A question about top fuel cars?
Discussion
a question that is intrigueing me if anyone can help, just before a top fuel car goes into stage the engine note changes and goes quieter, I've seen a helmet cam vid on youtube and the driver pulls a lever on his left hand side that appears to cause this change.
can anyone enlighten me as to what this is for?
can anyone enlighten me as to what this is for?
actually i the fact that the driver gets his foot of the clutch makes the RPM drop i guess 
in pre stage the clutch is still disengaged, you can also hear it when they're backing up from the burnout. When the car starts moving you hear the engine note change, thats when the driver engages the clutch, after that he disengages it again to keep the heat out of the clutch.
in pre stage the clutch is still disengaged, you can also hear it when they're backing up from the burnout. When the car starts moving you hear the engine note change, thats when the driver engages the clutch, after that he disengages it again to keep the heat out of the clutch.
As mentioned earlier, it's the extra fuel volume that alters the engine note of a fuel motor once they're in pre-stage and the second pump gets switched on. There's a similar change in note with a A Fuel alcohol dragster too, they don't add a fuel pump, but they up the fuel pressure in pre-stage.
Darkpino said:
actually i the fact that the driver gets his foot of the clutch makes the RPM drop i guess
in pre stage the clutch is still disengaged, you can also hear it when they're backing up from the burnout. When the car starts moving you hear the engine note change, thats when the driver engages the clutch, after that he disengages it again to keep the heat out of the clutch.
How do you back up from the burnout with your clutch disengaged? in pre stage the clutch is still disengaged, you can also hear it when they're backing up from the burnout. When the car starts moving you hear the engine note change, thats when the driver engages the clutch, after that he disengages it again to keep the heat out of the clutch.
Like i said. Take a youtube movie and listen to the engine note. When it stands still, then when it starts moving. You hear the engine note change till it moves and then it changes again to the normal engine note...
I know in this case what i'm talking about :P
Some teams you see pushing the car into the water box, thats also to keep the heat out of the clutch..
I know in this case what i'm talking about :P
Some teams you see pushing the car into the water box, thats also to keep the heat out of the clutch..
Darkpino said:
Like i said. Take a youtube movie and listen to the engine note. When it stands still, then when it starts moving. You hear the engine note change till it moves and then it changes again to the normal engine note...
I know in this case what i'm talking about :P
Some teams you see pushing the car into the water box, thats also to keep the heat out of the clutch..
The original question was about engine note in pre stage and stage, not during the pass. I know in this case what i'm talking about :P
Some teams you see pushing the car into the water box, thats also to keep the heat out of the clutch..
I wasn't talking about the pass either.
When in prestage the drivers pulls the fuel to the high side, a top fuel engine has 2 fuel pumps and before the pass both pumps are working only for 50%.
Then when he pulls the fuel to the high side he also gets his foot of the clutch pedal and puts it somewhere secure (his foot).
So thats what changes the engine note, the engine gets more fuel and the clutch starts dragging which makes the RPM drop...
When in prestage the drivers pulls the fuel to the high side, a top fuel engine has 2 fuel pumps and before the pass both pumps are working only for 50%.
Then when he pulls the fuel to the high side he also gets his foot of the clutch pedal and puts it somewhere secure (his foot).
So thats what changes the engine note, the engine gets more fuel and the clutch starts dragging which makes the RPM drop...
Darkpino said:
I wasn't talking about the pass either.
When in prestage the drivers pulls the fuel to the high side, a top fuel engine has 2 fuel pumps and before the pass both pumps are working only for 50%.
Then when he pulls the fuel to the high side he also gets his foot of the clutch pedal and puts it somewhere secure (his foot).
So thats what changes the engine note, the engine gets more fuel and the clutch starts dragging which makes the RPM drop...
I see, thanks for the explanation.When in prestage the drivers pulls the fuel to the high side, a top fuel engine has 2 fuel pumps and before the pass both pumps are working only for 50%.
Then when he pulls the fuel to the high side he also gets his foot of the clutch pedal and puts it somewhere secure (his foot).
So thats what changes the engine note, the engine gets more fuel and the clutch starts dragging which makes the RPM drop...
i always love this video demonstration of Top Fuel flow
http://www.youtube.com/watch?v=xGTbQuhhluY
think of 8x that much fuel pulling the rpm down
http://www.youtube.com/watch?v=xGTbQuhhluY
think of 8x that much fuel pulling the rpm down
Thanks for the info guys, that's definitely answered my question and makes sense the engine note changing with extra fuel and the clutch engaged. When I get home i'll post the you tube clip I was watching as the driver is almost constantly adjusting the fuel seemingly with a lower fuel pressure at startup right up to full pressure just before launch.
Thanks again :-)
Thanks again :-)
k's that, then? Sorry, couldn't resist :-)
this was the vid I was watching, I now understand more of what is going on, thanks guys
http://www.youtube.com/watch?v=gb2vf_ZYFMo
http://www.youtube.com/watch?v=gb2vf_ZYFMo
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