Vacuum Pumps

[Defiant]

One of the biggest reasons they leak more is because they (stroker motors) create more creankcase pressure below the rings, allowing them to fight the combustion pressure more.

I need to hear about this. For evey piston that goes down, another comes up. Where's this pressure coming from other than blowby?

When a crankcase has an excess of pressure, it will find anyway to escape.

Positive or negative. Too much case vacuum would also be destructive.

There are many things that are affected when you have too much crankcase pressure...
Any seals and or gaskets may be blown out...
It can actually prevent oil from draining down the head ports to the block (too much escaping pressure) Think of it as a straw, or tube with a bubble in it... the fluid can only trickle down at best.

I can't see that on a DSM. You have drains that are ½" across.

Worst was a poorly done (302) 347 Ford stroker... He ended up loosing everything but the very core engine parts... (block/head/crank/rods/intake)

A bum Ford. Go figure.

 

[Bostedquest]

1. I need to hear about this. For every piston that goes down, another comes up. Where's this pressure coming from other than blowby?
2. Positive or negative. Too much case vacuum would also be destructive.
3.I can't see that on a DSM. You have drains that are ½" across.

1. With a stroker you are increasing the "volume per stroke" correct? With increasing volume, you have the potential to increase pressure/vacuum. The arguement is the same from before. The principals are the same. You are just dealing with a larger volume.

2. Exactly. But I would rather have too little pressure and high quality gaskets then too much pressure... I would much rather the engine be sucking air in through a propperly vented port.

3. The Ford ports were 1/2" X 3/4" and he clogged one head, where the upflow of pressure prevented oil from draining propperly. That was a pain to figure out without removing both heads and inspecting them in the Autopsy... But on the "good" head, it was missing 2 valve stem seal springs... later to be found in the oil pan...

Just sharing what I know and what I have seen. I did not say the DSM would do it, and I did not say the DSM would not do it. I just said it is entirely possible.

 

[greycar]

The crankcase pressure will mainly come from blow by through the rings. When the pressure gets too great it will put a force#1 on the rings(compression and boost being postive pressure on the opposite side of the rings or force #2) causing ring chatter and even more blow by. This is when you'll start to blow out oil seals and gaskets. Ok will that said, now get to the point of the vacuum pump, a pump will draw far more air out of the engine than the typical PCV valve and the venting of the crankcase pressure. Ok so with a vacuum pump you can relieve the rings of the force #1, so whatever force #2 gets by the rings the vacuum pump will have its scavanged right away so you will have no crankcase pressure, complete ring seal will be achieved because the rings won't have the force#1 on them causing chatter, And if you set your clearances on your piston to wall correctly this will result in greater efficiency of you rings, gaskets and seals. And the more effecient your motor is the more horesepower you will make. This is only a mod for people who are running high compression, and/or highly boosted cars, and no 20psi isn't alot of boost unless you have a 14 to 1 compression ratio. My vacuum pump setup cost me roughly $400, in my opinion spending $400 on something else will usually do more for your car than a vacuum pump. A vacuum pump is really for the people making over 600hp, if you are making the power I would recommend it, if not spend you money more wisely.

 

[Bostedquest]

boosted cars, and no 20psi isn't alot of boost unless you have a 14 to 1 compression ratio. My vacuum pump setup cost me roughly $400, in my opinion spending $400 on something else will usually do more for your car than a vacuum pump. A vacuum pump is really for the people making over 600hp, if you are making the power I would recommend it, if not spend you money more wisely.

that is why the past page and a half or so we have been talking about the GM Elect vac pump that they used in the early/mid 80's... much cheaper and more moderate.

 

[NitrousBob]

Ring seal, Oil gets to the pan and more importantly to the sump faster, your not sucking oil fumed crankcase crap into the intake. The bottom line is these are great peices. I personally run one on my chevy and my talon. And unless you punch some large holes lets say bigger than 1/2 inch in the engine somewhere to vent . unplugging your pcv is pointless plus your rings aren't doing a good job without vacuum.

 

[kxc36g]

I don't want to jack such an informative thread, but I am looking for information on the use of Vacuum reserve canisters.

I know the normal use of the canister is to provide extra vacuum to the brakes on cars with large cams.

However, since the benefits of extra vacuum have been explained in this thread, this seems like an easy way to provide a little bit of extra engine vacuum--maybe not for a performance increase but for improved brake/BOV etc action. Installing a pump looks to be quite extensive in labor/cost and more for race cars.

Anyone want to chime in regarding this idea? I really don't have the facts to support this idea (there seems to be very little information on the net regarding vacuum reserve canisters), but I would appreciate any info.

