Vacuum pump tech; free up that hidden horsepower

[FE 065]

I never did like the OEM permanent vacuum leak PCV system designed into my 2002GTS to begin with.
..I liked it alot less when I installed a vacuum gauge to the plenum port behind the left TB, and went for a drive; the gauge didn't seem to register any vacuum at WOT.

Not good, the PCV system is dependent on engine vacuum to ventilate the crankcase, especially at WOT when you need it most.

Sooo, last summer I added a $260 electric vacuum pump from Summit Racing to my 2002 GTS to induce a vacuum in the crankcase.. The vacuum pump pulls 10 inches of vacuum in the crankcase at idle and most part throttle positions. At WOT there's 7-8 inches of vacuum.

That difference between idle and WOT vacuum shows that either pressure builds in the crankcase at high RPM due to blow by and oil frothing.. .. Or, that the same pinhole vacuum leak (can't find it!) that prevents my pump from pulling higher levels of vacuum at idle or otherwise gets worse at higher RPMs.
(The pump will pull and hold (when I shut it off) 22 inches of vacuum with a short length of hose and a gauge on it) It's probably the rear main seal being sucked in just enough to seep air in-a typical problem

High vacuum in the crankcase can add/free up horsepower ... For example, at 6000rpm the Viper engine has to pump about 1700CFM of air in the crankcase up and down.

Prostock cars and bikes use vacuum pumps, F-1 cars, NASCAR, too. A few years ago I was told that development GenIII Viper engines using the proposed (but never put into production) dry sump (high vacuum) oil systems gained like 35hp on the engine dyno.


In this post Jason Tarnutzer said this about West Coast Viper's high (15 in/Hg) vacuum dry sump system, The horsepower gains from this (although a by-product of the primary use) are about 40hp at the wheels on a car with cam, heads, etc The internet is full of articles and information about vacuum pumps and their horsepower benefits.

<font color="blue">Vacuum is cooool </font>


Here's a couple of Hot Rod Magazine articles that more than support the idea:

In the first, a 381ci SBC on an engine dyno gained 25-30HP "throughout the curve" with a belt driven vacuum pump pulling just 10in of vacuum in the crankcase.
A second test on that same engine while on the dyno, with the pump's vacuum line disconnected, showed the pump itself draws 6-9HP just to turn it over at high RPM..


The gross or total gain then could have been as much as shocked:..39HP.. at 'almost' 10in of vacuum minus the 6-9hp losses to drive the belt driven vacuum pump. Click to read the HotRod article



Another Hot Rod magazine dyno article on a 408ci SBC in the January 04 issue (see the chart on page 77) picked up a max gain of 19hp with a stronger belt driven pump pulling 10-13 inches of vacuum from the crankcase.
Without the same 5-10hp (or more..it was a large pump) lost for the belt drive that'd been more like a 24-29hp gain

Belt driven pumps cost $350-$550 plus hardware


<font color="red">Are you interested yet? $260-$550 for 25hp or more !? </font>


..Since the pump I'm using is electric, except for a little extra alternator drag, I just might be getting all the HP gain instead of giving up the 6-9hp that a belt drive would steal.. but it only takes a pinhole to limit max vacuum. (belt driven pumps are basically a race only item, needing to be rebuilt every 100hrs or so)


If I can find that pesky vacuum leak

You must be registered for see images

, I can pull higher levels of vacuum for more HP
Though there are warnings about pulling more than about 15in of vacuum concerning high vacuum and engine oiling.

Here's the vacuum pump : http://www.boomspeed.com/vipergts/vp.jpeg



Here's the pump installed on my front crossmember:
http://www.boomspeed.com/vipergts/GTSvp.jpg

I haven't had the chance to dyno or strip compare with and w/o the pump turned on, but I'm in.

I switch the pump on manually and use it all the time. If there's room for a belt driven pump under there, I may just do that someday..

 

[Streak]

I have worked with such applications in the past on past cars.....I am curious to see if you have any gains on the Dyno...

