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  #157  
Old 10-11-2016, 05:14 PM
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Re: 5.7L American Racing Headers!

Quote:
Originally Posted by jeepgcoman View Post
Wow, lots of info. and opinions on this thread....some good and some not so good. Jeff turned me onto this one and wanted me to give my input, for what it's worth.....which by the way isn't much. As he said, I have two Hemi vehicles (WK and LX) that are both modded exactly the same except the WK has a 90mm throttle body and the LX has and 85mm throttle body. Other than that, down to the custom modified SRT CAI's, they're the same.

I've been messing with almost any kind of internal combustion engines (from model airplanes, to autos, to aircraft turbines and everything in between) for longer than most of you have been alive.....well over 40 years. I've also, in the distant past, built race car chassis, racing transmissions and racing engines, so I feel I am at least a little qualified to put my TWO CENTS worth in here. A lot of stuff I'll say here has been covered in the 13 or so preceeding pages, and I agree with some of it and don't with others.....after all everyone is entitled to their opinions, even though they may be wrong.

Since this thread is about HEADERS, I'll first give you my opinion of their value on MOST newer vehicles, especially those with crappy exhaust manifolds and cat. backs, such as we have on our 5.7 Hemi's. I've not seen a much worse system on any factory semi performance vehicle as the one that came stock on our WK's. See the pix below for a comparison of the stock WK (left) 1.75 in. collector, stock LX (center) 2 5/8 in. collector, and my custom tubular headers (right) 3 in. collector that I had built over 5 years ago. If, along with an efficient low restriction cat. back, you don't think a well built header back system will make a significant improvement in engine performance (and economy), I am here to tell you that you're sadly mistaken. It's beyond me why Chrysler, or any other auto manufacturer would install a potentially serious performance engine in a vehicle and then CHOKE it up with a crappy exhaust system. After all, the engine is just an air pump, and the better the volumetic efficiency [VE] (the ability to process this air expressed as a %age), the better the engine will run, perform and provide better economy than one that is being strangled.

There are many other variables that enter into it too, not just the headers, to take into consideration when attempting to improve the VE. One needs to make sure the incoming air (intake system) is as unrestricted (and cool) as possible, cylinder heads/valves are properly sized, the valve timing (cam) is adequate for the desired purpose, the ignition system (coils/plugs/wires) is capable of delivering adequate spark at all operating RPM, and the exhaust (from header to tail pipe tip) is efficient enough to get rid of the spent gases with proper scavenging.....too small will restrict and too large will slow down the exhaust process. Our stock Hemi intake system (without the silencer and with an Airaid or SRT intake tube and a good low restriction air filter) is more than adequate to deliver more air than the STOCK 5.7 is capable of processing......which is less than 600 cubic feet per minute (CFM) at ~75-80% VE, or a little less than 660 CFM @ 100% VE. The stock airbox is capable of processing (ref: flow bench tests done on Hemi LX vehicles over on LXforums.com) just under 700 CFM.

I could go on and on here, but know that ANY GOOD LOW RESTRICTION HEADER BACK system that is properly set up on our Hemi WK's will deliver a quite noticeable difference in both performance and highway fuel economy, but in town mileage may not improve that much. On mine, with the current mods. (see signature), I routinely get 22-23 mpg (high of 24.41 mpg) on the highway and ~13-14.5 mpg in town. My quarter mile times have dropped more than a second from stock elapsed times.

Also, just installing a good header back exhaust system WILL NOT require a canned or custom tune, but also won't hurt any. With my mods. I've run the stock tune a couple times, just because everyone said it wouldn't work. It does work but is really crappy, as the stock tune can't take advantage of the better camshaft, higher RPM potential, and the transmission really doesn't like the additional power.....in fact it doesn't like the stock power either. IMO, if you want to make a noticeable improvement to your Hemi WK, the best place to start is the weakest link....the exhaust. If you want to go further, get a tuner (I prefer the Superchips with the Advanced Transmission Tuning Application), and further yet, add a cam. None of these mods. require a lot of work.....just $$$. The exhaust is, by far, the most costly.....my complete custom header back system ran ~$1400 about 5.5 years ago, the tuner about $400, and the cam/kit about $700-800. My dyno is the drag strip (I'd rather spend $$$ on mods. than dyno pulls), and I figure I've gained nearly 100 hp. as I am set up now. Next step for me would be a bigger set of heads, but they would be the most costly of all my mods. and only deliver about 30 more horsepower.

