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foot brake launches

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Hurst390 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/20/2016 at 7:03pm
Originally posted by Rebel Machine Rebel Machine wrote:

I stall well below the converter's flash point and get stronger launches. My converter flashes at 3,200 RPM and I stall on the starting line at 2,000. No problem holding it back with discs.

-Steve-

That's what I would do is flash the convertor...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Feb/20/2016 at 7:28pm
Originally posted by Hurst390 Hurst390 wrote:


Originally posted by Rebel Machine Rebel Machine wrote:

I stall well below the converter's flash point and get stronger launches. My converter flashes at 3,200 RPM and I stall on the starting line at 2,000. No problem holding it back with discs.

-Steve-


That's what I would do is flash the convertor...


Maybe I am thinking all peeps do that, as it is common knowledge to be below flash, so when you do floor it everything engages when by the time you release the brake.

My thoughts of a line lock would be to have an RPM switch and solinoid or pneumatic release setup. Also better brake pads may help. Ceramics and Carbon Metallics may offer better grab if there are some available. OEM linings are a lot softer at grabbing than performance stuff.
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Hurst390 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2016 at 7:21am
line lock at the wheels don't work for a trans brake substitute
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pipefactory Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2016 at 7:22am
So far my fastest run is 10.99. That was foot braking and getting up on the converter until it was ready to skid the front tires. That run had a 1.50 60 foot. If I flash from idle I get about a 1.65 60 foot and the car slows to 11.20's. Also another strange thing, on the dyno my power dropped off at 6200 and shifting at 6200 and launching at high rpm foot brake the car goes 11.30's. On one run I didn't catch the shift light and shifted at 7200 that's when I hit 10.99. Makes me wonder if I should replace my 904's 2.74 1st gear with the 2.54 maybe my rpm's are dropping too much going into 2nd shifting at 6200. Any thoughts? PS I don't like 7200 rpm's as I am running stock steel rods although have light pistons.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2016 at 7:49am
Maybe try to come up to a few hundred rpm below the point of pushing through the beams and flash from there?
Yes you might want to raise your 1-2 shift point, maybe 6800?
Are you running a manual valve body now or stock?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2016 at 8:09am
Over revving the engine and it goes faster is a sign of too low a stall speed in the converter.

The quickest way down the track is to stay in the maximum power band, so you need to rev higher than the power peak so you don't drop too far down on the power curve after the shift.

But with a good converter you can narrow the operating power band and you don't have to rev the engine so high. Shifting at 6200 with a non race converter will drop the engine way down to about 3600, way low on the power curve. So it makes sense when you over revved the engine and it went quicker. But with a 5500 converter you would still be in the power band after the shift, and the converter can multiply torque again. Easier on the engine and faster; win-win. The wide ratio gear set in the tranny can get you into traction trouble when you have a good converter.

Of course the converter has to work right for this, and there is some real junk out there.


Edited by Ken_Parkman - Feb/21/2016 at 8:13am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 79redspiritgt Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2016 at 8:46pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pfordamx Quote  Post ReplyReply Direct Link To This Post Posted: Aug/24/2016 at 12:49pm
depending on what type of racing your doing could make the difference in whats legal if your just test and tuning and going for et get a transbreak and put a line lock on the rear wheels to prevent the car from rolling out of the beams from driveline slack, and another on the front for burnouts . i personally if your brakes work good on the top end, i'd be looking for a looser converter, lots of nhra stocker guys hold on the line just fine with 4 wheel disc but they do have loose converters. 8inch converters and i don't think the drivability will be hurt as bad as you think.
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