 

[99 R/T 10]

Yeah, we need a before and after dyno comparison!

 

[Kiaser]

Very good read, can't wait to see the results! Keep us posted!

 

[Russ M]

Am I interested?

Yes!!!

Am I going to buy anything until you get us actual dyno results, rather than theoretical mumbling.

No...

Please run the dyno should be simple enough. Unfortunatly, expecting any hp gain from just a vacuum pump is probably being way to optimistic. Or everyone would be selling vacuum pump kits for every car ever made.

 

[VIPR GTS]

Larry Macedo, the Viper Guru to many of us, please respond with your thoughts.

 

[FE 065]

Re: Vacuum pump tech; free up that hidden horsepower

Theoretical mumbling? Well that's an amazing response considering I'm just giving the information to my fellow Viper owners, and I've taken the time to present it in a detailed manner.



I'm not selling anything, and my post is laden with facts. It appears you wouldn't know a fact if it landed on your head. ..You didn't read the HotRod Magazine article's results?



I'm just passing the accumulated information along to anyone who might have interests deeper than the latest chrome gas cap for their Viper. Along with helping n/a Vipers, vacuum pump science will benefit all those s/c and turbocharged Vipers with crankcases suddenly charged with pressurized blowby.



Much of the rest of the racing world uses vacuum pumps. They're talked about on just about every car performance forum but Viper forums.



Popular Hotrodding's newest issue just had an in-depth dyno-backed article about aerodynamicly re-shaped crank throw edges to help crankshafts cut through the heavy atmosphere, and teflon coatings for cranks to help them shed oil. All of those efforts gaining horsepower.


Just because you don't know about horsepower losses in the crankcase doesn't mean they're not there.


I'm not going to argue about it...

 

[FE 065]

Larry Macedo, the Viper Guru to many of us, please respond with your thoughts.

I mentioned it to Larry last year at Norwalk, telling him I had it on my car, of the HotRod Magazine article, and the use of vacuum pumps in the racing world. He said, "I'll have to check into that."


No problem, it's the new frontier boys (at least in the Viper world).. Better ring seal, more horsepower..

Vacuum pumps are banned in some drag racing organization's stock and superstock classes - because they're a non-OEM power adder.


Viper drag racers, road racers, all can benefit from it.

 

[GTS-R 001]

Re: Vacuum pump tech; free up that hidden horsepower

FE 065,

Good post!

Too bad RussM is such jealous weasel, he's just upset that you thought of this before he did. Kind of reminds me of another thread where RussM failed to think of something first........

 

[Greg Good Cylinder Heads]

Re: Vacuum pump tech; free up that hidden horsepower

Where a pump like this would help is on an engine that has low drag oil rings. I've seen people put vacuum pumps on engines with standard tension oil rings and not pick any power. The vacuum pump just lets you get away with lower tension oil rings that would otherwise not work without the added increase in pressure differential from the pump.

Also, make sure and NOT go above about 8-9 inches of vacuum on a wet sump system.

 

[99 R/T 10]

Re: Vacuum pump tech; free up that hidden horsepower

So what would the difference be if the crankcase is just vented out(instead of setup to recirculated back into the engine)?

 

[FE 065]

Re: Vacuum pump tech; free up that hidden horsepower

Moroso (click) has quite an inventory of vacuum pumps and related hardware. Jeg's, Summitt have it all in their catalogs. The performance industry has been hip to it for years


I've recently talked to an engineer from Maclaren Racing Engines who scoffed at a connection between vacuum in the crankcase and oiling problems, unless the engine had oiling weaknesses already.


I've also talked to people who swear 19in vacuum pulled the oil off of their bearings or rockers, but the question the engineer had is what's that thin film of oil care about vacuum?
There are precautions perhaps, so take note.


Some say they've gotten the best results at 15in vacuum. I'm not sure how much more is gained by going from 7in to 15in, but just under 30in vacuum is a perfect vacuum.
Meaning I guess that 7in vacuum is about a 25% reduction in the crankcase atmosphere, and 15in a 50% reduction.

