Nitro? Whaddaya mean?

So you would also think that synthetics oils, anti-foaming agents, anti-corrosion additives and every other component is also a crutch? The
fact that some nitro makes ALL glow engines run better doesn't make it a crutch. It is a fact of life. Very few engines NEED nitro. All will run better with SOME nitro.
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Ed Cregger wrote:

So all the top fuel dragsters use nitro as a patch to get the power they need, mabey they should just learn how to build more powerful engines instead.
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Courseyauto wrote:

Yes, they could. However mostly they are adapting stock engines, and nitro and supercharging os a simple way to crank more out up to the point the engines basically explode.
They COULD get more my making them rev higher, but what would be the point? Ther can use the stuff, sio=o its eaiser to do it than actually have to learn something about engine design.
Brute force and ignorance and throwing money rather than intelligence at a problem is as American as Apple Pie...:-)

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they
Stock? Hardly. The only thing in common is they have parts that LOOK familiar.

Read the specs at the end. 9500 RPM out of a big block is a feat.

Well, we all can't compete in the Olympics can we? Different strokes. Ignorance? Not as much as that statement. It's one of the things that keep us (and this life) interesting.
Greg
Thought you guys might like this.
* One Top Fuel dragster 500 cubic inch Hemi engine makes more horsepower than the first 4 rows at the Daytona 500.
* Under full throttle, a dragster engine consumes 1-1/2 gallons of nitromethane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.
* A stock Dodge Hemi V8 engine cannot produce enough power to drive the dragster supercharger.
* With 3000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition. Cylinders run on the verge of hydraulic lock at full throttle.
* At the stoichiometric (stoichiometry methodology and technology by which quantities of reactants and products in chemical reactions are determined) 1.71 air/fuel mixture for nitromethane the flame front temperature 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.
* Dual magnetos supply 44 amps to each spark plug. This is the output of an arc welder in each cylinder.
* Spark plug electrodes are totally consumed during a pass. After 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 the fuel flow.
* If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders and then explodes with sufficient force to blow cylinder heads off the block in pieces or split the block in half.
* In order to exceed 300 mph in 4.5 seconds dragsters must accelerate an average of over 4G's. In order to reach 200 mph well before half-track, the launch acceleration approaches 8G's.
* Dragsters reach over 300 miles per hour before you have completed reading this sentence.
* Top Fuel Engines turn approximately 540 revolutions from light to light!
* Including the burnout the engine must only survive 900 revolutions under load.
* The redline is actually quite high at 9500rpm.
* The Bottom Line; Assuming all the equipment is paid off, the crew worked for free, and for once NOTHING BLOWS UP, each run costs an estimated $1,000.00 per second. The current Top Fuel dragster elapsed time record is 4.441 seconds for the quarter mile (10/05/03, Tony Schumacher). The top speed record is 333.00 mph. (533 km/h) as measured over the last 66' of the run (09/28/03 Doug Kalitta).
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.
That folks, is acceleration.
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Greg wrote:

Indeed. Wheras an F1 engine of half the capacity redlines at around 18500 RPM and lasts more than 5 seconds...
But thse are not adapted stock engines, they are designed to do the job...
If you look at the specs you have posted, it becomes totally obvious that to get more power, given that these engines are being pumped so full of steroids thay can't deliver any more torque, what is needed is a higher revving engine.
Frm memory a drag engine peaks out around 5000 bhp? On ewhat 7 liters plus super charging?
Turbocharged 1.5 liter F1 engines achieved over 1000 bhp and NO NITRO.. That suggests that with correct design and no nitro at all, 5000 bhp on a blown 5 liter engine should be possible, albeit at somewhere in the 16-18k RPM mark.

No, its true. Top fuel engines are very crude. Development has gone eniterly in the direction of upping torque, rather than allowing them to rev more freely. For a given torque, power goes up as the square of RPM. Now I won;t claim that 19k RPM on that sioze of engine is possible, but certailny at least 50% more RPM should be available, giving double the Bhp for teh same peak cylinder pressures.
Couple an engine like that to a hi tech gearbox and traction control, and you would have a drag car that would simply wipe the floor with anything existing.

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The Natural Philosopher wrote:

Now consider a 2.5cc (.15 cub.inch) CL speed engine. No supercharging, no nitro. Around 2.7HP...well over 1000HP/litre.
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Brian wrote:

Exactly. All done with RPM. And 2-stroke., Of course its easier to get a little biity engine to rev than a big V10, but even so, thats where the power comes from. You can lekeep pouring nitro and fuel in until the piint comes where the presures in the cylinder cuse a hydraulic lock before firing: Beyond that you can't go, and even that is hopelessly inneficient, as teh gas comes out of te exhaist at HUGE pressure - with most of its energy intact.
More bangs per minute, not bigger bangs, is the real way to get POWER.
And building 7 liter negines that will do 15k RPM and BREATHE at that speed is just too complicated for most people.
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The F1 engines wouldn't turn the RPMs they are turning if they wer 7 liters. Something that people don't seem to understand is that HP will not go up in a straight line with displacement. As the engine gets larger the RPM gets smaller as the rotating mass goes up. The dragsters are looking for max torque not max HP. Still lots of tech there. Much of it on how to get huge mass flow into the engine and yet still ignite it. Composite rods and pistons, overhead cams, titanium cranks, etc are used to reduce the rotating mass and prevent valve float. Also the 5,000 HP figure is old, I think the last I heard they were at 7,000HP and the better ones are probably well above that and keeping mum about it. Special designed and built drag engines started about the late 60's, I don't think stock blocks have been used since the mid to late eighty's. Maybe earlier.
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John Force claimed 8000 for his Funny Car which is a Top Fuler with a body over it. There hasn't been a road-derived engine in these divisions for decades.
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Sport_Pilot wrote:

No, but they are 3.5 LITERS, and still do 18k RPM.

