Mines 3'' and I didn't notice any low end loss at all from the CAI, just sounded better. I did however feel what you are describing with one of the mufflers I tried before settling on the current Magnaflow.

 

HOGWASH! If he is truly losing low end torque, then he has lost BACKPRESSURE. Making the pipe diameter LARGER would increase air flow and therefor reduce backpressure even more and result in the torque curve moving higher in the rpm band.

However, there is not a significant difference in cfm flow whether using a 3" or 4" pipe unless the TB size is increased.

I've seen dynos run with most of the name brand CAI's and because the gains are not that great with just a CAI to begin with, the differences in the dyno numbers are negligible.

Some people feel gains with just a CAI because they want to feel gains, others feel a loss of power because they are expecting to feel these huge gains that simply are not there.

While a CAI is beneficial because it helps other mods reach their potential, the gains (or losses) from a simple CAI installation are not enough to be measured except by a dyno...

Oh and 287cc, I have a few friends in the "performance" industry, you'd be amazed at how many of these companies have NO R&D personnel at all, despite their ads. Many of these companies operate out of a corporate park with offices and a warehouse, that is basically just a "stopover" for their product on the way to consumers after the shipping container arrives from China! I'm not gonna name names, but you'd be shocked by some of them.
I've helped some of these companies setup booths for truck shows and it's amazing how many of them hire "temps" to man their booths. Some of these "experts" were at the same venue the week before hawking cooking products...

 

Well, I have to say....as one who has a 2008 4.7, that I also experienced the low end torque loss when I did all of that. I added a CAI first, then a new muffler and a Y pipe....I did notice a low end loss. Testing out my butt dyno, I then went back to the stock intake. The low end torque came back.....

I then replaced the Hemi Hat with a free flowing pipe and kept the stock airbox. That has seemed to work pretty well.

I actually started a thread regarding this and several agreed.

 

Well, the CAI is gone. I took it off and installed the stock setup back on it and it feels a tad bit stronger down low. I only ran the filter for a day, so I'm returning it to the store and getting my money back. I am going to buy window tint and order a set of the hood spear stickers in exchange

 

I went with a 3" in my homebrew CAI and have no problems, it actually help 6th gear pull better up these damn mountains in WV... i think its in ur head bro... and i never reset my pcm...... is that a bad thing?

 

Now THAT I can buy. The stock "Y" pipe is a terrible design and will cause a boatload of backpressure. Backpressure is actually inefficient as hell and makes the engine work much harder at low RPMs where there is not enough airflow generated for proper scavenging.
It's this "extra work" by the engine down low that gives the feel of more torque in the extreme low RPM range. It's good for the "butt dyno", but backpressure from a performance standpoint is NEVER a good thing.

Backpressure is exactly what it sounds like, pressure from exerted gases entering the engine from the exhaust end. A CAI, ported TB or any other mod installed BEFORE the engine will not reduce backpressure.

Now I have a CAI, Long Tube Headers, a freer flowing Y pipe and a very high 500 CFM muffler. My torque and HP numbers are up, but with the cats still in (just moved back to accommodate the LTs) I have about the same low end torque as stock, but after about 1800 rpms the torque gains begin to show up on a dyno, so I can't buy into the fact that JUST adding a CAI would make anyone's truck show a LOSS in low end torque numbers...

 

wow that was a fun read !

 

Now ya got me worried, I ordered a magnaflow-y, just haven't gotten around to putting it in yet. I don't want to lose any low end, this be-atch is heavy. Obviously not looking for a drag truck so I'm looking more for low end gains then high end HP.

 

^^^^ i thought u gained low end with a new y pipe? i am so lost on this thread

 

Nope, you'll lose low end with a freer flowing exhaust system. Especially with this engine!
The truth of the matter is, the HEMI is not a good truck engine, or at least in a heavy (QC 4x4) truck. It's ideally suited as a muscle car engine with it's relatively high torque curve and superior mid to high RPM Horse Power numbers.
Just look at how it compares to the venerable old LA 5.9 it replaced. It kills it in HP by 115, but is only slightly better in Torque, and that torque advantage is seen relatively high in the powerband.
The Hemi benefits down low by the inefficiency of "backpressure" which is actually bad for an engine in that it makes the engine work much harder for output! Freeing up the scavenging of exhaust gases increases performance, giving better HP AND Torque numbers, but also moves the already high torque curve of this engine higher in the powerband.
It's for this reason that I had my as-of-yet uninstalled cam ground at -4*, to increase the low end torque by a very good margin (at a sacrifice of extreme high end HP). I actually studied the hell out of this when deciding on a cam as well as picked the brain of TWO performance shop gurus who I'm sure tried to hide when they saw me coming.

That said, I've seen NO numbers to suggest that INCREASING air flow INTO the engine has a bearing on low end torque as it has NO bearing on backpressure. An engine is only going to suck in air when it needs it and only as much as it can hold. Now if you do what I and 08RAMMAN have done, increase the rate at which gases can be scavenged AND increase the inflow of air with a CAI and you WILL have a modest drop in low end torque. One important thing to understand, the Torque is NOT decreased when installing freer flowing mods, it's actually INCREASED, it's just up higher in the RPM band. If you look at dyno sheets enough with this engine, as I have, you'll see how the torque curve peaks higher but also shifts upward in the RPM band as these mods are installed...