Being able to use lower tension rings is a primary benefit, but the volume of air to be moved in an engine's crankcase at 6000rpm is worth considering. The air is not just simply and effortlessly exchanged between cylinders as one piston goes down while another goes up.


Newer Japanese crotch rockets have ports in their cylinders below the pistons to ease and quicken the air movement bewteen cylinders.

 

[FE 065]

Re: Vacuum pump tech; free up that hidden horsepower

So what would the difference be if the crankcase is just vented out(instead of setup to recirculated back into the engine)?

Using just breathers, the engine has to pump it out which takes hp, and worse yet oil contamination from blowby and moisture is greatly increased by only running breathers instead of at least an active PCV system. OEM PCV is fine for normal driving. At WOT though there's little engine vacuum left (TBs are wide open!) to pull vapors etc from the crankcase. Vacuum pumps are just the next step in evolution from header pan-evac systems. Pan-evac systems aren't effective unless you're using open headers, and the one way valve often fails due to the intense heat, allowing exhaust fumes to back up into the crankcase.

 

[ViperJoe]

Though there are warnings about pulling more than about 15in of vacuum concerning high vacuum and engine oiling.

Is engine oiling the only "bad" thing associated with high vacuum?

 

[99 R/T 10]

Re: Vacuum pump tech; free up that hidden horsepower

So what would the difference be if the crankcase is just vented out(instead of setup to recirculated back into the engine)?

Using just breathers, the engine has to pump it out which takes hp, and worse yet oil contamination from blowby and moisture is greatly increased by only running breathers instead of at least an active PCV system. OEM PCV is fine for normal driving. At WOT though there's little engine vacuum left (TBs are wide open!) to pull vapors etc from the crankcase. Vacuum pumps are just the next step in evolution from header pan-evac systems. Pan-evac systems aren't effective unless you're using open headers, and the one way valve often fails due to the intense heat, allowing exhaust fumes to back up into the crankcase.

Can you post a link of the unit you bought from Summit?

 

[Tom F&L GoR]

Maybe someone can recall the four cylinder Indy engines that were actually four sealed crankcases? The air under the piston would then act like a spring and for as much work put into the system, you would (ideally) get it back. Transferring air from one cylinder to the other (as in an open crankcase) you would not. I'm fuzzy on the actual application, though, since those engines were also turbo/dry sump...

 

[George Bryce]

Record holding bikes and cars work to maintain 25 inches at top speed. The biggest gain from crankcase vacuum is keeping the top ring sealed to the ring land at peak power and peak rpm. If you cannot hold vacuum at rpm, then you have bad blowby, blowby past the top rings and, or too small of a pump. The flip side to crankcase vacuum is crankcase pressure....that is from poor top ring seal. Most racers think that reduction in ring drag would be the gain here, but in reality it is a way to keep precious combustion pressure on top of the piston....rather than in the pan. GB3

 

[joe117]

I'll have to admit, I never heard of crankcase vacuum as a performance feature.

Since this is new to me, I have a few questions.

Isn't the idea of an OEM PCV simply to keep crankcase fumes from getting out of the engine and becoming an air pollutant?

Does the internal volume of the crankcase change as the pistons go up and down?

Is the performance gain due to less dense air being moved around inside the crankcase?

Is the performance gain due to less air to crank drag at lower pressure and thus less dense air?

Is the extra ring control provided by the crankcase vacuum important when the engine has a supercharger?

When the piston is on it's way down on intake stroke, the rings seat against the top of the groove, right?
This intake stroke is the only time that the rings are not driven against the bottom of the ring groove, right?
Can this pumped vacuum in the crankcase be enough to pull the rings down faster than the piston is dragging them?

I'm not arguing with anyone on this. Just trying to learn what it's all about.

