Top Fuel Dragster interesting facts!

[Casey]

* One dragster's 500-inch Hemi makes more horsepower then the first 8 rows at Daytona

* Under full throttle, a dragster 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 magnetos apply 44 amps to each spark plug. This is the ouput 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.

* Nitromethane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases.

* Spark plug electrodes are totally cosumed 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 it's 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.

* Dragsters 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 200 mph well before 1/2 track, launch acceleration is closer to 8G's.

* Drivers 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.

* Dragsters reach over 300 miles per hour before you have read this sentence.

 

[used2]

unreal!!!

 

[Schulmann]

Very impressive !

 

[Anaconda]

This has been going around the Internet for YEARS. I am not sure if that is the corrected list or not, but when this first started circulating, several facts were wrong (like temperatures). I don't know if this is the right one or not.

 

[Tom F&L GoR]

Another cool one is how few times the engine turns over.

At 9000 RPM for 4.5 seconds, the engine only spins around 675 times. And then it needs a rebuild!

 

[ACR steve]

Holly Sh_t

 

[Jerome Sparich]

There is so much wrong in that post it is not even funny. And that includes the one about rpms down the track. What, no account for clutch slippage? They are slipper clutches after all. I wish I had the time and the ambition to shoot holes in all of that.

Try searching that list over at nitromatter.com and see the people in the know (Top Fuel crew cheifs, etc.) tear those "facts" a new one.

Now back to my packing...........

 

[Anaconda]

Ahhh, so it IS the incorrect one.

Like I said, there is a corrected one circulating around too. I had the email at one point, but again, this is several years old.

 

[94RT10Ohio]

Just imagine if they used a V10...???

 

[Johann]

There is so much wrong in that post it is not even funny.

Yep, even the "corrected facts" making the rounds are sorely lacking in fact.

 

[Casey]

I was just forwarded the list from a friend. So I guess it's all BS, but it sounds pretty damn awesome!

Someone make up a good list with the same effect please!

 

[TOOOFST]

Learned lesson:
Next Top Fuel event buy the cheap seats!
Let's hope the terrorists don't get that technology!!

 

[Tom F&L GoR]

>And that includes the one about rpms down the track. What, no account for clutch slippage? <

Teach me. I didn't get this from any list, I estimated it using the max RPM, or 9000 RPM, for 100% of the race, which obviously includes the start - so it does account for lack of clutch engagement. I'd only be off by not using the correct average engine speed.

9000 RPM / 60 seconds = 150 Rev/sec

150 Rev/sec * 4.5 seconds = 675 revolutions

 

[Torquemonster]

re the blowers requiring more power to turn than a stock Hemi makes - the figure of 500hp absorbed by the blowers in Top Fuel has been bandied about for a few years. It is likely about right - but I doubt anyone has seriously stripped the blower off a Top Fuel engine and dyno'ed it then put it back on and redyno'ed to check. Dyno'g a Top Fuel engine is not exactly a common practice

anyone got a 7,000hp engine dyno for hire?

Tom, interesting point - but I think the engines turn even slower than that.

I may be out of date now - but Top Fuel engines typically rpm'd about 7500rpm.

The combination of 9000rpm and the explosive 6-7000hp mostly from nitro - exceeded the strength of the best rods... of course that may have changed in recent years - but even if so - the power levels have not changed much, so I doubt the rpms have either (based on trap speeds remaining similar to when they only rpm'd to 7500).

Top Fuel does not need to rpm like the other classes. We needed at least 8500rpm and often went to 9500 in Pro Mod to get the times, but that was on Methanol - a whole different animal.

For interest - an hour away from me we have an engine builder that has stroked his small block Ford out to 390 cubic inches, turns around 1020hp on carbs and race gas at 9700rpm. Given the short deck height, you can imagine the side angle on the rods at that stroke... Valve springs are 2000lb open There's very few engine builders on the planet that could build this and have it live. This engine lives a season of racing.

it is one of the only small block Fords in the world that has run a 6 second pass (dragster) on carbs, gas and no power adders. That requries a lot of technology - a lot of which we will not read about in a mag or book.

 

[Tom F&L GoR]

OK, I admit I did a little research before answering.

We used to supply engine oil to Brad Anderson Engineering when Shelly ran the TF car under the Western Auto colors. 9000 RPM was what I recall.

http://motortrend.com/features/consumer/112_0502_numbers/ article says 8500 RPM. Maybe it's the article everyone thinks is all wrong.

This article indicates NHRA had a rule change to impose an 8400 RPM limit for the 2005 season after four seconds into the race. Presumeably engines would be over 8400 to impose a limit of 8400.

http://www.findarticles.com/p/articles/mi_qa4078/is_200501/ai_n9477444#continue

In any case, if it makes the first estimation of 9000 RPM too high, the total crank revolutions during the event is even less than 675. I'm still hoping to learn about clutch slippage.

