On drag cars with the three-hole scoops on top of the blower (or carbs) I'm curious as to why the butterflies in the scoop don't open at all while the driver is warming the tires.
It's obvious why they flip all the way open when the light turns green.
What am I missing?

On the blower cars they're opening, just not much. Cracking the blades slightly on a Birdcatcher will allow a LOT of air in, planty to heat the tires or do a burnout.

Jody

There is a "limiter pin" in the throttle linkage that prevents the throttle from fully opening during burnouts - if you watch closely you will see the crew-chief walk up to the car, after the burnout and back-up and prior to the pre-stage, to check out the motor (leaks, noises & etc.) and remove the limiting pin.

I remember the first top fuel event I went to and seeing the first Top fuel dragster do its burnout, I was impressed....My buddy then told me that was only 1/4 throttle. :eek:

Instead of removing a pin, I beleive the cheif is switching the fuel system to the "high side". The driver im most cases can do this via a cable from the cockpit, or did anyway in the late 80's when I was around them... I figure to save weight, cars may not be equipped with the cables and levers anymore. Many cheifs did this with their hands... a guy lost a finger this way in the team I hung around when it contacted the blower belt.
The cars warm up and do the burnout on the low side, this setting allows more fuel from the pump(s), rinnin' 'm rich is cooler and safer for the engine. They'll switch to the high side when staging, you can really hear the difference when they go lean.
They'll crack the throttle pretty good and back right off for fear of over revving \ lifting the blower, they do not require much power to keep 'em smokin, especailly when the burnout area has been wetted.

Top fuel is an awesome thing!!

Originally posted by 68ragtop:
Instead of removing a pin, I beleive the cheif is switching the fuel system to the "high side".

Top fuel is an awesome thing!! The "switch" (valve) was at the fuel block on the rear of the injector set-up on our's - that's why the 'chief's' hands go the rear of the blower also...
The throttle cable had a groove in it near where it entered the cable body, this is where the pin/clip goes to limit throttle cable travel to @25% during fire-up and burnout.
I was showed the clip by the chief before we started to stage...

Things maybe way different now - been out for a couple years -
But, YES! "Top fuel is an awesome thing!! "

John

The high \ low lever was located at the fuel pumps right in front of the idler pulley on the car I was around.
I was 15, and was a pit gopher, and cleaned a lot of parts, and sometimes helped mix fuel. I mainly caught east coast races during summer vacation from school.
Needless to say, it was quite a rush!!

I remember Don Garlits opening and closing the throttle in rapid succesion during his burnout, for no apparant reason..

When he was almost done with the burnout, he'd "blip" the pedal about 10 times. Wa Wa Wa Wa Wa Wa... Does anyone remember that?? I think it was Swamp Rat XXXI (around the time of the backflip in e'town) Some beleive he was just trying to see if any one would copy him... a few did.

We lifted a blower during a burnout...(pre blower blanket days) perhaps it would have helped if the throttle was limited...

John, what car were you with and when?

I was around the Mr. Boston and then the King and Marshall cars 1984 to 1986 or so...

Alrighty... got it. Makes sense to me now.
I knew what the crewchief was doing after the burnout as far as the fuel goes. But I couldn't figure out why they'd only allow so much air in while doing the burnout.
Now I know.
graemlins/thumbsup.gif

Actually your all wrong. These are Hybrid top fuel cars. They do their burn out using an electric motor. After the burn out the crew chief reaches over and flips the batteries off and turns on the Nitro.

Hey it costs a lot to race these days. graemlins/clonk.gif

Wacky

I agree it is the pin and that is why they show it to the driver. I have never worked on a TF car but, that is my understaning of what happens. They also go from the low to the high side on the fuel circuit. Cool Stuff.

Originally posted by 68ragtop:

John, what car were you with and when?

I was around the Mr. Boston and then the King and Marshall cars 1984 to 1986 or so... 68rag;

I grew-up (well maybe...) on the 'left' coast around the L.A., Orange Co. and Huntington/Long Beach area. I began getting my sore teary eyes a few years earlier than you I quess - in the late 60's thru early/mid 70's. I crewed on several cars (Beachcomber and Destroyer Jeep) before I qualified for my license on Eddie Wilson's So. Cal. Dodge Dealers TF car. We were "show fillers" usually - but I got my share of "wins" - if they broke...
I was fun times, with only marginal pain involved - unlike some of my other vehicular and vessel based endevors... I am a firm believer that 'Speed does Not Kill' - it's some of the sudden stops that get you.
(hey - why are my ribs sore just writting this?)

I don't do much in the way of competion any more. But, I do have a couple of old "been there" time slips laying around here.
I may have gotten to old to run away - but I like to think I've learned were I shouldn't be in the first place...
( quote by 'Camaroman...")
"They also go from the low to the high side on the fuel circuit."
'Zackly' ! - about a fraction of a secound after the tree goes green (hopefully)... :eek:

A fun post;
John

[ 05-18-2004, 06:20 PM: Message edited by: Vintage 68 ]