Amazing info! Thanks for all the facts


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  #158  
Old 10-15-2016, 10:18 PM
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Re: 5.7L American Racing Headers!

Yes thank you for the info
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  #159  
Old 10-15-2016, 10:30 PM
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Re: 5.7L American Racing Headers!

Hi Eazy. I have an 07 57L... I'm interested in joining the group buy. Especially at free shipping and at a discounted price. Can you please pm me with the price for one with the cats included just like Nicks setup?! Thank you!!!
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  #160  
Old 10-17-2016, 08:10 PM
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Re: 5.7L American Racing Headers!

Quote:
Originally Posted by jeepgcoman View Post
Since this thread is about HEADERS, I'll first give you my opinion of their value on MOST newer vehicles, especially those with crappy exhaust manifolds and cat. backs, such as we have on our 5.7 Hemi's. I've not seen a much worse system on any factory semi performance vehicle as the one that came stock on our WK's. If, along with an efficient low restriction cat. back, you don't think a well built header back system will make a significant improvement in engine performance (and economy), I am here to tell you that you're sadly mistaken. It's beyond me why Chrysler, or any other auto manufacturer would install a potentially serious performance engine in a vehicle and then CHOKE it up with a crappy exhaust system.
I find it hard to believe that the stock exhaust is that bad on a stock engine. The people that engineer this stuff are more than qualified to design a system with adequate flow, and one that yields the best all around results.

I called American Racing twice in one day last week and got two different answer when I asked the following question: How much awhp can I pickup with a set of your headers on my 5.7L Jeep with a CAI and Diablosport handheld tuner? I got two vastly different answers, first answer was 15-20 awhp and the second time I got 45 awhp. I asked if they had any dyno information to backup those claims and got a resounding no both times.

Again, why is it so hard to see a true apples to apples comparison with dyno results to prove any of this?

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Michael Plummer
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  #161  
Old 10-21-2016, 08:13 PM
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Re: 5.7L American Racing Headers!

Well, I hate to say this but to each his own on what you believe and what you do to your ride. The engineers you're talking about "knowing" what they're doing may be correct, but the bean counters probably made them take some exhaust logs off the shelf in an effort to save $.20 per vehicle, knowing that the average Joe wouldn't know the difference or even care. Also, if your theory is plausable, why didn't they stick those "fine" exhaust logs on the WK SRT8. No, they put a set of tubular headers on it, because folks that purchase them want performance not one that's all choked up. If you don't think there is much difference and/or can't see the difference in both runner and collector sizes between the crappy stock exhaust logs and a good set of headers such as indicated in my pictures above, then I encourage you to continue running the stock setup. For that matter I'd even consider sending you my old stock logs for back ups. Also, if you want to bring your stocker down here we'll run yours and mine on the dyno one right after the other and see how they shake out. As much as I hate wasting money on dyno pulls, I'd be happy to pay for this one, just to show you how wrong you are. I know for sure the results I've gotten on every vehicle I've installed headers on, and they've all been substantially better than ANY vehicle with exhaust "logs" that dump one cylinder after another into a common restricted passage toward the collector.

Again, to each his/her own on your beliefs....even if they may be wrong.