 

[George Bryce]

All engines lose ring seal at some rpm. One way you lose seal is when the piston stops at tdc....and your ring keeps going. Things in motion tend to stay in motion.
Several things can help, lighter weight top ring, tighter ring lands, crankcase vacuum......etc. I cant give the farm away. GB3

 

[FE 065]

I'll have to admit, I never heard of crankcase vacuum as a performance feature.


Since this is new to me, I have a few questions.


Isn't the idea of an OEM PCV simply to keep crankcase fumes from getting out of the engine and becoming an air pollutant? That may be the primary application



Does the internal volume of the crankcase change as the pistons go up and down? The measured volume at any position would have to be the same. It still takes energy to move that air around



Is the performance gain due to less dense air being moved around inside the crankcase? Part of the performance gain could be attributed to that. How much? I don't know. Did Jason Tarnutzer, or DC have low tension rings on the engine that showed a horpsepower gain with a dry sump? If the Viper crank isn't actually in the oil anyway, a dry sump's primary horsepower benefit would have to be the vacuum it creates in the crankcase



Is the performance gain due to less air to crank drag at lower pressure and thus less dense air? Other than allowing a builder to use lower tension oil rings, I'd say so. If re-shaping the crank throw edges yields a HP gain then the atmosphere in the crankcase and aero improvements to spinning things inside of it would seem to be an area of interest



Is the extra ring control provided by the crankcase vacuum important when the engine has a supercharger?
Probably more so with a s/c. There's bound to be some blowby on almost any production engine. Forced induction would have to only add to the blowby wouldn't it



When the piston is on it's way down on intake stroke, the rings seat against the top of the groove, right?
This intake stroke is the only time that the rings are not driven against the bottom of the ring groove, right? Also during the power stroke


Can this pumped vacuum in the crankcase be enough to pull the rings down faster than the piston is dragging them? I don't know the specifics

I'm not arguing with anyone on this. Just trying to learn what it's all about. Discussion is always welcome

 

[Russ M]

Re: Vacuum pump tech; free up that hidden horsepower

Theoretical mumbling? Well that's an amazing response considering I'm just giving the information to my fellow Viper owners, and I've taken the time to present it in a detailed manner.



I'm not selling anything, and my post is laden with facts. It appears you wouldn't know a fact if it landed on your head. ..You didn't read the HotRod Magazine article's results?



I'm just passing the accumulated information along to anyone who might have interests deeper than the latest chrome gas cap for their Viper. Along with helping n/a Vipers, vacuum pump science will benefit all those s/c and turbocharged Vipers with crankcases suddenly charged with pressurized blowby.



Much of the rest of the racing world uses vacuum pumps. They're talked about on just about every car performance forum but Viper forums.



Popular Hotrodding's newest issue just had an in-depth dyno-backed article about aerodynamicly re-shaped crank throw edges to help crankshafts cut through the heavy atmosphere, and teflon coatings for cranks to help them shed oil. All of those efforts gaining horsepower.


Just because you don't know about horsepower losses in the crankcase doesn't mean they're not there.


I'm not going to argue about it...

There is a big difference between just creating vacuum in the crank case and actualy having a dry sump oiling system creating the vacuum. I may have been a bit harsh on my choice of words but, the end result is the same.

You already have the system on your car, 3-6 dyno pulls will take you 30 min. If it works I will be the first to buy one from you.

 

[Russ M]

Re: Vacuum pump tech; free up that hidden horsepower

FE 065,

Good post!

Too bad RussM is such jealous weasel, he's just upset that you thought of this before he did. Kind of reminds me of another thread where RussM failed to think of something first........

Excuse me?

Are you refering to the failed Vipair product? Which part would I be jealous of? The part where the manufacturer ripped of countless viper owners, or the part where he was proven to be a down right liar?

 

[joe117]

Re: Vacuum pump tech; free up that hidden horsepower

I asked,
"When the piston is on it's way down on intake stroke, the rings seat against the top of the groove, right?
This intake stroke is the only time that the rings are not driven against the bottom of the ring groove, right?"

