JT aftermarket exhausts hardly seem worth it.

[RavensEyeOffroad]

However the same engine in the Dodge Challenger puts out 303HP and 268 #/ft of torque so why can’t we have the same in the Glad…

Cooling is my first guess.

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[Kevin_D]

However the same engine in the Dodge Challenger puts out 303HP and 268 #/ft of torque so why can’t we have the same in the Glad…

Cooling is my first guess.

That's the reason I've read.

Kevin

 

[kd1yt]

I've periodically thought of an aftermarket exhaust. Then I think "what if I was presented with an exceptionally easy opportunity to save between $300-$1000" that I could either save or direct to something different where I see a lot more for it, and decide, nah.

I agree with the comments here that if you are willing and able to re-do both intake and exhaust with a specific aim in mind, and parts selected for that aim, and then very carefully and comprehensively tune with that same aim in mind, you can get some results. But I don't have the time and bandwidth (or budget) to do that "all in" approach. My luck I would get it dialed in and then my state would declare some kind of extreme prohibition and intrusive inspection on such things and I'd have to un-do it all back to stock.

We are definitely not in the era in which a carb swap and exhaust work unleash a bunch of untapped potential. But I remind myself that that's because this engine, and others today, turn out an amount of HP, torque, and economy, for a given displacement, that would have seemed beyond even hoping for 30-40 years ago. 3.6 liters (at about 60 cubic inches per liter) = about 216 cubic inches, making 285 HP - that's about 1.3 HP per cubic inch on 87 octane fuel, and there was a time when only a tiny swath of extremely uncommon premium production engines ever cracked 1 horsepower per cubic inch, from a narrow range of years during the 1960s (after they really learned how to do it and before emissions controls) (like the highest output 327 Corvette engine, and that was only the most expensive and high-strung 327) and those few engines were considered marvels, beyond reach or hope of regular drivers. And average drivers wouldn't tolerate those amazing high output engines' operating characteristics, where premium fuel was an absolute must, starting was unrefined, and idle was choppy, and the engines gave outsized fanfare of anything that they were doing.

We're actually living in the "good now days" of how good standard WonderBread engines have become. By saying that I am not disparaging anyone who wants to tailor them even further.

What I do wish is that this engine could be configured for more low end torque, like you'd get out of a skinny bore, long stroke inline 6. But I realize that this engine needs to accomplish a lot of things in a wide variety of vehicles and that those characteristics would be undesirable in many of those settings. And since I have an MT, I just remind myself to change my shift points from what I wish they were, to what will give me the result I want.

 

[Riccochet]

That's the reason I've read.

Kevin

And tuning, mostly. Different application and needs in a car versus a truck. Same reason the 5.7 hemi is rated differently in the Ram versus the Charger/Challenger. Comes down to where in the RPM range that they want peak power and torque.

 

[ACAD_Cowboy]

Imagine putting up with a situation where you could lose a valve, wipe the bearings or lose a cam lobe. If it starts it might not idle less than 1500 and if it did it would stink of fuel. Who didn't love the insanity of high output big blocks. Small blocks were better but only just.

I'd honestly take todays always start engines that can go the distance even if it means I'm not crankibg out 1 horse per cube.

 

[Jonny A]

I've periodically thought of an aftermarket exhaust. Then I think "what if I was presented with an exceptionally easy opportunity to save between $300-$1000" that I could either save or direct to something different where I see a lot more for it, and decide, nah.

I agree with the comments here that if you are willing and able to re-do both intake and exhaust with a specific aim in mind, and parts selected for that aim, and then very carefully and comprehensively tune with that same aim in mind, you can get some results. But I don't have the time and bandwidth (or budget) to do that "all in" approach. My luck I would get it dialed in and then my state would declare some kind of extreme prohibition and intrusive inspection on such things and I'd have to un-do it all back to stock.

