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Critique my exhaust plan

Monster Mopar

Monster Mopar

NAXJA Forum User
Location
Moses Lake, WA
89 renix stock motor, CIA, and bored throtle body in near future.

Pacesetter header link

A prebent tail pipe from walker 2.25" diameter link
I thought about the dynomax tail pipe but it's 2.5" and I'm worried about drone and loss of low end power. The hacked system my rig has on it now is 2.5" from manifold back and it seems to be lacking low end power and drone is horrible but may be due to the 2 crappy cherry bomb single chamber mufflers welded in series. :wow:

And then a magnaflow muffler, wasn't sure what size would be best so I'm leaning towards the thinest one 4" and picked the middle sized length 14" link

Deleted

input?? anything you might change?
 
Last edited by a moderator:
Install a cat would be first on my list, don't know about you but I hate driving behind some catless ricer on the highway, the fumes give me a headache.

The rest sounds fine to me but I'm not really picky about my exhaust setup at all.
 
I'd run a cat. It is federal law, and saying your area doesn't have inspections isn't really a good excuse anymore. Hasta After all, running without one will cause you to lose some low end. No cat and a magnaflow muffler WILL drone at lower RPMs. What kind of sound are you looking for? Also, Dynomax makes a 2.25" tailpipe for their newer XJ system. I have one on my XJ and it clears the factory hitch really well. I'd also recommend painting it with high heat paint to prevent rust.
 
Okay I'll look into cats.

Any one know where to source a good high flow but reletively inexpensive?

Hmm, I'll look into the dynomax 2.25" tail pipe

As for sound, just want a deep mellow tone that doesn't sound like ass when in higher revs. I want to keep the majority of the sound out side of the vehicle too so not to loud.
 
Monster Mopar said:
Okay I'll look into cats.

Any one know where to source a good high flow but reletively inexpensive?

Hmm, I'll look into the dynomax 2.25" tail pipe

As for sound, just want a deep mellow tone that doesn't sound like ass when in higher revs. I want to keep the majority of the sound out side of the vehicle too so not to loud.
Click to expand...

you can get compact universal hi-flows for $40-60 all day long.

wish i remembered where i got mine.

scrapped my old one for $80 and paid $40 for the new one. so i got a new cat and made money!
 
kastein said:
Install a cat would be first on my list, don't know about you but I hate driving behind some catless ricer on the highway, the fumes give me a headache.

The rest sounds fine to me but I'm not really picky about my exhaust setup at all.
Click to expand...


The smell you get driving behind the ricers is not caused by a lack of cat but a lack of tuning. It is actually the un-burnt fuel you smell. Yes, a cat would help to limit the amount of un-burnt fuel polution until it over heat and burn itself to a closed position. In the caribbean, there are many vehicles there from Japan the have no cat and the smell of un-burnt fuel is non exsistant.

To the OP. Ther are othe benifits to using a cat in addition to being:
1) A legal requirement,
2) The cat helps to clean the air
3) It also doubles a resonator thus reducing the drone,...ask me how I know
 
I got a Dynomax high flow cat and a 4" cylinder style Magnaflow muffler on mine, all 2.5" piping. Cost me maybe $150 total with extra piping to fit it all together.

Definitely need a cat because the muffler is a 'straight through' design, so it's pretty much just a resonator. Mine is dumped just past the rear axle. It's not quiet at all lol.
 
Monster Mopar said:
Okay I'll look into cats.

Any one know where to source a good high flow but reletively inexpensive?

Hmm, I'll look into the dynomax 2.25" tail pipe

As for sound, just want a deep mellow tone that doesn't sound like ass when in higher revs. I want to keep the majority of the sound out side of the vehicle too so not to loud.
Click to expand...

I second the performance-curve.com recommendation. They sell nice cats for pretty cheap. For a deep mellow tone, get a larger case magnaflow like the 20" or 22" long magnaflow. These you can also find on performance-curve.com. http://performance-curve.com/offsetcenter.aspx

They will be deep without too much drone. I also recommend the Dynomax catback. It has a nice tone but is barely louder than stock inside. Also fairly cheap and very easy to install. They have two kits, the one for renix XJs has the 2.5" pipe, and the kit for newer XJs has the 2.25" pipe. Both pipes have the same bends. I think the rockcrawler website did a dyno test with the dynomax exhaust on their Cherokee and saw a 5 hp or so gain as well as a small gain in torque.
 
techno1154 said:
The smell you get driving behind the ricers is not caused by a lack of cat but a lack of tuning. It is actually the un-burnt fuel you smell. Yes, a cat would help to limit the amount of un-burnt fuel polution until it over heat and burn itself to a closed position. In the caribbean, there are many vehicles there from Japan the have no cat and the smell of un-burnt fuel is non exsistant.

