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Hi everyone, I am new here and I have been lurking around the forum for information. I have a few questions. I have a stock 2008 chrysler 300c 5.7, 92,000 miles and I would like to add an air intake (AFE II or Air Hammer) first and then I have seen some places where changing the camshaft out will add horsepower, I'll put the link below. Does that really work and is it worth it? The next question is do I need to upgrade the exhaust? I don't really have an interest in upgrading it as it is expensive. Is there an order of upgrades that anyone would recommend or that you have done? My goal right now is to stay under $1,500.


 

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If you have a 5.7, you already have true dual exhaust from the factory. You're not going to gain much by "upgrading" it. You can change the sound, but you won't see a significant increase in performance.

If you're changing your airbox for noise, then a $70 eBay CAI will do just as well as any name brand unit. If you want a tiny increase in performance, you'll need to install a long ram intake that draws cold air, not warm engine compartment air. You could also modify your stock airbox and duct it to the grille or behind the headlight if you can find the room.

I don't know that I'd spend that kind of money on a pre-Eagle 5.7, because if it drops a valve seat and destroys itself, I'd be kicking myself for sinking another $1,500 into it. But if you really want a performance boost, a 6.4 cam and intake would be a worthwhile upgrade, especially if you pick up an MSD or Cirkit box to take advantage of the active intake.

To keep costs down, you might be able to score a 6.1 intake for a little less money and skip the wiring issues associated with the active intake.
 

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Thanks for the reply, I didn't know that about the exhaust. I'm going to keep looking at the intake options. Is dropping a valve seat common and is it common with higher mile hemi's? Is there anything else I would need to change besides the 6.4 cam, or is it just that one part?
 

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Hi everyone, I am new here and I have been lurking around the forum for information. I have a few questions. I have a stock 2008 chrysler 300c 5.7, 92,000 miles and I would like to add an air intake (AFE II or Air Hammer) first and then I have seen some places where changing the camshaft out will add horsepower, I'll put the link below. Does that really work and is it worth it? The next question is do I need to upgrade the exhaust? I don't really have an interest in upgrading it as it is expensive. Is there an order of upgrades that anyone would recommend or that you have done? My goal right now is to stay under $1,500.


Hi welcome. Does your hemi feel like it should have more power? When I first got mine I really wasn’t impressed, especially hearing how fast they are since the 70’s. Or are you just wanting to go faster
 

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Thanks for the reply, I didn't know that about the exhaust. I'm going to keep looking at the intake options. Is dropping a valve seat common and is it common with higher mile hemi's? Is there anything else I would need to change besides the 6.4 cam, or is it just that one part?
Here's a good thread on this subject from one of our sister forums.
 

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My advice is don’t do anything my just pass 160 000 without any problem. If you want fill your car more fast just buy a tuner and disable MDS and that’s it.
$ 1500 not enough money for complete good job.
 

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First, welcome to the forum. Here's my take on all this, FWIW. IMO, what you really need to understand about increasing performance is that what you're attempting to do is improve the volumetric efficiency (VE) of the engine. The Hemi's already have a lot of potential, and the secret is to unlock it. If you're looking at things for a daily driver that don't adversely affect driveablilty and don't cost a zillion dollars, you can easily pick up nearly 100 hp. with a few well chosen mods that are either non invasive or not too invasive. I've done all this stuff on all 3 of my Hemi's (two 5.7's and a 6.1), unlike some of the other folks that may not have done some of them. So, I think I have what I consider a pretty good handle on what works and what doesn't for daily drivers. Here's a few things that help and some that don't make significant differences. Also, know that these mods. are cumulative......you may not gain a whole lot with each one individually, but,add them all up and they do make a difference. Also, IMO, it's important to try to do your mods. in a "logical" order.....i.e. don't start with a performance cam......fix the intake, do a few other "bolt on" mods and exhaust, and then do the cam and other more invasive stuff. Also, IMO, a good tune is essential when stock or with any/all mods you do. Custom tunes may be needed for some, unless you're knowledgeable on electronic tuning and tuning principles. A good bonus for some of these mods can, along with added power, give you improved fuel economy. Example, my 5.7 LX gets 27-30 mpg on the highway and most of my driving is in hilly/mountainous terrain at elevations of about 2400-5000 ft. The 6.1 LX gets about 23-25 mph under the same circumstances.

Any 4 stroke engine is just a big air pump, so the efficiency of processing this air is what we're looking for......increase flow through the intake, compression, combustion and exhaust cycles. The 5.7 engine, at 100% VE is capable of processing 658.275 cubic feet of air a minute (CFM). Unfortunately, most modern, normally aspirated (NA) engines today have only a 70-80% VE, and some less and a few more than that. To put this in perspective, the stock 5.7 may flow anywhere from the high 400's to mid 500's CFM. These losses occur from poor design, accessories, restrictive cam timing and exhaust systems, etc. To it's advantage, the stock 5.7 LX has a pretty fair intake, cylinder heads, valve sizes and exhaust system from the factory. This makes a good starting platform to begin modding.

