Why doesn't someone come out with a 3" exhaust

[AZDustMuncher]

So I've done comparing of the HP ratings for the different vehicles that also have the 3.6L. I can't say I've checked them all but everyone that I've looked at makes more power than the one we have in our jeeps. One thing I've noticed about all the other vehicles is that they also have larger exhaust systems from the factory than the jeeps. That's one of the things I don't get about all these aftermarket bolt on systems for our jeeps they all use the same 2.5" exhaust pipes. If you go on any of the websites that give you calculators for how big of pipe you need for the horsepower your vehicle makes 2.5 is too small and will hurt performance. From everything I've looked at the max horsepower a 2.5" exhaust is good for is roughly 230 HP. If someone would come out with a complete exhaust with hi flow cats off the heads to 2.25 pipes that Y into a 3" exhaust I would seriously be interested. I monitor some of the exhaust threads hoping for something larger but IMO it's all the same crap. Below is one of tables I found.

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[nerubi]

Flowmaster says for a 200 - 250 cubic inch engine that 2.5" exhaust pipe is recommended up to 3" higher than normal horsepower.

 

[AZDustMuncher]

Flowmaster says for a 200 - 250 cubic inch engine that 2.5" exhaust pipe is recommended up to 3" higher than normal horsepower.

That's probably because flowmaster mufflers are crap. lol I would never put a baffled muffler on anything owned if I cared about performance.

 

[nerubi]

That's probably because flowmaster mufflers are crap. lol I would never put a baffled muffler on anything owned if I cared about performance.

Funny, others on the forum say it's the only thing they would put on. That's why I ignore everyone's opinion on the forum because it is only their thoughts no real proof. Besides you didn't credit the source of your table, Martha Stewart could have made it.

 

[AZDustMuncher]

Funny, others on the forum say it's the only thing they would put on. That's why I ignore everyone's opinion on the forum because it is only their thoughts no real proof. Besides you didn't credit the source of your table, Martha Stewart could have made it.

https://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/
https://m.roadkillcustoms.com/determine-proper-exhaust-tubing-size/
https://www.clown-shoe.com/single-post/2015/06/16/What-size-exhaust-is-the-right-size
http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

There's a few links. Flowmasters are old school, if you like the sound great. I would only consider one on a classic muscle car for cruising and not something I would use strictly for performance. A straight throw muffler will out perform them any day of the week. Besides all that FCA put larger exhausts on every other 3.6L I bothered to look up and they all had higher power ratings.

 

[Litfuse]

3” would be too much for this motor. It would lose some low end torque. Heck, even the Mustang GT only comes with 2.75” exhaust. My wife’s g37 with the 3.7 had 2.25” exhaust. With a tune, I could see how the 2.0 may see results from a 3” exhaust.

 

[AZDustMuncher]

3” would be too much for this motor. It would lose some low end torque. Heck, even the Mustang GT only comes with 2.75” exhaust. My wife’s g37 with the 3.7 had 2.25” exhaust. With a tune, I could see how the 2.0 may see results from a 3” exhaust.

Everything you listed has dual exhaust. Our jeep only has single exhaust. As far as losing low end torque with too large of a exhaust goes. I have heard a lot of people make this argument but I have not seen as nearly as much evidence to back it up. I'm sure there are cases where it is true but dual 2.25" into a single 3" does not seem unreasonable to me. There are are lot more cases IMO where improved airflow helps make more power. Also with the newer 8 speed transmissions it's not like I have ever been in a situation where I have felt like I was lugging around in my jeep needing another gear, even with 37's. Whenever I have punched my jeep it has always down shifted into a gear that has put me it a good powerband. I feel like the 3.6 was made to rev and it's not like the old days of 3 and 4 speed transmission where depending on the gear and speed you could get could get caught out of the powerband.

 

[Litfuse]

Everything you listed has dual exhaust. Our jeep only has single exhaust. As far as losing low end torque with too large of a exhaust goes. I have heard a lot of people make this argument but I have not seen as nearly as much evidence to back it up. I'm sure there are cases where it is true but dual 2.25" into a single 3" does not seem unreasonable to me. There are are lot more cases IMO where improved airflow helps make more power. Also with the newer 8 speed transmissions it's not like I have ever been in a situation where I have felt like I was lugging around in my jeep needing another gear, even with 37's. Whenever I have punched my jeep it has always down shifted into a gear that has put me it a good powerband. I feel like the 3.6 was made to rev and it's not like the old days of 3 and 4 speed transmission where depending on the gear and speed you could get could get caught out of the powerband.

My wife’s g37 was a single exhaust from the manifolds back to the mufflers. I do agree that the 3.6 likes to rev, but I don’t think a three inch exhaust would help much, at least without a tune.

 

[AZDustMuncher]

My wife’s g37 was a single exhaust from the manifolds back to the mufflers. I do agree that the 3.6 likes to rev, but I don’t think a three inch exhaust would help much, at least without a tune.

I'm not talking about a stock Jeep. I'm thinking ones with a aftermarket intake or supercharger with a tune. They go hand in hand as far as I'm concerned. I wouldn't do a tune on a completely stock vehicle of any kind and I wouldn't modify anything for more power without a tune.

 

[Chocolate Thunder]

A 3” exhaust is way overkill for the 3.6L naturally aspirated engine in our Jeeps and would not yield any significant usable power increase. Could you maybe show a 2 or 3 peak HP gain on a dyno run? Maybe. Wound it make any practical difference whatsoever in how the vehicle performs? No.

 

[Chocolate Thunder]

We cross posted. Lol. If you have some significant modifications to go along with the 3” it might be synergistic. Adding it along with cold air intake , headers, and a different tune might make some power. I don’t think it would be a lot but enough to notice on wide open throttle runs. On a forced induction engine it could be significant.

 

[AZDustMuncher]

We cross posted. Lol. If you have some significant modifications to go along with the 3” it might be synergistic. Adding it along with cold air intake , headers, and a different tune might make some power. I don’t think it would be a lot but enough to notice on wide open throttle runs. On a forced induction engine it could be significant.

3.6L does not have exhaust manifolds therefore headers are N/A. The current Y pipe on my JL doesn't even measure 2" on the OD. I'm gonna talk some $hit here but please know what actually comes on these JL's before you tell me how I'm wrong.

 

[Litfuse]

I'm not talking about a stock Jeep. I'm thinking ones with a aftermarket intake or supercharger with a tune. They go hand in hand as far as I'm concerned. I wouldn't do a tune on a completely stock vehicle of any kind and I wouldn't modify anything for more power without a tune.

I can see adding a three inch exhaust with added force induction. Not with an intake though.

 

[Litfuse]

3.6L does not have exhaust manifolds therefore headers are N/A. The current Y pipe on my JL doesn't even measure 2" on the OD. I'm gonna talk some $hit here but please know what actually comes on these JL's before you tell me how I'm wrong.

The 3.6 does not have headers but exhaust manifolds.

 

[Chocolate Thunder]

3.6L does not have exhaust manifolds therefore headers are N/A... I'm gonna talk some $hit here but please know what actually comes on these JL's before you tell me how I'm wrong.

Interesting... I learned something new today. I’ll leave you to it then. Good luck in your quest.

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