You said,
"Also during the power stroke"

If the great pressure of the combustion gasses during the power stroke isn't enough to drive the rings against the bottom of the groove,
how will the relatively small vacuum in the crankcase be enough to seat the rings against the bottom of the groove during the intake stroke?

Also, how much of a vacuum is created by the dry sump scavenge pump?
It would seem to me that it wouldn't be much since the scavenge pump is only designed to pull out oil at a greater rate than the pressure pump delivers it.
It really isn't designed to be a vacuum pump.

And,
I don't know for sure, but I would expect that air in the crankcase will be driven to swirl around with the crank.
This would "probably" reduce the speed delta between the
crank and the air.

I always thought that the smooth crank idea was to reduce power loss from contact with the oil.

Just a ballpark look at the numbers,
Lets say that the average circumference of the crank lobe circle is 1.5 feet.
Then,
at 6000 rpm, the crank is turning at a rotational speed of 9000 feet per min.

9000 feet per min is 150 feet per second or about 102 mph.

102 mph doesn't seem like enough speed to worry much about the aerodynamics of the crank lobes traveling through air.

If this idea of pumping a vacuum in the crankcase is a horsepower gainer when compared to simply venting it very well,
I don't yet understand it.

 

[Joel]

Re: Vacuum pump tech; free up that hidden horsepower

This is an interesting post. As an aside I read an article about an engineer who joins 2 Yamaha R1 motors together to make a 2litre V8 for use in cars such as the Caterham. Individually the motors make 150 bhp each with wet sump lubrication system. United on a common block with dry sump lube the motor made 350bhp. The engine builder attributed the 50 extra bhp to the dry sump and the reduction in drag over a wet sump system.

 

[FE 065]

Russ...I'm not selling them, just letting everyone know about the application. There is a big difference between just creating vacuum in the crank case and actualy having a dry sump oiling system creating the vacuum. Jason Tarnutzer said directly that the 40rwhp gain was a by-product of the WCV dry sump system. He attributed the gain to the vacuum. I think vacuum is vacuum. The magazine dyno results and of course the use of vacuum pumps in racing seem to back it up don't they? A guy at our local cruise added a Moroso vacuum pump to his low 10sec n/a, low 9 sec on NOS '65 Mustang ' because of the NOS' meaning he's expecting more blow by when he's injecting the NOS. (I'd assume) Another guy with a 383 Firebird told me he gained 30hp with the electric pump. Since his engine's always apart, he may have added low tension rings, or done something with his crank seals (some people turn them around) to help his electirc pump (same as mine) achieve 15in vacuum. Don Walsh (6 sec Pro 5.0 Mustang) told me the larger the crankcase volume the stronger the pump you need. A large V10 crankcase may need a belt driven pump for max gain then. You could just slip the belt on at the strip... I was thinking about running a belt driven pump by adding another pulley in front of the water pump pulley or adding a billet drive snout and pulley to the front of the crank. Though the un-pinned balancer may not be a good place to add more belt drag. (Gee if only a shop with the resources could make a bracket to mount/reverse mount a belt driven pump..) Joe the math may/may not add up. Like every other mod people will just have to make their own decisions. There's enough evidence that the science works, that I just went for it. Since I've never seen any reference to vacuum pumps on the Viper boards, I thought I'd fill you guys in.I do know there's almost zero OEM crankcase ventilation on a Viper engine at WOT; when blow by is at its' highest, and when you're hoping for max HP. I just placed a flat plate with 4 holes in it under the crossmember, put the pump on top and ran 4 bolts between them. The pump is connected to the OE hose coming from under front of the intake manifold, and it's plumbed to an aluminum catch can placed where the w/s washer bottle was. You guys are going to have to take it from here. If you do a Yahoo or Google search with key words; vacuum pump, horsepower, crankcase etc you'll see how they're being used.

 

[GTS-R 001]

Re: Vacuum pump tech; free up that hidden horsepower

FE 065,

Good post!

Too bad RussM is such jealous weasel, he's just upset that you thought of this before he did. Kind of reminds me of another thread where RussM failed to think of something first........