Thanks,
Chris

 

[beat90tsi]

I'm ready to throw one of these on, does anyone have specific information on the year and model of the GM cars that had these elec vac pumps? I was at Advance today, and they no longer make the elec vac pump that came on the 1991 Cadillac Deville with a 4.9. They were busy so I stopped using their computer to look up parts.

Basically, I think a part number, or at least the application for this GM pump that people keep mentioning would be a great addition to this thread.

Thanks,
Jon

 

[herostar]

I would also like to install a vacuum pump. Would someone who's done this already please chime in and give all of us some info on what pump you used, how you installed it, how much it cost, etc etc etc. Thanks

 

[MNGSX]

Well say that under normal situations the crankcase sees up to +2 Psi. If you have a pump that creates and holds 15" of vacuum, you have nearly eliminated that pressure that is there. That will allow more resistance free movement.

Some of those GM pumps create 18+" of vacuum when hard wired... that is some SERIOUS vacuum in under 2 CuFt of crankcase space... So yeah I would bet they have a pronounced effect if used right...

I'm interested in info on the GM pumps. If they can draw that much vaccum I'd hard wire it and run the adjustable relief valve from my previous post.

 

[Maglin]

Lots of good information in here. As for the one piston goes down another goes up and thus why the pressure. It's cause their is now a high pressure on the bottom of the dropping pistion and a low pressure on the bottom of the rising piston. If you can pull a constant of 15 in/hg their will always be a low pressure side and also the rings won't be hitting the ring lands with the brute force they would normally. I think this also helps will broken 2nd ring lands on highly boosted applications.

I've been fooling around with the use of the electric GM pump for a few months now. This threed has made up my mind as I was just toying around with the idea.

As for the way to hook it up. Are you guys currently running a mechanical pump plumming a line into the Valve cover? The current breather and PCV location are pretty small. I would think a -10 an line would be minimun. And are your running a catch can on your vac line? Cause I would think that you can still easily be sucking oil out of the line cause of the oil mist created by the valve train. Is their a need to run a relief valve?

I was planning on plugging the PCV port on the valve cover and removing the breather line and putting a -10 AN fitting in it's place after I bored the hole out. Would put the Vac pump behind the pass strut tower and have a catch can right next to it.

 

[Bostedquest]

Looking through and thought I'd get back in it...

The vehicles your looking for are the early-mid 80's full size GM boats. Nearly 100% of these cars had them at one point or another.

Also as far as mounting, from what I remember they have a 1/2 plastic fitting that runs inline style.
I would presonally run it off the PCV valve fitting. You can drill it out easily.

 

[beat90tsi]

No definitive answers on the elec GM vac pump yet?

I looked up a bunch of cars at the parts store, and I kept finding belt driven ones. The only elec one I found was on a 91 caddy, and it was discontinued.

 

[iwantawd]

i read through everything and maybe i missed it but where would you put the relief valve?

 

[Bostedquest]

No definitive answers on the elec GM vac pump yet?

I looked up a bunch of cars at the parts store, and I kept finding belt driven ones. The only elec one I found was on a 91 caddy, and it was discontinued.

The belt driven are AIR pumps, for smog... not vacuum pumps.

 

[Dauntless]

I tried this on my Formula Atlantic engine to see if there was any gain on the dyno, but found none. The crankcase vent line coming from the center of the valve cover was routed to the scavenge side of the dry sump pump, just like you see the Nascar guys doing, but we got nothing. This is a 12.7:1 normally aspirated Toyota 1.6 liter 4age engine, which is turned to 10,500 for road racing, and makes 250+ hp.

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[95AWD_TSI_TALON]

At this point I am not looking for HP gains that much. What I am looking at is my crank pressure ever since I have started cranking the boost up and reving higher is way to high. The dipstick blowing out/oil cap leaking is not fun anymore. I have forcefuly fixed those problems and now I am blowing out my VC gasket. And my motor is in tip top shape besides this problem.
My question is did you have problems before you installed the vacume pump? and if so did this mod fix it?
matt

 

[Dauntless]

At this point I am not looking for HP gains that much. What I am looking at is my crank pressure ever since I have started cranking the boost up and reving higher is way to high. The dipstick blowing out/oil cap leaking is not fun anymore. I have forcefuly fixed those problems and now I am blowing out my VC gasket. And my motor is in tip top shape besides this problem.
My question is did you have problems before you installed the vacume pump? and if so did this mod fix it?
matt

No, I did not have any engine problems before this mod. I was strictly looking for power.

Perhaps something like this would help.

