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is this really beneficial to a motorcycle? and if so, how?

edit: i mean for a motorcycle that leans.
 

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is this really beneficial to a motorcycle? and if so, how?

edit: i mean for a motorcycle that leans.
You're right, as long as it's only leaning left to right, the only benefit would be power from reduced crankcase pressure and oil control.

If the bike is leaning seriously front to back, or sees serious Gs, it becomes a way of saving the motor.

In a drag bike, there would be the potential to reduce the depth of the pan.

If it was for my own use, I wouldn't think about putting a bike motor in a car or sidecar rig without dry sumping it. A motorcycle engine could not be designed any worse for cornering, It starts with the pan, but doesn't end there.

If I was building a stunt bike for a professional, it would be dry sumped.
 

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Discussion Starter · #10 ·
Thanks for the responce Mr. MW, that was what I was looking for. I'm building my own system and that one gives me some good ideas. I was also thinking that with the motor turned sideways, That I would also but a drain or scavenge line to drain the head. I've seen this done on Radical with 1000.
 

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For gen info this is in a car. malracing1 is a hotshoe on our tracks. He's been flying his car with a tired oil cooled. The K4 will be nothing but trouble for the rest of us ;-) Can't wait.
Sorry Flip, some of us are just too chatty with strangers ;-)

Malracing, search on superchargers in this forum for some clever ideas on external crank drives.
 

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How is the scavenge pump driven, mechanical or electrical?
Looks like a mechanical connection to me.


I assume the main oil pump is still there providing the main oil pressure.
So just the removal of the oil flinging around the crankshaft area and the slight vacuum
created by the scavenging pump is enough to save 10hp even after driving the small
scavenging pump?
Do any race bikes run dry sumps, regulations permitting?


I don't see you saving 'unto 20hp' by replacing your mechanical water pump with
a 7.5amp electrical one though, even in a car.
Mechanical water pumps can't be that inefficient can they?
 

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How is the scavenge pump driven, mechanical or electrical?
Looks like a mechanical connection to me.

[/QUOTE]

Correct, the scavange pump is driven mechanically from the water pump drive


I assume the main oil pump is still there providing the main oil pressure.
So just the removal of the oil flinging around the crankshaft area and the slight vacuum
created by the scavenging pump is enough to save 10hp even after driving the small
scavenging pump?
Depends on the system.

The old home brew systems used a gilmer drive off the crank and used a car style stacked pump with scavange and pressure pumps stacked together.

The vacuum created by the scavange pump usually isn't slight. Up to 20" of vacuum, and atmospheric pressure is 29".

The Pair mods I've tested were in the 2" - 4" range. Good for 2 - 4 hp.

In general, it's a bad idea to go above 10" with a stock oil pump. You get burned on net positive suction head. Your oil is really hydrocarbon soup after any running time at all. It doesn't matter what bubbles first, the oil pump still stops pumping. With a dry sump system, the oil tank is positoned well above the crank, giving more net positive suction head than could ever be achieved with a pan.

And then there is that whole oil on the crank thing. The scavange pumps can be used to pull the oil out before it drains across the crank.


Do any race bikes run dry sumps, regulations permitting??
Not that I'm aware of, but I'm road race oriented. The additional power wouldn't be worth the additional weight.

I think it would be worth exploring on drag bikes. I understand the pro stock bikes use electric vacuum pumps, but I havn't seen one.

I don't see you saving 'unto 20hp' by replacing your mechanical water pump with
a 7.5amp electrical one though, even in a car. Mechanical water pumps can't be that inefficient can they?
On a car, the water pump can easily be 20 hp at peak rpm. Pump flow goes up linearly with rpm, pressure as the square of rpm, which makes power as the cube. The mechanical efficiencies are pretty low, and the pressure drop across the cooling system is deliberately high. And it has to work best at an idle with low air flow across the radiator.

I havn't taken a 1K water pump apart, but if I was an AMA inspector, I'd sure the hell know exactly what a stock impeller looked like. The water pump is actually a side issue in this discussion. The referenced dry sump system forces the use of an electric pump and the vendors have turned the problem into a feature. The real reason to use the water pump drive is to simplify and sanitize the installation.

To digress even further, an electric water pump is free hp on a bike. A motorcycle voltage regulator does not work like a car. With a car, the field current is varied to change the alternator output. With a bike, the alternator output is constant and what the bike doesn't need is shunted to a resistor. This is why a bike voltage regulator looks like a heat sink. It is. You can replace the alternator with a racing one, but this conversion is almost as much as a dry sump system. Race bikes do not have nearly the electrical load of street bikes because they don't run lights. Constant loss systems (no charging) is a bad idea with FI bikes because the battery voltage affects the fueling and the electric fuel pump load is high.

