Dyno Testing Bolt-ons On The 4.0

[JustDandee]

I was considering testing a "track pipe" maybe later down the road. I personally think the gain would be minimal, but I have been proven wrong before.

May just open it up, disconnect the pipe before it enter that rear cat- it’s 2 1/2 0 there and dyno with open exhaust. That is theoretical max that can be obtained and then it’s your results may very depending on exhaust components you chose. I have a little write up on a what I did w/o cat and 2 1/2 muffler. I am almost as quiet as stock for the lower rpm range and then sounds a little more like an old GT6 straight six in the higher rpm’s.

 

[Woodrow]

I've got a high flow Magnaflow 2.5 in my 97.

-Mac

Same. My exhaust has some odor. Yours? Could be less cat or tune issue for me. It would be nice to fix.

 

[JustDandee]

Same. My exhaust has some odor. Yours? Could be less cat or tune issue for me. It would be nice to fix.

Might be more if issue on the two cat TJ then the three cat TJ. I notice nothing with the down stream gone.

 

[macleanflood]

Same. My exhaust has some odor. Yours? Could be less cat or tune issue for me. It would be nice to fix.

I pick up to much trash. I can't smell much.

I did occasionally get a wiff...but that's all gone now that I've fixed my downstream O2 sensor with a used NGK. Strangely enough that also fixed recentt misfire codes.

-Mac

 

[srimes]

I pick up to much trash. I can't smell much.

I did occasionally get a wiff...but that's all gone now that I've fixed my downstream O2 sensor with a used NGK. Strangely enough that also fixed recentt misfire codes.

-Mac

I rarely notice it, but my wife complains. I think the PO gutted the cats.

 

[Wildman]

I guess because I grew up in the Pre-Cat era I don't notice the smell. I've ran my TJ without a cat & the V-8 and didn't notice any smell but who knows.
I've got 2 small cat's on the Hemi and it's dumping before the rear axle and so far haven't had any issues with fumes.

 

[Woodrow]

Might be more if issue on the two cat TJ then the three cat TJ. I notice nothing with the down stream gone.

Do you run a top? What is your exhaust tip configuration?

'97s just have 1 and mine is a high flow aftermarket version (Magnaflow). I've been running without a top recently and now notice the smell. Previously none noticed with soft top and half doors, with or with out sun rider top flipped back. My exhaust tip goes all the way back but exits pretty straight.

I'm going to try a turn down tip before the Rubicon trip next month because my wife is coming and its noticeable to her.

 

[ColoJeep]

Do you run a top? What is your exhaust tip configuration?

'97s just have 1 and mine is a high flow aftermarket version (Magnaflow). I've been running without a top recently and now notice the smell. Previously none noticed with soft top and half doors, with or with out sun rider top flipped back. My exhaust tip goes all the way back but exits pretty straight.

I'm going to try a turn down tip before the Rubicon trip next month because my wife is coming and its noticeable to her.

It's worth a try. Most women are like freaking bloodhounds with their nose ! , what's even more wild , is how a persons sense of smell is somehow tied to your memory. You have to do something , this is a no win situation if you don't .

 

[Rickyd]

Do you run a top? What is your exhaust tip configuration?

'97s just have 1 and mine is a high flow aftermarket version (Magnaflow). I've been running without a top recently and now notice the smell. Previously none noticed with soft top and half doors, with or with out sun rider top flipped back. My exhaust tip goes all the way back but exits pretty straight.

I'm going to try a turn down tip before the Rubicon trip next month because my wife is coming and its noticeable to her.

You could try a california cat if the money is worth the experiment. They aren't more money just because they are carb approved. They have more precious metals burning off hydrocarbons,etc. I never get that 1960's nostalgia burn to my nose and eyes.

 

[Woodrow]

You could try a california cat if the money is worth the experiment. They aren't more money just because they are carb approved. They have more precious metals burning off hydrocarbons,etc. I never get that 1960's nostalgia burn to my nose and eyes.

I’ll try the turn down tip first. One of the main reasons I run the high flow cat is the smaller size. It’s much easier to configure with the tuck that I have.

 

[JustDandee]

Do you run a top? What is your exhaust tip configuration?

'97s just have 1 and mine is a high flow aftermarket version (Magnaflow). I've been running without a top recently and now notice the smell. Previously none noticed with soft top and half doors, with or with out sun rider top flipped back. My exhaust tip goes all the way back but exits pretty straight.

I'm going to try a turn down tip before the Rubicon trip next month because my wife is coming and its noticeable

It’s may daily so running open top or enclosed soft top. Here is a link to a modest write up and part numbers sound clip too.

https://wranglertjforum.com/threads/dynomax-muffler-install.80032/#post-1721264

I retained the factory tail pipe- more focused on the muffler/cat restrictions. A down turn does give some incremental benefits it certainly won’t hurt.

 

[BlueC]

Do you run a top? What is your exhaust tip configuration?

'97s just have 1 and mine is a high flow aftermarket version (Magnaflow). I've been running without a top recently and now notice the smell. Previously none noticed with soft top and half doors, with or with out sun rider top flipped back. My exhaust tip goes all the way back but exits pretty straight.

I'm going to try a turn down tip before the Rubicon trip next month because my wife is coming and its noticeable to her.

