Holy cow! Major bottom end power loss

[914]

Traded trucks with a friend yesterday. I have a stock 2014 and he has a 2015 with a cat back exhaust and a CAI. I think he said it's a Magniflow and K&N.
I can't believe how flat the bottom end power is with his setup. Like night and day difference. What a waste. That's a lot of power to give up to have a nice sounding truck.
For all the newbies like myself, do your homework before you start modifying your truck!

 

[dhay13]

same gear ratios and transmissions?

 

[BigSloth]

same gear ratios and transmissions?

Exactly. If your truck has the 3.92 rear end with an 8 speed, and his has the 3.21 rear, there will be a night and day difference.

 

[914]

We both have 8speed tranny and 3.92 gears

 

[sicmadek]

I dont believe it for a second.

 

[BigSloth]

No. I mean, with longtube headers there is a slight bottom end loss, especially so with the 1 7/8 primaries. But just a catback? I've got the mufflex delete on mine, and I didnt notice any bottom end loss.

 

[SilverSurfer15]

:****sweak:

 

[darthdzl]

Does your friend baby his truck? Has he since day one?

If so, maybe it either didn't break in right (and might have lower cylinder pressures), or maybe it just needs a good Italian tune-up. Got any good open, near-deserted roads where you can open 'er up?

 

[Casper]

Traded trucks with a friend yesterday. I have a stock 2014 and he has a 2015 with a cat back exhaust and a CAI. I think he said it's a Magniflow and K&N.
I can't believe how flat the bottom end power is with his setup. Like night and day difference. What a waste. That's a lot of power to give up to have a nice sounding truck.
For all the newbies like myself, do your homework before you start modifying your truck!

Something besides catback and K&N is going on. I'd bet he doesn't have the 3.92 and just told you he did.

 

[914]

Maybe, IDK. I've got a big horn and he has a limited. According to my window sticker I got 3.92's.
I don't post much. I just hangout over here but after driving that truck yesterday I couldn't believe the difference. So I figured I'd post up to hear your guys thoughts.

 

[Graygoose]

Both same size tires?

I don't see a catback and CAI killing a ton of lowend...dunno.

 

[xrsman]

Crawl underneath and look at the front diff (if you're 4x4) and it'll say the gear ratio on it.

Like Greygoose said..he had a crew cab, do you have a quad? Both 4x4? Running the same fuel?

His truck is also heavier than yours.

Just some food for thought. My mods definitely made my truck faster!

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[csuder99]

This is the second thread in a week talking about low end power loss with after market exhausts, so allow me to stir the pot a bit
Read the following document https://www.mech.kuleuven.be/en/doctorates/persoons.pdf and once you understand it, go ahead and change your exhaust. Just kidding !
The point here is, it's not 1985 anymore and increased requirements for emissions and fuel economy have forced manufacturers to put a lot more engineering and testing into exhaust systems as part of the overall engine package. The likelihood that random muffler swaps improve one or more parameters without negatively affecting others is close to zero.

 

[GreenGoblin]

I dunno if it's the same or not but with my 2015 challenger I had the same problem after swapping my mufflers to bola. Come to find out, the computer in those cars learn your driving style and adjust your air/fuel ratio to your driving style to save fuel so when I swapped to a more free flowing muffler it was all jacked up. I pulled the fuse to reset my computer and it was night and day. The car will now bark the tires into 3rd gear even with traction control on. Just something to look into.

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[Goatman91]

You should see a low end gain with longtubes headers, it creates a vacuum effect in the cylinder. The only intake that is worth anything imo is a vararam, it's the only intake that will actually ram air, the stock intake is already a cai. And what size exhaust did he install? You'll have a power loss with duals and anything smaller than the factory 3 inch is a waste, I've always had better gains with single exhaust.

 

[sicmadek]

You should see a low end gain with longtubes headers, it creates a vacuum effect in the cylinder. The only intake that is worth anything imo is a vararam, it's the only intake that will actually ram air, the stock intake is already a cai. And what size exhaust did he install? You'll have a power loss with duals and anything smaller than the factory 3 inch is a waste, I've always had better gains with single exhaust.

Me and 3 others that i know of have gained from 2 1/2" true duals

 

[GreenGoblin]

You should see a low end gain with longtubes headers, it creates a vacuum effect in the cylinder. The only intake that is worth anything imo is a vararam, it's the only intake that will actually ram air, the stock intake is already a cai. And what size exhaust did he install? You'll have a power loss with duals and anything smaller than the factory 3 inch is a waste, I've always had better gains with single exhaust.

I've always been told that longtubes are for mid to top end gains while shorty headers are for low end. I know when I installed my shorty's with a ported throttle body and tune the low end would snap your neck

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[Goatman91]

Let me rephrase, shorties will increase power and torque from idle to midrange in rpms. Longtubes you will lose a little, not much, from idle to midrange but from mid to high rpm you will see big gains. It really comes down to aplication, the two are designed for different purposes.

 

[RLJ10X]

If both trucks are the same configuration, and one feels noticeably faster, I'm in the "Adaptive Driving"camp.

My 13 V6 Mustang, and my 14, 2 door Wrangler both turn into dogs if you don't know what you re doing. In those vehicles, at least once a day, I'll turn on the ignition, without starting it. I'll wait until all the beeping stops. Then I take 3 seconds to floor the accelerator. Hold it for 3 seconds, then take 3 seconds to let it back up. That fools the computer into thinking that you've just gone wot.

Pulling a certain fuse works also. But the gas petal thing is much easier.


I'm not sure if the above maneuver works for our trucks. But it's worth a try.