I guess the thread in LT1 about the 660rwhp NA LT1 kinda got me wondering.

How exactly do the top fuel (4 second cars) obtain the what, 6000hp they have I believe I read somewhere.

I read something in a mag I have somewhere that the engine sees a few gallons of fuel coming into it in a matter of a second or something.

If anyone knows, Im just really curious as to what kinda stuff goes on, heads, cams, blocks, CI, nitrous setups, FI setups. I mean it all just doesnt make sense how something can produce that much power.

 

A lot of it is the fuel. Nitromethane contains lots of it's own oxygen. Here's a short writeup frm HowStuffWorks:

http://www.howstuffworks.com/question642.htm

There is also another reaction with nitro which isn't exactly combustion. It's more of a "cracking" reaction which releases more power. I don't fully understand it, however.

Here's a few more "facts" courtesy of www.dieselinnovations.com

* The 500-inch Hemi makes more horsepower than the first 8 rows at Daytona.
* Under full throttle, a the engine consumes 1 1/2 gallons of nitro per second, the same rate of fuel consumption as a fully loaded 747 but with 4 times the energy volume.
* The supercharger takes more power to drive then a stock hemi makes.
* Even with nearly 3000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into nearly-solid form before ignition. Cylinders run on the verge of hydraulic lock.
* Dual electronic magnetos apply 44 amps to each spark plug. This is the output of an arc welder in each cylinder.
* At stoichiometric (exact) 1.7:1 air/fuel mixture (for nitro), the flame front of nitromethane measures 7050 degrees F.
* Nitro methane burns yellow. The spectacular white flame seen above the exhaust pipes at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases.
* Spark plug electrodes are totally consumed during a pass. After 1/2 way, the engine is dieseling from compression-plus the glow of exhaust valves at 1400 degrees F. The engine can only be shut down by cutting of its fuel flow.
* If spark momentarily fails early in the run, unburned nitro builds up in those cylinders and then explodes with a force that can blow cylinder heads off the block in pieces or blow the block in half.
* The engines twist the crank (torsionally) so far (20 degrees in the big end of the track) that sometimes cam lobes are ground offset from front to rear to re-phase the valve timing somewhere closer to synchronization with the pistons.
* To exceed 300mph in 4.5 seconds dragsters must accelerate at an average of over 4G's. But in reaching 250 mph well before 1/2 track, launch acceleration is closer to 8G's.
* Drivers must shut off before the finish line, or even dual parachutes will not stop the car.
* If all the equipment is paid off, the crew worked for free, and for once NOTHING BLOWS UP, each run costs $1000.00 per second. Bear in mind here that the engine behind all this Herculean output is a modified offshoot of a common American big-block V-8

The more nitro that can be crammed in, the more power they get. The engine is basically hydrolocked with the liquid nitro.

Note that burning occurs thruout the power stroke and most of the exhaust stroke. The excess fuel burned in the upturned headers give a significant amount of download onto the tires.

The engines turn about 8000 for 4.7 seconds or so, or less than 700 revs in anger before they are rebuilt.

Most of this is so bizzare that it's difficult to believe. So is 6000 hp from 500 cubes, IMO, but it happens.

 

It takes 2000 HP just to turn the blower.

 

Just a little factoid stuff...

Nitromethane is a military grade explosive.

A mixture of Nitromethane and, I believe, Aniline, is used in devices like the Mine Clearing Line Charge and hasty tank traps.

In the MCLC a hose attached to a rocket is filled with nitromethane based explosive and fired into a mine field where it's detonated and the overpressure sets off the mines.

In a hasty tank trap, you use a device similar in concept to a Ditch Witch, which lays underground sprinkler hose.

You bury the hose well underneath a road, and if you have to "blow the road", you pump the NM explosive into the hose and detonate it, which creates a large trench that both wheeled and tracked vehicles can't drive through.


Nitromethane can also be used as a sensitizer in an ANFO explosive (Ammonium Nitrate + Fuel Oil), to achieve a brisance (burn velocity) comparable to PETN and RDX. (the major ingredients in C-4 & Semtex)


So the amazing thing about Fuel Cars is not how much power they produce, but how they manage to keep the engine intact long enough to make a pass!




And no... I'm not going to teach any of you juvenile delinquents how to make explosives, so don't ask!

 

Nitromethane isn't much of a primary explosive unless you have a sensitizer in it though - but when you do it can definately work as such - aniline (as you mentioned), or really most organic amines will work as such - you just want something that is highly soluble so you get proper dispersion. But in the context it is used here I don't think you are going to get in a situation where it becomes a primary explosive (any hopefully you don't have any detonating caps stored with you fuel )



I have heard that before, but not 100% sure I buy it. (the 4* the energy volume part). But not sure what they actually mean by "energy volume". Say 60,000 lbs of thrust per engine, * 4 engines - your typical 747 is making 240,000 lbs of thrust. If we assume a speed of 330 knots that is 240,000HP. Now sure, that is power, not energy (not sure what energy/volume is) - but 240,000HP vs. 6,000HP.... don't know if I see that comparison happening. Evey if they are talking simply "cruising" for the 747 I think it takes ~60,000HP at 330knots.

