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A Top Fueler’s roots supercharger takes as much as 1200 hp to turn at maximum output or about what a built to the hilt 2JZ will do and produces over 80 lbs of boost.  The blast from the exhaust headers alone produces over 1200 lbs of downforce or about twice as much as all of the Cyber EVO’s wings splitter, canards and diffusers together, making a substantial contribution to traction at the big end.

cyber evo

The fuel system for Top Fuel engines is pretty interesting.  The rules prohibit computer controlled engine controls so the fuel mixture is controlled by a complex series of pneumatic valves and electro-mechanical timers which progressively add fuel in stages as the car travels down the track.  Electronic traction control is illegal so the clutch acts like a traction management system.  The clutch pressure plate has multi-stage engagement where its amount of slip is varied by the activation of many sets of borg and beck type fingers with progressively higher and higher clamp loads. The clutch fingers are also controlled by a similar complex array of electro-pneumatic valves and timers so the power can be put down progressively as the car moves down the quarter mile. Tuning the fueling and clutch engagement progression is critical for a fast run as is an art in itself. 

Containing all of this violence is difficult and running it takes a large amount of people doing a precisely choreographed dance that must be done without error or hesitation, any deviation from the drill results in bad things happening, really bad things, all of which are expensive and some can result in serous injury and even death.

explosion

We had the privilege of being part of the crew that accompanies the car to the burnout box.  The experience was pretty scary because there is a complicated check list that the crew must do with precision and discipline to just simply stage the car.  Nearly any deviation from this procedure results in the engine blowing up spectacularly. It went something like this.  As the car is pushed to start line behind the burnout put and the body is lifted.  The car is started on methanol with a squirt of gasoline into the butterflies to help it light off initially.  If too much gasoline is squirted in start up, the car will explode.  The engine is cranked over by a huge electric motor, powered off of the support trucks electrical system that is inserted in the blower drive.  The engine is cranked and hopefully starts, when it starts the motor is removed. 
Once the engine fires up and develops a somewhat stable idle, the crew chief switches the master fuel control from its rich start position to lean. If he forgets this step the engine will blow up in seconds. If the driver fiddles with the throttle the slightest bit here, the engine will blow up as well. The crew lowers the body and the driver has to proceed to the burnout box fairly quickly due to the engines lack of cooling system, any dawdling here will cause the engine to blow up.

top fuel explosion

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Comments

jere
# jere
Wednesday, March 03, 2010 9:15 PM
Wow! That is crazy. I had no idea about how easily those things blow up. How much does one run down the track cost? (one without the engine blowing up ;)
8695Beaters
# 8695Beaters
Wednesday, March 03, 2010 10:01 PM
I read HOTROD magazine (probably one of the few here who do, but every once in a while there is some very good info that comes through that mag) and a few months ago they made up a list of 101 things ANY car guy should do before they die. One was stand between two Top Fuel cars at the starting line. My dad took me to an NHRA event when I was 6 and I don't remember much, but I do remember moving to half track (after sitting at the starting line), because the sound was too much for me. I can't wait to go back.

Isn't it something like $75K a run? They basically rebuild the entire engine from the bottom up with brand new parts after every run. What amazes me is they do all that in 70 minutes. It's so cool watching them tear apart a motor in mere minutes. If it weren't for SAE West, I would try to make it to Englishtown this year.

Oh and a moment of silence for the Phoenix NHRA fan who was killed a few weeks ago. It is a very dangerous sport.
MTSB
# MTSB
Wednesday, March 03, 2010 10:28 PM
Cool post. I go to the Vegas drags every year in both April and October. Last year I learned a lot about the motors when talking with a guy from Autolite/Fram. Believe he said he works specifically in spark plug development.

