Single Or Dual Carbs

[sflsurfrider]

I run a single 44/48 tlr modded carb and love it ( Watercraft Factory does the same mod). It always runs. If need be I can pull it off go through the whole carb and reassemble and install a very short time. When the weather changes from warm to cold, humid to dry its real easy to readjust the low and high speed if necesary. One less thing to fail.

I run a ported 61x cylinder, 62t cases with all the bolt on goodies and it hits hard and crisp. For freeriding or freestlye its my choice. If you are going to race, run wide open alot or have a hugh monster motor like pauls and need to move alot of air of course duals are the way to go.

For reliability, good performance, and easy maintenance a single is the way to go.

Just my 2 cents worth.

Brad

i have the identical setup. nice and crisp.

 

[WaveDemon]

what about if the engine is making say 80ho on a single and a dual
are you saying the dual will use more gas

if both carbs were to make the same power why would I have a second carb to begin with? :biggrin:

 

[waxhead]

because it would give you more torque
but i see you have come around to realising that the single carb makes less hp

 

[hangtime]

I run a single 44/48 tlr modded carb and love it ( Watercraft Factory does the same mod). It always runs. If need be I can pull it off go through the whole carb and reassemble and install a very short time. When the weather changes from warm to cold, humid to dry its real easy to readjust the low and high speed if necesary. One less thing to fail.

I run a ported 61x cylinder, 62t cases with all the bolt on goodies and it hits hard and crisp. For freeriding or freestlye its my choice. If you are going to race, run wide open alot or have a hugh monster motor like pauls and need to move alot of air of course duals are the way to go.

For reliability, good performance, and easy maintenance a single is the way to go.


Just my 2 cents worth.

Brad

Thanks Brad ,I think I will go with the single for good reliability,performance and easy maintenance.
I ride ocean and never go WOT for more than a few seconds and really like the idea of easy maintenacnce and tuning :arms:

 

[WaveDemon]

because it would give you more torque
but i see you have come around to realising that the single carb makes less hp

yes, 2 carbs make more hp most of the time (as long as you aren't over carbing your motor). I don't want peak power though. I want low end torque. I don't care about top speed, most of my riding is between 2-10 mph. A single carb should give you more air velocity going into the manifold giving you better fuel atomisation for more efficiant fuel burn down low. a single carb will hold you back when RPM's increase and limit your peak power. My single carb set up is a serious arm streacher. I'll admit I've never had my current cylinder on a 62t bottom though.

 

[Mile9c1]

A single carb should give you more air velocity going into the manifold giving you better fuel atomisation for more efficiant fuel burn down low.

I think duals would give you better atomization, since they have twice as many orifices to do the job. The air speed going into the intake runners is the same in either case.

 

[Matt_E]

How so? Assuming the intake area of the single is smaller than that of duals, the single must have a higher air velocity through it.

 

[Mile9c1]

Because the amount of air going into the engine itself is mostly a function of RPM's (the engine is an air pump, remember). Not speed through the carb. When the faster moving air spreads out to two cyliners, it slows down.

What makes one think that "faster" moving air atomizes better? You could easily think the opposite.

I would think that 10 little gas streams would mix better than 5 bigger ones. That's why in automobiles, multipoint fuel injection is superior to central fuel injection (also known as throttle body injection). Am I right or am I right?

 

[WaveDemon]

Because the amount of air going into the engine itself is mostly a function of RPM's (the engine is an air pump, remember). Not speed through the carb. When the faster moving air spreads out to two cyliners, it slows down.

What makes one think that "faster" moving air atomizes better? You could easily think the opposite.

I would think that 10 little gas streams would mix better than 5 bigger ones. That's why in automobiles, multipoint fuel injection is superior to central fuel injection (also known as throttle body injection). Am I right or am I right?

Did you know that throttle body injection makes better torque at the expense of upper end power? That is why chevy used to put it on trucks while putting TPI on camero's and vettes so your theary doesn't hold. Plus the 62t also has bigger intake runners which also slow down air speed. the smaller throttle plate area and smaller intake runners equal a stronger draw on the carb which makes more torque and less HP.

Someone lend me a 62t case and we'll test it out.

edit - i'll need a set of 38's and 44's for the test...