We are definitely not in the era in which a carb swap and exhaust work unleash a bunch of untapped potential. But I remind myself that that's because this engine, and others today, turn out an amount of HP, torque, and economy, for a given displacement, that would have seemed beyond even hoping for 30-40 years ago. 3.6 liters (at about 60 cubic inches per liter) = about 216 cubic inches, making 285 HP - that's about 1.3 HP per cubic inch on 87 octane fuel, and there was a time when only a tiny swath of extremely uncommon premium production engines ever cracked 1 horsepower per cubic inch, from a narrow range of years during the 1960s (after they really learned how to do it and before emissions controls) (like the highest output 327 Corvette engine, and that was only the most expensive and high-strung 327) and those few engines were considered marvels, beyond reach or hope of regular drivers. And average drivers wouldn't tolerate those amazing high output engines' operating characteristics, where premium fuel was an absolute must, starting was unrefined, and idle was choppy, and the engines gave outsized fanfare of anything that they were doing.

We're actually living in the "good now days" of how good standard WonderBread engines have become. By saying that I am not disparaging anyone who wants to tailor them even further.

What I do wish is that this engine could be configured for more low end torque, like you'd get out of a skinny bore, long stroke inline 6. But I realize that this engine needs to accomplish a lot of things in a wide variety of vehicles and that those characteristics would be undesirable in many of those settings. And since I have an MT, I just remind myself to change my shift points from what I wish they were, to what will give me the result I want.

Your observations and explanations of HP per cu inch historically are what I always tried to explain. Not as well as you. You are right. We all always want more. That 3.6 Pentstar engine is what most any enthusiasts would love back in 70's 80's 90's and 2000's. It ain't a slouch. But when you compare it too a big ass MODERN V8, it is lacking, what engine ain't? Would I like a Hemi? Hell yeah! Do I need one? For a DD? Hell no! 1.3 HP per cu inch... Good Now Days, indeed.

 

[Spur]

My exhaust cost $250 and I did it for sound. Really like the sound. Performance gains really only come with a proper tune. Maybe Pulsar or livernois someday for me.

While under warranty don’t want to crack the ecm and pulsar still seems unreliable.

If pulsar becomes reliable, I will probably go that direction.

 

[Kevin_D]

I've periodically thought of an aftermarket exhaust. Then I think "what if I was presented with an exceptionally easy opportunity to save between $300-$1000" that I could either save or direct to something different where I see a lot more for it, and decide, nah.

I agree with the comments here that if you are willing and able to re-do both intake and exhaust with a specific aim in mind, and parts selected for that aim, and then very carefully and comprehensively tune with that same aim in mind, you can get some results. But I don't have the time and bandwidth (or budget) to do that "all in" approach. My luck I would get it dialed in and then my state would declare some kind of extreme prohibition and intrusive inspection on such things and I'd have to un-do it all back to stock.

We are definitely not in the era in which a carb swap and exhaust work unleash a bunch of untapped potential. But I remind myself that that's because this engine, and others today, turn out an amount of HP, torque, and economy, for a given displacement, that would have seemed beyond even hoping for 30-40 years ago. 3.6 liters (at about 60 cubic inches per liter) = about 216 cubic inches, making 285 HP - that's about 1.3 HP per cubic inch on 87 octane fuel, and there was a time when only a tiny swath of extremely uncommon premium production engines ever cracked 1 horsepower per cubic inch, from a narrow range of years during the 1960s (after they really learned how to do it and before emissions controls) (like the highest output 327 Corvette engine, and that was only the most expensive and high-strung 327) and those few engines were considered marvels, beyond reach or hope of regular drivers. And average drivers wouldn't tolerate those amazing high output engines' operating characteristics, where premium fuel was an absolute must, starting was unrefined, and idle was choppy, and the engines gave outsized fanfare of anything that they were doing.

We're actually living in the "good now days" of how good standard WonderBread engines have become. By saying that I am not disparaging anyone who wants to tailor them even further.