First, don't waste your money on a Cold Air Intake, the stock one is more than adequate for the displacement of the engine. You can make a few improvements to it though to make it even a little better. Here's what I did to mine. On each I added a second air inlet and ran a flex tube from the airboxes out to behind the grills so it pulls in ambient air, not hot engine air like many of the aftermarket CAI's do. Second, I added a 392 Challenger Intake Air Temperature Sensor (IAT) which is longer than the stock one and samples air temperature near the center of the intake tube, NOT from near the outer wall like the stock one. Part Number 5149279AB. For anyone wanting to do this to an 05 and I think at least some 06 Hemi's with the black plug, you'll have to change over to the gray plug/pigtail, Pant Number 05014003AA. I am not exactly sure when the changeover was made, but the gray plug is what is needed. Both my 05 5.7 and 06 6.1 came with black plugs. Anyway, what this IAT Sensor does is read the cooler intake air and tells it to the PCM which, in turn, allows slightly more timing than with higher temperature air. I even went so far as to install a rheostat on my 05 so I can adjust the IAT any way I want. I have found that running it about 20* cooler than ambient seems to work the best for slightly increasing timing.

Along these lines, you'll want a high flow performance air filter element that still filters well. Back in July 2013, Mopar Muscle Magazine did dyno tests on power losses created by the various accessories and components. They found that, compared to no filter at all (no restriction), to a standard paper element air filter the engine, at peak power, lost 14.4 horsepower and 10.4 lb. ft. of torque. A good, high flow filter only lost 5.9 horsepower and 5.5 lb. ft. of torque.

Next in line is the throttle body. A lot of folks think bigger is better here (I used to think that too), but this is not true with a somewhat modified NA 5.7 or 6.1 Hemi. I have 90 mm throttle bodies on both of my 5.7's and an 85 mm unit that I had laying around on my 6.1. The stock size for both the 5.7 and 6.1 is 80 mm. Tests I've read on both these show loses of a couple horsepower (with the 90 mm) to a gain of up to about 5. horsepower. On all three of mine, about the only difference I've noticed is slightly better throttle response.....no noticeable power difference when read with the butt dyno. My recommendation is to leave the stock 80 mm one in place or go no bigger than 85 mm, and then only after you're about done with all your other mods.

Now to the intake manifold. DO NOT put a 6.1 or higher manifold on your 5.7. You'll lose power. I won't say anymore about this....just watch the video.

There is not a lot you can do to improve the combustion cycle unless you pull the heads and do head work and mill a bit off them to slightly increase the compression ratio. Porting the stock heads WILL NOT give you a giant gain in power on a stock displacement 5.7. Ask me, I know for a fact. Porting, polishing and milling .030 in. off them maybe gave me an additional 25 horsepower.....12 hp. for the port and polish and 12-13 for the increased compression. Also, to even get this much, the intake, cam and exhaust would also have to be changed/modified. I will say that if you have an early 05-06 and some 07 Hemi and pull the heads for ANY reason, I'd highly recommend you change, at a minimum, all of the intake valve seats to hopefully give you added insurance that you won't drop a valve seat somewhere down the line. I replaced all of the valve seats on both of my 5.7's when I had the heads done. Bottom line, don't waste your $$$ on porting and polishing UNLESS somewhere down the line you plan on increasing the engine displacement. Then you can possibly get much bigger gains. Hemi Head Test - Mild & Wild

Now, let's talk cams. Proper selection of a cam will probably be one of the two most important steps in reaching the goal for your daily driver. Do lots of research and then do some more BEFORE you select a cam, paying particular attention to lift, duration and lobe separation angles. Most folks think that bigger is better, but this isn't necessarily true IF you are using the vehicle as a daily driver. Installing a cam from a 6.1, 6.2 or 6.4 may sound cool, but in most NA 5.7's, it will be too much cam for the displacement/heads and you may end up losing power. The stock 5.7 "soccer mom cams" are meant for low end, smooth, operation and sacrifice, to some extent, mid-range and especially top end power. The stock cam in my 6.1 was a mid/top end cam, but lacked a bit on the low end....where I drive it about 90% of the time. The low end was adequate, but mostly because of the 25 more cubic inches of displacement. All of the cams I use are relatively mild so as not to adversely affect idle and driveability. Their power ranges are in the advertised neighborhood of 1500-6000 RPM and, with all of them, when they hit about 3000 RPM on up it's like switching on another engine.....there is that much difference.

The stock 5.7 exhaust system, log manifolds, cat.back and mufflers/resonators are really not that bad for a stock setup. See picture below which shows, left to right, 5.7 Jeep exhaust log, 5.7 LX exhaust log, and finally a collector on a "standard" aftermarket style header. The sizes of the collectors are respectively, 1 5/8 in. for the Jeep, 2 3/8 in. for the LX and 3 in. for the aftermarket. Also there is a difference in the two stock 5.7 log primary sizes which are not readily visible. The tubular headers also have individual primary tubes and don't dump directly into the path of the other cylinders on that bank.Tell me which one will flow better? Generally, long tube headers will work better than "shorties" and mid-length headers fall in between, and all will help to some extent when compared to the stock exhaust logs. A guess.....10-15 hp. for shorties and maybe double that for long tubes. Smog nazi states may have restrictions on some/all of these, so check your local laws. Use of High flow catalytic converters won't probably make much difference over the stock ones, but good, low restriction, straight through (no switchbacks) mufflers will help a little. One other caution with the 5.7 exhaust is to not go with larger tubing (such as a 6.1 system) than stock, unless you're very modified and/or are planning to go to forced induction of some sort. You'd probably end up losing some power due to reduced scavenging.

