Idea: Ultimate carby intake for B series motors.

[BigElCat]

The original throttle body would be replaced with an adapter. A flat plate with a round tube stub in it. The carb would be mounted up by the radiater support sheet metal, at least for the B3. The B6 would have the carb under the hood somewhere.

A metal tube or rubber hose would go from the carb to the adapter. This tube could be heated with 110v heat tape for cold climate start ups. You'd have to spin the motor a little longer to get it to fire.

You'd be limited to a manual choke. I'd have to rig an indicator light to remind me to take the choke off.

[BigElCat]

I did talk to matt dickmeyer a little about a better intake, he wants to design a really good intake for us carby guys so i told him i will definitely be getting one. I think he is just extremely busy right now. I can see the use of the efi intake but like somebody said earlier what about the hood? My air filter just barely clears the hood by like a 1/4 inch

The carb would be down low, in front of the motor. With a tube across the valve cover. Clearance is no issue. Maybe I could draw a sketch and scan it.

Matt's going to reject this, cause it ain't his idea. Oh well.

[drumnerd33]

I see what your saying but i think that may be a little too far for the mixture to travel.

[drumnerd33]

Im not 100% sure on this but with a carb dont you want as straight as possible into the engine? gets the air and fuel delivery more direct.

[drumnerd33]

My buddy used to have a 510 and he said i should do what he had with the dual side drafts... he loved it said it helped a ton, ive been kinda looking a them but i like my weber now and matt ported and polished my intake but he said he didnt spend too much time on it cuz it is a waste, he said the design of the stock intake is terrible, im assuming he means how it is a port to each side then splits again into 4

[Movin]

As stated above the intake pressure transitions would be a nightmare to tune unless you vaporized the gasoline first then metered it with a propane carb, or just run propane. A liquid fuel with that much metal would flow great but the effective fuel mixture would be impossible to tune even with a mild cam. Adding a cam to this would be worse than impossible then add thermal variations ...

Give a slide carb a nice straight shot at the back side of the intake valve and they do fine. Really fine

[BigElCat]

Im not 100% sure on this but with a carb dont you want as straight as possible into the engine? gets the air and fuel delivery more direct.

Yes. The B6 2nd gen is a better design, but it won't fit the B3.

The stock B3 EFI intake is much superior to our stock carb intakes in term of air flow. The entrance in the middle, turning 90 degrees and dividing the air flow both directions has design disadvantages as well as advantages (equal length). I think you could 130 whp out the B3 system I'm describing. If your dad can jet a bike carb, I could make the adapter.

Having the mixture travel a long way could be a problem. The tube would cross the header, so at least it hot, helping with vaporization. The concept of a whole new carb intake has been toyed with for years. It ain't simple. It will be $600.00 for the first one. My solution is inexpensive and waiting to be tried.

[BigElCat]

As stated above the intake pressure transitions would be a nightmare to tune unless you vaporized the gasoline first then metered it with a propane carb, or just run propane. A liquid fuel with that much metal would flow great but the effective fuel mixture would be impossible to tune even with a mild cam. Adding a cam to this would be worse than impossible then add thermal variations ...

Give a slide carb a nice straight shot at the back side of the intake valve and they do fine. Really fine

I don't know what you mean by intake pressure transitions. We have a propane thread workin'. Propane does not belong here. These aren't slide carbs.

A double wall tube could be made using header heat to maintain fuel vaporization.

[drumnerd33]

Yes will be expensive but i know that if matt designs it he has all the correct machines for testing and the knowledge behind it. He said im looking at a 20 hp loss in my intake alone:cry_smile: that sucks..... Im not saying yours wouldnt work, but i am saying i think tuning would be a nightmare and you will have problems with puddling. I just did a little reading on intake designs for carbs and they said straight and short will net high rpm hp but lose your low end torque, they said long runner gives you low torque but you lose some hp in high rpm, and it said puddling is a problem with long runners.... so there is gonna be a happy medium here.

[BigElCat]

My buddy used to have a 510 and he said i should do what he had with the dual side drafts... he loved it said it helped a ton, ive been kinda looking a them but i like my weber now and matt ported and polished my intake but he said he didnt spend too much time on it cuz it is a waste, he said the design of the stock intake is terrible, im assuming he means how it is a port to each side then splits again into 4

Yo! I road in a 510 with dual side draft webers. Bad Ass! There's no B3 intake for these. Check out Bravezak's B6. He got to the only dual carbs on the forum, and they're cool. Not side drafts though.

