Fuel Car?

[Taylorman]

Im wondering what causes the fuel engines to drop cylinders. I heard them say on tv that when the engine unloads due to smoking tires it causes them to drop a cylinder. What causes this? What actually happens in the engine to cause this?
Also, what prevents fuel and alcohol cars from popping a wheely when they leave the line? Pro stock cars pop wheelys, why don't fuel cars?

[h2oski2fast]

Also, what prevents fuel and alcohol cars from popping a wheely when they leave the line? Pro stock cars pop wheelys, why don't fuel cars?
The clutch setup is why they dont pull the wheels. The clutch is setup to slip and engages at different times while going down the track. Too aggresive clutch settings and you get tire spin.

[h2oski2fast]

Oh and to answer the 1st question, there is too much fuel in the cylinder for it to burn and once they go out they stay out because more fuel is going through it.

[Taylorman]

So tire spin unloads the engine which puts to much fuel in the cylinders? Im looking for a detailed explanation of what puts a cylinder out.
Thanks

[ekimzark]

they do lift the front end sometimes dont know any of the whys or whats but it does happen sometimes
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-- www.dragboatphoto.com

[Taylorman]

Yes, your right, sometimes they do but for the most part they dont. Im just wondering with all that power, what keeps them on the ground.

[Infomaniac]

Not enough load on the engine is what puts them out most of the time. Trying to compensate for a poor race track. or just trying to get it down the track. They all make too much HP and the trick is getting it to hook up. Keep the engine loaded enough to not drop cylinders and not overpower the track.
And the clutch is not fully engaged until about 1,000 ft so not many wheelies.
Plus they pull out a ton of timing within the first second of the run and feed it back in gradually along with the clutch.

[lucky]

basicly your flooding your cylinder with so much fuel , It cant ignite - the alky car i get to help with every once in a while will burn right around 3 gallons in a quarter mile .

[SmokinLowriderSS]

Yea, the fuel quantity those things consume is frightening (as is the several thousand HP they produce). :eek:
A wheelie would actually indicate a "perfect" launch (unless the tires break) as it indicates 100% weight transfer to the driving wheels. Any time the fronts are on the ground, some weight is not available to the drive tires for traction. :cool:
The Top Fuel guys are running so much fuel through those engines that, should a cylinder fail to fire, the remaining liquids & vapors, when added to by the blower forcing the intake on the next cycle, stands a serious chance of HYDROLICKING the cylinder. The results are spectacular of course (and expensive) :2purples: :2purples: :2purples: Odly enough, I have also seen cars loose both magnetos just moments after the start, and make a great run, dieseling the whole 1/4-mile. That darned Nitromethane is really a low-grade explosive more than it is a motor-fuel (do not confuse with nitroglycerine tho).

[Taylorman]

Last year in Houston i spoke to an alcohol driver who hydrolocked 2 motors in one day. Pretty amazing what a Keith Black block looks like after that.
So if a plug misfires, it may not relight causing a cylinder to flood with fuel and not relight?
What im not clear on is why and how does the engine drop cylinders when it unloads. What causes this?

[DUECE'SDAD]

I dont care that much for racing now days, i mean its amazing to see them go that fast and awesome in person, but it basically like two computers racing and the one that drops the least amount of cylinders wins, But you got to drop atleast one or you will tire smoke so bad you gotta lift. No scientific info here, just my stinky a$$hole i mean opinion ! ! ! ! I would still like to drive one though. But i like watching 9 and 10 second cars that gotta be drove ! !

[h2oski2fast]

Last year in Houston i spoke to an alcohol driver who hydrolocked 2 motors in one day. Pretty amazing what a Keith Black block looks like after that.
So if a plug misfires, it may not relight causing a cylinder to flood with fuel and not relight?
What im not clear on is why and how does the engine drop cylinders when it unloads. What causes this?
As the tires begin shake (which is essentually a form of wheel hop) / spin (causing RPM increase) the driver pedals (lifts on the throttle) the car. When this happens, it causes the air/fuel mixture to change radically (do to the fact that you just shut down the butterflies on the intake). This overloads the cylinders with fuel, some come back yo life and some don't. Remember these engines are like switches, they are either on kill or off, there is no in between.

[Infomaniac]

I dont care that much for racing now days, i mean its amazing to see them go that fast and awesome in person, but it basically like two computers racing and the one that drops the least amount of cylinders wins, But you got to drop atleast one or you will tire smoke so bad you gotta lift. No scientific info here, just my stinky a$$hole i mean opinion ! ! ! ! I would still like to drive one though. But i like watching 9 and 10 second cars that gotta be drove ! !
Dustin - there is no computer controlling anything in top fuel racing.

[SmokinLowriderSS]

Dustin - there is no computer controlling anything in top fuel racing.
Now aren't the clutchings and ignitions computer-controlled as have been referenced above? I always supected so but never knew.

[Taylorman]

Now aren't the clutchings and ignitions computer-controlled as have been referenced above? I always supected so but never knew.
No, the clutch is not computer controlled. They are set up with feeler gauges. Not sure about ignitions.

[sdba069]

The clutch is changed by decreasing or increasing counterweight which in turn changes how long it takes the clutch to lockup.

[Taylorman]

I watched a spectator try to pick up a clutch disk in the pits last year in Houston. I guess he just wanted to check it out. He did not realize it had just came out of the car. It burnt the shit out of him, i had to laugh. Heres your sign.

