Ok, this is out there, but.....

Did anyone know that the downforce applied to a Nitro Funny car or top fueler by the exhaust is around 200 lbs per cylinder. This is proven. Ever see the pipes on these cars? They are braced and not built lightly.

This is why you often see funny cars drift to the right or left on a pass when they drop a cylinder.

Now fact or fiction. Does a stack in a diesel truck add 30 or 40 lbs of down force to the truck on a pull?

The thought would be, that the larger the stack the less effect it would have because of the reduced velocity.

This 30 or 40 lbs (and this is all speculation) could be an advantage.

Trucks with turn outs could be leaving something on the table.

Now, you decide......

Pulling Thoughts by Freighttrain

Ok, this is out there, but.....

Did anyone know that the downforce applied to a Nitro Funny car or top fueler by the exhaust is around 200 lbs per cylinder. This is proven. Ever see the pipes on these cars? They are braced and not built lightly.

This is why you often see funny cars drift to the right or left on a pass when they drop a cylinder.

Now fact or fiction. Does a stack in a diesel truck add 30 or 40 lbs of down force to the truck on a pull?

The thought would be, that the larger the stack the less effect it would have because of the reduced velocity.

This 30 or 40 lbs (and this is all speculation) could be an advantage.

Trucks with turn outs could be leaving something on the table.

Now, you decide......

Pulling Thoughts by Freighttrain
:pound: I think a 15lb bottle negates that issue

:pound: I think a 15lb bottle negates that issue
A 15 lb bottle actually is worth another 20 lbs on the velocity downforce.
So, now we are talking 50 - 60 extra pounds.

Remember how we couldn't figure why the stack bracket was bending (down)?

Does a diesel turn enough RPMs to have that effect ?

i call bs...on both accts. negligible at best...yer joshin

Does a diesel turn enough RPMs to have that effect ?
It not so much the RPM's as it is the amount of air that flows, which is a lot, considering these turbocharged engines develope as much as 200 psi of drive pressure pre turbo.

This Theory is supported in many way's

Refer to the example in the original post.

Ever notice that it can take 3 firemen to handle a firehose?
I know this is water, but the same theory.

Another example would be the simple leaf blower.

A standard leaf blower will generates about 5 - 8 lbs of pressure @wot

This can be felt as you hold it in your hand

Now convert that to the amouint of air trying to escape from an exhaust stack.

A underboost diesel might just be a little more than you think.

A few extra pounds is a few extra pounds. Would it give some type of advantage? Can't hurt

Something to think about.

Ok, this is out there, but.....

Did anyone know that the downforce applied to a Nitro Funny car or top fueler by the exhaust is around 200 lbs per cylinder. This is proven. Ever see the pipes on these cars? They are braced and not built lightly.

This is why you often see funny cars drift to the right or left on a pass when they drop a cylinder.

Now fact or fiction. Does a stack in a diesel truck add 30 or 40 lbs of down force to the truck on a pull?

The thought would be, that the larger the stack the less effect it would have because of the reduced velocity.

This 30 or 40 lbs (and this is all speculation) could be an advantage.

Trucks with turn outs could be leaving something on the table.

Now, you decide......

Pulling Thoughts by Freighttrain
i like your thinking,maybe haveing it come out the hood will work likke adding more hanging weights out the front?

then im pointin mine out the back for the drags and to the frt and up for the sled....not.
very minor..turbulence yes..downforce no


mash the pedal and shoot a wter hose into the exhaust stream....im bettin it dont hardly deflect the hosestream

Myth Busters!!!!!!!!

i would say it doesnt create enough downforce to change what downforce is on the truck due to the aerodynamics heading down the track. scale the situation down and maybe but heavy trucks i think it plays no part. you would think that when you hit the throttle in nuetral the truck would squat down instead of rocking side to side.

how about in neutral you arent making boost and when your at 50 psi theres way more air comeing out the pipe. maybe ? i dunno? i agree with richard , lets call mythbusters!

Why don't you put a truck with a stack on a scale, turn the engine off. Then get the weight with the truck wide open with max revs. Then:

Weigth of truck revving - weight of truck off = actual downforce

If there is no difference or actual downforce then you will know. Unless someone knows the exact massflow and velocity of their exhaust to do the math theory behind it.

Why don't you put a truck with a stack on a scale, turn the engine off. Then get the weight with the truck wide open with max revs. Then:

Weigth of truck revving - weight of truck off = actual downforce

If there is no difference or actual downforce then you will know. Unless someone knows the exact massflow and velocity of their exhaust to do the math theory behind it.You are not making any boost in neutral :nod:

put the truck in 4wd and in drive and build boost.

put the truck in 4wd and in drive and build boost.

Mine will walk through the brakes long before it builds enough boost to measure anything substancial

Maybe you need better brakes. Ok I now have left myself open for come backs.:p

Maybe you need better brakes. Ok I now have left myself open for come backs.:p

or less hp :cool:

You need a 7 post machine for this. I wonder if RCR or HMS would let me use theirs :eek: :pound:

or less hp :cool:


good comeback....have u dynoed that truck yet? just curious

Last year @ 492hp, 1060 torque
Quite a bit has has been squeezed since then. That was only tune & air intake

ok, This Is Out There, But.....

Did Anyone Know That The Downforce Applied To A Nitro Funny Car Or Top Fueler By The Exhaust Is Around 200 Lbs Per Cylinder. This Is Proven. Ever See The Pipes On These Cars? They Are Braced And Not Built Lightly.

This Is Why You Often See Funny Cars Drift To The Right Or Left On A Pass When They Drop A Cylinder.

Now Fact Or Fiction. Does A Stack In A Diesel Truck Add 30 Or 40 Lbs Of Down Force To The Truck On A Pull?

The Thought Would Be, That The Larger The Stack The Less Effect It Would Have Because Of The Reduced Velocity.

This 30 Or 40 Lbs (and This Is All Speculation) Could Be An Advantage.

Trucks With Turn Outs Could Be Leaving Something On The Table.

Now, You Decide......

pulling Thoughts By Freighttrain

I Think Your Right So The Only Thing I Can Think Is That If Your Stack Is Up Then You Need To Drop Down To 7600 Lb. :d