Improving your IDA´s...

[JS]

Nicolas, I seem to remember at JPM´s flow bench, trimming the screw ends on the butterfly shaft improves the flow through the carb by 2cfm. And that it equals 5cfm at the valve.

Who would have thought?

I had a broken shaft after doing this , so i like  more to get the flow from the heads  

Udo

Hi Udo, I was talking about trimming the ends of the screws, not the shaft itself. Just had this done to my carbs last weekend.

[Torben Alstrup]

Well, for some it doesn't matter..

If it´s tested on the flow bench, the bench was probably out of calibration, and the person doing the work was doing it all wrong.
If it´s tested on a dyno, the dyno was probably badly calibrated and thereby giving false results.
If it´s tested on the strip and ends up giving you more top speed the photo cells on the top end were placed in the wrong place, giving you false results.

Each to his own. There´s many roads to Rome.

HAAH !!

Well, this certainly created a discussion. But the discussion is not done on the correct basis. This modification is NOT based on power gains alone. It is just as much based on a "need" to get especially the newer Spanish IDA´s to run smoother on the street.
What this mod does, is smoothing out the transition from idle to full load much better than conventional aux venturies. The reason is that the vertical transition actually does not atomize the mix as good as the newly developed "nozzle" in lack of a better word.
On top of this you get the improovement of roughly 19 CFM @ 24" compared to conventional aux venturies, which converts to roughly 5 hp on engines set up in street trim. By that I mean no super radical cams compression etc.
Yes we can pull about 240 hp out of stock 48´s and about 275 out of 51,5´s on a good day. Problem is, most of the guys that buy this upgrade are already pushing those limits. So they see it as a relatively cheap way to gain another 5 - 7 hp and some top end speed on their race engines, because they could´nt care less about driveability. For them its all out. From what I know about airflow this mod will be progressively more efficient the closer you are to the convetional limit of the IDA´s. That part is relatively simple dynamics.

We are now heading into dark winter, and it will be some time until we can go out and test on the track. But I know 2 racers that bought this kit, and both are pushing the limits of their IDA´s as it is. Both will go on the dyno and make before & after pulls to determine ecactly how much the gain is on their engine.

The stacks doesnt achieve anything special. But they look good   And fit well. So the guys that buys JayCee stacks now have an alternative.

Personally I´m hoping that this system will also be developed for new spanish etc IDF´s, because they SUCK! BIG time with the emulsion. And I will aid in that if I can.

T

[OC1967vw]

When was the last time you saw a NEW go fast addition for the IDA that actually works?


Installed one of the old 44mm venturies so you can see the difference. Pretty cool huh?

Not really. Whoever dreamed this "modification" up does not understand fluid dynamics, the coefficient of discharge, the concept of the theory of the coefficient of discharge, and Bernoulli's principle of air flow velocity.

This "fix" just defeats the function of the Weber 48IDA.

Here is the basic question: The Weber 46/48 IDA has been around since 1962. The concept of flow dynamics such as flow velocity and flow discharge go back to the Roman engineer Frontinus who designed the water transmission system for Augustus Caesar. Torricelli improved on the effects of pressure (which ties to the use of the auxiliary venturi and main venturi and air speed velocity through a constricted orifice) in 1643.

And doesnt somebody think that, given the last almost 50 years of the IDA being used, somebody would have thought about this before?

Fluid and Flow dynamics have not changed in over 2000 years. One would think that Weber's engineers most likely were trained in fluid and flow mechanics.

Amazing. A new discovery in fluid mechanics in 2011. Sorry to disappoint the designer of this "modification" but I am not convinced. Removal of the auxiliary venturi compromises the transition design of the 48IDA and makes it unusable on the street. Passini talked about this way back in 1968 in his "Weber Carburettors" books.

[JS]

When was the last time you saw a NEW go fast addition for the IDA that actually works?


Installed one of the old 44mm venturies so you can see the difference. Pretty cool huh?

Not really. Whoever dreamed this "modification" up does not understand fluid dynamics, the coefficient of discharge, the concept of the theory of the coefficient of discharge, and Bernoulli's principle of air flow velocity.

This "fix" just defeats the function of the Weber 48IDA.