Dynos do exist that can measure more than a top fuel can put out. The issue is that the motors cannot run long enough to do a dyno run without blowing up.
DieselTech
# DieselTech
Wednesday, March 03, 2010 11:36 PM
So if the fuel system needs no throttle plates why do they have butterflies on the scoop? To help starting?
Street Surgeon
# Street Surgeon
Thursday, March 04, 2010 6:04 AM
Cool article, like the others I had no idea how close to the edge these motors were. Seems like if you even look at it funny they might blow up, much like my DSM's :D
MTSB
# MTSB
Thursday, March 04, 2010 8:44 AM
Another way they can blow up is by running out of fuel. Every NHRA race has the same starter, Rick Stewart. He runs a stop watch at the line to monitor how long the cars are running before they make the pass. If they take too long and there is a risk that they have burned up too much fuel he will not start the race.



Look for him next time you are watching in person or on TV. Always has a straw hat on and is looking at his stopwatch.
Mike Kojima
# Mike Kojima
Thursday, March 04, 2010 9:22 AM
I think thats more because of a rule about staging wars. I think you can only stall so long under the rules. I know the NHRA came up with a bunch of rules at are supposed to reduce engine failures and oil downs that screw up the show for spectators and mess up tv scheduling, like limiting the amount of nitro. Notice that Top Fuel cars are not as loud anymore?

I think the throttle valves are more for idle control and engine run stability than actual engine speed control.

A Top Fueler has only two throttle positions, closed and wide open. Ever see the show Jesse James must Die where he kept on blowing up the top fuel bike because he kept trying to modulate the throttle?
1984
# 1984
Wednesday, March 31, 2010 5:08 PM
Mike, "This craziness creates an intensity for the crew which can only probably be equaled by the deck crew on an aircraft carrier recovering planes. At night. During a storm. While under attack from enemy fire."

Sorry man, your analogies go way too far sometimes. I'm sure any veteran that has gone through what you described would tear you a new asshole.
Mike Kojima
# Mike Kojima
Wednesday, March 31, 2010 6:11 PM
You are right, I have never been on the deck crew of an aircraft carrier but I have been on the crew of a Top Fueler. One of my best friends is a vet that was a deck crew chief. He has told me many stories on what goes on the flight deck and what can happen.

From your comment, I am sure you have never been working close to one these cars either. What I wrote was from my notes from interviewing the crew chief and driver of this car as well as other chiefs and drivers.

Before I could take part in the drill they had to carefully brief me and we had to do several dry runs for safety. Adhering to the drill was drilled into my head because the consequences of doing something incorrectly, even the slightest thing is pretty high. There are many ways to ruin a lot of expensive equipment and get hurt around one of these cars.

So think what you want. I actually was there and did it.
1984
# 1984
Thursday, April 01, 2010 3:37 PM
I've never worked closely with a NHRA dragster. The closest I got was behind the barrier at the starting line. I'm not denying you did what you did and that NHRA racing can sometimes be dangerous. I've just never heard of a high rate of injury or death for the crew. It is usually the driver that gets injured or has a fatal accident. I just didn't see the similarities between working on a dragster crew and being on an aircraft carrier, in a storm, trying to recover aircraft, while having the enemy shoot bullets and bombing you. I have been in neither situation but it just seems logical to me that the latter would be way Way more dangerous than the first.
1984
# 1984
Friday, April 02, 2010 8:30 PM
I've seen a documentary that was specifically about what goes on on a flight deck with interviews from all the people, top to bottom. I admit it is a dangerous job for the deck crew. But from what information I could find, the last US aircraft carrier that was attacked was in world war two. So I guess your friend must be pushing 100 years old in order to have experienced your statement.
Mike Kojima
# Mike Kojima
Friday, April 02, 2010 10:40 PM
If you whant to read whatever you think into whatever I write then what can I say.
Miata Phil
# Miata Phil
Sunday, September 04, 2011 2:45 PM
I recall my first time around Top Fuel cars. We heard a huge explosion from the parking lot, and watched the shock wave spread out from the stadium, setting off car alarms as it went. You could see the dust cloud and the gravel in the parking lot shake as it pushed through, and feel it in your ears and chest. When we got to the stadium and asked what happened, someone calmly replied that a head gasket blew. That was my first indication of the incredible power and force being contained in those cylinders and being described here in this article.

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