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 Post subject: Methanol crossover mods
 Post Posted: Mon Sep 19, 2011 1:23 pm 
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HAs anyone ever seen/done a type of knurling to the crossover in the metering block. I saw one the other day that At first I thought was threaded but upon closer inspection they appeared to be intentionally knurled. Has anyone ever seen any booster spray pattern/emulsification improvements from this?


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 Post Posted: Mon Sep 19, 2011 3:46 pm 
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Creating surfaces that promote turbulence causes the turbulent flow conditions to occur earlier than on a smooth surface so the metering of the fuel changes slightly at the transition zone to turbulent flow. In other words there is a leaner period slightly earlier in the fuel curve. The result that one person may get will most likely be different to another due to the many factors that control the transition points. Turbulence promotes mixing of different substances, so provided the main well air bleed rate is small the effect will be to improve the dispersion of the air bubbles.If the air rate is too great everything falls in the bin, however the point where that occurs is higher in the air flow rate than a tube with less turbulence. So what that means is creating turbulent flow improves the stability of the fuel flow rate. as slugging flow is avoided until higher in the air flow range. Basically you can run larger high speed air bleeds with a turbulence generator that without one.


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 Post Posted: Mon Sep 19, 2011 6:50 pm 
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Thanks Sir!! I havent measured them yet but the crossovers appeared bigger than .190/.200. If that is the case is it the "turbulators" that allow this? I will get a chance to measure them soon.


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 Post Posted: Mon Sep 19, 2011 7:31 pm 
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Go to the Dambest website and download his patents. His patents cover anything in the mainwell like threads or ridges that create turbulence, anything other than a smooth surface.


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 Post Posted: Tue Sep 20, 2011 8:18 am 
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SonnyJames wrote:
Thanks Sir!! I havent measured them yet but the crossovers appeared bigger than .190/.200. If that is the case is it the "turbulators" that allow this? I will get a chance to measure them soon.
Yes the use of turbulence generators resists the air bubbles from coalescing, it allows a greater air volume to be maintained in the flow without the air forming onto one big blob taking up the entire diameter of the tube (sort of like when you see a big bubble rise in a siphon hose). If the flow tube is on the large side of things and the HSAB is large then the air can form a slug like in a siphon hose. If you look closely at a siphon hose air slug you will see the fluid flowing around the outside of the bubble, it's a condition that is specific to laminar flow, but if you add a turbulence generator you prevent that from happening. Basically you define the point of turbulence and bypass the point of laminar bubble coalescing. Its only necessary to do it in a carby tuner sense if you have large air bleeds. Its a good technique for using a large discharge tube for fuels like alcohols so that you can physically get the volume out into the booster. It improves the low speed performance of a large diameter main well. The result as far as the engine tuner is concerned is you can tune the engine more successfully over a larger air flow range.

The principles and effects of turbulence generation have been well known for a long time. It was first written about in the late 1890's I think. The down side of it is you have to generate a larger booster depression compared to natural turbulent flow. So if you have the generators you need a booster that generates higher depression without sacrificing CFM capability. You have to redesign the Standard Holley booster for more 'signal' to use generators really successfully. Look at DAMBEST 's boosters, thats why they are different.

So in a marketing sense it might be justified to claim it improves emulsification.


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 Post Posted: Tue Sep 20, 2011 10:43 am 
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I've see those boosters before. the only thing is their carb has a double venturi and the booster sits below the top one. That ought to change the operation a bit...


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