Here is the basic question: The Weber 46/48 IDA has been around since 1962. The concept of flow dynamics such as flow velocity and flow discharge go back to the Roman engineer Frontinus who designed the water transmission system for Augustus Caesar. Torricelli improved on the effects of pressure (which ties to the use of the auxiliary venturi and main venturi and air speed velocity through a constricted orifice) in 1643.

And doesnt somebody think that, given the last almost 50 years of the IDA being used, somebody would have thought about this before?

Fluid and Flow dynamics have not changed in over 2000 years. One would think that Weber's engineers most likely were trained in fluid and flow mechanics.

Amazing. A new discovery in fluid mechanics in 2011. Sorry to disappoint the designer of this "modification" but I am not convinced. Removal of the auxiliary venturi compromises the transition design of the 48IDA and makes it unusable on the street. Passini talked about this in way back in 1968.

"I reject your reality and substitute my own."
Adam Savage, Mythbusters.

[OC1967vw]

When was the last time you saw a NEW go fast addition for the IDA that actually works?


Installed one of the old 44mm venturies so you can see the difference. Pretty cool huh?

Not really. Whoever dreamed this "modification" up does not understand fluid dynamics, the coefficient of discharge, the concept of the theory of the coefficient of discharge, and Bernoulli's principle of air flow velocity.

This "fix" just defeats the function of the Weber 48IDA.

Here is the basic question: The Weber 46/48 IDA has been around since 1962. The concept of flow dynamics such as flow velocity and flow discharge go back to the Roman engineer Frontinus who designed the water transmission system for Augustus Caesar. Torricelli improved on the effects of pressure (which ties to the use of the auxiliary venturi and main venturi and air speed velocity through a constricted orifice) in 1643.

And doesnt somebody think that, given the last almost 50 years of the IDA being used, somebody would have thought about this before?

Fluid and Flow dynamics have not changed in over 2000 years. One would think that Weber's engineers most likely were trained in fluid and flow mechanics.

Amazing. A new discovery in fluid mechanics in 2011. Sorry to disappoint the designer of this "modification" but I am not convinced. Removal of the auxiliary venturi compromises the transition design of the 48IDA and makes it unusable on the street. Passini talked about this in way back in 1968.

"I reject your reality and substitute my own."
Adam Savage, Mythbusters.

Interesting. So you are substituting your own theory of fluid and flow dynamics for historical mechanical engineering? That would mean that every pipe that transmits water, every sewer that transports waste, every water transmission line in every farm, hamlet, town, and city world-wide is designed in error.

I am sure that the Mythbusters (both of them) might have a problem with your thinking.

However you are certainly entitled to that thinking.

[JS]

When was the last time you saw a NEW go fast addition for the IDA that actually works?


Installed one of the old 44mm venturies so you can see the difference. Pretty cool huh?

Not really. Whoever dreamed this "modification" up does not understand fluid dynamics, the coefficient of discharge, the concept of the theory of the coefficient of discharge, and Bernoulli's principle of air flow velocity.

This "fix" just defeats the function of the Weber 48IDA.

Here is the basic question: The Weber 46/48 IDA has been around since 1962. The concept of flow dynamics such as flow velocity and flow discharge go back to the Roman engineer Frontinus who designed the water transmission system for Augustus Caesar. Torricelli improved on the effects of pressure (which ties to the use of the auxiliary venturi and main venturi and air speed velocity through a constricted orifice) in 1643.

And doesnt somebody think that, given the last almost 50 years of the IDA being used, somebody would have thought about this before?

Fluid and Flow dynamics have not changed in over 2000 years. One would think that Weber's engineers most likely were trained in fluid and flow mechanics.

Amazing. A new discovery in fluid mechanics in 2011. Sorry to disappoint the designer of this "modification" but I am not convinced. Removal of the auxiliary venturi compromises the transition design of the 48IDA and makes it unusable on the street. Passini talked about this in way back in 1968.

"I reject your reality and substitute my own."
Adam Savage, Mythbusters.

Interesting. So you are substituting your own theory of fluid and flow dynamics for historical mechanical engineering? That would mean that every pipe that transmits water, every sewer that transports waste, every water transmission line in every farm, hamlet, town, and city world-wide is designed in error.

I am sure that the Mythbusters (both of them) might have a problem with your thinking.

However you are certainly entitled to that thinking.

Sorry ´bout that, the quote just made me think of you. 