What I do wish is that this engine could be configured for more low end torque, like you'd get out of a skinny bore, long stroke inline 6. But I realize that this engine needs to accomplish a lot of things in a wide variety of vehicles and that those characteristics would be undesirable in many of those settings. And since I have an MT, I just remind myself to change my shift points from what I wish they were, to what will give me the result I want.

It’s worth mentioning that before 1972, horsepower was measured as SAE Gross, which was very optimistic. In 1972 the measurement was SAE Net, which really lowered the numbers. Then in 2005, SAE J2723 came along, which is a more realistic measure of engine output.
And horsepower is a derived number, anyway.

Kevin

 

[BrentMG]

I just purchased an MBRP exhaust. Got it dirt cheap. Didn't really plan on ever purchasing one. Figured it didn't sound bad online and it might help just a smidge with MPG. I'm sure the .01 it will help will be justified in 40 years for the cost of it.

 

[ShadowsPapa]

It’s worth mentioning that before 1972, horsepower was measured as SAE Gross, which was very optimistic. In 1972 the measurement was SAE Net, which really lowered the numbers. Then in 2005, SAE J2723 came along, which is a more realistic measure of engine output.
And horsepower is a derived number, anyway.

Kevin

Derived? Well, unless you use a dyno and actually measure it. Otherwise yes, it's calculated for marketing, etc.
Horsepower is work done, so it can truly be measured and proven.

One of the pages from my 73 Javelin 360 - real numbers, not calculated or "derived" -

 

[takeitsleazy]

Most practical reason to swap a Jeep exhaust is for clearance. Less practical is for sound. That’s pretty much it. That said, I have an afe and they’re good

 

[Kevin_D]

Derived? Well, unless you use a dyno and actually measure it. Otherwise yes, it's calculated for marketing, etc.
Horsepower is work done, so it can truly be measured and proven.
<snip>

"HP is calculated from the following formula: HP= (torque X RPM)/5252. Dynos that only measure hp are making a series of calculations. Force = Mass x Acceleration, Work = Force x Distance and Power = Work / Time. The mass is the weight of the rollers. The acceleration is obtained by measuring the speed the rollers. "

www.thedieselgarage.com
​

Kevin

 

[ShadowsPapa]

"HP is calculated from the following formula: HP= (torque X RPM)/5252. Dynos that only measure hp are making a series of calculations. Force = Mass x Acceleration, Work = Force x Distance and Power = Work / Time. The mass is the weight of the rollers. The acceleration is obtained by measuring the speed the rollers. "

www.thedieselgarage.com
​

Kevin

Yes math has to be done to calculate the amount of work being done but it's specific, unlike the old calculations used for marketing car HP. I know HP- but you made it sound like it was all theoretical and conjuring up numbers and that it wasn't actually measured in real tests.

We had a small dyno in high school and one of the things the teacher did to demonstrate HP was to check out small engines (like 3 to 15 HP)
Interesting how accurate advertised HPs were on those things. If it said it was 5hp, we measured within a tenth of 5 hp.

 

[mellendic]

Most practical reason to swap a Jeep exhaust is for clearance. Less practical is for sound. That’s pretty much it. That said, I have an afe and they’re good

I have the AFE shorty, and like it... the sound and the clearance, I also have no rear tire underneath so more clearance, better departure angle. I also got the AFE intake and scorcher module, that did give me appreciable horsepower... but it was intake, output and programming. It takes a system to make things better. Also gears.

 

[oldhp3]

Remember the exhaust manifolds are built into the heads. They flow pretty good but not great. All for packaging the "power plant" into various different vehicles. Between that and the cat's I doubt any HP or torque gains from after market systems under 4K RPM where the engine spends 99% of it's time are real. Those "HP & Torque" gains are at wide open throttle. At least Ma Mopar did make the exhaust pipes off the engine equal length with a nice 2 into 1 "Y pipe". I like the quiet, but that's me.

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