Dual exaust on a 2F?

[highlandcruzer]

Any thoughts? My thought was that it was too much, maybe undesirable. But my budee's CJ7 has got me thinkin again. Stock 258 with a weber, header, no cat, and tru dual 2 1/4 [I think] pipes , through two dynomax mufflers. This thing sounds awsome. Like old school V8 muscle. Out of this straight 6. Every body comments on how good it sounds, from idle, all the way through the RPM range. And it runs like a bat out of hell [old jeep bat] sure seems like its a healthy set up. I might copy it on my 40. What do you guys think?

 

[35inchoverdrive]

This is just my opinion...so...it's worth what it costs you-

It seems that people who are unfamiliar with cars hear and see generic things like dual exhaust, and just associate them with coolness and horsepower and what not. If you actually have two exhaust manifolds...then sure...why not, but when I see someone with an inline engine with dual exhaust I wonder if he's going to slap a "Type R" badge on his ride next. It doesn't help your performance in any way, and it's just more time and money that you could have spent on something to make you rig better instead of trying to look or sound cool to people that don't know anything about cars. The jeeper may have that "muscle car sound", but that's all he's got. Muscle cars were not cool simply because of the noises they made. That's not why car people and non-car people alike, came to revere them. They were cool because they were packing some serious power, and the sound was just a side effect.

 

[highlandcruzer]

I'm a function over form [ or sound] guy too. Thats prolly why we drive Landcruisers. I'm not saying that I think his exaust is providing any gain in performance, over my single setup. But I'll admit that its nice to here a throaty , [Not to read,obnoxiously loud] exaust , when you need to get on the skinny peddle a little bit . I guess, what I'm asking, is if anyone else is like me , then, what set up are you running on your 2F that is "healthy" and sounds good ? My 40 sounds pretty good at idle, but just sound like a loud hum, at cruising speed or when I get on it . What muffler etc. Would there be any reason why you would'nt run duals? Maybe its just his Dynomax mufflers. I realize exaust sound is a matter of opinion , maybe I'm kinda redneck. AS a matter of fact I told my freind , he was stupid to put duals on his straight 6 ..............But damn ,it sounds good!!

 

[35inchoverdrive]

To each his own...
The best my 40 has ever *sounded* was when I tore off my exhaust at Tellico. At idle and relatively low in the power band, it sounded like a monster, but whenever I had to rev it, the thing just sounded like an airplane. Right now I've got just a header and a Flowmaster. It doesn't buzz, but it doesn't turn heads either. I don't think I've ever heard a Dynomax muffler on an F/2F, but that might be the way to go in the sound department. You could just yank one of the Dynomax's off of the CJ when he's not looking. It's not like he *needs* both of them, and maybe he won't notice just long enough for you to take a test run with it on your rig.

 

[highlandcruzer]

Good thinkin'!!!!

 

[workingdog]

"It doesn't help your performance in any way"

That just ain't true. In the 50's and 60's, when V8's were rare and everything was running a straight 6, you could get dual exahuast manifolds from Fenton and other vendors to run dual exhausts. It was the hot ticket. The sound out of a dual exhaust straight 6 is legendary.

It's like putting on dual carbs. They are both throwbacks to a different era - like our 40's.

Peter

 

[35inchoverdrive]

"It doesn't help your performance in any way"

That just ain't true. In the 50's and 60's, when V8's were rare and everything was running a straight 6, you could get dual exahuast manifolds from Fenton and other vendors to run dual exhausts. It was the hot ticket. The sound out of a dual exhaust straight 6 is legendary.

It's like putting on dual carbs. They are both throwbacks to a different era - like our 40's.

Peter

What kindof power numbers did these 'performance' dual exhaust manifolds on inline engines produce over 'performance' aftermarket single exhaust manifolds? If my claim that dual exhaust on an inline engine doesn't have any power gains over a single exhaust system, "just ain't true," then I'm sure there are some specs out there to prove me wrong.
Dual carbs are a totally differnt story. That was a way of getting more air and fuel into an engine before technology made that setup obsolete. Dual carbs actually solved a problem for an engine that was able to handle more air and fuel than a single carb setup in that era could deliver.
Also, those manifolds may have been the 'hot ticket' then, just like it is the 'hot ticket' now to do some exhaust and airbox mods on an economy car and then somehow a Civic becomes a race car. There are some fast imports out their, but many of them are still just economy cars with lots of stickers, and people just eat that stuff up.

 

[bbalbano]

My 1st frame up was an 84 cj7, the 258 was a tough motor and when I put my offenhauser intake, holly carb and better exhaust it definitly increased the horsepower. I didnt do it for the sound that puppy was a bat out of hell, Im a big fan of the 258 so I dont think your idea is a bad idea. With that said this is my 1st 40 and I havent even had a chance to test out this F motor yet so I cant really compare the 2. Not to mention my 258 had a performance camshaft which gave me great low end torque I used to smoke other jeeps of the line...