As for fluid and flow dynamics, you clearly know much more than me(and anyone else on the Lounge) about the subject. I´m just an amateur who bought something that improved the horsepower output of my engine as seen on back-to-back testing. I´ll leave the theoretical stuff to you. I´m sure you have a good explanation on the increase in top speed.

[OC1967vw]

When was the last time you saw a NEW go fast addition for the IDA that actually works?


Installed one of the old 44mm venturies so you can see the difference. Pretty cool huh?

Not really. Whoever dreamed this "modification" up does not understand fluid dynamics, the coefficient of discharge, the concept of the theory of the coefficient of discharge, and Bernoulli's principle of air flow velocity.

This "fix" just defeats the function of the Weber 48IDA.

Here is the basic question: The Weber 46/48 IDA has been around since 1962. The concept of flow dynamics such as flow velocity and flow discharge go back to the Roman engineer Frontinus who designed the water transmission system for Augustus Caesar. Torricelli improved on the effects of pressure (which ties to the use of the auxiliary venturi and main venturi and air speed velocity through a constricted orifice) in 1643.

And doesnt somebody think that, given the last almost 50 years of the IDA being used, somebody would have thought about this before?

Fluid and Flow dynamics have not changed in over 2000 years. One would think that Weber's engineers most likely were trained in fluid and flow mechanics.

Amazing. A new discovery in fluid mechanics in 2011. Sorry to disappoint the designer of this "modification" but I am not convinced. Removal of the auxiliary venturi compromises the transition design of the 48IDA and makes it unusable on the street. Passini talked about this in way back in 1968.

"I reject your reality and substitute my own."
Adam Savage, Mythbusters.

Interesting. So you are substituting your own theory of fluid and flow dynamics for historical mechanical engineering? That would mean that every pipe that transmits water, every sewer that transports waste, every water transmission line in every farm, hamlet, town, and city world-wide is designed in error.

I am sure that the Mythbusters (both of them) might have a problem with your thinking.

However you are certainly entitled to that thinking.

Sorry ´bout that, the quote just made me think of you.  

As for fluid and flow dynamics, you clearly know much more than me(and anyone else on the Lounge) about the subject. I´m just an amateur who bought something that improved the horsepower output of my engine as seen on back-to-back testing. I´ll leave the theoretical stuff to you. I´m sure you have a good explanation on the increase in top speed.

With all due respect to you, you might read-up on the design of the internal combustion engine. Horsepower is the output of the compression of a mixture (air and fuel in the right combination) in a measured area with a set volume (cylinder and cylinder head). That is to say, the higher the compression the more the power output. The direct byproduct of this is cylinder heat. The carburetor is only a metering unit as it mixes air and fuel in the necessary proportions (the carburetor does not create horsepower as you state) and distributes that mixture to the cylinder through the intake manifold. Air flow through the carburetor does not have a direct relationship to increased horsepower (you cannot put more mixture into a confined area with a set volume capacity and expect more horsepower). Increased output is the product of higher cylinder pressure (hence higher cylinder wear) .

The best example of why this modification will not work is to watch an aerodynamic test in a wind tunnel. The flow of an airstream over a car body is the same as a liquid flowing over the same design. The flow characteristics  and properties of fluid and air, although of different densities, are very much the same.

Rather than use a kph factor as a test, the more telling test would be your engine on a dynomometer with standard weber 48IDAs tested for ouput at every 1000 rpm increase through the rev range up to 8000 to 10000 rpm. We add sensors to measure air flow speed through the carburetor barrel at the four points in the carb barrel that Weber did their measurements (it is in their technical manual). We then install your carbs with your modifcations and replicate the test.

My guess is that the air flow rates through the standard 48IDAs (with both the auxiliary and fixed venturies will show a greater (faster) air flow through the carb barrels of the standard 48IDAs versus your 48IDAs without the auxiliary venturies because of the design characteristics that the Weber engineers incorporated some 50 years ago. We are talking flow speed and not horsepower here. We are talking the discharge rate through the main venturi here.

Lastly, removing the auxiliary venturi completely compromises the Weber design and function as it eliminates the mixture enhancement through the transition phase from idle to low rpm to full out run.

The bottom line is their your carbs. You can do whatever you think is best to them. But dont you think that the designers at Weber working with the engineers from Ford and Porsche and Ferrari, the three manufacturers noted for their use of Weber carrburetors on their competition cars at the time, would have figured this out?

Just thinking out loud.....

[bilboa2]

peabody, here........