The real issue is "hold up". With a conventional pan type oil system, the minimum capacity of the pan is set by the "hold up" of the engine. Check your oil level after running the engine. It isn't there. Hopefully there is enough left to both cover the pick up and satisfy the NPSH requirements of the oil pump when you're under power. The difference between the running and cold oil levels is the "hold up".

If you do anything that changes the "hold up", you run the risk of smoking the motor. That would include oil viscosity and the G loads on the motor. Lower viscosity oil is actually safer to a point because the hold up is lower. Changing your oil more often reduces the oil level required to keep the pump going because you flush the contaminants that bubble the oil.

With a dry sump, you're not limited to the capacity Suzuki designed into the pan. The hold up thing can go away as well because you can suck oil out of the corners it hides in. The new motors have less drainage from the head than the original SRADs did. Foaming and sloshing are also reduced or eliminated by the dry sump storage tank. Need more pump? Fine, screw it on.
 

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Very intriguing.
I think I will try it out on my track bike.

Why do you think it will be too heavy?
The dry sump pump parts look reasonably light.
Need to add the oil can. One difference is that oil can will be a bit
higher up - CG. Place it above the crank case breather box?
Might be able to run a litre or so less oil, thus saving 2lb but changing it more often.

Now that electric water pump is a monster (for a bike) it's 2lbs.
I couldn't find any smaller ones. What would be the maximum flow rate required on the 1k?
It's around 100w max so the stock charging system should handle that no problem.





Fantastic Maxsym engineering (dry sump GP motor)
 

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Very intriguing.
I think I will try it out on my track bike.

Why do you think it will be too heavy?
The dry sump pump parts look reasonably light.
Need to add the oil can. One difference is that oil can will be a bit
higher up - CG. Place it above the crank case breather box?
Might be able to run a litre or so less oil, thus saving 2lb but changing it more often.

Now that electric water pump is a monster (for a bike) it's 2lbs.
I couldn't find any smaller ones. What would be the maximum flow rate required on the 1k?
It's around 100w max so the stock charging system should handle that no problem.
I'd run it on a drag bike, especially one that was set up to leave hard.

I don't see how the added weight and hassle would be worth it on a road racer unless it was engineered into the bike from the start. If I was designing a GP bike from scratch, it would absolutely be dry sumped. My HD building buddies would be on me like ants at a picnic for all the colostomy bag comments I've made about their engines over the years.

I wouldn't reduce the oil capacity by any more than I'd convinced myself I'd reduced the hold up with the scavanging pumps.

I'd probably start with the water pump recommended by Maxsym. There's power in cooler water as well, but most of it needs to be done in the radiator.
 

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Hopefully there is enough left to both cover the pick up and satisfy the NPSH requirements of the oil pump when you're under power.

I got a little laugh out of this (no offence intended). Your average garage mechanic doesn't have a clue what NPSH is. Hell, I worked with 'engineers' that designed pumps that didn't understand NPSH. Anyhow, what kind of NPSH does an oil pump usualy need? I always wondered, especialy in sport bikes where the oil pump experiences quite a change in RPM. Much like discharge head, NPSH increases with RPM, and NPSHr increases with flow.

One of my concerns is a dry sump system would be the 'quality' of the oil by the time it reaches the oil pump. A lot of entrained air could really screw the whole set up. Adding a scavange pump could cause excessive foaming that could add a crapload of entrained air.


Also, for what it is worth, high backpressure in the cooling system is a good thing. Assmuming constant speed, the flow produced by a centrifugal pump increases as the restriction on the outlet is reduced. But, as the flow increases, so does the power requirement. Choking back the flow is a good thing... to an extent. Choke the flow too much, and the pump will cavitate. If I was building a 1/4 mile motor, I would trim the impeller and choke the flow back. It would not be practical for street use at all.
 

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NPSH, pressure at the pumps input I believe. More relevant to steam systems or other liquids likely to vaporize at low pressures, no?
There is a pressure drop in the pump itself, so your input pressure must be high enough that the pressure drop
inside the pump doesn't cause the liquid to vaporize or bubble and cause cavitation in the pump.
I think a well designed dry sump system should be less susceptible to foaming.
In the catch tank the foam would be on the top and the feed to the main oil pump would be at the bottom.
If it foams just make the oil catch tank capacity bigger?
 

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I was thinking of starting with the water pump as well. It is also the cheaper part after all, but then I need something to fill in the
hole left by the mechanical water pump removal:)

So run it at maximum flow/current without a thermostat and just block of the radiator a bit if it's too cold.

I hear a good target would be around 160F for max hp.
 
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