Power curve distribution

[txdodge]

I've got a 2012 5.7 with Vararam CAI and the 87mm TB. Planning on changing the headers, exhaust, fan and adding a tuner eventually. With the current setup I've noticed that around 3k-4k RPMs the power really increases. Is there any way to get a more even distribution of power across all RPMs, or increase the power at lower RPMs? I'm thinking that a tuner might help, but I'm more concerned that accomplishing this will entail changing cams, gears and doing all sorts of other expensive mods I had not planned on! What started off as a simple "I think I'll add a cold air intake" has turned into a riddle, wrapped in a mystery, inside an enigma.....my bank account cried the day I joined this board!

 

[UNBROKEN]

You're feeling the SRV switch from short to long runner in the intake manifold. It has nothing to do with any mods you have done.

 

[txdodge]

You're feeling the SRV switch from short to long runner in the intake manifold. It has nothing to do with any mods you have done.

Yeah, I should have been more clear.....the mods definitely made a difference, but I only feel them at higher RPMs. What is SRV?

 

[UNBROKEN]

Short Runner Valve.
It helps keep the low end TQ up by switching to a short runner at low RPM and a long runner at high RCM.

 

[txdodge]

Short Runner Valve.
It helps keep the low end TQ up by switching to a short runner at low RPM and a long runner at high RCM.

I'm not sure what short runner and long runner mean.....in a nutshell, is there anything that can be done about it?

 

[UNBROKEN]

A short intake passage is better for low end torque. A long passage (runner) makes more power at higher RPM's. For a naturally aspirated truck it gives you the best of both worlds and I wouldn't advise messing with it unless you ever go to some form of forced induction.

 

[Kaiser]

Most bolt on modifications you make are going to increase your mid-upper rpm power and not much to increase and some may even sacrifice a bit of low rpm torque and hp. A tuner may help if you can adjust timing to help some with low end and off idle power. A converter or gears may be your best option to help with smoothen that transition you are talking about.

 

[wickedwhite2012]

From what i have noticed your long tube headers seem to help your bottom end a little. With cutting off your cats you lost a little more bottom end but you gain it back on top. Correct me if I am wrong.

 

[Hemi450hp]

I would start looking into an upgraded tq converter. That is going to give you all the power you want off the line, and is also going to free up more of the power you already have.

The tq converter is hands down the most noticeable mod you can do for off the line performance.

 

[ZCR]

Long intake runner length is for the low end torque short is for the high end. It's just like the old carbed intakes; stock was usually a dual plane (long runner) for good initial and low rpm throttle response. When you wanted to get some more performance you swapped to a single plane (short runner) or a tunnel ram that had a large vertical plenum but short runners, a cam with more overlap/lift/duration, and some long tube headers. This was all at the cost of idle quality, low end throttle response and low end torque.

The exhaust side is kind of the opposite; factory manifolds/shorty headers give the most low end torque.
Decreasing backpressure allows for more high rpm power, but a loss of low end torque.

 

[txdodge]

I would start looking into an upgraded tq converter. That is going to give you all the power you want off the line, and is also going to free up more of the power you already have.

The tq converter is hands down the most noticeable mod you can do for off the line performance.

Is a tq converter a single part upgrade, or do I have to get a tq converter plus other mods to get it to work? Also, is it a DIY install, or does it entail pulling the tranny out etc.... And last question....Am I going to lose anything at the high end with a tq converter, or does it just boost the low end with the high end staying the same?

 

[Polaris Pro]

I would start looking into an upgraded tq converter. That is going to give you all the power you want off the line, and is also going to free up more of the power you already have.

The tq converter is hands down the most noticeable mod you can do for off the line performance.

Which one do you recommend? I have a quad cab Hemi with 3.55 gears and 35 inch tires.