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Negative crank case pressure - 2 Bhp for nothing!!!!!


knight

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I have been trapsing throught the ZX12R tech forum.......aparrently those boys are connecting the reed valve emissions air suction valve assemblies - located in the cam cover - to the crank case breather hose - which at high rpm results in a crank case vacuum of around -4psi......which aparrently gives you a 2Bhp power increase for nothing!!!! :shock: ....the big question is ......has anyone tried this on a Bird yet?....I dunno if this has been discussed here before as i am new to this forum.....would be interested to know all your thoughts!

aparrently is makes the piston rings seal better and reduces blow-by, therefore increases cylinder pressure and power......gotta be worth trying! :grin:

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Kawasaki head on a bird???.......errrr no thets not quite what I meant! :???: .....on the US spec birds they already have the reed-valve air suction devices located in the cam cover! - what I wanted to know was had anyine connected those standard air suction devices to the c.case breather hose and noticed a power gain on the rolling road?......

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You got it - when you drop yer bird/busa/12R - people like me stuff the engine into some form of 4 wheel'd thingy!......my engines previous owner did a lovely job of folding the forks in half using a car bonnet - I dont think he is gonna have kids either going by the state of the fuel tank - I think he must now have 3 adams apples :cry:

Yep cut 3 inches off the sump - fits a treat in the back of my car and goes like stink! - for racing only.

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For circuit racing in the UK-England, on tracks like Brands hatch, Silverstone, Snetterton etc..... its generally called "slicks and wings" type racing, the cars look like formula Ford 2000 or F3 cars...... or if you are not too familiar - like a small Indy/F1 car - with nice big aerofoils for loads of downforce - my car for instance will do 0-60 in less than 3 seconds, top out at 140Mph in 6th gear, and weighs 380Kg - without me in it.

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You need to have it hosted somewhere. Somewhere people can get to without having to log in. Then when you've dropped it somewhere, you hit the "%7Boption%7D" box, put in the address on where the pic is..such as http://www.blahblah.com/mypics/pic.jpg and close it by hitting that "%7Boption%7D" box again.

Help?

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This is nothing new,creating negative pressure makes oil less prone to stick to the crankshaft weights and reduces aerodynamic drag too.

That is why all GP motors are deep or dry sump to keep oil away from crank plus there are scrapers and screens.

Real race motors use scavenging pumps or evacuator breather systems that are connected into exhaust header and rely on vacum created in the pipe.All that to create negative pressure in the crankcase.

You can gain up to 5% more power.

Negative pressure in the crankcase does improve sealing by rings since force pushing them against the wall increase.(Pressure above the ring-pressure belowe the ring)X surface area.

Another way of doing this is to put one way valve between airbox and crankcase breather.

People were using air pumps on GSXR 1000 and rerouting them to suck from crankcase,normally they supply exhaust with the fresh air for emission purposes.

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Did a search on pair/sucker over at suzukihayabusa.org and found some info.

It doesn't seem to cause any problems and some claim there is a power gain.

Unfortunately no one did back to back dyno runs before and after to document changes.

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Negative crankcase pressure (or at least very low crankcase pressure) helps the rings seal, your oil seals to do their jobs, and reduces pumping losses in the engine.

In other words, it reduces the effort required to push the piston downward, as there is less pressure on the underside of the pistons.

ProStock cars discovered this probably 10 years ago, when they started installing air pumps, hooked up backwards, to their crankcases for evacuation purposes. Big gains on those motors, where every hp counts.

Pro Stock Bikes have been using them for a few years, too, and Angelle Savoie's team had 3 installed on her championship winning Suzuki, until NHRA changed the rules, only allowing one pump. Her team was able to run 3 because of the weight advantage she provided, so the other teams whined accordingly, and the rules were changed.

Now they run the biggest pump they can possibly fit on the bike.

Probably won't make a big difference in force fed applications, but naturally aspirated engines should see a noticeable improvement from lower crankcase pressures.

I'm just not sure that hooking up the hoses as you describe will actually result in lower crankcase pressures, unless someone, somewhere, can prove it.

Why not try it on your own ride, and let us know the results. :idea:

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dont think he is gonna have kids either going by the state of the fuel tank

I don't know about back pressures and stuff, but as far as I know the dent in the tank is not a result of the guy slaming at it with his balls...

He probably did, but the dent comes from the frame flex. The tank being attached up front and in the back, absorbs the energy...

Cheers,

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Does your car look kinda like this?

200311271841514034366296.jpg

Not mine, but a good customer/friend. I've had the privlage to baby it a few laps around MAM, but nothing serious. If only I had the money.........

This one is a rotary powered Formula Mazda.

200311271474313065231002.jpg

I'd love to see the XX powered one.

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  • 3 weeks later...

I dunno if you guys are still interested in this.....I was on the gixxer forum earlier and one guy had back-to-back tested this on a dyno......and with thie reed valve assys linked to the crank case breather hose he noticed a gain of 2.6Bhp.......not bad for nothing! :razz:

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