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 Post Posted: Mon Jun 14, 2010 12:52 am 
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Hi Mark, your points about carby sizing for an engine combo are absolutely right. there is no rule, you have to find the right choice. There is a thread on ST about it at the moment but nobody listens over there. All they do is argue that something isn't possible when Ive actually done the opposite. I have done normal things and also abnormal things and been smart enough to see things and figure out why, but they dont want to hear that so I give up.
It is easy to do a billet block and a Weber style emulsion for a Holley, that's what the Weber power plates were. But they didn't take off because of a combination of factors, some political, some legal, some just -'its too hard for the mass market'. Your not a mass market dude, your a limited market person, hard to find those people.

The best thing to do with any flow situation is to minimize turbulence, so attention to all those corners etc is important, but Holley are not going to do that for the price of carbys.

With regards to carby sizing; you cant approach anything in an engine as a finite concrete thing, if that was the case, engines could be worked out mathematically and it would have been done a hundred years ago, but it wasn't and that was the time when the finest human minds worked on the latest technology(engines). A lot of the things developed then were done with precise physics in mind, not stuff done by amateurs like us. All we have done since then is used the precision in combination's of ways. Look at anything you want, its individual function was all invented a century or more ago.
If you only consider the effects of changing a carby CFM then you must arrive at the conclusion that all other factors being equal (and I mean perfectly equal as in a scientific sense) then changing the restriction at the carburetor will only change the vacuum in the inlet system. That has a profound effect upon the gassing levels in the inlet tract and in the cylinder, because the vacuum in the cylinder is determined by the inlet energy available, restrict the intake a small amount and the pressure in the cylinder during intake is reduced a LOT. Its just like sequential jetting in liquids, just like a IFR after a main jet, same stuff. If an engine has insufficient energy to achieve optimum gassing of the fuel you can make more power by restricting the inlet and forming gases in the intake system. Its not difficult to understand, gasoline etc has chemicals that gas at different temperature, temperature is a measurement of energy level, not enough energy input and the temp is lower and it stays as a liquid. Simple really.
You have a choice in an engine, either compress it and heat it that way or vacuum it and allow the molecules to gas that way. It doesnt matter, what your ultimately doing is altering the difference in energy from the liquid state molecule to the pressure exerted upon the liquids surface. Its the pressure that stops the molecule transitioning to the gas state. If you choose vacuum you utilize the energy that is already contained in the molecule to convert it to a gas state, that is a very efficient way to do it. If you choose compression, you have to wait for the Kinetic energy to transfer via convection to increase the energy in the liquid to a point that is high enough to allow the gas state within the increased pressure that you used to create the energy transfer in the first place, that is a slower way to do it. Sort of like chasing your tail a bit isn't it. But you need higher and higher compression to generate more energy release for the actual combustion phase so your stuck. Obviously you can place too much restriction to the intake and the engine reduces power, its not about finite numbers, you have to try things and figure out what actually happened that made a gain or loss, then redesign.


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 Post Posted: Sun Jun 20, 2010 4:50 pm 
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jmarkaudio wrote:
After reading through this again, I saw something that stuck out a little more. I know Mark and Eric work the boosters for the carbs they set up, and I may be wrong but figure more of the carbs they do are 4150 versions. What stuck out was the booster being a point that may cause the fuel to go turbulent with E85. Would there possibly be an advantage using a straight leg booster over a downleg with the 4150, but even more so would a straight leg be more beneficial on a Dominator over an annular booster. A straight leg booster would not have the channel disruption in the booster that the fuel would have to navigate in an annular booster.


Well, a booster that has some particular characteristic or advantage in one area may have a more significant disadvantage in another. I like the annulars over the straight in the Dominator (many more choices for starters) and I have made both annulars and downlegs work very well in the 4150's with E85. Depends on the engine and car on which booster I like, but the minimal emulsion we have discussed before seems to be a pretty solid constant. And no offense but that's about all I care to give up on the subject ;)

BTW Can't speak for Mark, but I am doing both 4150's and Dominators.


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