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-   -   3" exhaust on 4.7 too much? (http://www.jeepgarage.org/f196/3-exhaust-on-4-7-too-much-14294.html)

emtclark 10-23-2010 09:42 AM

3" exhaust on 4.7 too much?
 
Looking to install Kolak's 3" cat-back exhaust on my 4.7 WJ. I live in Colorado at 6,100 ft altitude. Unfortunately, my local exhaust guru advises against that large an exhaust because of low-end torque loss due to altitude. :eek:

I put the same exhaust on my '93 5.2 ZJ with no problems; worked flawlessly, same location (Colorado, 6,100 ft). :thumbsup:

Do I need to open up the intake (cold air intake) to offset the (possible) torque loss?

Thanks

robpp 10-23-2010 10:13 AM

Re: 3" exhaust on 4.7 too much?
 
yes. open up the intake to compensate. maybe consider a small port on the tb for increased flow as well.

emtclark 10-23-2010 10:29 AM

Re: 3" exhaust on 4.7 too much?
 
Thanks. What's been the best selling/performing CAI for the 4.7? I'd like to consider doing a home brew intake VS spending $200-300 on a kit.

Suggestions?

Scottina06 10-23-2010 11:28 AM

Re: 3" exhaust on 4.7 too much?
 
also look into the HO cams...big performance jump

FlyinRyan 10-23-2010 03:00 PM

Re: 3" exhaust on 4.7 too much?
 
Quote:

Originally Posted by emtclark (Post 289345)
Looking to install Kolak's 3" cat-back exhaust on my 4.7 WJ. I live in Colorado at 6,100 ft altitude. Unfortunately, my local exhaust guru advises against that large an exhaust because of low-end torque loss due to altitude. :eek:

I put the same exhaust on my '93 5.2 ZJ with no problems; worked flawlessly, same location (Colorado, 6,100 ft). :thumbsup:

Do I need to open up the intake (cold air intake) to offset the (possible) torque loss?

Thanks

Having had both, I would stick with the 3". I had gains across the rpm range. These gains were quantified in my 1/4 mile timeslips- yes, even in my 60' times. Air density changes due to elevation do not have a noteworthy impact on what a motor "likes" or needs.

Opening up the intake is a good idea, the 4.7s need it, regardless of whether you're talking about the intake tube itself, or the TB/manifold.

FlyinRyan 10-23-2010 03:03 PM

Re: 3" exhaust on 4.7 too much?
 
Quote:

Originally Posted by emtclark (Post 289380)
Thanks. What's been the best selling/performing CAI for the 4.7? I'd like to consider doing a home brew intake VS spending $200-300 on a kit.

Suggestions?

Alot of people go with a K&N FIPK, but I personally opted to homebrew one myself. I used 4" aluminum piping, DEI Cool tape, and sillicone couplers.

emtclark 10-23-2010 10:43 PM

Re: 3" exhaust on 4.7 too much?
 
Quote:

Originally Posted by FlyinRyan (Post 289491)
Alot of people go with a K&N FIPK, but I personally opted to homebrew one myself. I used 4" aluminum piping, DEI Cool tape, and sillicone couplers.

Thanks Ryan, do you have a picture of your home brew intake?

emtclark 10-23-2010 10:48 PM

Re: 3" exhaust on 4.7 too much?
 
Thanks for the replies guys. That helps and once I have it on I'll look into both the CAI and the F&B throttle body to open up the intake more. What about the Superchips programer? I looked into previous threads about an "order" to the mods for the 4.7 but one never was suggested...

Scottina06 10-23-2010 11:08 PM

Re: 3" exhaust on 4.7 too much?
 
the superchips or an SCT tuner is def. a mod needed for the 4.7

Unholyskorn86 10-24-2010 12:12 AM

Re: 3" exhaust on 4.7 too much?
 
I got one for my 4.0, and if it is anything like the 4.7.....it is well worth it just for the fact that my acceleration was just spot on....from a 2 second delay. That and the mileage across the board for me (note this might not be for every case) was increased slightly.

Oh yeah, good luck bro let us know how ya do.

ilirdino 10-24-2010 02:48 PM

Re: 3" exhaust on 4.7 too much?
 
I'm definitely thinking 3" pipes for my WJ but I don't have the elevation issue to grapple with. I love the exhaust note with a Flowmaster 50 and a K&N 77 and I can only imagine the gloriousness with 3" pipes.

What is the general consensus regarding the F&B TB?

FlyinRyan 10-25-2010 02:37 AM

Re: 3" exhaust on 4.7 too much?
 
Quote:

Originally Posted by ilirdino (Post 289877)
I'm definitely thinking 3" pipes for my WJ but I don't have the elevation issue to grapple with. I love the exhaust note with a Flowmaster 50 and a K&N 77 and I can only imagine the gloriousness with 3" pipes.

What is the general consensus regarding the F&B TB?

The F&B is a piece of artwork....it is the absolute best of the best.When you have the resources to make a new TB casting from scratch, its only natural that it's going to be better than any stock casting based unit out there.


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