Edit: One other thing, most of us on this thread are talking about EARLY HEMI WK's (05-08), not the later ones, like yours, with VVT. Have you taken a look at your exhaust manifolds? They may be quite different from those on the early Hemi WK's. Also, I believe yours has the "Eagle" heads it, which are very similar to the 6.1/6.4 heads.....bigger valves and bigger "D" shaped ports. Folks that have dyno'ed the EARLY stock Hemi WK's usually have pulled only ~265-275 AWHP. Most folks over on the LX forums used to pull ~285-295 RWHP, but most of them also didn't have 4WD,
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  #162  
Old 10-21-2016, 08:31 PM
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Re: 5.7L American Racing Headers!

Quote:
Originally Posted by jeepgcoman View Post
Again, to each his/her own on your beliefs....even if they may be wrong.
This discussion for me isn't about me being RIGHT or WRONG. It's about seeing if anyone has a TRUE apples to apples comparison with DYNO RESULTS on a WK2 5.7L.

Let me make one thing clear. If I install the ARH long tube headers on my 2014 Jeep and I pickup 30-40-awhp......... I WIN and the investment well worth it. Because I could give a rat's azz if I was wrong. I just don't want to end up paying all the money to do this and end up seeing a little increase in HP to the tires.

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  #163  
Old 10-22-2016, 05:06 PM
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Re: 5.7L American Racing Headers!

Mike, I can't speak to your WK2, as I am not familiar with it nor the type exhaust system installed on it from the factory. I really doubt that there is anyone out there YET that has done the dyno testing. You could be the first, since you've obviously done a pull or two on your WK2. Since this thread was initially addressing the early Hemi's which do have a soccer mom exhaust on them, there is a substantial difference when headers AND a good cat. back are installed. As I said, I am not into dyno pulls mostly because I'd rather spend the $$$ on other things, plus I don't really care if I gain 10 or 30 more horsepower here and there with the different mods......as long as I end up with a little more performance and a little better fuel economy. These were my goals when I started messing with mine. Unfortunately, the "mod. bug" hasn't left me and I am beginning to look for other more invasive stuff (so far my mods have only involved removing valve covers, rocker assemblies, and front cover) I can do to mine. I'd still probably not get too invasive and just do heads (~$2000 for around 30 hp......dyno proven on the early Hemi's), and roller rockers. I'd only mess with the rotating assembly if I blew something up though. I generally keep my vehicles almost forever, so a couple bucks here and there for mods. over the years doesn't really bother me that much. I've also given thought to low boost forced induction, but for that one, I can't (yet) get past the price of doing it.
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  #164  
Old 10-22-2016, 10:38 PM
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Quote:
Originally Posted by Robertjeep07 View Post
Im looking for a set of jeep headers also has anyone found or installed a set yet
I just bought a 2014 Jeep SRT with headers and exhaust by aFe already installed by the previous owner. Thing sounds badass and this thing hauls! Just messing around a couple weeks ago, I made 3 attempts getting 4.3 to 60 each time using launch control. Maybe i'll try the paddle shifters someday. Previous owner somehow pulled off a 3.9 according to the computer. Haven't had it dynoed. No other mods, no tune, no CAI. I've listened to other exhausts and headers on YouTube and granted, it's just YouTube audio, but I wouldn't trade them for anything else. Plus, the piping is nice 16 gauge stainless. Should last a bit longer than 18 gauge. I'm no expert on this stuff, though. Just my opinion
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  #165  
Old 10-27-2016, 02:39 PM
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Re: 5.7L American Racing Headers!

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Originally Posted by wkjoe79 View Post
I wanna add one more thing. For anyone following my build they know I'm using eagle heads so I have the D shaped exhaust port. I purchased my OBXr SRT8 kit with high flow cats for 680$CND. My recommendation....get the srt headers which fit and are a true dual setup and with your money saved add a good free flowing catback system. You will be very pleased. Only hiccup would be a slight mod if you want to retain the egr system for emissions purposes but it's an easy mod and instructions are easy to find.


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There is no EGR on the eagle motor, I found that out the hard way after I had already modified my srt take off exhaust manifold. Look up my install thread, lots of pictures
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