[Infomaniac]

Now aren't the clutchings and ignitions computer-controlled as have been referenced above? I always supected so but never knew.
Nope no computer controls. They are computer monitored. They do have pneumatic controls that are on timers. Activated by the driver leaving the line. Things happen in a timed sequence from there regardless of what happens to the car.
The clutch levers do work off of centrifugal force but on a fuel car the "cannon" only lets the throw out bearing move as much as set up with the pneumatic timer system. the feeler gage set up is the baseline "lever angle" setting. As the clutch wears during a run the lever angle changes as well.

[boatslayer]

what keeps them from poping wheelies is the wing on the front , i forgot the numbers but there is an enormous amonut of down force aon that front wing . and since they are excelerating so fast the down for is there as soon as the hit the gas

[Moneypitt]

The wheely problem is somewhat solved by those funny things sticking out the back of the frame with wheels on them. You will quite often see a crew member measuring the height just before a run as this data is not computer recorded. If the chassis climbs to high in the front the rear weight is supported by these funny looking things, and that will unload the tire, causing tire spin and the front will come back down. Of course this spoils the run so the height is critical to proper traction. What do you suppose they call those things sticking out the back???..............MP

[Taylorman]

The wheely problem is somewhat solved by those funny things sticking out the back of the frame with wheels on them. You will quite often see a crew member measuring the height just before a run as this data is not computer recorded. If the chassis climbs to high in the front the rear weight is supported by these funny looking things, and that will unload the tire, causing tire spin and the front will come back down. Of course this spoils the run so the height is critical to proper traction. What do you suppose they call those things sticking out the back???..............MP
Ok im not that dumb. Wheely bars of course. I do know a little about this stuff, im just trying to get a little more technical knowledge on how these cars run and operate. I just dont see how they leave so fast and the front wheels don't leave the ground. Even the pro stock cars lift the front tires on takeoff.

[BIGJOEDUCKSLAYER]

LEVERAGE HAS SOMETHING TO DO WITH THIS,NOTICE HOW LONG DRAGSTERS ARE.FUEL AND EVERYTHING ELSE THEY CAN GET TO FRONT OF CAR WITH OUT TO MUCH WIEGHT KEEP FRONT DOWN ALSO,CLUTCH SLIPPAGE ASLO KEEPS FRONT DOWN. PROSTOCK MOTOR MAKE A BUNCH OF POWER BUT NOT NO WHERE NEAR WHAT A TOP FUEL DRAGSTER MAKES SO THEY DO NOT SLIP CLUTCH LIKE DRAGSTERS.PROSTOCK CARS ARE ON WHEELIE BARS A LONG WAY DOWN TRACK BEFORE AERODYNAMICS KICK IN AND FORCE CAR DOWN. :crossx:

[TBONE1904]

basicly your flooding your cylinder with so much fuel , It cant ignite - the alky car i get to help with every once in a while will burn right around 3 gallons in a quarter mile .
Im curious what the setup is on the engine your speaking of. My engine builder says I will be fine with my 2 gallon tank I just bought!!! I am running a super gas and C or B gas car. I am hoping the engine your speaking of is blown or ?

[TBONE1904]

Nope no computer controls. They are computer monitored. They do have pneumatic controls that are on timers. Activated by the driver leaving the line. Things happen in a timed sequence from there regardless of what happens to the car.
The clutch levers do work off of centrifugal force but on a fuel car the "cannon" only lets the throw out bearing move as much as set up with the pneumatic timer system. the feeler gage set up is the baseline "lever angle" setting. As the clutch wears during a run the lever angle changes as well.
I am blessed to be around my dads friend Chuck Beal (Top Fuel Funnycar) and Infomaniac is correct all the clutch settings are pneumatic, but are monitored by computers. Dropping a cylinder on the burnout or launch when the tires spin is because of rev's. The only anology I can think of (Im enjoying cocktails by the way) is pumps, when there is no water (unloaded) they spin way to fast and usually burn up the motor thats why you dont run a pump too long unloaded. Cavatation is a different phenomenon that burns up pumps. To be competitive in pro NHRA classes the engine is on the edge of blowing up everytime while loaded, so when its unload there are multiple things going haywire! An engine runs based on a serious of events happening in a specific order. If that order is altered bad things can happen. On a top fuel car you have so many different components on the ragged edge trying to go in sink, when you unload the tires at high rev's it throws the order off. It could be the exhaust valve not opening quick enough, something in the rotating assembly breaking, etc. The point I am trying to make is there isnt one cause of every engine failure in top fuel classes

[TBONE1904]

Ok im not that dumb. Wheely bars of course. I do know a little about this stuff, im just trying to get a little more technical knowledge on how these cars run and operate. I just dont see how they leave so fast and the front wheels don't leave the ground. Even the pro stock cars lift the front tires on takeoff.
lol...One interesting phenomenom is a back halved car will pull the front wheels much higher than a tube car! The reason is time with the front end in the air is time you lost. Think of the 3 pro classes well actually 4 if you count the bikes from pro stock to top fuel dragster as progressions. I will say it Top Fuel Funny car is way harder to drive that a Top Fuel Dragster even though the dragsters are faster. Short wheelbase cars have more trouble handiling power than longer wheelbase cars. BIGJOEDUCKSLAYER made some great comments the moment of inertia to raise the front wheels on something longer requires more work. Horsepower is work. Pro Stock and Fuel cars are very different in the setup and really cant be generalized together. Acceleration is the most complicated act. Fuel cars have more power than they can ever (currently atleast) transfer to the ground standind still. That is why the clutch setup on a fuel car is how you win, so....Top Fuel Cars chassis length is based on trying not to lift the front wheels, however if they hook better than normal they will pull the front wheels a bitchassis