P10104591.jpg


Other miscellaneous mods such as under drive crank pulleys, hotter coils, lower ratio gearing, etc. do make varying differences and can be done at almost any time. If you do mods that significantly increase power, mostly cam and exhaust, I would highly recommend some modifications to the transmission too......slightly higher pressures, improved up/down shift schedules, and torque management settings. A good tune can address most of these concerns. Depending on the selected mods it is easily possible to gain anywhere between about 25-125 or so horsepower. Most important to me is to have fun and enjoy the fruits of your labor......and try not to worry about the hit to your pocket book.
 

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Actually I don’t understand what you want racing car or every day car, my car is every day car . If you want make do something good you need from good budget.
 

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Wow, Magnuman, nice comprehensive summary of modding our cars. Thank you!


Sent from my iPad using Tapatalk
 

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Hi everyone, I am new here and I have been lurking around the forum for information. I have a few questions. I have a stock 2008 chrysler 300c 5.7, 92,000 miles and I would like to add an air intake (AFE II or Air Hammer) first and then I have seen some places where changing the camshaft out will add horsepower, I'll put the link below. Does that really work and is it worth it? The next question is do I need to upgrade the exhaust? I don't really have an interest in upgrading it as it is expensive. Is there an order of upgrades that anyone would recommend or that you have done? My goal right now is to stay under $1,500.


Just a suggestion I learned on here. The post was similar to yours. And one of the replies that the computer learns your driving habits, and if the previous owners drove it with slow easy starts and never getting over 55 mph it’s going to be that car. It said unplug the power train control fuses in fuse box under the hood for 20-30 seconds and plug it back in. Then next time you drive the car. Drive the car making fast starts from stops. And stay in the throttle for a little bit and do that for about 10 minutes. I read it is the #4 another said #11and #18. I unplugged all 3 Then I drove it and the first time I took off I could tell the difference immediately. Like I was driving a different car mine is a 2008 300C too it’s free and it’s quick , so you might want to try it
 

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You're right, Wolfman, but you really don't need to go through all that. You can just disconnect the battery at the forward control module for a couple minutes and it'll do the same thing or, if you have a more advanced scanner, they have a routine that resets them without disconnecting the battery. What these procedures do is reset all of the baseline adaptives in the PCM. Otherwise, if the adaptives are not reset, it'll take quite a lot of "spirited" driving to make things change. The Transmission Control Module (TCM), located under the dash on the driver's side, works in concert with the PCM to control the shifts for all conditions. The stock one is torque sensing based and really lags compared to the PCM. It adjusts to how you've been driving in the "recent past" not the way you are currently driving. This means the TCM is always behind the curve. It can take up to ten minutes of "spirited driving" for the adaptive tables to update and adjust to this new type of driving. The remedy for this is to pick up a Mopar Performance TCM (about $200 or so) which is more logic based and adapts immediately to any changes in your driving style. The WOT up shifts are a lot firmer but the light throttle up shifts are just a little firmer than stock. Really worth the $$$, IMO.
 
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Actually I don’t understand what you want racing car or every day car, my car is every day car . If you want make do something good you need from good budget.
These are by no means race cars. The goals for most folks that mod. their vehicles do so to gain a little more power than stock and also to achieve better fuel economy. For instance, on my two 5.7's, a Jeep Grand Cherokee and a Dodge Magnum, I've gained about 100-120 horsepower and improved my highway fuel economy on each by about 25%. I also keep my vehicles almost forever, so the cost of these mods are not an issue for me. Also, with the ever increasing price of fuel, the "get well" time to recover the cost of the mods. is much shorter as time goes by.
 

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These are by no means race cars. The goals for most folks that mod. their vehicles do so to gain a little more power than stock and also to achieve better fuel economy. For instance, on my two 5.7's, a Jeep Grand Cherokee and a Dodge Magnum, I've gained about 100-120 horsepower and improved my highway fuel economy on each by about 25%. I also keep my vehicles almost forever, so the cost of these mods are not an issue for me. Also, with the ever increasing price of fuel, the "get well" time to recover the cost of the mods. is much shorter as time goes by.


Definitely you don’t understand my question !
I don’t ask you what junk you drive insane ...
 

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Definitely you don’t understand my question !
I don’t ask you what junk you drive insane ...
You have not asked one single question in this thread.

But I would agree with the "you don't understand" part. I don't think that anyone understands whatever it is that you're trying to say.
 

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Good, give me one reason asking for something and I will 😂😂😂
You said, "Definitely you don’t understand my question !”

You
said that.

Are you able to see your own responses? Because you're acting as if you aren't aware that you said that.
 
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