That is not so. What they need is *controllable* torque for the initial phase, and then total power once the tyres have stopped slipping for the later phase of the run.
all other thngs being equal, you can get the same toruqe on the back wheels from a higher revving lower torque engine by upping the back axle ratio..

F1 engines use pneumatic valves. And - not sure - no cams at all.

Probably the only time I bothered to attend a drag race.

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Is it 1.5 liters or 3.5?

It's not very often that the tires stop slipping. Nowdays they spin down the entire race. The almost not quite catch up near the end. Sometimes when the track is very stickey they stop spinning about 3/4 of the way down. Tire spin at the start is controlled primarilly by clutching along with throttle control. If the track is especially slippery they detune the engine, which usually means less nitro is used in the fuel mix.

Two problems with that, one is that you lose considerable power through the drive train. The other problem is that you will need a thrird and possibly a fourth gear. Even though they now use planitary gear drives you loose time and more importantly traction each time you shift gears.

The AA dragsters don't need pneumatic valves. Its not the pneumatic valves getting the RPM's up, rather its the breathing, low rotating mass, and low gearing. The pneumatic valves are used to prevent valve float to ALLOW and KEEP the RPM's up. Since the AA fuel dragsters have no real advantage with that high an RPM pnuematic valves are not needed. Actually I can see some advantage from the lower drag due to the lack of valve springing and cams. I would not be suprised if someone is expermenting with this. I am not sure what the top RPM of these engines are these days, it is probably higher than either of us have quoted.

Another thing about high nitro racing engines. Power and RPM has gone up in F1 due to a large extent the areodynamics of pumping as much air through the engine. In AA dragsters its due the the hydrodynamics of pumping fuel through the engine, and the ignition systems to ignite the very wet mixture. I don't know if you know this but nitro is as easy to ignite as alcohol or gas. Once ignited nitro is a monopropellent, that is it can burn without air, so the richer the mixture the more power you have. Also with 100% or near 100% nitro you are limited only by how much fuel you can pump in without causing hydralic lock. In the 60s you were limited to as rich a mixture as the spark can ignite, notice the huge dual magnetos of the modern dragsters. Of course with such a rich mixture the air fuel mixture is more of a liquid than a gas, this also contributes to the lower RPM's.
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Sport_Pilot wrote:

3.5 currently.
1.5 was the old turbo engines. About 1100 bhp in 'qualifying trim' - i,.e. built to last as long as a drag engine does.
Current NA engines were about 800bhp last time I looked.

With an auto box possibly.

Modern racing auto boxes as used in WRC and F1 are about 60ms to shift. Traction control as used in F1 and tuned up for drag type conditions would probably solve the whole issue and make drag racing completely boring.
Not that it is particularly exciting as it is, or F1 for that matter.

Basically whjat you are sayng is that since what is needed is not actual power per se, because they already have more than is actually needed to spin thw eheels all the way to the pots, but a dead simnple setup that will allow massicve torque, so there is no need to use gearing, and not really any partcular power that could be obtained by allowing teh engones to dop e.g. 12k rpm.
In short, never mind the RPM, just fill em up with nitro and buold em like brovck shithouses.
Which is basically what I started out saying.
They are optimised not for power, but for controllable torqe. and ENOUGH power to lsip the wheels all the way :-)

Yes. Exceopt that in F1 there is simply a ;limit to how much air CAN be pumped. In teh ,imit you can fill teh cylibnder at BDC with air at just under (or under race conditions somewhat over, by ram effect and somewehat by tuned exhaust effect) atmospheric pressure. That's it. No nitro. Standard fuel. You have to utilise that oxygen as best you can - that really limits the bang per firing stroke.
If you want more power you HAVE to rev the thing higher, so all engine devlopment is about getting the engine to phsyically hang together at high rpm, and also to allow it to breathe up there. And then fine tiuning it so its not toally 'cammy' and undriveable.
I haven't been in tht area for a couple ofyears, but last time I was,
it was a toss up as to whether the craks and rods, or the valves, would let go first. Mostly it seems to be the valves, as dropping a valve still seems to be the common way to blow up
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Current NASCAR engines (5L?) are getting 800-900hp using pushrods, two valves per and carburetors! These big cars will do around 250mph if let loose. They have to use carb restrictors on the superspeedways and still qualify with 200+ mph LAPS! 1950s technology and gasoline.
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Some Europeans do not understand that the appeal of NASCAR is that the cars are on almost equal footing. So winning is more about driving and pitting skills. However there is some tech getting into these cars. Mostly aerodynamics, engine tricks that get more power with restrictor plates (However any large advances here just result in smaller restictor plates on following races), tires, and suspension especially on the road courses. The large purses now attract a lot of drivers from other venues of racing. Often a driver, especially rookies, are switched with a ringer road racer for the road courses. The better NASCAR drivers usually do as well as those ringers.
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Sport_Pilot wrote:

Most Europeans don't understand the appeal of NASCAR, period.:-)

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Most Europeans don't understand. Period.
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Paul McIntosh wrote:

Wheraes with Merkins, its 'nearly all' :-)
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Some people need more power with helicopters so we use 30% nitro,there is a BIG difference in performance with the 30%. with the Rc boats we use 60% nitro if you want to win.
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Same with warbird racing. 60-70% nitro is not unusual with the YS four strokes. I never wanted to mod my engines so I used 50% max.
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Start here:
http://www.swraracing.com / http://www.pylonworld.com/rc_pylon/scale/rc_scale_pylon.htm
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