Out of curiosity, what fuel are you running? I ask because different fuels create different smells. Most guys (probably chicks too) think burning ethanol (E85) smells like dirty socks with a hint of sugary something. I have a car (no cats) I run a little LL Avg gas in and guys know it instantly. Just something of interest, changing the fuel won't replace a good cat burning that crap out of the exhaust, and you really need to get that exhaust tip as far back and away from the cab as you can.

BTW, the wife and I got gassed once. Since then, I've bought some standard battery operated house smoke & CO alarms and tossed them under my passenger seats. Just something I've been recommending to everyone when the opportunity comes up.

 

[Rickyd]

Out of curiosity, what fuel are you running? I ask because different fuels create different smells. Most guys (probably chicks too) think burning ethanol (E85) smells like dirty socks with a hint of sugary something. I have a car (no cats) I run a little LL Avg gas in and guys know it instantly. Just something of interest, changing the fuel won't replace a good cat burning that crap out of the exhaust, and you really need to get that exhaust tip as far back and away from the cab as you can.

BTW, the wife and I got gassed once. Since then, I've bought some standard battery operated house smoke & CO alarms and tossed them under my passenger seats. Just something I've been recommending to everyone when the opportunity comes up.

View attachment 629066

Fish flavor?

 

[BlueC]

Fish flavor?
View attachment 629067

I'd prefer to smell bacon over dirty fish.

 

[Woodrow]

Out of curiosity, what fuel are you running? I ask because different fuels create different smells. Most guys (probably chicks too) think burning ethanol (E85) smells like dirty socks with a hint of sugary something. I have a car (no cats) I run a little LL Avg gas in and guys know it instantly.

I run 91 octane pump gas which, around here is all 10% ethanol. You can get non-ethanol and I do use that in my Mustang because it sits more. But it’s over one dollar more per gallon and that car smells the same as the jeep on cold start before the cats warm up (but not in the cabin).

Just something of interest, changing the fuel won't replace a good cat burning that crap out of the exhaust, and you really need to get that exhaust tip as far back and away from the cab as you can.

I think changing the tip will be the answer. My current tip blows pretty much straight back.

I don’t really want to lengthen it for clearance reasons, but I’m guessing a turn down, like the stock tailpipes, will will help direct flow away from the low pressure zone behind the tailgate and prevent exhaust from being sucked back into the cabin.

BTW, the wife and I got gassed once. Since then, I've bought some standard battery operated house smoke & CO alarms and tossed them under my passenger seats. Just something I've been recommending to everyone when the opportunity comes up.

View attachment 629066

Wow. What happened? Did you get sick or pass out. CO can be pretty dangerous.

 

[ColoJeep]

I run 91 octane pump gas which, around here is all 10% ethanol. You can get non-ethanol and I do use that in my Mustang because it sits more. But it’s over one dollar more per gallon and that car smells the same as the jeep on cold start before the cats warm up (but not in the cabin).

I think changing the tip will be the answer. My current tip blows pretty much straight back.
View attachment 629076
I don’t really want to lengthen it for clearance reasons, but I’m guessing a turn down, like the stock tailpipes, will will help direct flow away from the low pressure zone behind the tailgate and prevent exhaust from being sucked back into the cabin.

Wow. What happened? Did you get sick or pass out. CO can be pretty dangerous.

Either down turn or dumping out the side , hard to say which will be most likely to keep exhaust out of the low pressure area. Maybe a quick and dirty long 45 that is quickchange for highway and easy removable for off road. Curious to see what ends up working for you guys.

 

[BlueC]

Wow. What happened? Did you get sick or pass out. CO can be pretty dangerous.

Didn't get to the point of passing out. We took a short, (10-ish minutes) rainy winter day drive to get groceries in my Jeep, so top and doors, windows up. About halfway there we both got a headache, and she started feeling dizzy, so I rolled my window down thinking fresh air might help her, and it did. After the store, and the headaches went away inside the store, she noticed an exhaust smell inside the Jeep, which threw red flags for me. A few days later I had my local exhaust shop check it out, and they found a loose manifold bolt or two.

Since then, we've had kids and my tolerance for risk has diminished, so I've strategically placed smoke & CO alarms where they should be, like my old cars and in my garage, extra ones in the house etc. When I put a CO alarm in my garage (detached) I found out just how little one of my old cars has to run to set that thing off.

 

[Rickyd]

Didn't get to the point of passing out. We took a short, (10-ish minutes) rainy winter day drive to get groceries in my Jeep, so top and doors, windows up. About halfway there we both got a headache, and she started feeling dizzy, so I rolled my window down thinking fresh air might help her, and it did. After the store, and the headaches went away inside the store, she noticed an exhaust smell inside the Jeep, which threw red flags for me. A few days later I had my local exhaust shop check it out, and they found a loose manifold bolt or two.

Since then, we've had kids and my tolerance for risk has diminished, so I've strategically placed smoke & CO alarms where they should be, like my old cars and in my garage, extra ones in the house etc. When I put a CO alarm in my garage (detached) I found out just how little one of my old cars has to run to set that thing off.

Did you check out your firewall and shifter boots for openings?

 

[BlueC]

Did you check out your firewall and shifter boots for openings?

Not well, but I did find a tear in my boot that's about an inch long. I still haven't fixed that. Probably need to add it to the to-do list.

 

[GoldenGorilla]

I've strategically placed CO alarms where they should be, like my old cars and in my garage, extra ones in the house etc.

Us Coloradans are pretty sketchy. Lock your doors.