FYI Some Top Fuel Facts

[23T]

Just read an article by Trey Capps in FASTLANE MOTORSPORTS NEWS, a Hemi top fueler makes more HP than the first 8 rows @ Daytona, burns 1-1/2 gal nitro per sec, the same rate as a loaded 747 but @ 4X the energy. The blower takes more HP to drive than a stock hemi makes. At WOT the fuel/air mix is compressed into a near solid form before ignition, causing the cylinders to run on the verge of hydraulic lock. The stoichiometric air/fuel is 1.7:1 and the plug electrodes are burned off @ 1/8 mile and the engine is running on heat of compression as the front flame of nitro burns @ 7050 'F. The engine can twist the crank torsionally 20' that sometimes the cam lobes are re-ground offset front to rear to re-phase the valve timing somewhere closer to piston sync. All this happens in 4.5 sec andf if all is paid for, nothing breaks, and all work for free you can enjoy this for only $1000.00 sec while putting your body through 8 G's of force @ the launch. and a car going 200 MPH with a flying start could not beat you in 1/4 mile.

But the most astounding thing your engine will only turn 540 revolutions from light to light

[Bagherra]

Makes me want to race one...and yet...scared of it at the same time.

[djswwg]

..........more awsum than life itself!!!!!!!!!!!............djs

[skankweirdall]

It's really quite an engineering marvel to get that out of that. Think about it. Of course the fact that it doesn't have to last very long has a lot to do with it.

[Tim_K]

Pretty interesting, but I have to question that 540 revolutions part. That can't be right. I could believe 5400, but not 540.

I read in last years' NHRA rule book that Top Fuel cars can only have a 3.20 axle ratio. No more, no less.

[23T]

Originally posted by Tim_K
Pretty interesting, but I have to question that 540 revolutions part. That can't be right. I could believe 5400, but not 540.

I read in last years' NHRA rule book that Top Fuel cars can only have a 3.20 axle ratio. No more, no less.

I thought it was wrong too until I really thought about it.
9500RPM but the run is just 4.477 sec do the math

[djswwg]

I did the math. 9500 divided by 60 seconds is 158.33333 revs/sec. That number x 4.477=708.85831 revolutions total. where did the 540 come from? How much of the other info in the article is inacurate? .........djs

[23T]

Originally posted by djswwg
I did the math. 9500 divided by 60 seconds is 158.33333 revs/sec. That number x 4.477=708.85831 revolutions total. where did the 540 come from? How much of the other info in the article is inacurate? .........djs

I just cited the write-up, but I dont think the engine will be turning 9500 from light to light.

[John Kunkel]

These "facts" have been making the rounds and are actually mostly lacking in fact.
Not only is the revolution math wrong but so is the contention that the spark plug electrodes are burned away early in the run and the engine diesels the rest of the way. If the ignition in a cylinder quits, it pumps raw fuel out the pipe, easily seen.
The air/fuel mixture statements are contradictary.
The original version of these "facts" also claimed that the drag chute had to be pulled at half track or it wouldn't be able to stop the car from 300+ mph.

[72Challenger]

There are a few other "facts" in this article that bear scrutiny. More HP than the first 8 rows at Daytona would would mean over 12000 HP. It requires less than 4000HP at the wheels to accelerate those cars to the numbers that are typically posted. Yes, that's still an amazing amount of power, but I can't believe the drive train is eating up 67% or more of the engine output.

Of course if he had meant the first 8 cars instead of rows this could be more like it.

[Billydelrio]

If the Daytona restrictor plate engines make in the neighborhood of 370 hp., 370(16)=5920 hp., then the "front 8 rows" is not too unrealistic.

Top fuel tire has about a 115" circunference. A 1/4 mile is 15840 inches. 15840/115 = 138 so a top fuel tire only makes 138 revs in a 1/4 mile. 138(3.20)=440 so a top fuel engine will only rotate 440 times with a 3.20:1 final gear. (no tire or clutch slippage and no tire growth)

I just wanted to add fuel to the other side!!!

Billy

[72Challenger]

DOH! Restrictor plates - I overlooked that little tidbit. Okay, so maybe at Daytona & Talledega it is 8 rows. I'd say that's still a reporter taking liberties to make things sound more impressive than they really are.

[DartGT66]

A top Fuel engine does not wind 9500 rpm, 8000 rpm is about max since the nitro burns so slowly. Cylinder peak pressures in them are actually lower than in a Blown Alcohol engine.

[jelsr]

Like DartGT66 said, the 426 based fueler is limited to about 8000 RPM. This is partially due to the pushrod angles. This was one of the reasons for the "new" Hemi in the Pro Stocks. The pushrod and lifter need to be straight in line to turn 9000+RPM. Same thing goes for the small block, 59 deg vs 48 deg.

[JVMopar]

I don't know the exact a/f ratio but I'd believe it's 1.7:1

Top fuel motors actually have quite low compression ratio's (I think it's less than 7:1). The reason is that nitro methane contains almost enough oxygen to support it's own combustion. So the more fuel you get into the cylinder the more power you'll make. Hence the need for 2 ignition systems because if a cylinder misfires hell yea you'll see it. A big cloud of smoke will come out of the back along with some metal parts, most likely some flames, oil, more fuel, etc.

Those engines put more fuel into them than they have quench area so if a cylinder misfires it hydro locks and boom. Expensive misfire.

[DartGT66]

Actually, the Top Alcohol engines with the very same pushrodangles and similar valvetrain can take a lot more rpm.