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Lose Trq with long tubes??

5565 Views 14 Replies 9 Participants Last post by  O_Racing
Ok so I'm about to purchase Kooks long tubes and high flow cats for my 6 speed 392. I know, overall I'm going to pick up power/trq, but will I be loosing any trq down low? I really don't want to mess with the 392s flat torque line. Thanks.


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From the reading I have done u will lose some. I don't know how much, but the way I have always understood it is long tube for more top end and shorteys for more low end.

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I have read stuff saying both things, I tend to think you can't lose with longtubes. People seem to post rather large gains with them overall, and at sea level even if you do lost 5 ft/lbs or whatever for a small part of the powerband initially, I can't imagine you would feel that, and then you have the large gains over most of the powerband to look forward to.
For a variety of reasons that involve physics, it turns out that long tube headers do the best job building horsepower and torque from mid-to-high RPMs. These are great for high-revving engines and at the track, but they do sacrifice some low-RPM power.

Shorty headers deliver more power horsepower and torque from idle to the mid-RPM range. This makes shorty headers perfect for your daily drives.
X2 on what Cuda said.... Every car that I have put LTs on (six), the tq band shifts upwards, sometimes over 3K RPM whcih can hurt you on the street. Granted these were not 392s with goobs of low end tq to begin with so it may not be as noticable with a 392 as with the old 360 (5.9s). Can't beat the sound though, nothing sweeter.
I know this doesnt count since your talking about the 6.4, but my RT gained torque through the whole RPM. I hear quite a few people saying that long tubes lose low end but I have never seen any proof. Not discrediting what the guys above have experienced, its just what I have seen.

Here is my comparison
http://www.challengertalk.com/forums/f18/rt-before-after-arh-long-tubes-135953/

Here is another guy who already had a custom tune, then added the headers showing what they are good for by themselves.
http://www.challengertalk.com/forums/f175/kooks-headers-install-dyno-230817/

This proves to me that long tubes do not lose torque on the low end (on the 5.7 at least).
First thanks for the replies. Secondly, I'm not going to mind dropping a little bit of torque down low, but do you think the overall gains at mid and up high will be worth the LTs? I do plan on head/cam work,in the near future.


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what i say, well if you launch on the street at 3k and above and stop driving like a sissy, the long tube and loss of tq is not or no longer an issue; just sayin'....lol

ok don't get your panties in a bunch now...

the X pipe is also an important factor in low end torque; i am installing magnaflow cut outs on on my magnaflow 16885 comp series for road course;

i can't imagine how much low end torque i am going to lose bypassing the magnaflow X pipe but at least i will pick up some Hp between 4k and 6.5k which is the band where it is fun to drive the tank

jmo

ODP
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what i say, well if you launch on the street at 3k and above and stop driving like a sissy, the long tube and loss of tq is not or no longer an issue; just sayin'....lol

ok don't get your panties in a bunch now...

the X pipe is also an important factor in low end torque; i am installing magnaflow cut outs on on my magnaflow 16885 comp series for road course;

i can't imagine how much low end torque i am going to lose bypassing the magnaflow X pipe but at least i will pick up some Hp between 4k and 6.5k which is the band where it is fun to drive the tank

jmo

ODP

I've got the same cat back as you, minus the cut outs. So your saying since I have that beautifully crafted work of art "X" pipe from Magnaflow, even with the long tubes, there shouldn't be that much of a loss down low?


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I doubt you'll notice the tq loss on the 392s anyways.
Can one install those cutouts after the x pipe? Just curious. Does MF sells those?


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Also depends on the diameter tubing you get. 1 3/4 long tubes won't lose that low end tq and will gain some but won't have as big of a top end as 1 7/8 will. All depends on what your application is. Supercharger? Then go with 1 7/8. 1 3/4 might be better for N/A unless it was a 426 stroker or something.
Also depends on the diameter tubing you get. 1 3/4 long tubes won't lose that low end tq and will gain some but won't have as big of a top end as 1 7/8 will. All depends on what your application is. Supercharger? Then go with 1 7/8. 1 3/4 might be better for N/A unless it was a 426 stroker or something.

Kooks only makes 1 7/8. I'm staying NA and not stroking the motor. Just doing , eventually, all head work and cam.


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Kooks only makes 1 7/8. I'm staying NA and not stroking the motor. Just doing , eventually, all head work and cam.


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They will make 1 3/4 if you request it.
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I've got the same cat back as you, minus the cut outs. So your saying since I have that beautifully crafted work of art "X" pipe from Magnaflow, even with the long tubes, there shouldn't be that much of a loss down low?


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no issues there; torque imo whould be maintained
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I've got the same cat back as you, minus the cut outs. So your saying since I have that beautifully crafted work of art "X" pipe from Magnaflow, even with the long tubes, there shouldn't be that much of a loss down low?


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I doubt you'll notice the tq loss on the 392s anyways.
Can one install those cutouts after the x pipe? Just curious. Does MF sells those?


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back online; on leave across Europe, with the fancy 90 hp Renault Diesel Engines...lovely

anyway, yes the MF manufactures the cut outs and they are pretty well made; i have them at home ready to be installed;

MF cut outs on challengers are not proven for the challenger; it will most likely be a b$tch to install as the only ones i have seen on a challenger are the electric ones that are remotely controlled; but they need to be welded in

the ones i got will need some cutting on the exhaust pipe near the cats; anyway this is for another thread

i thought of the same HEMIZSP, but at the end there is no point to have the cutouts so far away from the exhaust manifold; at this point we are speaking of an open exhaust setup, with no cats and only tubes to drive gases on the car sides

imo and re: the challenger i am looking for less torque and more top end power; with weight reduction i need less torque and i can also be less mindful of throttle action under apex and corner exit; right now, in certain conditions this car can be a bit fish "tail'y" with that much torque on road course; losing some torque when also losing weight is ok

for me it is also getting used to driving on the track in the roughest condition possible; a race car is loud, it is hot, it smells gasoline at time; it feels line a sardine box on wheels

noise it the first thing i want to get used to right away; i also have to pay attention to my engine noise to figure out its rev; i used to know when to shift just by listening to the engine

the challenger damps everything with carpets, under hood insulation; with my helmet on and the air flow trough the window the engine is not so easy to listen to

with the cutouts i will feel more in sync with my horses

finally, pass the 4k rev threshold i don't think X pipes are doing anything important with torque as the exhaust pulse frequency is so high that then balancing act of low/high pressure the x pipe is doing is pretty much useless

need to check on this; but x pipe have never been spoken about maximizing high end torque

ODP
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