 

[Ziffdaddy]

IMHO, Since a dual set up on a V-8 is accepted as being a good power producer, why wouldn't an I-6 benefit from a dual set up? It's seems that the only reason people are saying that it doesn't make power is because the exhaust manifold is only on one side and since the V-8 is on two sides, it somehow makes more sense.
So.....by that logic, a (theoretical) inline 8 (or 10, 12, 16 etc...) wouldn't benefit from dual exhaust....not buyin' it. I believe there would be a measurable difference in a single/dual set up for an inline six.....just not as much as an 8 because of the two piston difference in breath. just my opinion, though....

 

[Ziffdaddy]

Just seems logical...to a point, of course. more air in-more air out. Hell....run 6 single pipes out the back! hehe.

 

[35inchoverdrive]

Just seems logical...to a point, of course. more air in-more air out. Hell....run 6 single pipes out the back! hehe.

If the number of manifolds doesn't have any bearing on it, then why stop with the number of cylinders? I'm headed out to the garage now to fashion a 7 pipe exhaust for my F.

 

[Ziffdaddy]

Huh?

 

[35inchoverdrive]

IMHO, Since a dual set up on a V-8 is accepted as being a good power producer, why wouldn't an I-6 benefit from a dual set up? It's seems that the only reason people are saying that it doesn't make power is because the exhaust manifold is only on one side and since the V-8 is on two sides, it somehow makes more sense.
So.....by that logic, a (theoretical) inline 8 (or 10, 12, 16 etc...) wouldn't benefit from dual exhaust....not buyin' it. I believe there would be a measurable difference in a single/dual set up for an inline six.....just not as much as an 8 because of the two piston difference in breath. just my opinion, though....

The increase in power doesn't come from the addition of tubing or a muffler. The increase in power comes from the removal of some of restriction of the flow of exhaust. With a V-engine, a single style, factory exhaust take the exhaust flowing out of two manifolds and squishes it all into a single pipe and out the back. The dual setup in that case removes some of the bends and the restriction of all of the gasses having to cram into the juction. On an inline engine you've got everything exiting from a single manifold and it's not going to make any difference if you then split a single pipe into a dual pipe downstream of that.

 

[Ziffdaddy]

To clarify, I was referring to 'true' dual exhaust on a six, not a single header that comes off the manifold and splits into a thousand pipes. Like my van's V-8, obviously, has two manifolds....it merges and becomes one pipe....not as good as two separate pipes.....if an I-6 had two 3 into 1's that separately left the vehicle in their own individual pipes, there would be a greater/faster evacuation of exhaust....hence better breathing for the engine.....obviously to a point. If you have giant carbs and a crapload of air going IN the engine...it definitely helps to be able to get it out faster....That's why I said the 8 would obviously benefit on a larger scale because of the greater volume of air it uses.

 

[Ziffdaddy]

I think we might actually agree with each other, but we were looking at it differently. Goodtimes.

 

[35inchoverdrive]

I think we might actually agree with each other, but we were looking at it differently. Goodtimes.

Maybe so. We could just go on rephrasing what we said in the previous posts, going back and forth until we reach 100 posts each. *sigh* That being said-
I suppose it's *possible* to be flowing so much air through an inline engine that a single manifold/header design could be inadequate. I don't think that's the issue with the F/2F or the 258, but I suppose it's possible. In racing applications I can't think of any Skylines or Supras that run(or ran) dual exhaust on an inline engine and I'm pretty sure they are moving some massive amounts of air in and out those powerplants. Someone may correct me on that though, as I am just a casual observer of such things...and...I am a fool.

 

[highlandcruzer]

My understanding of exaust is that, while yes, you want your engine to be able to exhale easier than stock manifolds often allow, improving performance with headers etc. There is a point where greatest efficiency is reached , where the exaust gas pulses actually "pull" and create vacuum. And increasing pipe volumn would reduce efficiency. Thats why I wondered what was best for 2F, If that dual set up might produce less power than a certain sized single pipe. I know we're not dealing with racing engines hear If there is'nt much difference , I'd like mine to sound as torquey as it is.

 

[Ziffdaddy]

Good point....not the part about you being a fool.....hehe....but I wouldn't mind looking for any hard data on the possible benefits if they exist....again, a true dual system. Oh well....it was fun while it lasted. We'll do it again sometime.

 

[Ziffdaddy]

If the number of manifolds doesn't have any bearing on it, then why stop with the number of cylinders? I'm headed out to the garage now to fashion a 7 pipe exhaust for my F.

My understanding of exaust is that, while yes, you want your engine to be able to exhale easier than stock manifolds often allow, improving performance with headers etc. There is a point where greatest efficiency is reached , where the exaust gas pulses actually "pull" and create vacuum. And increasing pipe volumn would reduce efficiency. Thats why I wondered what was best for 2F, If that dual set up might produce less power than a certain sized single pipe. I know we're not dealing with racing engines hear If there is'nt much difference , I'd like mine to sound as torquey as it is.

I'd be interested to hear what it sounded like....if it is a true dual system, I bet it would sound pretty badass.

 

[Ziffdaddy]

not sure why that just multi-quoted....ah well...