What does "Top Fuel" mean in car racing terminology?


#1

Wouldn’t car racer folk always use the best fuel available? So why the “Top Fuel” distinction for certain types of races?


#2

It is the class name. It refers to the TOP (fastest/quickest) class running FUEL (i.e. mostly Nitromethane), not gasoline or alcohol. The cars are the long skinny ones usually called “rails”. There is an alcohol fueled version called "Top Alcohol Dragster with similar engines and design but running the safer and easier on engines methanol. They probably make 3500 hp these days instead of the Top Fuel cars 10,000 hp

FYI, Funny Car got its name because early ones had relocated rear axles for better traction and they looked kinda “funny”


#3

Not all race cars use gasoline for fuel. Many use alcohol.

However, in drag racing the fuel of choice for dragsters is Nitromethane. This is highly explosive thus allowing the supercharged engines to develop upwards of 7000HP and propel the dragsters down the quarter mile strip in less than 4 seconds. These specialty racers are called Top Fuel dragsters.

Edit: because of the explosiveness of this fuel, the lifetime of these engines is only about a mile. Then they have to be replaced.


#4

Of course doing a simple search on Google would have furnished the answer to this question plus all kinds of You Tube videos of these impressive machines.


#5

Top Fuel cars only race to 1000 feet now rather than 1320 in the name of safety.


#6

Also, NHRA requires these engines to be torn apart and rebuilt after every single run. It takes a good crew about 45 minutes to do this, (there’s a maximum allowed by the NHRA, but I don’t remember what it is) but the engines and cars are designed to accommodate this activity, the crews are highly experienced engineers who train to do this, the “kit” is already organized and ready, and there are fewer systems in the car to interfere. But damn, these guys are GOOD!


#7

And yet they’re still hitting 330 mph. Go figure.


#8

Current NHRA rules restrict the fuel used in Top Fuel to a nitromethane/methanol blend with a maximum of 90% nitromethane. All other fuels are prohibited so they can no longer use nitro/propylene oxide blends.

Nitromethane is a dense fuel, heavier than water, around 9 pounds per gallon and is surprisingly difficult to set on fire. You can literally snuff lit kitchen matches in a cup of nitro. When you finally do manage to ignite it, it burns with a pale greenish blue flame, almost invisible in daylight. That’s why you usually see the pit crew squirting a shot of gasoline into the intake while cranking the engine.

The last time I bought nitromethane, a gallon costed about $38 dollars, but I’m sure it’s cheaper if you buy it in bulk. It’s gotten a lot harder to buy since Timothy McVeigh mixed a bunch of that stuff with ammonium nitrate and blew up the Alfred P Murrah Federal Building in OKC.


#9

Thank you for saving me the trouble. GEEEEZE!


#10

One of the more interesting things about nitromethane and methanol is that when you mix the two, the temperature of the liquids drops markedly as the two liquids dissolve each other. Something I found out when mixing my own model airplane fuel. It doesn’t become ice cold, but it’s much cooler than the component liquids were before they were mixed.


#11

They will pull 5 G’s plus on launch and exceed 3.5 G’s the entire 1000 feet… So 330 mph! Yeeow!


#12

Length of race was shortened because of the Scott Kalitta crash in Jersey?


#13

Interesting that during a 4 sec run, the motor only turns 1000 revs total. 8k rpm is 60 sec. Spark plugs melt after 2-3 sec and motor is in compression ignition mode. No spark.


#14

The ability to reach 330 MPH IN 1000 feet is exactly why they no longer run 1320 feet. With speeds that high, there was not a long enough track to reliably stop before going off the end. Cutting back to 1000 feet is for driver safety.


#15

Thanks for the informative posts :slight_smile:


#16

Does it matter if you’re only going a thousand feet?


#17

A top fuel dragster uses just under 23 gallons per run. That includes warmup and burnout, both absolutely necessary with each run.


#18

Take a ride on a top fuel dragster.


#19

That’s about $900 just for the fuel.


#20

Peanuts compared to a complete engine rebuild between runs.