My first ever dragstrip experience/timeslips - Page 2 - Chevelle Tech
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post #16 of 90 (permalink) Old Jun 8th, 20, 1:21 PM
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Re: My first ever dragstrip experience/timeslips

I call that a very successful day. My first day at the track was 15.34 and I thought I was tearing it up. That was in a '58 Impala.
You should be quite happy but now is when the addiction begins.

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post #17 of 90 (permalink) Old Jun 8th, 20, 1:23 PM
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Re: My first ever dragstrip experience/timeslips

Something is off....that MPH and ET don't show anywhere near 680 Hp unless the car weight is 5200 lbs.

At 4000 lbs for a fully loaded '72, it is only showing you 540 Hp flywheel, maybe 470 Hp at the wheels.
if it really is 3600 lbs, its even worse....465 Flywheel Hp and 435 wheel Hp.

Gearing will effect ET, but it won't effect MPH much....MPH is almost completely dependent on vehicle weight vs power regardless of gearing.


the 60' id good for a street driven car....but total HP is sorely lacking somehow. Time to do some serious carb, ignition tuning. seems to be WAY down on power unless the dyno was a lie.

What size/brand carb, and what are your ignition timing specs...initial, total mechanical advance, what RPM is total advance reached??

what's the exhaust system consist of?? Header primary tube size and length??
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post #18 of 90 (permalink) Old Jun 8th, 20, 1:31 PM
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Re: My first ever dragstrip experience/timeslips

No matter what the numbers and weight of the car is, what's important here is having fun with your car and form the looks of it he sure did. Good job on your first day out. I remember my first day the car ran 17's and I thought it was a rocket ship.
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post #19 of 90 (permalink) Old Jun 8th, 20, 2:10 PM
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Re: My first ever dragstrip experience/timeslips

Good to get back to the dragstrip - good start here. What size exhaust (out the back side etc.) are you running? Or were these times above done with open headers. What fuel pump set up are you running? I think you got some more potential mph there but wanted to see if anything might be holding you back.
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post #20 of 90 (permalink) Old Jun 8th, 20, 2:10 PM
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Re: My first ever dragstrip experience/timeslips

As long as its not broken it was good day. You can make a running car faster. Can't do much when it doesn't run!!! And yeah, there is a lot that can be gone through. The car right now has 10.90 mph, and once you figure that out I'm sure it will go faster than that.
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post #21 of 90 (permalink) Old Jun 8th, 20, 3:01 PM
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Re: My first ever dragstrip experience/timeslips

Nice shakedown outing for sure! Post your full time slip so the real racers can see the incrementals. You might get some better guidance yet.

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post #22 of 90 (permalink) Old Jun 8th, 20, 3:11 PM
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Re: My first ever dragstrip experience/timeslips

Folks...it was the OP's first time out. Let me him breathe a little bit.

Yes.....that MPH is not indicative of the claimed HP.....but he's made three or so passes.

Give the guy some time.

There's definitely more in this combo.....but that doesn't mean it's not fun as is.
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post #23 of 90 (permalink) Old Jun 8th, 20, 3:44 PM
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Re: My first ever dragstrip experience/timeslips

Great first time out for sure! Lots of potential I am sure.

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post #24 of 90 (permalink) Old Jun 8th, 20, 4:19 PM
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Re: My first ever dragstrip experience/timeslips

Quote:
Originally Posted by blue_69_malibu View Post
Folks...it was the OP's first time out. Let me him breathe a little bit.

Yes.....that MPH is not indicative of the claimed HP.....but he's made three or so passes.

Give the guy some time.

There's definitely more in this combo.....but that doesn't mean it's not fun as is.
Street cars almost always run more MPH than their ET would suggest. They aren’t optimized race cars, the vast majority compromise when it comes to converter, gears and suspension.

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post #25 of 90 (permalink) Old Jun 8th, 20, 5:34 PM
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Re: My first ever dragstrip experience/timeslips

The reason I asked the questions is there may be some low hanging fruit. Sometimes the engine does well on the engine dyno and it goes to the track and something comes up because a part of the car was not ready for the new motor. I had this experience myself back in 1990 when I had this really good 454 and I could not figure out why the mph was not faster (or get any faster). I decided to unhook the exhaust and - Shazam - I picked up .5+ second and 5 mph (113 to 118). Well I realized my 2.5 inch non-mandrel bent muffler shop (you know the ones that get crinkled in the machine down to like 2 inches) that went all the way back to the bumpers was an issue. Next week put on a 3 inch system and bigger mufflers and was able to narrow the delta down to 1 mph and .1 second. Sort of a double hit as the motor was tuned on the engine dyno for a free flowing exhaust thus the exhaust was restrictive and it was also running rich. I also agree with OP and others seat time helps and just getting it out there with some pretty good runs is great.
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post #26 of 90 (permalink) Old Jun 8th, 20, 5:45 PM
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Re: My first ever dragstrip experience/timeslips

121 mph with 28" tire and 3.50 gear is less than 5600 rpm even with 10% converter slip, you need to raise your shift points up as you said, you might want to raise the fuel levels in the bowls and use a pump cam that delivers later as you are at part throttle when you leave. 680 HP needs fuel volume I assume you have some type of upgraded fuel pick up from the tank?
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post #27 of 90 (permalink) Old Jun 8th, 20, 7:17 PM
 
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Re: My first ever dragstrip experience/timeslips

Im not trying to hi jack this thread but I have a question? if he made max torque at 4900 and max HP at 5900 wouldn't you set the shift point a 500 rpm more than the max torque since the HP is a calculated number?
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post #28 of 90 (permalink) Old Jun 8th, 20, 7:22 PM
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Re: My first ever dragstrip experience/timeslips

drag race isn't a tractor pull, HP makes the time lower
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post #29 of 90 (permalink) Old Jun 8th, 20, 7:41 PM
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Re: My first ever dragstrip experience/timeslips

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Originally Posted by SteveDeluxe300 View Post
Im not trying to hi jack this thread but I have a question? if he made max torque at 4900 and max HP at 5900 wouldn't you set the shift point a 500 rpm more than the max torque since the HP is a calculated number?
no

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post #30 of 90 (permalink) Old Jun 8th, 20, 8:22 PM
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Re: My first ever dragstrip experience/timeslips

If you're crossing the line at 4800 rpm, you're effectively leaving power on the table by ensuring your engine never makes full power in 3rd gear at all. Traction permitting, you'll absolutely run quicker and probably faster with gears that have you at or just above hp peak rpm as you cross the finish line. That said, you may not want to make that compromise for a street car. Lots of really good suggestions from other folks-remove front swaybar, etc.

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