Who's running lth's with 1 7/8 on 3.55s?

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Millertime

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Anybody running the jba or obx headers in a truck with 3.55 gears? I hear people say you will loose some low end tq but I'm wondering from the guys who have them how bad it is?

I'm looking for more power while towing, which in my 5 speed is usually 1500-3k rpm range or so I'd guess? When I'm heading out west it kicks down and gets up pretty high pretty often though also.

So I guess I'm not building a drag race truck, but I also don't want it to be an absolute **** out of the hole either lol, so what's your experiences guys?
 

Paluby

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Anybody running the jba or obx headers in a truck with 3.55 gears? I hear people say you will loose some low end tq but I'm wondering from the guys who have them how bad it is?

I'm looking for more power while towing, which in my 5 speed is usually 1500-3k rpm range or so I'd guess? When I'm heading out west it kicks down and gets up pretty high pretty often though also.

So I guess I'm not building a drag race truck, but I also don't want it to be an absolute **** out of the hole either lol, so what's your experiences guys?

For your purpose the 1-3/4" would probably be better suited.
 
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Thought about it more and I'm prob in the 2-3.5k rpm range more often.

I guess what I'm wondering is at what rpm is the "tq loss" at? And you actually lose torque compared with a stock manifold or is it just not as much torque as 1 3/4 primarys?

Paluby have you ran 1 7/8 headers before?
 

brusk

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I'm still confused on this myself. On my 2007 I had OBX headers, muffler, Intake and Tuner and picked up more torque at every RPM. Is there something in the VVT that can be tweaked at those RPM's or something tuning wise that can be done?
 

Paluby

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Thought about it more and I'm prob in the 2-3.5k rpm range more often.

I guess what I'm wondering is at what rpm is the "tq loss" at? And you actually lose torque compared with a stock manifold or is it just not as much torque as 1 3/4 primarys?

Paluby have you ran 1 7/8 headers before?

I'm running them now along with a laundry list of other bolt ons. I've got an 8spd and 3.92's as well. I tow often and have no issues at all.

I believe what people are referring to is the difference of gains between the two sizes. They aren't saying you will lose torque compared to manifolds.
 
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I'm running them now along with a laundry list of other bolt ons. I've got an 8spd and 3.92's as well. I tow often and have no issues at all.

I believe what people are referring to is the difference of gains between the two sizes. They aren't saying you will lose torque compared to manifolds.

Ok thanks for that info. I figured with the moe I save vs arh headers I could get gears, or tb and some other crap that should more than make up for the diff.
 
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I'm still confused on this myself. On my 2007 I had OBX headers, muffler, Intake and Tuner and picked up more torque at every RPM. Is there something in the VVT that can be tweaked at those RPM's or something tuning wise that can be done?

What gear ratio did you have? Did you notice any loss while driving?
 

Paluby

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Ok thanks for that info. I figured with the moe I save vs arh headers I could get gears, or tb and some other crap that should more than make up for the diff.

Yeah, torque converter with your 6spd would probably do wonders for torque management depending on what size you went with. Do you already have a tuner?
 

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Tuner, 4.10/4.56 gears, tq converter, and JBA longtubes will make for a very strong combo. The gear and converter will give you all the tq you need down low, and the headers will take over up top.

I'm not a fan of 1 7/8" headers with 3.55's and stock converter, but that all changes after adding the gear and converter.
 

brusk

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Tuner, 4.10/4.56 gears, tq converter, and JBA longtubes will make for a very strong combo. The gear and converter will give you all the tq you need down low, and the headers will take over up top.

I'm not a fan of 1 7/8" headers with 3.55's and stock converter, but that all changes after adding the gear and converter.

Is this just a Part throttle problem?
 

