Header thrust:

[lmfoley79]

Basically what I'm saying is having the thrust directed between the track(hard solid surface) and the car allowed the effect of the push to be far more effective than venting the gas into the open air.

[7800ebs]

 hot expanding gas explosively vented UNDER the body shell

10000 sq inches of under body      1/2lb pressure = 5000 pounds of lift

wait.... now I understand Nascar bodies / front fender / wheel well configuration 

nascar sucks ...

their cars down

fans too...

[Koncretekid]

It seemed to me that I had read something about exhaust thrust being used in WW2 aircraft so I googled it and found this on Wikipedia: "Ejector exhausts[edit]

The Merlin consumed an enormous volume of air at full power (equivalent to the volume of a single-decker bus per minute), and with the exhaust gases exiting at 1,300 mph (2,100 km/h) it was realised that useful thrust could be gained simply by angling the gases backwards instead of venting sideways.

During tests, 70 pounds-force (310 N; 32 kgf) thrust at 300 mph (480 km/h), or roughly 70 horsepower (52 kW) was obtained which increased the level maximum speed of the Spitfire by 10 mph (16 km/h) to 360 mph (580 km/h).["

These motors produced up to 2,000 horsepower.

Tom

[Dynoroom]

So...... I have a question.......

If we disconnect the drive line on a fuel car............ point the exhaust toward the rear of the car............then hammer the throttle............ will it move?

[jacksoni]

And by proper careful design of the ducting, the P-51 had useful thrust from the radiator cooling ducts rather than drag. We could use some of that sort of design ('cept prolly run afoul of the radiator rules. Oh Well. )

[7800ebs]

Dynoroom..

Austin Coil did that test.. way back in the 90's

still waiting for the ET....

Should be done next year.. though   

[Old Scrambler]

I'm envisioning a LARGE flat bumper on a push-car staying no more than an inch from the exhaust tips to detect any movement

[lmfoley79]

So...... I have a question.......

If we disconnect the drive line on a fuel car............ point the exhaust toward the rear of the car............then hammer the throttle............ will it move?

That was my question too. 3000lbs thrust should make it beat a 60's era muscle car to the 60' line.

[Rex Schimmer]

Mike,
Maybe the real question should be: If we take an enclosed container with one end open, and pump 100 gpm of 90% nitro into it at 500+psi and ignite it, will it become a rocket? Which is exactly what fuel motors are doing. The 4000 lb number is not mine it is the number that the crew chiefs, Jimmy Prock, Mike Green, John Medlen etc, are talking about.

Rex

[Dynoroom]

True that Rex  

Just asking a question. I learned a LONG time ago....... Never say never.

I also learned from a real smart racer the word..........

Deception.  

Beside, I know more than a few racers who went through the trouble to run the exhaust all the way out the back of the car........ Maybe not for thrust though.   

[jl222]

So...... I have a question.......

If we disconnect the drive line on a fuel car............ point the exhaust toward the rear of the car............then hammer the throttle............ will it move?

 This happened to us at EL mirage with the 222 Camaro. We fired the car up and my brother took his time getting in the push truck. Troy was blipping the throttle and it moved several ft away from the push truck. We angle the exhaust back and up to get downforce and thrust. We set the hood on top of the car when warming up and have to hold on to it when blipping the throttle as it almost blew off once.

 If a top fuel car has a cylinder go out it moves to that side from the thrust from other side.

  JL222

[RichFox]

Somebody has to mention the Convair aircraft UA was flying when I started there. Two 2800 cubic inch blown hemi engines on race gas. ( more or less) With Exhaust Augmentation. Cool headers and cowling to dump the exhaust out behind the engines and provide thrust. Someone else can Google it and find out how much. Then look up Turbo compounding. 3350s

[dw230]

When the late, great Don Vesco  set his 458 MPH record a few years ago someone on this board indicated that maybe the location/angle of the exhaust pipe was illegal because it appeared(my word) to contribute to the thrust/speed of the vehicle.

I should have posted this in the Friday Funnies thread I think,
DW

[John Burk]

Large amounts of header thrust is unique to blown nitro engines that need long cam overlap to let liquid fuel cool the exhaust valves . That the nitro released it's oxygen in the headers and turned them into rockets was an unexpected bonus . A little later somebody tried aiming the thrust upwards for traction . Thrust comes from pressure being less on the open end of the tube than in the other directions .

[stay`tee]

What has been the average increase in "mph" with the headers at 45*  , the answer to this would be found there,  ,,,