launch rpm

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motorhead446

motorhead446

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What's your launch rpm? I have a
Duster with iron head 440/727 4:30 gear 28" x10 tires. Spool all together 11.77-11.90 et with 60' times around 1.58 1.60. My converter is a turbo action 3800 stall, 11". Ive been launching at 1500-1900. Id like to experiment with higher launches, any suggestions?
 
Trying going up in 100 rpm increments and keep an eye on your 60 foot. The car will tell you what it likes or doesn't like.
 
I'm curious as to what you want to accomplish? I'm guessing you're foot braking? If you're running brackets and trying to be competitive, just slightly play with a few hundred rpm's and your staging depth to get the best reaction times that you can comfortably repeat over and over. That's where these races are won.

If you just go out to make some quick runs and have fun, as long as you have good bite and good brakes, i'd try loading that baby up as hard as you can against the converter a few runs and see what happens?

Your flashing the converter now, and that usually gets you the most stall, but depending on how well your chassis works, going hard and preloading everything may get you a little more 60' and et. I've run a few 12sec cars with moderate converters similar to yours and got the best times loading them hard. It really depends on what your after and how the car's setup works. Most cars react differently, so just give some things a try.
 
OldmanRick said:
I'm curious as to what you want to accomplish? I'm guessing you're foot braking? If you're running brackets and trying to be competitive, just slightly play with a few hundred rpm's and your staging depth to get the best reaction times that you can comfortably repeat over and over. That's where these races are won.

If you just go out to make some quick runs and have fun, as long as you have good bite and good brakes, i'd try loading that baby up as hard as you can against the converter a few runs and see what happens?

Your flashing the converter now, and that usually gets you the most stall, but depending on how well your chassis works, going hard and preloading everything may get you a little more 60' and et. I've run a few 12sec cars with moderate converters similar to yours and got the best times loading them hard. It really depends on what your after and how the car's setup works. Most cars react differently, so just give some things a try.
Click to expand...

Im mainly trying to improve my ET. The last time out my et improved to nearly what it used to be 10 yrs ago when i raced. I used to run 11.68-11.70 consistently. The car basically sat for 10 yrs. I added weight with wheels and tires, glass windsheild and my gut. I also changed carb from an 830 holley dp to a 750 mighty demon, dist from mallory to msd pro billit and msd wires. last out i ran 11.79 off the trailer, and broke out in rd one with a 11.77 on an 11.82 dial.

I suppose my concerns are that by loading up the suspension hard will not allow it to work as well.
 
so you added weight to your hotrod and yourself then put on a smaller carb. plus let it sit for 10 years and you expect it to run as hard as it did. ok I got that but your thinking may have to be revisited.
 
OldmanRick said:
Your flashing the converter now, and that usually gets you the most stall, but depending on how well your chassis works, going hard and preloading everything may get you a little more 60' and et. I've run a few 12sec cars with moderate converters similar to yours and got the best times loading them hard. It really depends on what your after and how the car's setup works. Most cars react differently, so just give some things a try.
Click to expand...

motorhead446 said:
I suppose my concerns are that by loading up the suspension hard will not allow it to work as well.
Click to expand...

Sorry, i should have said depending how well or not your chassis is working. The cars I was talking about were stock street suspensions with V8 T-bars, stock shocks, etc. (meaning stiff). Just factory stuff with slicks bolted on.

That's why I said give it a try. We'll never know on paper or a screen, only the track will tell. :D
 
I was told yrs. ago if you have a good converter you should not need to bring it up agianst it that's the pont in getting one in the frist place.its to shock the chassie like a clutch.and if it wasn't you need more converter.were ever your converter locks up should be around 1000 rpms.above were your cam starts making power.how do you check your stull speed well drive along at around 30mph.and in high gear.(asoming you have a manual shift valve body) let up on the gas pedle then stand on it watching tha tic and were ever you see the tack stop and start pulling the car that were your converter is locking up....I have know a lot of big time racers in my time that didn't know that.sorry if I steped on any toes I did not read all the coments on this.but Im sure there are a lot of good racers on here that has already ansered your Qustion. all of this is assuming you have a car that is working and just because the coverter says its a 35 or5500 stull dosent mean it is unless its a costum vert for your car and that a nuther ball game.be safe and think before you stab it....Artie
 
well I finally read all the post and as they say.or like I said a lot of good racers on here.the only thing I disapprove of is your choice of carb.I call them wheel chocks.haha another thing is I have had cars set over the winter inside and unheated shop and accumulate rust under the valves to where it took about 2 or 3 races to clear up......hope this helps you Im back quite .......Artie :lurk::lurk:
 
The more "general use" a car - the harder it is to make it repeat and work. meaning the convertor you have is not a drag race convertor, so it will not be as consistent in high gear especially. I agree with everyone - you have to play around and fill in a log book to see what works. A friend with a video camera at the starting line helps too when you look at loading the suspension. I found with mine, almost the same stuff from the sound of it, that it liked to be on the brakes and brought up to 2500, then floor it. It would stick the tires and go. Any lower or higher and it would hit the tires too hard (early design Hoosier Quick Times) and spin a turn ot two.
 
Thanks for the input. I should have added also that I have ss springs, CE adjustable shocks, small block torsion bars. The rear housing is braced, 4:30 gears. MT et street radial 275 60 15 tires. Msd 6al ign. Next time out I'll just try stepping up rpms until I find the sweet spot. I suppose my initial question I was trying to see if I was way off with my launch. Thanks again.
 
after a bit of testing I have found that my car likes 2200 rpm, 18 psi tire pressure( M/T ET street radial). It ran 11.77(poor burnout) 11.71, 11.69. 11.67 at norwalk this weekend. It seems to be where it used to be. Not really enough passes to say its consistent but i feel its getting there. I weighed in while there and found the car weighs 3450 with me in it, im 250. so, 3200lb iron headed 440 70 duster.
 
Have you tried more air pressure?

We've got cars going a bunch faster with the same tire running 20-22. They tend to like a bunch of air.
 
crackedback said:
Have you tried more air pressure?

We've got cars going a bunch faster with the same tire running 20-22. They tend to like a bunch of air.
Click to expand...
Id like to try more air, maybe at my local track or when we go to union grove in a few weeks to race with a friend in that area. Still tinkering with some other things like collector extensions, weight removal.
 
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