[Movin]

I don't know what you mean by intake pressure transitions. We have a propane thread workin'. Propane does not belong here. These aren't slide carbs.

Not competing with a propane thread but pointing out that liquid fuel would have to be completely vaporized before metering to have a controllable mixture. To put a slide carb where the throttle body is will run but will have hesitations and bogs, hard starts ect that will make it undesirable to drive.

Intake vacuum is intake pressure. Thinking in terms of pressure has advantages.

My mistake I thought mukuni or slide was mentioned but a weber or dellorto will not do any better with acres of metal to transit before it hits the intake valve.

[BigElCat]

Yes will be expensive but i know that if matt designs it he has all the correct machines for testing and the knowledge behind it. He said im looking at a 20 hp loss in my intake alone:cry_smile: that sucks..... Im not saying yours wouldnt work, but i am saying i think tuning would be a nightmare and you will have problems with puddling. I just did a little reading on intake designs for carbs and they said straight and short will net high rpm hp but lose your low end torque, they said long runner gives you low torque but you lose some hp in high rpm, and it said puddling is a problem with long runners.... so there is gonna be a happy medium here.

I hear you. A dual side draft would be best. Matt's not a caster though. I suppose it could be TIG'd out of aluminum plates and tubes. The carbs are high dollar. I'm going to keep toying my idea though. If I could keep it vaporized, it would be great for my application.

[drumnerd33]

For sure if you have an idea and time then do it! I will be watching for the outcome cuz i def dont like losing 20 hp to a stupid intake design

[BigElCat]

Not competing with a propane thread but pointing out that liquid fuel would have to be completely vaporized before metering to have a controllable mixture. To put a slide carb where the throttle body is will run but will have hesitations and bogs, hard starts ect that will make it undesirable to drive.

Intake vacuum is intake pressure. Thinking in terms of pressure has advantages.

What do you mean by "slide carb"? Gasoline is completely vaporized after metering in carbs. Start up would be slower. What pressure (vacuum) changes? You mean where the tube would transition at the plenum?

[Movin]

What do you mean by "slide carb"? Gasoline is completely vaporized after metering in carbs. Start up would be slower. What pressure (vacuum) changes? You mean where the tube would transition at the plenum?

Please do not take this wrong I feel like the little kid that knows how to catch fish in the creek telling college professors how to catch em !! I know you know most this stuff, just making sure we are on the same page as far as terminology goes.

The slider carbs are round slide or flat slide and by design work well with engines that have pulsed intake pressures such as one or two cylinders per carb. OHV two stroke or four stroke engines with one carb per cylinder are typical. Two or four of these carbs would work well on a festy four. Side draft aimed as close as possible at the intake valve would be ideal.

Gasoline or any liquid fuel is never vaporized completely, mostly just atomized. A liquid fueled engine has to have a throttle position sensor or an accelerator pump to make up for the atomized fuel mix that condenses on the intake passage surfaces when the intake pressure increases ( you step on the gas ) . Vaporized fuels such as propane do not condense when pressure rises so there are no accelerator pumps or tps's needed for proper fuel mix during these transitional periods. The weight of the atomized mixture as opposed to a vaporized mixture is also a factor. If gasoline was heated far beyond boiling but under spontaneous ignition temperatures the resulting vaporized fuel could be metered like propane and would not suffer the tune problems that intake pressure pulses, larger than normal condensation-able surfaces and temperature fluctuations would induce.

Enough heat to the intake manifold to mitigate this problem would not be possible without introducing side affects that would be undesirable.

Intake pressure allows thinking in terms like computer controlled systems use and tuning for altitudes and pressurized systems becomes much easier to think through rather than in terms such as intake vacuum. You have intake pressure until air is no longer present. You have more intake pressure until the turbo and or supercharger can deliver no more. Just one scale to think about from absolute vacuum to peak boost PSI.

Intake pressure pulses are difficult for the average carb to meter accurately. Mukuni and SU do well, and complex venturi carbs such as dellorto, holly and weber do well with a knowledgeable tuner.

A liquid carb manifold needs a lot of heat where puddling could occur such as directly below a downdraft carb where the 90 deg. occurs to deliver the charge to the intake valve. A chrysler 225 slant six with its fan shaped intake is a good study in compromising side affects for the best result with a single carb.

If it runs its all