[Frallan]

You can do whatever you think is best to them. But dont you think that the designers at Weber working with the engineers from Ford and Porsche and Ferrari, the three manufacturers noted for their use of Weber carrburetors on their competition cars at the time, would have figured this out?
[/quote]

Engieers at Ferrari, Porsche and Ford have NOT invented everyting to a level that no one else can improve on it.
I normally do not take this approach on a  forum but in this case I will, in my mindset, you have an attitude problem that will not bring you forward in what we need, an open mindset.
The world is maybe not flat, maybe it is not even round.....new discoveries are done every day.
Back off and accept that there is something new in this approach for Weber 48 IDA.

I will only listen to you, or alternatively if someone else proves this wrong by practical back to back tests.
IF that happens, I will be first in line to appologise.

[kingsburgphil]

peabody, here........

As in Professor Peabody?

[OC1967vw]

Engieers at Ferrari, Porsche and Ford have NOT invented everyting to a level that no one else can improve on it.
I normally do not take this approach on a  forum but in this case I will, in my mindset, you have an attitude problem that will not bring you forward in what we need, an open mindset.
The world is maybe not flat, maybe it is not even round.....new discoveries are done every day.
Back off and accept that there is something new in this approach for Weber 48 IDA.

I will only listen to you, or alternatively if someone else proves this wrong by practical back to back tests.
IF that happens, I will be first in line to appologise.

Sounds like you look at weber downdrafts and see a square barrel where the rest of us see a round barrel. the test methodology for this "mod" is laid out above. to be done on the dyno.fluid and flow dynamics havent changed in 2000 years. this "mod" will not work and slows airspeed flow through the barrel. there is a reason why Weber designed the DCOE and IDA carburetors the way they did and including the auxiliary venturi stacked on the main venturi. What you are also saying is that Weber didnt know what they were doing all these many years when they were producing a wide variety of carburetors for all different applications.

thats ok. keep dreaming. afterall, you have rather rare Webers....they are square barreled.

[OC1967vw]

peabody, here........

I rather like Sherman.....

[OC1967vw]

peabody, here........

As in Professor Peabody?

Sherman always had an inquiring mind, dont you agree?  

[danny gabbard]

Anybody know what the dinner special is at denny's?

[OC1967vw]

Engieers at Ferrari, Porsche and Ford have NOT invented everyting to a level that no one else can improve on it.

And pigs fly....oops the Boeing engineers are wrong on the aerodynamics of pigs

[OC1967vw]

Anybody know what the dinner special is at denny's?

chicken fried steak,mashed potatoes, and veggies-raspberry iced tea. sundae for desert

[OC1967vw]

Engieers at Ferrari, Porsche and Ford have NOT invented everyting to a level that no one else can improve on it.
I normally do not take this approach on a  forum but in this case I will, in my mindset, you have an attitude problem that will not bring you forward in what we need, an open mindset.
The world is maybe not flat, maybe it is not even round.....new discoveries are done every day.
Back off and accept that there is something new in this approach for Weber 48 IDA.

I will only listen to you, or alternatively if someone else proves this wrong by practical back to back tests.
IF that happens, I will be first in line to appologise.

Ever looked at a jet engine on todays modern jet planes? air going in the front creating thrust on the exit....look at the engine pod on a 747.....its a larger version of the venturi in an ida or for that matter, any weber carburetor......I know.....you dont fly

[JS]

Rather than use a kph factor as a test, the more telling test would be your engine on a dynomometer with standard weber 48IDAs tested for ouput at every 1000 rpm increase through the rev range up to 8000 to 10000 rpm. We add sensors to measure air flow speed through the carburetor barrel at the four points in the carb barrel that Weber did their measurements (it is in their technical manual). We then install your carbs with your modifcations and replicate the test.

My guess is that the air flow rates through the standard 48IDAs (with both the auxiliary and fixed venturies will show a greater (faster) air flow through the carb barrels of the standard 48IDAs versus your 48IDAs without the auxiliary venturies because of the design characteristics that the Weber engineers incorporated some 50 years ago. We are talking flow speed and not horsepower here. We are talking the discharge rate through the main venturi here.

"So we finally got to see a live flow test on JPM Dyno Day. The gain by switching from a "conventional" venturie to JPM´s vents and stacks was 19cfm!
The size was 42mm both on the old and new."

