Reading over previous post about BLP twin oval blade carb got me to thinking.
I’ve heard the criticism of the SV1 single blade carb as being a loss of the venture affect. I’m confused now to a degree. How important is this and why wouldn’t the SV1 be “workable”? That is to say, at least having potential if the twin oval blade carb works?
What am I missing… or what say you about the comparison…
Carb Experts..venturi, twin oval, SV1...??
Moderator: Team
Re: Carb Experts..venturi, twin oval, SV1...??
No takers?
That Adds to confusion...but perhaps tells me something too...
That Adds to confusion...but perhaps tells me something too...
Re: Carb Experts..venturi, twin oval, SV1...??
It is a great question, I would like to see what others say....
I often have thought why we do so much to improve atomization and then what is first thing in the way, something to separate air and fuel,
I often have thought why we do so much to improve atomization and then what is first thing in the way, something to separate air and fuel,
If it isn't broke push it harder 
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swampbuggy
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Re: Carb Experts..venturi, twin oval, SV1...??
Hey Tuner, i must admit i don't have enough high up math education to understand the information in the links you provided LOL, wish i did though ,Mark H.
Re: Carb Experts..venturi, twin oval, SV1...??
The way to gain understanding of math which seems complex like the Reynolds Number is to use the calculation on several different things you are familiar with and already have an empirical understanding. Write it out with pencil and paper and use a calculator to crunch the numbers. After several iterations you will begin to see the trends and it will start to make sense.
The Reynolds Number identifies or describes whether or not fluid flow is laminar or turbulent. As velocity increases, there is a range of erratic flow in which laminar changes to turbulent and will change back and forth at random. Below that velocity range = flow is laminar, above that velocity range = flow is turbulent, in that range = flow is erratic. Turbulent flow sort of restricts itself, makes the hole smaller or the wing bigger than it actually is. Obviously, erratic flow in a carburetor cannot be tolerated.
The Reynolds Number identifies or describes whether or not fluid flow is laminar or turbulent. As velocity increases, there is a range of erratic flow in which laminar changes to turbulent and will change back and forth at random. Below that velocity range = flow is laminar, above that velocity range = flow is turbulent, in that range = flow is erratic. Turbulent flow sort of restricts itself, makes the hole smaller or the wing bigger than it actually is. Obviously, erratic flow in a carburetor cannot be tolerated.
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pamotorman
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Re: Carb Experts..venturi, twin oval, SV1...??
on the holley 3 barrel they moved the rear boosters closer together compared to a 4 barrel. I would guess they did a lot of flow measurements before deciding where to place them.
Re: Carb Experts..venturi, twin oval, SV1...??
Great...glad others are interested..
So is there anything laminar in a running engines intake track?
I’m not following the links without explanation....
So is there anything laminar in a running engines intake track?
I’m not following the links without explanation....
Re: Carb Experts..venturi, twin oval, SV1...??
No. The flow goes turbulent virtually as soon as it starts.
Felix, qui potuit rerum cognscere causas.
Happy is he who can discover the cause of things.
Happy is he who can discover the cause of things.
Re: Carb Experts..venturi, twin oval, SV1...??
Tuner...I’ve always been impressed with your thoughts, knowledge and explanations. I’m just not understanding what you’re trying to say...
It’s like I offended...why the short reply?
Re: Carb Experts..venturi, twin oval, SV1...??
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man.
Being reasonable, you could answer your own question with the math in the links.
Re: Carb Experts..venturi, twin oval, SV1...??
Clearly I am the unreasonable man....
I persist in asking questions that have simple answers..to some
Yet there are numerous examples of various design air/fuel metering devices successfully used on performance engines. If the answers are so simple why do we see the various designs?
I persist in asking questions that have simple answers..to some
Yet there are numerous examples of various design air/fuel metering devices successfully used on performance engines. If the answers are so simple why do we see the various designs?
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jmarkaudio
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Re: Carb Experts..venturi, twin oval, SV1...??
I'll try to be as tactful as possible...
A carb is (should be) designed to accurately meter the correct amount fuel to match the airflow at all throttle positions and loads. In addition it should also atomize the fuel sufficiently to get equal distribution to all cylinders, however that is rarely the case and in some instances very poor. It is not necessarily the carbs fault, some intakes and engine combinations do not allow for it, or limit the carb size to get it close enough. You can look at some factory dual plane setups that will actually stagger metering differently in all 4 corners to get the engine in a somewhat happy zone. Now you can make the carb small enough that it vaporizes the fuel very well, a Quadrajet primary is a good example, by keeping the velocity high you atomize and vaporize the fuel more completely, making the mix of air and fuel more homogenous, this make distribution more even and the engine is happy. Until you try to make more power at higher RPM's and WOT, the HP looses it take to pump the air the the restriction become large, and small enough and you lose airflow as well. So you go bigger and bigger until you lose power, starting in the lower RPM ranges and working up until the carb is too big to sufficiently atomize and vaporize fuel to get even distribution. So finding the right balance of size is part of the equation. The RPM range the engine sees will have a big factor, an engine that runs primarily over a 1000-1500 RPM range will tolerate a larger carb than an engine that sees a 6000 RPM swing.
