December 15, 2006
How much does my carb flow? That's an often asked
question and there are a couple ways to answer it. Most companies without wet flow simulators have to use a dry number and then they de-rate it (a little) to get their best guess of a wet flow "real world" number. However, that really doesn't work very well because the ever expanding fuel cone under the booster traps slower moving air under the fuel umbrella and reduces the cfm to a varying degree.
So here are a few guidelines when determining cfm. If
your dominator has throttle blades that are stamped #228 (2″ in diameter) chances are its not going to properly exceed the high 1200 cfm range. If your 4150 carb has a venturi (the thinnest area) that is 1.58 inches or less the chances are it won’t exceed 1000 cfm. Now it takes some serious tweaking and working to get a 4150 to exceed 1000 cfm, so if your throttle shafts aren’t super thin and every possible edge that can catch air hasn’t been worked on, then you are going to have a tough time hitting those numbers.
Which leads us to another area of deception. Recently
a newly opened carburetor company named “csu” began advertising that they had the fastest blow through carburetor. Their ad on their website proclaimed they had achieved 207 mph (reports say it was in an #1800 dragster that burned 7 out of 8 pistons on the run). It was also noted by some folks on a forum that yet another carburetor company also claimed to have the fastest blow through carburetor (in a very heavy door car) at 199 mph. At this point, I received an email pointing me to this discussion and informing us if we were aware that our World Record of 208 mph was actually and legally verified to be the fastest.
In researching this article we heard of even further claims of another dragster by another company that possibly achieved 218 mph.
So to save the “csu” company a bit of embarrassment I
contacted them and informed them that their ad was
incorrect and they were second fastest or even third
fastest based on their supplied information and possibly even slower than that. They could install an asterisk on their ad to disallow other racers/designers achievements to make their statement accurate (like the fastest yellow pinto in the world etc..). They said they would look into it and possibly take the false or uninformed advertisement down. Time has gone by and their ad is still posted.
This type of advertising, fraudulent cfm ratings and
false or misinformed claims of performance is actually
hurting everyone. It causes mistrust with racers. They don’t know who to believe. This is exactly the kind of forward confrontation that needed to occur 15 years ago when the cfm wars started. Do you remember when 4150 series carb were being advertised as flowing almost 1100 cfm? Tests performed at our shop on these carburetors had them barely flowing 960.
Deception is a required trait in playing poker and its
implementation may allow you to win the hand. In racing we have a couple of almighty masters who overlook us all. The stopwatch and the dyno. These masters will correct the deception, but unfortunately only AFTER you have purchased the deceitfully advertised product.
Thanks for reading.