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Old 01-30-2006, 07:40 PM   #1
BillyBobJoe
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Default explaining proper carb and exhaust size

everyone either wants to upgrade their carb or has done it. same with exhaust. this lesson may seem a little wierd but it may help some of you understand why not go too large but to keep it big

First off, fill a large glass of water. Trust me . Take a small coffee straw and suck some up...you'll see you can only get so little so fast. Think of your mouth as the engine and the straw as a small carb.

Next, take a larger straw, say normal size found anywhere, snd suck again and it will go at a decent rate and at a rate that you can still swallow without drowning yourself.

If you take a huge *** straw the size of your mouth, you may not be able to get anything to your mouth.

Now exhaust, same principle but backwards. Take the small straw and blow on the water, you see it move a little in the concentrated area, wooptie do, however you can probably keep blowing for a prolonged time due to the amount of backpressure, this is bad, too much back pressure on an engine creates problems.

The medium size straw will blow more air and still allow a little backpressure so you can keep blowing and the engine will actually gain torque and horsies while being able to exhale properly.

As for the big **** straw, the air only reaches as far as you can blow and may barely move the water at all. Plus due to the lack of backpressure you run out of air rather soon. This shows that with too big of exhaust, say anything over 2.5" for you small block boys like me, will end up losing power.

Now this is a little wierd but everyone keeps asking ?s like why cant i put a nice sized 600-650cfm on my 289...well you can, but you'd better make sure it has enough mods to need something that big.

if you all understand this, which i hope you do, maybe Soaring can move it to the FAQ for when more nubs come looking for this type of advice.
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Old 01-30-2006, 08:09 PM   #2
Shifty101Easy
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Default RE: explaining proper carb and exhaust size

very nice explanation.
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Old 01-30-2006, 08:12 PM   #3
Soaring
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Default RE: explaining proper carb and exhaust size

Good stuff BillyBob. Now, if I can hear a big HUAHH from everybody, I'll make it a FAQ.
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Old 01-30-2006, 10:26 PM   #4
redstallion
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Default RE: explaining proper carb and exhaust size

HUAHH!!!

good analogy with the straws
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Old 01-30-2006, 11:19 PM   #5
Markstang1969
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Default RE: explaining proper carb and exhaust size

Why water and not Pepsi? I like Pepsi. What about those old paper straws you used to get at the malt shop. Those weren't good for anything.

oh yea HUAAH!
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Old 01-31-2006, 01:21 AM   #6
BillyBobJoe
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Default RE: explaining proper carb and exhaust size

lol, thanks guys
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Old 01-31-2006, 02:45 PM   #7
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Default RE: explaining proper carb and exhaust size

Done! Check the FAQ.....
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Old 01-31-2006, 04:04 PM   #8
65GTin GA
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Default RE: explaining proper carb and exhaust size

Good info for beginners. So many people seem to think bigger is better and with carbs and exhaust it just ain't so. Like you stated, the size of the carb and the exhaust has a lot to do with your engines ability to utilize it, too much and you WILL actually get less hp. Gotta mix and match everything carefully - carb, cam, heads, valve size, compression and optimum back pressure in the exhaust. Lots of novices go out and buy a big Holley 4bbl, drop it on an otherwise stock motor and think they just gained gobs of power.
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Old 02-01-2006, 12:22 AM   #9
Markstang1969
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Default RE: explaining proper carb and exhaust size

Too big of an exhaust and you may get a boost in HP, but loose a lot of torque. Your engine will rev, but won't have the ooooomph to move the car.

Here is a good article if you have the time. Section one of five.

Mustang Monthly- Plans for Ponies-How To Plan For And Build In Real-World Power
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