Little Motor, Little Tires, Little Nitrous...

Our Shop Mule's Electric Crankcase EVAC System...


Below are some pics of the electric crankcase evac system that's currently on the Shop Mule. The engine is now able to use narrow 1.2mm compression rings and low tension 12lb oil rings. Due to the reduction of ring drag, the engine picked up about 325rpm at idle over the old shortblock with no other changes. The fitting and hose attached to the fuel pump blockoff plate are used to monitor crankcase vacuum...

The valve covers are circle track units that come with welded fittings for crossover breathers. We made some push-in fittings to replace the crossover assy (machined from Delrin plastic and feature double o-rings), making them easy to remove when adjusting valves or adding oil. No extra baffles are needed inside the valvecover...

The oil seperator was glued together from common schedule 40 PCV pipe, then turned down in a lathe just to make it look a little better. Holes were made using a holesaw in a drill press, the hose barbs are made from plastic ABS pipe connectors. The whole thing with bracket only weighs about 8oz...

The electric evac pump was hidden behind the firewall, under the dash. It pulls around 4" Hg on 12v, about 8" Hg when powered by a 18v cordless tool battery pack. I added a dropping resistor and a relay, Around town the pump operates on 9.5 volts (pulls around 1"Hg). When the nitrous comes on, a relay gives the vac pump full voltage...

The electric vac pump used is a Delco 215-425, available new from ebay or amazon for around $100. The hoses are -12 lightweight pushloc (3/4" id), and fit the electric pump's ports perfectly. The pump can also be found in wrecking yards, as Ford used it on various models as a smog pump, but they also used it on Mustang Cobra R's as a crankcase evac pump for the supercharged engines. They can be mounted in any position. The only modifications needed are soldering the motor wires to prevent overheating, and removing the foam inlet filter from the housing. I also attached an exhaust hose to route the fumes outside the passenger compartment, under the car.

One huge side benefit...no more engine oil leaks!!!

Here's a look at the inside of these pumps. With the rubber motor cover removed, you can see the spade connectors that have to be soldered to keep them from overheating or vibrating loose...

Here you can see the foam filter that needs to be removed...

Most of these pumps are basically the same internally, just clocking of the inlet/outlet is different. Here's a list of vacuum drawn at various voltages...
...1"Hg @ 9.5v
...4"Hg @ 12v (draws 12amps @12v)
...7"Hg @ 16v
...8"Hg @ 18v
The pumps flow freely internally when not running, so a failed pump will still vent crankcase pressure and not damage the engine. Most of the noise that the pumps emit comes from their exhaust port, which sounds much like a vacuum cleaner. With a pump mounted inside the car, the pump cannot be heard when the engine is running.
Here's a short list of applications and part numbers to look for...
Delco 215-425
Autozone 32-3501M
A1-Cardone 32-3500M
Ford F6ZE-9A486-DC
'07 Cobalt
'03-'09 Mustang Cobra R
8 cyl SVO Taurus

When buying re-mans from parts houses, some have reported that their's came without the cover, so be sure that the pump you buy comes complete before you order it.

Evac pumps don't really increase power much themselves, but they do allow you to run lower tension piston rings which can net you quite a bit of power. The reduced cylinder wall friction also increases mileage and the engine runs cooler as well.
Quick crude example...
Take two mostly identical engines, except one shortblock requires 40ft/lbs to roll over using regular oldschool piston rings, the other uses a modern low-tension ring pack and requires only 13ft/lbs to roll over. That's a constant savings of almost 8hp at 1500rpm. If your car cruises at 2500, that equals a constant savings of roughly 13hp while you are driving down the hiway. As a bonus, WOT at 7000rpm, the low-tension shortblock would have about 36 more hp on tap. The bores will also show a lot less wear.

Have Fun!!!


Here's an update on the crankcase evac system...

I added an adjustable pcv valve to the separator tank and a large check valve to the end of the vac pump's outlet hose, allowing the adjustable pcv valve to draw the crankcase vacuum during casual driving. No more need to rely on the electric vac pump. Now it draws 15"Hg in the crankcase while driving down the hiway, without even turning the electric pump on (idling around, about 8 to 10"Hg). The electric vac pump is still in place, but only comes on to take over when the intake vacuum drops during WOT. I have ran this setup a couple years now, only problem i've had was initially sealing the engine up to handle the high vacuum. Here's a pic of the modified pcv valve added to the top of the separator tank...

I've never gotten more than a drop or two of oil in the bottom of the separator tank, the pcv is not pulling any oil either...

Here's a pic of a pcv valve cut open...

I modified it by adding a screw to the top, allowing me to adjust the minimum flow position of the tapered piston. Basically, turning the pcv valve into an adjustable orifice...

I've got low tension (gapless top) rings in the engine, 4 spd manual, 3.73 gears, and no overdrive. It's about 3000rpm down the freeway, so without a good vacuum on the crankcase, it goes thru a quart of 5W-20 synthetic in about 250 miles. The electric vac pump worked ok by itself, but I'm getting around 20mpg out of this combo, so i wanted to squeeze a little more mileage out of it. My goal here was to eliminate vacuum pump's constant 14amp draw on the car's electrical system.

With this hybrid pcv/electric evac setup, there is no need to worry about over-heating the electric vac pump, as it's only used for a few seconds at a time. Since i'm only using the electric vac pump for short bursts of WOT, i could easily power it with a 16v or 18v cordless tool battery pack if i wanted to, but I have not seen a need to do that even when spraying a 250 shot.

Note for those with BOOST that may be concerned about possible check valve failure...the pcv valve acts as a check valve if the flow direction is reversed, so an in-line check valve failure under boost conditions would make the pcv valve revert to it's highest restriction mode. Due to the electric pump's flow thru impeller design, any resulting crankcase pressure would be relieved thru the electric vac pump's outlet port, even if the pump were not on or had failed.


Here's another update...
Converting the electric vac pump to more efficient brushless power!

Here's a pic of my original electric vac pump dis-assembled...

Here's some side-by-side pics of the vac pump's original motor (top) that will be replaced with the new brushless motor (lower)...

Here's a pic of the brushless motor sitting in place...

Here's a pic of the mounting flange mis-match. I am thinking of turning a piloting tool to center the brushless's shaft in the pump housing, then simply bonding the motor base to the pump's housing just for proof of concept...

Same diameter shaft @ 5mm. The brushless uses machined flats for securing things like pulleys onto the shaft, the vac pump's original motor uses a serration in the shaft that the impeller was pressed onto. The brushless needs it's shaft location modified slightly, basically pushing the shaft thru the outer shell so that the impeller can be attached. I planned on cutting some slight serrations in the brushless shaft with a Dremel, then fixing the impeller to it with Locktite...

This version of a brushless is called an "outrunner" that's used in RC helicopters. Basically an inside-out version of the typical brushed 12vdc electric motor, as the outer shell/magnets rotate around it's stationary windings...

Rated for 45 amps continuous, the vac pump's original motor melts at about 1/2 that. Bought for $45, the 627 Kva motor is rated for 800 watts max, 45 amps continuous. I bought a 60a speed control for $25.90, also a "servo tester" for $3.44, so now i will have a simple dial to adjust motor speed. Should be all i need to get my variable speed brushless version of the electric vac pump up and running for testing. Should be able to dial in any rpm up to 9100 on 14v to see just where the sweet spot is for drawing maximum Hg.

These brushless motor kick ass in power and efficiency over the original brushed motors, much lighter too!


Make Your Car's Diaphragm Style Clutch ADJUSTABLE!!!

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