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More noticeable at part throttle and while towing or climbing hills/mountains. At the track, guys with stock 3.21-3.55 gears and converter also cut slower 60' times than the guys with 1 3/4" headers. Now add the gear and converter, and there isnt much of a downside to running a 1 7/8".
 

brusk

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More noticeable at part throttle and while towing or climbing hills/mountains. At the track, guys with stock 3.21-3.55 gears and converter also cut slower 60' times than the guys with 1 3/4" headers. Now add the gear and converter, and there isnt much of a downside to running a 1 7/8".

Any chance there's Dyno sheets showing stock vs 1 3/4 vs 1 7/8 overlays? What RPM's seem to be the most affected? Any chance there's any dyno runs even showing RPM's that low? I know getting these autos to run low RPM's on the Dyno is a chore, didn't know if anybody had come up with any better tricks to get them to stay it the desired gear.
 

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Its almost impossible to start a dyno pull on 1 of these trucks below 3600rpms. That is why we test everything at the dragstrip instead of on the dyno.
 

RLJ10X

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Your truck is making plenty of power right now.

You're at a BIG mechanical disadvantage with those rotten 3.55s. I've been there myself. I have also considered power adders. After gears. I'm satisfied.

If I were you, the decision would be: 4.56s, or 4.10s. If I were doing a lot of towing, I'd do 4.56s. If that turns out to be too short, put on 35" tires. You can't lose.
 
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Not sure I want to go as deep as 4.10s, I still would like decent mpg when I'm not towing things. 3.92s my buddy has seem like they woukd be ok, would that work?

I have a hemifever tuned tuner on the way, and have an e fan and Volant intake on the truck now, just thinking future plans is all.
 

Hemi450hp

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The jump from 3.55 to 3.92 isnt much, so most guys go straight to 4.10. Last thing you want to do is spend $1000 for parts and labor for a gear swap and not feel the difference. Even with 4.56 gears and 32" tires, I'm only turning 2400rpm at 70mph. With 3.92's, I was turning 2000rpm at 70mph.
 

brusk

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Its almost impossible to start a dyno pull on 1 of these trucks below 3600rpms. That is why we test everything at the dragstrip instead of on the dyno.

ok so no way to lock in a certain gear on the dyno yet? I know I've expressed disappointment with the tuning options on this platform but why wasn't anybody figured out a software or hardware based option of locking a certain gear? I know it's not the most optimal but maybe trying 1st gear on a load dyno instead of a dynojet could be good for torque comparisons. HP numbers will be way off but the shape of the graph should be constant.
 

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Its not just this platform...its all Dodge, Chrysler, Jeep in general.

I dont see it as an issue though as we have already tested every one of these parts on the street, track, and most while towing as well. We have tested them on 3rd gens, 4th gens, 2wd and 4wd as well. Some guys like looking at a piece of paper that tells them what there truck is doing where others prefer to actually get in the drivers seat to find out what it is doing.

If you cant tell, I am not a fan of dyno's...haha.
 

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Tuner, 4.10/4.56 gears, tq converter, and JBA longtubes will make for a very strong combo. The gear and converter will give you all the tq you need down low, and the headers will take over up top.

I'm not a fan of 1 7/8" headers with 3.55's and stock converter, but that all changes after adding the gear and converter.


I just installed 1 3/4" long tubes last weekend and can tell there was a loss down low (5 speed with 3.55 gears). I'm running the 87 octane hemifever tune and prior to install could break the tires loose. After the install I cannot spins the tires, but the truck does scream mid to top. Guess I'll be needing a torque converter in my near future....just have to convince the wife that something else is broke with the truck, haha. Haven't towed yet, but will be tomorrow with the sleds and will see how she does pulling through the hills.
 

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I'm running the JBA 1 7/8" long tubes. On the factory 3.55 gears. Along with a set of 32" tires. I can tell that I lost a little bit of low end power. But the mid to top end pull. More than makes up for it in my mind. The truck is really screaming now from 20mph and up. Although I do plan on installing a set of 4.10 gears from Matt this summer. It's mostly just for that ***** and giggle factor than for necessity. Lol.


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