 

Well, maybe 400+hp.

You couldn't put 2000 hp through a 3 inch timing belt moving at 200+ ft/sec, especially when the engine/blower accelerate from 1800-2000 rpm idle to 8000(engine)/12000(blower) in a few tenths of a second.


Nitro can also be used as a rocket fuel, so maybe Top Fuel really is rocket science.

Anyone familiar with Hydrazine? A couple of guys tried some in fuel dragsters in the 60s. Mixed with nitro it makes the fuel more shock sensitive, as well as nasty to humans. Big booms though.

 

i went to the drags here in germany. i had all day pit passes i got a rod and piston that was still warm and a head from a top fueler i paid 60 bucks for it all. i was standing about 10 feet away from one of the dragsters while they were setting it up it took all i could do to stand 10 feet away at idle and my eyes started watering i felt like i was in a C.S chamber then he revved it one quik time and i thought my ears were going to pop i couldnt hear good for about 2 days. i have lots of pictures of thier engines and stuff they were pretty good about letting me get some closeups of thier setups and the thing about the spark plugs is true i have 2 of them autolite 50s i believe is what they are and yes the electrode is completly gone. and talking about fuel consumption my cousin owns (SNIPER) the monster truck (Robert French) from cali and his truck has 2500 and some change. he moved it from his moms house to 1/8 mile down the road and burnt 15 gallons of alcohol so i believe the fuel consumption on a top fueler

 

I was under the impression that the "energy volume" referred to the potential energy stored in that 1 1/2 gallons of fuel burned per second, ie. a gallon of nitromethane has 4X the potential energy as 1 gallon of jet fuel.

 

I'm just thinking they used the wrong terms, maybe they meant that the fuel car makes more power per pound of weight compared to a 747.

using 240,000 HP at 330 knots(I think the newer 747s make anywhere from 59,500 lbs or thrust to 63,300 lbs)

With a max take off weight of 875,000lbs to 910,000 lbs

thats about .27 HP/lb

for the fuel car at 6000 HP and minimum of 2100 lbs thats

2.86 HP/lb.

thats still way more then 4 times the power to weight ratio of the 747 but maybe thats what they are talking about?

I dunno you guys are the genius's

P

 

What about gearing? I have always wanted to know what kind of gear ratio (transmission and rear) allows a car to be able to get off of the line hard and travel 330 mph. They are 1 speed right? I assume it does not take much gear to get off the line with 6000 HP on tap.

 

Wow. Thanks guys, this stuff is quite amazing, keep the replies coming Im sure others are quite interested as well.

BTW anybody know anything about the nitrous guys? Or are those that I am thinking only on the funny cars in the 6 second area?

 

Jet fuel is about 30-35 MJ/L, Nitromethane is only about 10MJ/L (both at STP)

You have to burn alot more nitromethane to make the same amount of power as an identical volume of jet fuel.





Now that's getting crazy Hydrazine is some really nasty stuff - you could run it through the catalytic converters on our car with a nozzle out the back and duplicate a basic jet engine (massive decomposition to ammonia, nitrogen, and hydrogen - then the hydrogen burns with air if you are really lucky)

Chris

 

Top fuel cars all run a mandatory 3:20 rear gear. A good friend of mine just bought Bruce Littons complete top fuel operation, he's going to run most of the NHRA season this year. I'll try to get some general info about cam specs, head flow#'s etc.

 

I'll take your word for that, but its worth mentioning that with a stoich AF ratio of 1.7:1 for nitro and jet fuel being much closer to diesel or gasoline, you can burn a lot more fuel per displacement of the engine. I don't know exactly what the original author meant by energy volume either though.

3.20 gear, some slippage, and big **** tires that expand and act like a centrifugal clutch of sorts.

-brent

 

TF and FC have gear rules. 3.20 is the gear as WickedFast said. Of course the tires grow a lot during the run so there is some variable ratio.

Yep, it's one speed forward. Additionally the clutch slips a lot! It is applied at a rate determined by mechanical timers: no computers allowed. You can see the carbon dust from the many plates pouring out of the bellhousing area. Too much clutch and they go up in smoke. Remember the engine goes to 8000 almost immediately and the car catches up. 6000 hp @ 8000 is about 4000 lb-ft torque. All of that is trying to wind up the rear axle housing. You can see the torque reaction in the chassis as the 300 in wheelbase TF chassis arches it's back nearly a foot!

At speed, the rear wing gives something like 6000+ lbs of downforce.

While acceleration near the line is better than 5 g, that's"eyeballs in". When the drag chutes come out it's that or more "eyeballs out". Detached retinas can be a major concern to the drivers.

TF cars run about 60% faster than a F1 or Cup car ever goes. There are about 43 people in the "300 MPH Club" at Bonneville Salt Flats. That's ever. In a typical weekend NHRA meet, there are more 300+ runs than thatjust in Top Fuel. Add Funny Car and the number doubles.