To the OP. Ther are othe benifits to using a cat in addition to being:
1) A legal requirement,
2) The cat helps to clean the air
3) It also doubles a resonator thus reducing the drone,...ask me how I know
Click to expand...
it's the same thing, unburned fuel in either case. My point was that the cat will somewhat reduce it or eliminate it entirely unless your motor is badly tuned / has a bad sensor, in which case you'll notice the mileage/wallet hit pretty quickly anyways.
 
Pacesetter header [URL="http://www.summitracing.com/parts/PSM-70-1191/" said:
link[/URL]
Click to expand...

Be advised... I originally ordered a set of these this style Pacesetter header and prior to taking the Heep apart, decided to do a test fit of the two pieces. They did not register to each other. There was a good 0.25" difference in the center to center dimensions with the down tube portion being wider.

I called Pacesetter to find out just how these allegedly jig welded parts could be so far off. I was told:
"Those pieces are creted on two different assembly lines"

I asked:
"Do you test fit prior to shipment?"

Response:
"No"

They offered to exchange them for another set and when I asked if that set would be checked for fitment prior to shipment and the answer was:
"No"

So I returned them to my Vendor and purchased a set of headers (from a different company) that actually bolted in.

Just beware and make sure your Vendor will take them back if they do not fit together. Also, the method Pacesetter uses to clamp the collector to the downpipes is shakey. Get a pair of full circle clamps or it will most likely leak and or fall apart.
 
Monster Mopar said:
89 renix stock motor, CIA, and bored throtle body in near future.

Pacesetter header link

A prebent tail pipe from walker 2.25" diameter link
I thought about the dynomax tail pipe but it's 2.5" and I'm worried about drone and loss of low end power. The hacked system my rig has on it now is 2.5" from manifold back and it seems to be lacking low end power and drone is horrible but may be due to the 2 crappy cherry bomb single chamber mufflers welded in series. :wow:

And then a magnaflow muffler, wasn't sure what size would be best so I'm leaning towards the thinest one 4" and picked the middle sized length 14" link

No cat, for now, I don't have any testing or inspections where I live.

input?? anything you might change?
Click to expand...

Monster Mopar,

I am have been researching a new exhaust system for my 98 also, here is what I have found.


For the header I would go APN they are copies of Banks header. Also they are cheaper than pacesetter. APN header
Write up of install..

From the header back, I would double check your size. Mine goes from the flange to 1.50" for about a foot (in the two bends) then 2.0". I would like 2.5 though out, I don't think it would be feasible to have someone mandrel bend just that section for me. Summit sells one of the cheapest intermediate pipes I have seen so far.

I would have to agree with everybody else running a cat. I am still looking for the cheapest one, JC whittney caught my eye with this set-up. But unfortunately its only the cat.

For the muffler, I would agree with you on magnaflow. I have not found a size I like either. Still looking though

Hope this helps, might be able to save you some time..
 
I have had good luck with the Magnaflow cat on a previous 4.0 engine. It sounded pretty good with a 50 series flowmaster.
 
Milford Cubicle II said:
Just say, "I think you should install a cat" and leave it at that. Don't go spewing BS about losing "low end."
Click to expand...

How am I spewing BS? Temporarily run a test pipe where your cat is and tell me what happens. Even a high flow cat does restrict flow, not much, but it makes a noticeable difference from a test pipe. The same reason why running a 2.5" pipe flows better than 2.25" pipe. There is less restriction. That restriction helps with back pressure and low end torque. If you don't believe me then see for yourself. I have done it, and that is why I said it. I have no reason to steer people the wrong way.
 
Back pressure is a myth guys. You really want the highest air velocity possible to create a scavenging effect. To large a pipe and the velocity goes down, as does power. The whole idea behind high flow cats & mufflers is to get the gases out faster (higher speed of exhaust gases), not create less back pressure.
 
RCman said:
Back pressure is a myth guys. You really want the highest air velocity possible to create a scavenging effect. To large a pipe and the velocity goes down, as does power. The whole idea behind high flow cats & mufflers is to get the gases out faster (higher speed of exhaust gases), not create less back pressure.
Click to expand...


So if your running no muffler or cat a 2" pipe would be good?
 
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