Have you read the whole thread, or just post #1? These tests were made on the same wet-flow bench that were used to develop the venturies.

Sorry, didn´t catch why top speed can´t be a measure of change in horsepower. I even thought that a dyno was measuring change in speed and the time it takes to make that change.

[Bruce]

The Weber 46/48 IDA has been around since 1962.

1964, actually.

[OC1967vw]

The Weber 46/48 IDA has been around since 1962.

1964, actually.

My printed sheets are dated July 1964, Shelby told me that it was late 62/early 63 when he first saw the 46IDA set upon a porsche motor at the factory.....He was alreadywell along on bringing the AC bodies into the states.

[Bruce]

The carburetor is only a metering unit as it mixes air and fuel in the necessary proportions (the carburetor does not create horsepower as you state) and distributes that mixture to the cylinder through the intake manifold. Air flow through the carburetor does not have a direct relationship to increased horsepower (you cannot put more mixture into a confined area with a set volume capacity and expect more horsepower). Increased output is the product of higher cylinder pressure (hence higher cylinder wear) .

So I guess what you're saying is if you swap out a set of IDAs for some 36IDFs, the engine will make just as much hp?

. Air flow through the carburetor does not have a direct relationship to increased horsepower 

I can't believe you posted that.

[Bruce]

The Weber 46/48 IDA has been around since 1962.

1964, actually.

My printed sheets are dated July 1964, Shelby told me that it was late 62/early 63 when he first saw the 46IDA set upon a porsche motor at the factory.....He was alreadywell along on bringing the AC bodies into the states.

I bet he was looking at IDMs.  Most people can't tell the difference.

AC Cobras were being fitted with 48 IDMs in 1963.  

And over at Porsche, the first 904s that were sold in late 1963 for the 64 race season had 46 IDMs.

[OC1967vw]

Rather than use a kph factor as a test, the more telling test would be your engine on a dynomometer with standard weber 48IDAs tested for ouput at every 1000 rpm increase through the rev range up to 8000 to 10000 rpm. We add sensors to measure air flow speed through the carburetor barrel at the four points in the carb barrel that Weber did their measurements (it is in their technical manual). We then install your carbs with your modifcations and replicate the test.

My guess is that the air flow rates through the standard 48IDAs (with both the auxiliary and fixed venturies will show a greater (faster) air flow through the carb barrels of the standard 48IDAs versus your 48IDAs without the auxiliary venturies because of the design characteristics that the Weber engineers incorporated some 50 years ago. We are talking flow speed and not horsepower here. We are talking the discharge rate through the main venturi here.

"So we finally got to see a live flow test on JPM Dyno Day. The gain by switching from a "conventional" venturie to JPM´s vents and stacks was 19cfm!
The size was 42mm both on the old and new."

Have you read the whole thread, or just post #1? These tests were made on the same wet-flow bench that were used to develop the venturies.

Sorry, didn´t catch why top speed can´t be a measure of change in horsepower. I even thought that a dyno was measuring change in speed and the time it takes to make that change.

I did. The problem with your statement is that the measurement of flow is not the same as airspeed. Two vary different functional elements. that is why Weber engineers measured flow at the top and bottom of the venturi as well as shape the nozzle in the auxiliary venturi to enhance airspeed. not flow. there is a reason for the internal shaping of a venturi-to enhance airspeed. Flow is quantity-it is not airspeed. airspeed is the quickness through a metered portal.....again look at the jet engine pod. Top speed is always a function of aerodynamics and the movement of air around a shape-the body is always pushing air-the sleeker the faster-the comparison: put abone stock early 911 motor in a bus and test it for top speed in a straight line ala Bonneville. Take the motor out and put it ina type 1 body and road test over the same distance in a straight line-what do you think is the fastest car? the bus or the bug? Another example: the early 356s had vw motor/transmissions but were much faster than bugs with the same power train

[Jon]

It's the actual physics that don't change... but the laws we write to define them are rewritten as soon as we find faults with them.

The way you are talking OC1967 I can see no need for the Nascar teams or F1 teams to do any development to their airpumps... they should just read the book, or buy a Ford engine.
Hell even Weber changed the design of the aux venturi thru the years... must have not have read the book right on the first attempt??
Holley makes several types of boosters... why aren't they just doing it right?

