Engine/Transmission (1994 - 1998) RPM Drop after takeout with sled

[thaile]

First I just want to say that I know that the RPM's are going to drop after you takeout with the sled however, how much are some of you all seeing once you get out of the clutch. I have a 96 Dodge converted to a six speed, 0 plate, laser cut delivery valves, 5000 rpm governor springs, . 120 over lines, II 5 X . 022 injectors, Helix three cam, Marine pistons and a few other things. However, I take off at the line at 4800 rpm but when I get out of the clutch she drops to like 3100 and then slowly cllimbs to 3300 before the sled catches me at the end and drops me under the turbo. Do you all have any suggestions, to big of injectors for the pump, some other idea, I don't know give me your thoughts. Oh ya I have industrial Injection K31 hybrid pulling turbo if that helps. Thanks.

 

[NCovey]

Just curious, are you just dumping the clutch, or are you rolling it out a little bit before you are completely off the pedal?

 

[BigYellowIron]

What gear, tire size, rear ratio? What timming are you running? Are you running the stock inj pump? There is alot of varibles that come into play here! I have to say your brave pulling that EEP clutch over 4200. I hope you have a blanket. After seeing mine after i took it out, the flywheel was cracked in several places.

 

[Don Tanklage]

ah yes, the launch...



dont know if it applies to your pullin truck but in drag racing only 5 things contribute to what happens when you throw the clutch



roll out (circumferance of tire)



static clutch pressure



timing



gear ratio



2-step rpm



if the rpm gets pulled down i either give it less clutch and/or roll out (go to shorter tire) - and more gear and/or timing and/or launch rpm



thats with a gasser but i would think the princibles are the same...

 

[JGheen]

Sounds like your just pulling in to high a gear choice. Since your running the 6 speed, I would say your trying to pull in 5th low... . I would try 4th low and see how it reacts. I tried 4th low once with my NV4500 and it just fell on it's face everytime. Since then 3rd low has been my choice pulling gear and I have had quite good luck with that.

 

[thaile]

Here are some of the answers to the questions you all asked. The truck is no longer a single wheel I converted it to duals with a new dually bed. The gear ration is still 3. 55, but I am running 285 75 16's for tires and they are pretty aggressive. Lockers in the front and back. I don't think I am in to high of a gear 4th low in the six speed. I pulled that gear forever with a lot less power than what I should be making now. The timing is set at 40 degrees on the motor. I am not super hard on the clutch I role out of it pretty quick to try and make it live for a little while. Although now after 5 only three acutally making it down the track it needs adjusted really bad because after my last hook you now have to start the truck in gear to get it to move. What clutch are you running Big Yellow Iron as I knew you were looking for one not to long ago. Oh yeah it is still the stock inj pump with the mods I listed above. Hope this helps give you all the info to help me figure this out. Thanks.

 

[BigYellowIron]

I got one from Craig McElfresh. its a nice clutch has sintered iron disk and a 1/2 inch floater.



I think all of your mods are to much for your inj pump. That kind of RPM on a stock pump is where your prob is. Not enough fill time in the pump cam. You need to get a 13mm pump and a quick fill cam. PM me and we can talk about it more.

 

[BigYellowIron]

What did you decide to do?