vacuum pump

[427 S/O]

Heard some good news about belt drive vacuum pumps, their suppose to generate as much as 30+ HP at 3000 + RPM. Anyone have info on this?. If this in fact true, I wonder if the pump could be driven off the drive shaft and keep the engine bay clean?.

[fordracer]

I had a supercharged Mustang that had problems leaking oil. I put on an electric vacuum pump from a LT1 Camaro an a switch adjusted for 0" of vacuum. Tee it in to the PCV valve. Didn't seem to help much at the track ( not enough RPM's would be my guess ) but the oil leaks stopped. My 0.02

[427 S/O]

Electric vaccum pump, interesting, I'll check into that.
Thanks

[Hotfingrs]

A vacuum pump is only going to help if you have the rings to use it. The 30+ hp comes from using low tension rings and the vacuum seals the ring to the piston land. I had one engine built with low tension rings. I used an electric pump for this. On the Cobra I've got medium tension rings and also run negative pressure in the crankcase. With low tension rings if you don't run negative pressure you'll use oil like crazy. I've got a couple of electric pumps that I'm not using if anyone is interested, both are GM models.

[justa6]

Although your right about the rings I believe your incorrect that they are the only advantage.

The guy that did the machine work on my motor had done a lot of Busch, IMSA, etc motors and he told me that they've spent a lot of dyno time confirming the usefulness of pulling a vacuum in the crankcase. One of the big advantages is that instead of the pistons working against ambiant air pressure on the downstroke they are not "pushing" against anything. True that the rings seal better but you don't have the pumping loss.

Japanese motorcycles gain some power by having "equalizing" holes between each cylinder (below the rings at BDC) so that instead of pushing against crankcase pressure they have the air relieved below the piston by the upstroke on the next door cylinder. So I agree that power will definitly increase with a vacuum in the crankcase. As you know I'm going to use my dry sump pump to do it in my motor and will call the number of the guy you gave me for the vacuum break as I think that is also a great idea.

Regards and thanks again,

[427 S/O]

A fella on FORDMUSCLE.COM gave me a pretty good idea, he uses a late sixties early seventies ford smog pump, the type that has two holes in the back of the aluminum case, the stock fittings can be removed and threaded to use earls or russells fittings, he runs the outlet to a moroso catch can, about $50.00 and the inlet to either the valve cover or intake. NAPA list the smog pump at about $50.00. Justa6 is right, any vacuum assist in the crankcase is a plus.

[Hotfingrs]

Bob you're right about the piston on the down stroke, I guess the point I was trying to make is that you won't see 30+ hp without the low tension rings...I don't really know how much negative pressure would be worth with stock rings, certainly no where near the 30 mark...

[justa6]

I was told by my engine guy that I'd pick up in the vicinity of 20HP because the motor revs so high. He also said that my crankcase is much smaller than a V8's that that may be part of the reason it works so well on the V6. He also told me that I could run VERY think oil 5/30 or even 0/30 with the dry sump with no problem and pick up another 5-10HP at 8,000RPM. I'm not sure I want to do that although my oil pressure is 100psi at 8,000 so it would probably be all right. I guess I'm just old school when it comes to oil as its hard for me to run the Mobil 1 10/30 I'm doing now. Any opinions?

Thanks,

[Hotfingrs]

I know your engine, but I don't know your engine if you know what I mean....I'd have to go with your engine guy, until you have proof of something different. I use mobil 1 in my everyday cars, but my engine guy doesn't like synthetic oils, so I run 25-50 in the cobra or a 20-50 if I can't find the 25-50...

[justa6]

Funny how we think alike. I asked Gary (Engine guy) about running the light weight oils as I always used 20/50. He said that with a normal oil pump (wet sump) system it would be correct. Except with a Dry Sump the flow is so much more ( he called it velocity) that the thinner oil is more appropriate. Anyway motor pulled the dyno runs on 10/30 NON synthetic with the last one stabilizing at 7800 RPM (I was "soiling" my pants) to see how the oil temp would react and then letting it come back down after around 2 minutes (felt like an eternity). He told me that since the oil temp hardly moved at peak HP then the motor was fine. He said Mobil 1 would work fine as they were using it in a lot of the race motors and had good luck with it. He also told me that sythetics were a problem for a long time but that the newer stuff was OK.

Anyway, thanks again for the input,

Regards,

[Hotfingrs]

What kind of oil temp did you see??

[justa6]

Oil temp was around 170 and doing a very slow increase a degree at a time and the older guy that runs dyno had done a lot of the Busch versions of my motor and he looked over at me (knew I was worried like an expectant father and said "its doing what it was made to do" and smiled. He was referring to holding at the 7800 RPM. He also told me that if it had the Titanium valves that we took out they'd have brought it up to 8600 sustained. Glad we went to the Stainless

One other thing is they think my oil temp is way too low. It runs around 165 degrees and Gary told me to try and get it up to 210 or so. He said it would "make more power" that way. Cool water hot oil...

Did you dyno your SBC? If so how did they do it?

Regards,

[Hotfingrs]

165 is to low. I run about 200-210 on the street and when I get into it the temp goes up to 240.... the only thing titanium I ran are the retainers and keepers....engine made 603 hp@6700 and 512tq@5300 I shift at 7200 when I need to, and redline is 8200

[Mr.Fixit]

Yes belt driven vacuum pumps can help you make more horsepower, but....

They really only have much of an effect at good RPM, they are impractical on the street, the air you suck out of the crankcase needs to blown into something, to catch the oil you're pulling out with it. They really have a greater effect on motors with low tension piston rings which wouldn't seal right without the crankcase vacuum. Mostly a drag racer item. You wouldn't want to run it off the driveshaft because it needs to be coupled to engine rpm, not vehicle speed. Just get a dry sump oiling system, the benefits are much more numerous, and you'll pull crankcase vacuum as well. If you have a money tree that is.

[justa6]

Check the "view my photo gallery" picture all the way on the right side and you'll see a Weaver Dry Sump pump. I run the Dry sump system with no problems on the street. The dry sump will pull a vacuum if you seal the valve cover vents. And your absolutely right the oil has to go somewhere. I plan on making the vent set up on top of my oil tank with a setup that will allow the air out but return the oil to the tank. Possible?

Also as Jack has said before you should have some method to regulate the vacuum so its not too much. By the way Jack great numbers on Torque and horsepower. How many cubic inches?

Regards,