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[MNGSX]

I tried this on my Formula Atlantic engine to see if there was any gain on the dyno, but found none. The crankcase vent line coming from the center of the valve cover was routed to the scavenge side of the dry sump pump, just like you see the Nascar guys doing, but we got nothing. This is a 12.7:1 normally aspirated Toyota 1.6 liter 4age engine, which is turned to 10,500 for road racing, and makes 250+ hp.

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Um you had a dry sump before so you will get nothing. Also the oil pan design will come into play. You did'nt have much of any windage to begin with.

A street car style wet sump pan with little, no or moderate windage control will see gains.

More gains come from low tension rings as we will use vaccum to make them happy and not ring tension and the associated friction. Its the ticket for a wet sump...

 

[Coup D E'Tat]

Bringing this back from the dead.

I'm looking for info on the GM electric pumps to help with some blowby I've been getting on a motor with 130 compression (cold motor, 150 before I put the cams in, also cold test.)

Now, if i've read this correctly, I should bore out the breather passage on the valve cover, use a bigger fitting and run the pump off of that to a catch can? Currently, I'm running a straight fitting in place of the PCV and an open breather tube, and I blow the dipstick out and leak a little oil out from under the oil cap, and don't have the funds to rip my block out.

This idea sounds like it could be a very possible solution for me, and I'd like to hit up the bone yard tomorrow, so can anyone give me a model/year to grab one off of? I'll be on the look out for the 80's GM "boats," but any specific info would be great.

Thanks a lot, and please correct me if any of my thoughts are incorrect.

Jesse

 

[MNGSX]

You might need two of them....

On another forum we calculated how much hp an electric motor would need to be really effective..

To maintain 14"-15" of vacuum at sufficient CFM you would need 1.0 HP DC motor it would draw over 60 amps and also be very heavy...

 

[Coup D E'Tat]

Heading up in a bit, trying to find 1 or 2 LT1 pumps.

From somewhere else, "The (LT1) smog pump pulls 23 inHg @ 12V, draws 5 amps."

Now, what should I run as far as a restrictor. Something like this - http://store.summitracing.com/default.asp?target=egnsearch.asp&autoview=sku&N=305283?

As far as a vac. gauge, any sepcific place to tap into? What should I be looking for as far as too much vacuum?

Also, anyone running the exhaust scavange setups instead of a pump?

 

[MNGSX]

The backpressure caused by a turbine makes the exhaust type useless... The only domestic V8s I see at the track with the exhaust scavenge have open headers...


Two LT1 pumps will get you somewhere.. It may take 3 or more to hold 15" of vaccum to readline..

It will outperform no pump at all and probably cruise better on the before mentioned car with worn rings..

I'll be back to edit this with a link to a electric as potent as the mechanicals.. I just need to find it again..

http://www.starvacuumpumps.com/viewPart.php?id=STR.04.06.000

its 24V

Now you see why I recomend a GZ...

I may offer an install kit upon requests... Basically just copy my own work as a favor for very little...

Use the GZ relief valve tapped into the PCV hole and draw from the oe breather port..

 

[Coup D E'Tat]

I know you are recommending two pumps, but my question is why? Are your reasons from experience or theory? The reason I ask is because there seems to be numerous people running one GM pump with good results.

If I went the GZ route, I believe it would be maybe $325 for everything (pump, pulley, belt, my own mounting setup, relief valve and the lines,) which is still cheaper than the cost of a Moroso pump, but a little more than I wanted to spend. If I have to, I will, though. Just trying to watch my finances right now.

Would a setup for power brakes be of any use? Summit sells 12V electric kits that are supposed to produce up to 20" Hg. for $280, but I'm not sure if it would be of any use to me.

Thanks a lot for your advice/tips. Just trying to learn what I can about these setups.

 

[MNGSX]

The power brake ones just run vaccum to the brake booster not the crank case.

You will get results from the electrics but put on a vaccum gauge and watch it going thru the gears the vaccum will be weak with one pump and will dip under boost and RPM with two...

Trust me holding 15" of vacuum thru the power band is plenty effective...

 

[Coup D E'Tat]

Alright, thanks. I thought the answer on the brake setup would be a "no," but wasn't sure if anyone had ever rigged one up otherwise.

I can get my hands on two LT1 pumps, would the stock 12V be enough to pull a decent amount of vacuum? It seems as though it would be enough to solve my problem here.

And believe me, I'm not trying to look past your information, as I'm sure you know what you are talking about. It''s just that, as I said earlier, people seem to be having good results with 6-8" Hg., and the GM pumps in general.

I wish the thread had more than two people discussing this, though. The more information the better.

Jesse