Blip of the throttle (1 Viewer)

[Crew Chief Pro]

It hurts pistons if it isn't tuned correctly. Many of the teams will go on the high side and raise the rpm slightly to seat the clutch. Saves parts that way.

I love it, nothing makes your hair stand on end like a fuel snap.

 

[Nitrohelper]

It hurts pistons if it isn't tuned correctly.

What would it hurt on the pistons?

 

[nick name]

It hurts pistons if it isn't tuned correctly. Many of the teams will go on the high side and raise the rpm slightly to seat the clutch. Saves parts that way.

I love it, nothing makes your hair stand on end like a fuel snap.

And what exactly gets seated on the clutch and why is it necessary?

 

[twostep]

And what exactly gets seated on the clutch and why is it necessary?

According to this publication (Dick LaHaie talking), it's to remove microscopic high spots on both the clutch discs and floater plates. This is a good read, by the way.

Top Fuel Dragster - Google Books

 

[Toby]

When the clutch disk is 'cut', the surface is straightened out but leaves a vinyl record like surface. It used to be Top Fuel guys wanted to eliminate this and 'seating' the clutch became the thing to do for about everyone. I worked on the Winston team from 98-2001. We didn't hit the throttle but Alan would lean into the throttle for a couple seconds. After one warmup we took the clutch out and realized we weren't doing ourselves any favors. Right towards the end of the Winston days, we started moving away from it.
Now Alan just puts the pumps on the high side and has the driver take his foot off the clutch with the brake still applied to calculate the 'tug'. That is the average engine rpm with the clutch in vs clutch out and brake applied.

It took a couple runs to learn how much softer the clutch was at the hit. If you watch a PS team, they cut the disks after every run to straighten it out and also to introduce the grooves into the clutch surface again. I ran a Comp eliminator clutch dragster for a while. I didn't have the time between runs to surface the clutch. I would have to compensate for the clutch after the first run on a surfaced clutch because it would be more aggressive. Just because there was literally more surface area of the clutch disk against the floater.

 

[nick name]

When the clutch disk is 'cut', the surface is straightened out but leaves a vinyl record like surface. It used to be Top Fuel guys wanted to eliminate this and 'seating' the clutch became the thing to do for about everyone. I worked on the Winston team from 98-2001. We didn't hit the throttle but Alan would lean into the throttle for a couple seconds. After one warmup we took the clutch out and realized we weren't doing ourselves any favors. Right towards the end of the Winston days, we started moving away from it.
Now Alan just puts the pumps on the high side and has the driver take his foot off the clutch with the brake still applied to calculate the 'tug'. That is the average engine rpm with the clutch in vs clutch out and brake applied.

It took a couple runs to learn how much softer the clutch was at the hit. If you watch a PS team, they cut the disks after every run to straighten it out and also to introduce the grooves into the clutch surface again. I ran a Comp eliminator clutch dragster for a while. I didn't have the time between runs to surface the clutch. I would have to compensate for the clutch after the first run on a surfaced clutch because it would be more aggressive. Just because there was literally more surface area of the clutch disk against the floater.

Thanks, Toby. When I asked the question, I was wondering if I'd get an answer from someone who'd been part of a Pro team who'd be able to explain the variables along with why most teams don't do this any longer.

When I first started racing Pro Stock, the drill was to dial in more clutch on every pass the assembly remained in the car. I don't know for sure who was the first to take a scientific approach and service each round but would guess it was either Larry Morgan (who was working very closely with Frank Carstensen and AFT) or Warren.

We were right there too (Ash & Worden) and were literally laughed at for doing all that extra "useless" work. The laughing stopped pretty quickly after the team (due to some very strong talent) was able to show up from time to time, qualify well, and go rounds.

I guess I picked up on the original statement since I've seen a bunch of times when "but everybody does it" has been counterproductive. I would not begin to second guess any of the legends of the sport but have no hesitation in pointing out that the laws of science and physics still hold true.