Drag racing question

[Crime Scene 96]

Ive been studing track racing videos for a while now, and ive noticed something interesting exhaust wise. I only see one of the following:

1. A simple pipe diameter no larger than 2.5 inch all the way out.
2. Open headers
3. Turndowns

But ive never seen anyone with big tips or tails pipes larger than 2.5 inch.


Anyone care to explain?

[JZ9C1LT1]

Large tailpipes are basically for show, doesn't do much with horsepower.

There are some cars running 3" pipes all the way out the back.

[Blue Wail]

Most cars with 3" pipe have the exhaust system dumping right in front of the rear axle to avoid the restriction of the bent pipe going over the axle. That is why you don't see 3" tailpipes. My drag car is this way.

-Nab

[Jeff Green]

The pipe size is a reflection of the engine power so the more power then the bigger those pipes need to be. Most stuff you see at the drag strip is 600HP or less and a 2 1/2 to 3" pipe is right for that.

A longer pipe also helps your low end torque as compared to an open header. What NAB said is correct and most drag cars vent the exhaust before the axle or out the sides so they don't face the restriction of the bends needed to go over the axle. Those bends add a lot of restriction over the normal straight pipes or open headers.

I bet I'm the only fast car that runs a full exhaust over the axle to the back bumper with mufflers on every pass, no open pipes or headers. I have blown pieces out the 4" dual exhaust so that tells you how much pressure is there and why no one does this in drag racing. I only do it because it's one more thing that makes this car different than what you are going to normally see but it's not the best way to do things.

So a smaller right size pipe will make you faster than a pipe too large as that will push your power band way up or beyond your RPM range. 2 1/2 or 3" is right for most cars and why you see it so much.

[Big Kahuna]

Originally Posted by JZ9C1LT1

Large tailpipes are basically for show, doesn't do much with horsepower.

There are some cars running 3" pipes all the way out the back.

The what now?

[Big Kahuna]

BTW Dan from Clear Image will tell you himself - the BEST way to make more power is to taper the exhaust as you go. In other words 3-4" up near the engine and then taper to 2 1/2" at the end. But of course anyone who wants to look good as well as go good wants bigger tailpipes.

Dan made these one-off for me but now I'm pretty sure he produces them for anyone that wants them. The polished part continues all the way up over the axle so it looks good between the rear tires and the wheel well where on every other exhaust system except the original Flowmaster you could see the break in the pieces of pipe fitted together.



-----



-----



-----



-----



As Uncle Pauly says..."Anyone can go fast. Anyone can look good. But there's very few people that can go fast AND look good!"

Jeff Green is one of them, his car is spotless clean. So is Uncle Pauly, Pat Gish, and Mikey Harris among others.

[angelo]

Originally Posted by Big Kahuna

BTW Dan from Clear Image will tell you himself - the BEST way to make more power is to taper the exhaust as you go. In other words 3-4" up near the engine and then taper to 2 1/2" at the end. But of course anyone who wants to look good as well as go good wants bigger tailpipes.

This is a point worth repeating... Air temp at the header is WAY hotter than air temp at the tail pipe.

Hot air moves fast, and cold air moves slow...with that logic, the exhaust pipe diameter from engine to bumper should be SHRINKING....not getting bigger.

-ALF out...

[Boilermaker]

Crime Scene, ya done good. Ya gave BK (The Exhibitionist) a reason to show off his pipes, again.

[Boilermaker]

I'm partial to brushed stainless. Takes five seconds to clean after racing with a 3M pad.

[Big Kahuna]

Originally Posted by Boilermaker

Crime Scene, ya done good. Ya gave BK (The Exhibitionist) a reason to show off his pipes, again.

Look who's talking. Keep posting the same pics of your busted ass car that ain't moved in 4 years on FB. Thx.