I believe there is a long list of reasons for why Weber designed such a CFM robbing booster in the first place.
First of all the carburetor was large enough for anything they were fitted to... if one is to little, fit four! - Today many people have engines that are on the absolute limits of what the IDA48 can handle, especially if the engine is of a "low" cc.
It's much more expensive to machine a venturi such as JPM's, as opposed to casting something that will do the job - it involves a lot of testing and fine tuning.
They made the carburetor to fit many different applications, some engines have strong pulses, some have weaker. - JPM makes stuff for the VW stroker engine mainly, so he has a much more defined application than the boys in Bologna.

I salute anyone developing new stuff for our old cars, stuff with a performance purpose, and best of all, it's not available in blue or red!

[OC1967vw]

The Weber 46/48 IDA has been around since 1962.

1964, actually.

My printed sheets are dated July 1964, Shelby told me that it was late 62/early 63 when he first saw the 46IDA set upon a porsche motor at the factory.....He was already well along on bringing the AC white bodies into the states.

I bet he was looking at IDMs.  Most people can't tell the difference.

AC Cobras were being fitted with 48 IDMs in 1963.  

And over at Porsche, the first 904s that were sold in late 1963 for the 64 race season had 46 IDMs.

Bruce, probably a difference in your understanding of cobra history. Shelby brought over white bodies without motors. Ford 260s installed in LA. As to what was installed by AC on whatever motor they were using before Shelby had them manufacture white bodies for him, I dont know nor do most cobra enthusiasts. not in their orbit.
As to the 904s, the 597 4 cylinder carrera engine was installed versus the 904 gts which had both 4 and 6 cylinder motors. the 6 cylinder motor had the ultra rare 46ida 3 barrel carburetor (not the ida3c) while the upgrade kit from the factory included the 46ida 2 barrel downdraft for the early production 904s with the 4 cylinder motor first tested in August 1963 at weissach (3 prototypes).

[OC1967vw]

The carburetor is only a metering unit as it mixes air and fuel in the necessary proportions (the carburetor does not create horsepower as you state) and distributes that mixture to the cylinder through the intake manifold. Air flow through the carburetor does not have a direct relationship to increased horsepower (you cannot put more mixture into a confined area with a set volume capacity and expect more horsepower). Increased output is the product of higher cylinder pressure (hence higher cylinder wear) .

So I guess what you're saying is if you swap out a set of IDAs for some 36IDFs, the engine will make just as much hp?

. Air flow through the carburetor does not have a direct relationship to increased horsepower  

I can't believe you posted that.

Bruce, my typo. meant airspeed through the carburetor and not air flow (measured in quantity)-two different concepts. As to your earlier comment, the carburetor is always the last piece to the motor design. at least it was when carburetors were used. Again, the carburetor is a large metering unit fitted and matched to the design of the motor. It is a large metering unit dealing with quantities of fuel and air and combining them in such a way as to produce maximum power output of the motor design and components. Hence the importance of balance amongst the variables-the main venturi, the idle jetting, the air correctors, and the main jet since these parts all are part of the metering function.

[OC1967vw]

It's the actual physics that don't change... but the laws we write to define them are rewritten as soon as we find faults with them.

The way you are talking OC1967 I can see no need for the Nascar teams or F1 teams to do any development to their airpumps... they should just read the book, or buy a Ford engine.
Hell even Weber changed the design of the aux venturi thru the years... must have not have read the book right on the first attempt??
Holley makes several types of boosters... why aren't they just doing it right?

I believe there is a long list of reasons for why Weber designed such a CFM robbing booster in the first place.
First of all the carburetor was large enough for anything they were fitted to... if one is to little, fit four! - Today many people have engines that are on the absolute limits of what the IDA48 can handle, especially if the engine is of a "low" cc.
It's much more expensive to machine a venturi such as JPM's, as opposed to casting something that will do the job - it involves a lot of testing and fine tuning.
They made the carburetor to fit many different applications, some engines have strong pulses, some have weaker. - JPM makes stuff for the VW stroker engine mainly, so he has a much more defined application than the boys in Bologna.

I salute anyone developing new stuff for our old cars, stuff with a performance purpose, and best of all, it's not available in blue or red!

thats fine. I realize that you have a perception of webers and holleys and carburetion in general. All your points have been answered in print and in design over many years. And yes that does include the question of why weber incorporated the auxiliary venturi into both the IDA and DCOE carb designs. It isnt to boost power output. By the way, please enlighten us with the various other applications (that is other cars and motors) that the 48IDA was used on. I for one am curious. As to your other points, I could address them. I too agree that innovation is to be valued. However, I stand by my position that removing the auxiliary venturi makes the carburetor thoroughly intractable on the street at idle and low to mid range rpms-again airspeed through the barrel.