 

[Torquemonster]

Tom that was excellent info. The strength of the rods must be unbelievable to handle both the explosive power levels/delivery(engine acceleration) plus those rpms.

can't help re clutch slippage - I was never involved in that aspect. I can tell you what happens when you set it too tight tho.... we wheelied at 200mph across the finish line. Front was 6" in the air.... not recomended.

 

[Johann]

The imposition of the 8400 rev limit in no way implies that higher rpms were considered normal, and damn sure not 9000; the target maximum rpm is closer to 8000.

The main reason for the rev limiters is to limit "excursions" in rpm that lead to engine failures and track oil downs. The 9500 "red line" stated in the most current version of the "facts" is the ultimate failure point, not a red line.

Trying to compute engine rpm's by extrapolating from top speed is difficult because of tire growth, the 32" diameter tires grow to over 43" at speed due to centrifugal force. At that tire diameter with the 3.20 gears it's easy to run over 330 mph without exceeding 8400 rpm.

 

[GR8_ASP]

Top fuel and funny car use lock-up clutches. They lock about mid track which acts like another gear. They "slip" through the whole first half of the track to keep the revs high and constant.

It was an interesting story to hear that when a lock up clutch was first tried, the top fuel teams had no idea they were losing so much to slippage, figuring it was only at launch.

 

[Jerome Sparich]

I'm still hoping to learn about clutch slippage.

Well I do not have the time to get into all of it now, but just think about this.
The slipper clutch in a Top Fuel car does not lock up until approx. half track.
The RPM's in the car vary dependant on how much the clutch is slipping.
Tire growth affects the RPM's the engine sees.

The RPM limit is to keep speeds down as the Goodyears have been known to explode, and they have taken Darrell Russell from us. (Search chunking tires at below link also.)

Like I said, a search as www.nitromater.com will give all the facts about what is true and what is false in the statements in the first post, and also yours Tom.

When a Top Fuel team owner, crew chief, and others who do this say it is bunk, it is bunk.

Now I have got to get some rest. God night all.

 

[Tom F&L GoR]

Jerome, We are not on the same wavelength about something.

I agree the clutch is designed to slip. Therefore at the start line, the engine speed is high. As the vehicle accelerates, the clutch slips less. So the engine speed may drop or stay at 8400 RPM. In any case, the engine speed may average 8400 RPM for the entire event. Maybe average even less than 8400. I gathered from your original comment that you think by not accounting for slip, the total engine revolution calculation would be incorrect by being too low, but everything you are saying points to a total revolution count that is even lower. Thanks for agreeing with me?

 

[Bill M]

Another one.

Putting all of this into perspective:
You are driving the average $140,000 Lingenfelter "twin-turbo" powered Corvette Z06. Over a mile up the road, a Top Fuel dragster is
staged and ready to launch down a quarter mile strip as you pass. You have the advantage of a flying start. You run the 'Vette hard up
through the gears and blast across the starting line and past the dragster at an honest 200 mph. The 'tree' goes green for both of you at that moment. The dragster launches and starts after you. You keep your foot down hard, but you hear an incredibly brutal whine that sears your
eardrums and within 3 seconds the dragster catches and passes you. He beats you to the finish line, a quarter mile away from where you just passed him.

Think about it, from a standing start, the dragster had spotted you 200 mph and not only caught, but nearly blasted you off the road when he passed you within a mere 1320 foot long race course.

 

[Anaconda]

About the clutches, don't they essentially "weld" together about halfway down the track? I heard or read that the heat was so intense that the welding occurs by itself.

Is any of that correct???

 

[Ted Bigham]

About the clutches. Yes, the clutch is made of several plates. By the end of the race they are all one piece. When you get a rear view look at a launching dragster, you can see a horizontal spiral of black smoke/dust out the center of the car. That's the clutch disintegrating.

 

[Johann]

Actual clutch disc welding is another claim in one version of the "facts". "Welding" is a colloquial term to describe the clutch lockup.

Since there is no neutral position to disconnect the engine from the drivetrain, a welded clutch would mean the car would be unmovable if the clutch was literally welded together, yet you see them being towed back to the pits after each run.

 

[Jerome Sparich]

About the clutches, don't they essentially "weld" together about halfway down the track? I heard or read that the heat was so intense that the welding occurs by itself.

Is any of that correct???

I have a more than a few used clutch plate that are signed by drivers etc. They do "weld" themselves together so to speak. But not solid in one piece. They do separate when they are taken out.

Tom, I am not sure of the exact number, but yes we do agree. That number is not correct.

When I have time I will ask a crew chief to look at the computer data and see just how many times they do rotate down the 1/4.

 

[Anaconda]

I put the word "weld" in quotes, because I didn't think that was exactly the correct term. I meant essentially melt into one combined mass.