[taylanemilyme]

Does a Carb add good power and if so, how much?

 

[fourwd1]

Does a Carb add good power and if so, how much?

Compared to what ?



Compared to a stock carb, a higher CFM carb should result in a HP increase (after all, you're burning more fuel). But to get the full advantage you'd need a header, free flowing exhaust, and a mild cam.

Too many variables to say how much.

 

[taylanemilyme]

My bad
I meant compared to stock.
If I wanted to make the exhaust a little better, would I benefit some if I ran a larger pipe from the manifold bacvk to a performance muffler? ( A budget Exhaust)

 

[84toyotabeeter]

its not the fuel that nets you the HP its the amount of air being pushed threw the motor, but a header and eaxust you would definetly feel the gain i wouldnt go over 2" on the pipe

 

[benwill1]

Going from stock to Weber 32/36, you can feel the difference. The Weber let the engine rev to a higher rpm.

 

[80_pickup]

its not the fuel that nets you the HP its the amount of air being pushed threw the motor, but a header and eaxust you would definetly feel the gain i wouldnt go over 2" on the pipe

why wouldn't you go over 2''?

And im pretty sure if you get too high cfm carb it wont work lol. Hell if i know can anyone give me some insight on cfm?

 

[jamesn]

why wouldn't you go over 2''?

in exhaust system design and theory there is what is known as the "scavenging effect". the pulses of air being forced through the exhaust system carry their own amount of inertia and will have a small vacuum behind them. that small amount of vacuum can be used to help the other pulses move through the system. if the pipe is too small, its choking the system. if its too large, it is too big for the scavenging effect to be effective. if the diameter of the pipe is the right size, it works throughout the operating range. in the case of the 22r engines, 2 inches seems to be about right. the gains are in the few HP range, but they are there. and relatively easy to get.

 

[80_pickup]

in exhaust system design and theory there is what is known as the "scavenging effect". the pulses of air being forced through the exhaust system carry their own amount of inertia and will have a small vacuum behind them. that small amount of vacuum can be used to help the other pulses move through the system. if the pipe is too small, its choking the system. if its too large, it is too big for the scavenging effect to be effective. if the diameter of the pipe is the right size, it works throughout the operating range. in the case of the 22r engines, 2 inches seems to be about right. the gains are in the few HP range, but they are there. and relatively easy to get.

Interesting, never heard that, i always heard the bigger the pipe the better, less restriction.

 

[84toyotabeeter]

yeah and less back pressure=loss of bottom end little gain top end these engines arnt high horse power so there is no need to go that big

 

[benwill1]

I ran my truck race truck on a chassis dyno last year. It made more torque and power with a section of 2 1/2" pipe that ended in front of the rear axle than it did with an open header. The legnth of pipe helps "pull" the gasses out.

 

[80_pickup]

I ran my truck race truck on a chassis dyno last year. It made more torque and power with a section of 2 1/2" pipe that ended in front of the rear axle than it did with an open header. The legnth of pipe helps "pull" the gasses out.

Then why do dragsters run it straight off headers.

 

[spotvangogh]

I had a Chevy 350 with a 3.5’’ pipe. With no muffler I got moor power. With my 88 22re the best for power and fuel economy is 2.5” pipe small muffler and a flowy cat. Whey better to have a cat then not
Big engines don’t like bake presser little engines need some but not to much
Plus if u can find the pipe race specs (which I cant for my toy) they will tell you the length in mm to get blow back, header pipes usually need to be custom. Blow back is when that half a millisecond between a cylinder firing their is a vacuum that pulls a small bit of air up the tail pipe and in to the combustion chamber.

 

[80_pickup]

I had a Chevy 350 with a 3.5’’ pipe. With no muffler I got moor power. With my 88 22re the best for power and fuel economy is 2.5” pipe small muffler and a flowy cat. Whey better to have a cat then not
Big engines don’t like bake presser little engines need some but not to much
Plus if u can find the pipe race specs (which I cant for my toy) they will tell you the length in mm to get blow back, header pipes usually need to be custom. Blow back is when that half a millisecond between a cylinder firing their is a vacuum that pulls a small bit of air up the tail pipe and in to the combustion chamber.

What planet do you live on in which catalytic converters are for performance....

 

[jamesn]

I had a Chevy 350 with a 3.5’’ pipe. With no muffler I got moor power. With my 88 22re the best for power and fuel economy is 2.5” pipe small muffler and a flowy cat. Whey better to have a cat then not
Big engines don’t like bake presser little engines need some but not to much
Plus if u can find the pipe race specs (which I cant for my toy) they will tell you the length in mm to get blow back, header pipes usually need to be custom. Blow back is when that half a millisecond between a cylinder firing their is a vacuum that pulls a small bit of air up the tail pipe and in to the combustion chamber.

i think you need to review the workings of the otto cycle engine. "blow back"? 3.5 inch diameter on a 350? really. header pipes usually need to be custom. i really do not know what you are talking about. do you?

 

[benwill1]

pipe

Then why do dragsters run it straight off headers.

Dragsters engines are built for peak HP at one rpm, even the dragsters need that short section of pipe...my engine is bult for low end torque and a wide power band. For a street 4cyl, you just are not going to flow the air like a top fuel dragster.

 

[jamesn]

Then why do dragsters run it straight off headers.

many reasons. weight and ease of access being one of them. nobody wants to fight a header off in order to pull a head between runs. i have done it and it is a real pain. another reason dragsters run the exhaust the way they do is to have the ability to spot a dead/misfiring cylinder while it is running down the track. if you watch drag racing, you will see what i mean.

 

[80_pickup]

Dragsters engines are built for peak HP at one rpm, even the dragsters need that short section of pipe...my engine is bult for low end torque and a wide power band. For a street 4cyl, you just are not going to flow the air like a top fuel dragster.

I believe you are wrong, The short piping on exaust is to keep the exhaust fumes away from the air intake. That little ammount of tube is not going to server any other purpose lets be serious here. because then i could say that " My headers have 1inch tube for each cylinder so its causing mega suction"

 

[jamesn]

i suppose that i can see how you might think about it like that. i would recommend a few books for you to read. start off with

Internal Combustion Engine in Theory and Practice http://tinyurl.com/2vynex

and then read Smokey Yunicks power secrets
http://tinyurl.com/2zlhhs

followed by Scientific Design of Exhaust & Intake Systems
http://tinyurl.com/yocb6h

 

[CrunchyM5K]

I couldn't give you a good comparison because when I replaced my stock carb with a weber 32/36, I was getting about 12 mpg and I couldn't do 85 mph, when I did change the sound did get deeper though.

 

[benwill1]

I believe you are wrong, The short piping on exaust is to keep the exhaust fumes away from the air intake. That little ammount of tube is not going to server any other purpose lets be serious here. because then i could say that " My headers have 1inch tube for each cylinder so its causing mega suction"

If you run an engine with steel valves, nothing bolted to the head, and a cam with a lot of overlap...you will warp the exhaust valves. In an open wheel dragster, I don't think you'll worry about fumes in intake above 10 MPH. I never said anything about the primary tube size.