 

[waxhead]

Wave demon i understand what you are saying but since the weak area in the intake is the 61x cases
i dont know that that would add to extra signal at the carb
as the carb only see air passing through it
not whats happening afterwards or before
so less flowing cases will in fact have a lower draw on the carb than higher flow cases

 

[WaveDemon]

Wave demon i understand what you are saying but since the weak area in the intake is the 61x cases
i dont know that that would add to extra signal at the carb
as the carb only see air passing through it
not whats happening afterwards or before
so less flowing cases will in fact have a lower draw on the carb than higher flow cases

I don't know were the flaw is in the 61x case but if it is filling the same size cylinder I would think a smaller carb and/or intake tract opening whould just increase draw.

long and small runners have alway created torque while short and wide runners have always created horsepower. I don't know why it wouldn't apply here.

If the 61x case has a flaw then I'd like to see what affect changing to a single carb 62t would have.

 

[Mile9c1]

Did you know that throttle body injection makes better torque at the expense of upper end power? That is why chevy used to put it on trucks while putting TPI on camero's and vettes so your theary doesn't hold.

Please tell me you're joking! That makes no sense... at all!! TBI sucks ass, those TBI motors are absolute DOGS in trucks (and they get worse gas mileage). Go ride in a Chevy truck that has a Vortec, I think they started in 1995. Vortecs pull much better, hands down. BTW, if an engine makes more horsepower, it has more torque. Because the formula for horsepower equals torque x some numbers. That's it.

 

[Mile9c1]

I have an LT1 engine (basically a Vortec engine) in one of my cars, it has 260 horsepower and 330 ft-lbs of torque. How much power/torque does the TBI 350 make? Let me guess, it's not even close.

The reason the Vorec's rev higher is they have much better heads than those TBI engines.

The function of a carb or fuel injection is simply to add the correct ratio of fuel to the incoming air.

 

[WaveDemon]

Please tell me you're joking! That makes no sense... at all!! TBI sucks ass, those TBI motors are absolute DOGS in trucks (and they get worse gas mileage). Go ride in a Chevy truck that has a Vortec, I think they started in 1995. Vortecs pull much better, hands down. BTW, if an engine makes more horsepower, it has more torque. Because the formula for horsepower equals torque x some numbers. That's it.

yea, those numbers are rpm... . torque is power.The formula is:
horsepower = rpm x torque / 5252

you can have a relitivly low torque motor but high horse power if it reves high enough.

your examples of efi don't really apply because I'm talking about gettig a better burn though fuel atomisation. in a carb that is made by a long turbulant path to the chaimber. in EFI it is made with a high pressure injector pointed directly at the chaimber.

How's this, it is well known that freeride engine builders keep the intake manifold and boost ports rough as well as the boots porst long for more low end power in the surf. Long and turblulant.


in the car world everything i'm talking about is accepted, understood, and applied all the time. I don't understand why it's so rejected here.

 

[WaveDemon]

I'm willing to listen to explanations that say torque isn't impotatant in a pwc because... (pump in effisiancies, the speed at wich a watercraft motor revs, etc...)

 

[Matt_E]

Because the amount of air going into the engine itself is mostly a function of RPM's (the engine is an air pump, remember). Not speed through the carb. When the faster moving air spreads out to two cyliners, it slows down.

I hear you. However, take a 62T engine...one with OEM duals, one with 44 single.
At equal RPMs, the dual should have a higher air velocity through the carb than the duals.
Correct?
(BTW, I am not saying that's better)

 

[Mile9c1]

At equal RPMs, the dual should have a higher air velocity through the carb than the duals. Correct?

The single would have a higher velocity moving through it. But who says that's better?

Nobody argues that smooth ports are better than rogh ones.

Torque is good to have everywhere, no question about that. But I don't think a single makes more torque than duals. Especially if your only argument is that the air is moving faster through the carb.

On a lower horsepower engine, I think a single might be fine.

 

[Matt_E]

Durr....typing early in the morning again...:biggrin:
yes, I meant the single should have higher air velocity.
I don't know why this would provide more torque. (I didn't make that point, either!)

Higher air velocity theoretically means better - faster - throttle response. However, from talking with Paul about this, more volume at lower speed is better for low end than higher air speed with less volume.

 

[Big Kahuna]

in a nutshell both setups work, just each has its different attributes

here is what I found........

with the single setup using OEM 44. Power was very precise and smooth.
with single TLR Modified 44. Power hit really hard, but was almost like hitting a light switch at times (More abrupt power)
with Dual Team Scream Modified 44's, Power was equally has strong, more power hitting in the midrange vs. down low (Better for arial type tricks) with smooth power transfer (not like a light switch)


as for fuel consumption, the single modded 44 drank gas....

 

[Matt_E]

as for fuel consumption, the single modded 44 drank gas....
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I imagine it would...with high air velocity ripping on these jets like that.