GEAR ?
 

dragster weighs about 1700 33.5 tires motor about 600hp,406,,60'120,finish 550 its not coming out of the hole real strong,it has a 433 gear in it now,,im leaving the line at 4800 and shifting gears at 6800,,i think i'm crossing the finish line at around 6200 not 100 %,,,? WHAT GEAR DO I NEED 456,488,,,,thanks steve

If ultimate performance is your goal, I would shift 5% over the RPM that peak horsepower was measured at on the dyno. The trap rpm should also be at least 5% over the peak horsepower rpm. I have to guess what your speed is based on the rpm you gave of 6200 and tire diameter 33.5 gives me a speed of 135 MPH currently at 6200 rpm. If you put 4.88 gears in it you will be at 6939 RPM going 135. If your guess on rpm in the traps is off and you go faster then the error is in your favor to get higher rpm's in the traps. I hope this gives you some info to decide what gear to use. 4.88's are going the right way unless your rpm guess is way off. Remember that this mechanical advantage will make you ET quicker and probably faster too so any increase in the MPH will make the rpm higher in the traps as well.
Bruce

i am guessing at what rpm is at the finish line,i tried looking but it small and don't have much time lol,my speed is 125 right now,,the dragster comes out kinda lazy and then about the time it hits second gear its like a rocket,my 60' is only 1.20 and 5.50 overall,,played with the timing a little,,not real sure there either,but 38 may be the best spot for it,,motor is great,sounds runs good,burn out real good,just needs help getting out of the hole,,,,thanks steve


p.s-i think there want be a big difference in the 456 gear,,433 and 456 is not much differences

How high you want to zing the motor ?

What brand of conv and is it a sprag or spragless ?

ptc 5800 converter,not sure if sprag or not,,,,6800 would be just about it on the motor,,thanks steve

Do you know what the stall flash is and the recovery after shift ?

I think 4:88 is to much, I used to run a 355 sbc that'd go 5.40s with a 4:10 gear and 60ft 1.15-6 no issue, took me 3 converter changes to get there though.

the guy who built my trans and converter says its not the trans or converter,go figure,,everyone else says it is not my motor,,so the guy that built my trans has a 456 gear that was only run one week at pinks,so i'm buying it for $150 and trying it,,i'm still saying it could be a tight converter,,,steve

I also agree on a tight converter :D You knew my thoughts already,
Example, 5400 stall flash way tight on mine 1.130 60ft, 5900 still tight but 1.065 60ft makes a huge difference. Remember you can tune some 60ft into it with the 4 link.

i'm going to put the 456 in it and give it a try before checking into the converter,,,i believe the converter is tight but he don't want to think so,,,it is a 5800 ptc,,i'm going to flash it on my car and see what it will flash,,he thinks my motor is weak and not making enough horsepower,i don't think so

my motor is a 400 30 over flat top pistons,670 something roller cam,eagle rods,eagle standard stroke crank(cast)brodix heads after all the angle milling and pocket porting there about 240 plus cc w/208 valves,100%new bearings(rod,main,cam,all new gaskets,brand new engine,,i'm thinking a 406 with about 600 hp,,,what you think,,its not my motor,,,,steve

I was done with this string after giving my earlier advice on gear but since you guys brought up the converter possibility this is what the numbers tell me. You have 33.5 tires if that is correct then the roll out is 105.24", next you have 4.33 gear ratio. You said that you are running 125 MPH at the stripe and guessed your rpm at 6200. If your converter had little slip like mine does at 4.75% or less, then the rpm WILL BE 5701 with these variables given at 125 MPH unless there is a denominator that is incorrect in the question. If you saw 6200 rpm that would be a bad sign for the converter for sure, not an opinion. If your stator was bad and I have had one bad right from new, which made the diagnosis challenging to say the least, My car drove off the starting line like a turtle then acted like it hit the bottle 50' out. This is sort of what you were describing at first. But the 6200 rpm does not wash no matter what, and by a lot. A 31 inch tall tire with a roll out of 100" will only net you 6000 RPM at 125 mph with a good converter slip ratio so I am saying that you know what tires you have, but the converter has to be south in a big way to give the high rpm you report at the stripe based on the MPH . I gave my gear ratio advice on my guess of 135 mph based on the info you were giving at that time exempting your MPH. It's NOT tight, its just about falling apart LOOSE ! and probably with a bad stator to boot.
I would mull it over a bit before the gear change..........
Bruce

Do this before ya change the gear, go out to the car pull the launch chip and stall it this way and see what it goes to. Do not hold it there for long ( but just see where it goes, this will not be the same as the track stall flash but will give us a idea. I still think its tight, a motor of that size/power can get away with 6200-6300 in a digger. This may save you the time and money or a gear change.