So how do we make more power, how can we use a bigger carb? We find ways to better atomize the fuel leaving the carb despite lowering the pressure difference a larger carb has. Better atomization from the boosters is a large part. Using fuel with the proper vaporization curve for the engine and temperature range it runs. Work on the intakes, make the distribution more even between the cylinders. Texture in the intake surface can help. On an 8 cylinder going from 4 barrels to 8, placed over the runners. This allows for more precise control of each cylinder.
Now to the oval blades. BLP no longer offers them, they are being manufactured by a new company Get'm Garage. I can build them as well as several others, and of course Get'm will build them direct. I have built several, and even did some testing with two different sizes the past two weekends. Because they still use 4 boosters and 4 corner idle they still allow some control over distribution like a traditional 4 barrel, and I have not seen anything detrimental with two oval blades vs 4 round. Like any other carb they have to be sized appropriately for the combination. They also use any of the standard Holley style boosters, my favorite is still an annular.
Now for the single blade. There are some running them successfully, some that struggled. Like any other carb proper calibration for that engine/combination is necessary, and to make power relatively even distribution is key. At WOT and smaller RPM bands a lot can be done to make most anything work. The issues I see is one large blade at part throttle positions, the air the air (and fuel) is not directed the same to all 8 cylinders. With a 4 barrel, oval blade, or using two carbs you have a lot of idle and transition passages to direct the fuel, the ability to more precisely control the mix. One big blade the transition works only on the front side because the front of the blade makes the travel up the bore. If you notice a 4 barrel has it's idle and transition metering discharge on the side of the blade that travels up the bore. Most of the issues I've seen or heard of with a single blade carb come from this area, the incorrect metering or inability to correctly meter the fuel at part throttle positions, unable to evenly distribute the air and fuel to all cylinders. For those that have been successful thats great, I hate seeing anyone spend money and not get what they expected. Distribution can be a funny thing on some engines, some higher efficiency engines can be tolerant, for others the combination just fits. Others not so well.
As far as boosters, discharge nozzles, and spray bars, each can have a place were the design works. Lots of lawnmowers, weedeaters, and others have worked fine with a simple tube discharge. Small high velocity throttle bores and limited or fixed RPM will work with very simple designs.
So why use a booster? Because it creates a stronger signal to meter the fuel with, and enhances the pressure drop to atomize and vaporize fuel easier. The result is better distribution. Why use an annular? Better distribution than a straight or down leg. Why use smaller discharge holes, and more so not to restrict proper fuel flow at maximum demand? Better distribution. I've seen the difference with 8 O2's.
With 4 boosters the potential to distribute fuel equally is higher, and with the ability to push the size larger. With 8 even better.
A carb is (should be) designed to accurately meter the correct amount fuel to match the airflow at all throttle positions and loads. In addition it should also atomize the fuel sufficiently to get equal distribution to all cylinders, however that is rarely the case and in some instances very poor. It is not necessarily the carbs fault, some intakes and engine combinations do not allow for it, or limit the carb size to get it close enough. You can look at some factory dual plane setups that will actually stagger metering differently in all 4 corners to get the engine in a somewhat happy zone. Now you can make the carb small enough that it vaporizes the fuel very well, a Quadrajet primary is a good example, by keeping the velocity high you atomize and vaporize the fuel more completely, making the mix of air and fuel more homogenous, this make distribution more even and the engine is happy. Until you try to make more power at higher RPM's and WOT, the HP looses it take to pump the air the the restriction become large, and small enough and you lose airflow as well. So you go bigger and bigger until you lose power, starting in the lower RPM ranges and working up until the carb is too big to sufficiently atomize and vaporize fuel to get even distribution. So finding the right balance of size is part of the equation. The RPM range the engine sees will have a big factor, an engine that runs primarily over a 1000-1500 RPM range will tolerate a larger carb than an engine that sees a 6000 RPM swing.
So how do we make more power, how can we use a bigger carb? We find ways to better atomize the fuel leaving the carb despite lowering the pressure difference a larger carb has. Better atomization from the boosters is a large part. Using fuel with the proper vaporization curve for the engine and temperature range it runs. Work on the intakes, make the distribution more even between the cylinders. Texture in the intake surface can help. On an 8 cylinder going from 4 barrels to 8, placed over the runners. This allows for more precise control of each cylinder.
Now to the oval blades. BLP no longer offers them, they are being manufactured by a new company Get'm Garage. I can build them as well as several others, and of course Get'm will build them direct. I have built several, and even did some testing with two different sizes the past two weekends. Because they still use 4 boosters and 4 corner idle they still allow some control over distribution like a traditional 4 barrel, and I have not seen anything detrimental with two oval blades vs 4 round. Like any other carb they have to be sized appropriately for the combination. They also use any of the standard Holley style boosters, my favorite is still an annular.