Excuse me?

Are you refering to the failed Vipair product? Which part would I be jealous of? The part where the manufacturer ripped of countless viper owners, or the part where he was proven to be a down right liar?

Russ,

FE 065 posted the info to inform viper owners of something that may help them, he did not sign up to be abused or berated by a self serving individual such as yourself. Your behaviour is childish and unnecessary.

RE the Vipair, I believe you said to me on the phone " I didn't know how to do a proper dyno run for this, you should have given me instructions on how to do it!" , the only liar here is you Russ.

 

[Joe Dozzo]

I have one of these vaccuum pumps just sitting on a shelf.

I have a very simple installation question for you... Does your vent line run to a catch can somewhere? How much oil do you see?

Many thanks,

Joe

 

[Greg Good Cylinder Heads]

Re: Vacuum pump tech; free up that hidden horsepower

I've also talked to people who swear 19in vacuum pulled the oil off of their bearings or rockers, but the question the engineer had is what's that thin film of oil care about vacuum?

With a dry sump oiling system you're not limited to a certain amount of vacuum. The problem with a wet sump system is that as the vacuum increases, drawing oil becomes from the pan becomes increasingly difficult for the oil pump. It's a pressure differential thing.

 

[Tom F&L GoR]

Re: Vacuum pump tech; free up that hidden horsepower

FE 065, great topic and great to bring up all sides and sources.

Engine oil pumps can put out tens of gallons per minute, so even a fraction of this pumped to the valve train and draining back through the lifter valley will cause a shower of oil on the rotating crank assembly. Dry sumps don't allow this and **** up the oil from the valley and other parts of the engine. The crank doesn't (shouldn't) dip into the oil even in a wet sump so it runs drier except for what's slung off to wet the walls. Instinctively this should free up a good chunk of Jason's 40 hp to the flywheel. Some say they get a majority of this with crank wipers and good windage trays. http://www.circletrack.com/techarticles/34178/

Dry sumps accidentally pull a vacuum because the suction pump(s) volume is greater than the pressure pump. It gets complicated if you wanted to test the theory that vacuum creates power in a dry sump engine; you'd have to figure out how to run the pressure pump at the same speed (because it takes power to pressurize the oil) and the suction pumps would somehow have to vary the crankcase vacuum without changing their power requirement. You could bleed more air, but then you're also reducing the work needed to run them. Interesting to set up a valid test for this!

Which really does lead back to the external, independent vacuum pump. Adding one with an external power supply to either a dry or wet sump engine would give you the two test conditions where all else is equal except the crankcase vacuum.

Cylinder pressure can be over 1000 psi peak, but averages less than 200 psi (brake mean effective pressure.) If the combustion pressure averages 200 psi and you reduce the pressure on the other side of the piston from atmospheric to a perfect vacuum, then the pressure differential goes from 200 to 201 psi. Ignoring many, many other issues, if that 1/2% applied directly, you'd gain 2 hp out of 400 horsepower.

Stating the obvious by now, it would seem a major share of Jason's 40 hp should come from eliminating the oil around the crank assembly, and a minor component from the added vacuum. And you're only a dyno test away from showing which of the experts that having posted so far have made the best guess. Good luck!

 

[FE 065]

I have one of these vaccuum pumps just sitting on a shelf.

I have a very simple installation question for you... Does your vent line run to a catch can somewhere? How much oil do you see?

Many thanks,

Joe

I put a catch tank here: http://members.tripod.com/norwalkvipernats/tank.jpeg
(you'll probably have to paste that URL into your browser since Tripod doesn't allow remote accessing most of the time)

I removed the OEM w/s washer bottle and put the catch tank in its' place. One time I did see evidence of oil on the fenderwell as if it blew out of that little filter after running hard through all four gears, but none in the catch baffled catch tank (?).


Typically I'm getting little to none in the tank, which may be due to my accessing the crankcase via the OE lifter valley hose rather than a valve cover; - and I use the pump whenever the car's running.