sorry but i already took it down to have the gear put in,,i took the center section to my trans builder,i went with a 456 gear,,i think the 488 would be a little to much for my rpm's,i want to stay under 7000 for sure,,i'm going to start leaving the line at 4400 or 4600 i think 4800is just a way to start spinning the tires,i want to shift at 6600 or 6400 and not 6800,i think 6800 is to much for a cast crank(eagle),i will flash it as soon as i put the gear and tires back on,


i could be wrong on the finish line rpm,but i am pretty sure it was either 6000 or 6200,,i think my friend has a tach were i can recall,maybe i can check it for sure this friday

another thing guys i forgot to mention,last friday the car ran a 5.50,5.52,5.55,,,took it back this weekend and ran a 5.87,5.78,5.71,5.71,,we change the timing from the first week,but after the 5.87 we started changing the timing to find were we was,i will say a lot of ppl were running a lot slower,just before we raced they cut all the rubber off the track and maybe put down to much vht,i'm hoping with the 456 gear and a better track and find a good timing,it will run a 5.40's,,,steve

ok put the 456 gear in it and took it to the track last night and it went 5.30's with a 1.17 60' ,,steve

so it gained only 3 in the 60 but gained 2 tenths after that ? What was the rpm change ? Conv flash, recovery after shift and weather better ? did you also check the gear and make sure it was a 4:10 and not a 3.90 ?
You want to help the 60ft more ? 4 link 4 link 4 link, car had a bb in before and is setup a bit different then a sb car, how many holes from the bottom is the top front bar ? Good to see gains for sure, but a lot fo the gear change you made.

Dave i should of said 5.39 that's in the 30's LOL,and that was hand shifting with no light just guessing were to shift at,the 2 step was shifting it way to soon,,but we dead locked the distributor and set the timing on 40,,weather was hot but did cool off when it got dark,not sure what your ? is on the gear,,the gear i had in it was a 433 and now i put a 456 in it,,the 4 link bar in the top front is in the fifth hole from the bottom,,and the bottom 4 link is in the second hole from bottom,,thanks steve

ah I got ya so a bunch of little changes may of affected it, any ideas why it was shifting so fast ? If you want a little more 60ft move that top front bar down 1 hole :D Take advantage of it

what will it do to the et overall ?,,i said 2 step but rpm act.switch are together,,something in the switches(2 step ,act switches)i guess,we put it in low and held the transbrake a mash the gas and it stuttered at 4600 and as soon as we let out of gas it changed into second,so something in the wire,,we are going to wire it into the mega 450 box and run it off the rpm's in the mega 450 box,,steve

figure out whats wired wrong, shifting by rpm in the mega box is illegal in both nhra and ihra. If you get the 60ft faster it should gain et also, no reason you can dip into the 20's with things right at this point. My best suggestion is hook up the tach in the mega box and hook up the replay and take all guess work out of what things are actually at.

why do they even make boxes that serve as a delay box and an rpm activated switch? Like you said it's illegal.....and only bracket racers would buy a delay box, so..

its been replaced with the Elite 500 without them features now :)

you can still use the tach during testing and watch the reply :D

I am not saying it's ok to cheat....BUT, 2 questions

1) What is the advantage of the delay box shifting for you vs the MSD box?

2) How the heck would you get caught?

I guess nhra/ihra think people can control rpms by it, Ive never seen it happen. You can still use the box to shift by time as it will work good.

Tech checks them around here at most places tells ya to turn the delay box on and go to the screen

you can use the mega box to shift by time,but not rpm,,thats crazy,,i just had a friend to tell me thats the way his is and thats the way i should do it,i don't know myself,,,,steve

correct, if he won and someone said look at his box for a tach .. he'd be screwed thats been a rule 3yrs now atleast

you dont have your yellow/gray wire backwards on the RAS do ya ?

they are pretty easy to wire

Steve are you running gas or alcohol, if you're running alcohol i think you have something left in it yet. When i first built my 377" motor, i put it in my friends 1850lb hardtail, we put 2 7/16" stacks on it, 456 gear, 16X33's, 5500 stall 1.76 PG. Leaving on a 4200 chip and shifting at 6800, it ran 5.16, with 1.14 60 ft. at Memphis. We pulled the high side chip out and ran 8.23 @ 158 in the qtr.
We ran the car at Super Chevy 2005 at Memphis and dialed 5.15 and broke out in the 3rd round with a 5.14. Never looked at the recall on the tach, but i'm sure it was zinging on the qtr. mile pass. i still have the motor in my Malibu but with a toilet bowl. Of course it don't run worth a crap in my car because it doesn't have enough torque for a 3200 lb car, best 6.52@102 and 10.59@125mph.

Zip.

zip i'm running gas,,david i'm sending you some pictures and wiring on this thing to your email,,,steve

Ill give them a look over and shoot ya a reply here after a bit got a few things to do today :D