After all, its just opinion based on fact....isnt it?

[Jon]

All your points have been answered in print and in design over many years. And yes that does include the question of why weber incorporated the auxiliary venturi into both the IDA and DCOE carb designs. It isn't to boost power output.

You are right, it's there to boost the signal to the carburetor on low rpm's. Without having to put to much work into it. Well, JPM has put that amount of work into it and are now, CNC machining it at great expense - so now you have the choice; same or better function, and higher CFM.

OR, better functionality/drivability and the SAME cfm as your current setup....  meaning you can now run a much smaller venturi and still have the same CFM as a much larger one.

By the way, please enlighten us with the various other applications (that is other cars and motors) that the 48IDA was used on.

As am I, my point was that Weber made carburetors and sold it to whoever wanted them.

[Frallan]

Ever looked at a jet engine on todays modern jet planes? air going in the front creating thrust on the exit....look at the engine pod on a 747.....its a larger version of the venturi in an ida or for that matter, any weber carburetor......I know.....you dont fly
[/quote]

The fact that continue to you come with these statements proves your attitude again. I was pissed of yesterady for such a stone-age attitude, looking at what has been posted and that you still go on just makes me smile.

Flying?
I built airplanes duirng 1975-1980. My last year I had evolved to be part of the final test program due to some of my inventions.
Today I do not fly everyday, just a Platinum frequent flyer. In fact in about two hours I fly from Barbados to Trinidad and then onwards on another flight.
I know your comment was not related to the real reality if I fly or not, but I just had to.It was too funny for me not to answer ;.) Over and out....

[Frallan]

Now by the way and I know Johannes is not claiming that he invented this, he just adapted it and manufactured.
ADV is not new.
http://speedtalk.com/forum/viewtopic.php?p=114043&sid=c056963d110096a4fc8cc1944e05e9ca

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by #84Dave » Sun Jun 08, 2008 12:58 pm

Alan...... we performed the very thing you discuss with a pair of 50DCO side-draft Weber's we run on a full-race, roller-cammed 2.0L Ford 4-cylinder. We removed the booster and standard venturi(choke), then manufactured what I call an ADV (annular-discharge-venturi) that runs the full length of the carb throat. The formula's that we used? For the holes in the discharge ring, we measured/used the area of the standard booster discharge 'hole'. We then found/calculated that [9] annular discharge holes, .062" in diameter, would equal, plus 3-4%, the area of the standard discharge hole on the 50DCO booster. That's what we used. The diameter of the venturi? For good 'snap' off paved-oval corners, we decided to flow the carbs with standard venturi's near 80% of the throttle blade base diameter. We had flowed the carbs with standard 38/40/42/44/46 mm diameter chokes and decided we needed an ADV that flowed nearly the same as 40mm & 42mm chokes(~80% of 50mm). Subsequent to milling a lot of aluminum, cut-and-try, we found that a 36mm diameter ADV flowed dry air right at a standard 42mm choke/booster. So....... for short-track paved ovals, we manufactured 36mm ADV's. They worked well beyond our wildest expectations! And the most amazing thing? The 'main well' signal at the ADV was 33% better than the same signal with a 42mm choke/booster. Which led to a jetting situation. Even though the 36ADV flowed dry air as well as a standard 42choke/booster, if I jetted the carb for the 42, it was pig rich. So I wound up jetting about the same as a standard 36-38 choke. I contribute the jetting situation to mixture QUALITY(annular discharge) and signal strength. Then we got wild and crazy! One of our tracks was the very high speed Mesa Marin (now bulldozed) 1/2-mile @ Bakersfield, CA. Nearly WOT with a 1000rpm operating band around the track. We built 38 ADV's specifically for that track. The 38 ADV flowed dry air about the same as a standard 46 choke/booster. And the main well signal was 37% better with the ADV. Over [3] seasons and [6] races @ Mesa Marin, we were undefeated with the ADV's. Bottom line? If our Weber/ADV experience is any indicator, and we had the machining capability/time, none of our carbs would have a booster...... even the Holley's! Dave