Now for the single blade. There are some running them successfully, some that struggled. Like any other carb proper calibration for that engine/combination is necessary, and to make power relatively even distribution is key. At WOT and smaller RPM bands a lot can be done to make most anything work. The issues I see is one large blade at part throttle positions, the air the air (and fuel) is not directed the same to all 8 cylinders. With a 4 barrel, oval blade, or using two carbs you have a lot of idle and transition passages to direct the fuel, the ability to more precisely control the mix. One big blade the transition works only on the front side because the front of the blade makes the travel up the bore. If you notice a 4 barrel has it's idle and transition metering discharge on the side of the blade that travels up the bore. Most of the issues I've seen or heard of with a single blade carb come from this area, the incorrect metering or inability to correctly meter the fuel at part throttle positions, unable to evenly distribute the air and fuel to all cylinders. For those that have been successful thats great, I hate seeing anyone spend money and not get what they expected. Distribution can be a funny thing on some engines, some higher efficiency engines can be tolerant, for others the combination just fits. Others not so well.
As far as boosters, discharge nozzles, and spray bars, each can have a place were the design works. Lots of lawnmowers, weedeaters, and others have worked fine with a simple tube discharge. Small high velocity throttle bores and limited or fixed RPM will work with very simple designs.
So why use a booster? Because it creates a stronger signal to meter the fuel with, and enhances the pressure drop to atomize and vaporize fuel easier. The result is better distribution. Why use an annular? Better distribution than a straight or down leg. Why use smaller discharge holes, and more so not to restrict proper fuel flow at maximum demand? Better distribution. I've seen the difference with 8 O2's.
With 4 boosters the potential to distribute fuel equally is higher, and with the ability to push the size larger. With 8 even better.
Mark Whitener
www.racingfuelsystems.com
____
Good work isn't cheap and cheap work can't be good.
www.racingfuelsystems.com
____
Good work isn't cheap and cheap work can't be good.
Carb Experts..venturi, twin oval, SV1...??
Mark’s comments concerning carb size, boosters, atomization 4-barrels, twin blades, etc. are all accurate.
The twin blade obviously flows more air than a comparably sized 4-barrel due to the increased venturi/throttle bore area. (For instance: Our largest 4150-flanged TB flows more than a 1250 Dominator at nearly half the weight & size and our smallest TB is comparable to a 650.)
The twin blade design naturally improves distribution. (Keep in mind; what is happening under the carburetor matters more than what is happening above the carburetor.) Looking at the bottom of a carb: A 4-barrel has an area between all 4 throttle bores [cloverleaf] that produces low pressure. Loosely referencing Tuner’s links above; low pressure = air/fuel separation. If left alone; the cloverleaf causes flow loss and distribution issues into the manifold plenum & intake ports. A merge-style spacer definitely helps, but doesn’t fix this transition issue. A twin blade does not have this cloverleaf area; it has a smooth transition into the plenum & therefore no loss of flow or distribution. In fact; an inexpensive open carb spacer makes the most power throughout the rpm range with the twin blade – which is a significant cost saving over a merge spacer. Also, twin blades are light. A 1230 cfm TB weighs 6.5 lbs while a 1230 cfm Dominator (1050) weighs more than 12 lbs.
We can manufacture 4-barrels or twin blades. At the end of the day; the advantages of the twin blades make it a more desirable product for us to produce. We’ve built, dyno tested and track tested 4-barrels and twin blades. In no case has a 4-barrel beaten a twin blade in comparable testing. Otherwise; we would be building only 4-barrels…
The twin blade obviously flows more air than a comparably sized 4-barrel due to the increased venturi/throttle bore area. (For instance: Our largest 4150-flanged TB flows more than a 1250 Dominator at nearly half the weight & size and our smallest TB is comparable to a 650.)
The twin blade design naturally improves distribution. (Keep in mind; what is happening under the carburetor matters more than what is happening above the carburetor.) Looking at the bottom of a carb: A 4-barrel has an area between all 4 throttle bores [cloverleaf] that produces low pressure. Loosely referencing Tuner’s links above; low pressure = air/fuel separation. If left alone; the cloverleaf causes flow loss and distribution issues into the manifold plenum & intake ports. A merge-style spacer definitely helps, but doesn’t fix this transition issue. A twin blade does not have this cloverleaf area; it has a smooth transition into the plenum & therefore no loss of flow or distribution. In fact; an inexpensive open carb spacer makes the most power throughout the rpm range with the twin blade – which is a significant cost saving over a merge spacer. Also, twin blades are light. A 1230 cfm TB weighs 6.5 lbs while a 1230 cfm Dominator (1050) weighs more than 12 lbs.
We can manufacture 4-barrels or twin blades. At the end of the day; the advantages of the twin blades make it a more desirable product for us to produce. We’ve built, dyno tested and track tested 4-barrels and twin blades. In no case has a 4-barrel beaten a twin blade in comparable testing. Otherwise; we would be building only 4-barrels…
Mike Laws Performance