see what happens...

[67dragtruck]

I've run the ford pumps and the moroso pumps. For me the ford pumps actually pulled more vacuum, 18-20". The ford pumps are much more quirky about being cleaned out of oil residue or they come apart. I would not recommend them at all for street use. The moroso's are nice pumps and usually pulled 16-18" for me. I never had any oiling problems come up from running the pump. But, they never got a ton of street time either. The furthest was on the power tour and I went about 475-500 miles in 2 days. If you run one of these types of setups make sure you are running good valve covers. At one shop I know, it sucked a pair of cheapie aluminum moroso valve covers right down onto the rockers.

As for power. A guy I know runs IHRA pro stock and on a 1580 HP 800" motor it makes 85 HP. I have always thought there might be more benefit on a nitrous motor than on a naturally aspirated.

I also always ran my pumps with a cog belt system. I seem to remember running them at about 60% of the motor rpm. By the time you buy the drive mandrels and pulleys to do this along with the pumps, it gets into some real money for sure. My friends that tried running them with the v-belts seemed to always have trouble.

Tom

[67dragtruck]

Here's a pic of a moroso run with the cog type setup on my small block from the dragtruck. I ran -12 lines, with the fitting welded into the valve cover and the outlet side to one of the moroso cans.

Unfortunately to get a pump, the lines and fittings, the can, the pulleys and drive mandrel, you are talking about spending 800-900. That's tough to take for a 500 HP motor. You can probably find the same power somewhere else for less.

Tom

[85sqbdy]

years ago, a friend of mine used a secondary air injection pump from a late model s-10. somehow, he rigged it to pull a vacuum instead of pump air and got it to suck a milk jug flat in less than a second. i'm guessing that's at least 10hg. who knows he never put a guage on it. he remote mounted it out of site. it seems to work great, and you can't even hear it running. anyway, jegs now sells a similar setup using what looks like the exact same pump. part number 555-52215k. sells for $465 for the kit.

http://www.jegs.com/images/mini_100/.../555-52215.jpg

[71Dragtruck]

Originally Posted by 67dragtruck

Here's a pic of a moroso run with the cog type setup on my small block from the dragtruck. I ran -12 lines, with the fitting welded into the valve cover and the outlet side to one of the moroso cans.

Unfortunately to get a pump, the lines and fittings, the can, the pulleys and drive mandrel, you are talking about spending 800-900. That's tough to take for a 500 HP motor. You can probably find the same power somewhere else for less.

Tom

A bit off topic, but how is or was that manual rack for steering, compared to original power and old style strong arm? Was thinking of going that route when I do a Fat Man front end. Maybe DJ could answer too with the extra BB weight on it.

[djracer]

it doesn't turn as easy as power but much easier than stock manual.

[67dragtruck]

Originally Posted by 71Dragtruck

A bit off topic, but how is or was that manual rack for steering, compared to original power and old style strong arm? Was thinking of going that route when I do a Fat Man front end. Maybe DJ could answer too with the extra BB weight on it.

When I originally installed it I had a BBC combo in it. It steers great and much better than the factory stuff.

Tom