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Discussion Starter #1
Hello everyone,
I’m looking to do some mods this winter and I have a 2005 300c 5.7 rwd and its stock besides the cold air intake and 2 cherry bomb vortex mufflers with no resonators. I’m wanting to make it faster I’m not looking to run at a track, or anything just add more HP and speed. I’ve slightly looked through this site and its really outdated so not sure what’s still available since it’s 2020.This is my first 5.7 hemi and don’t know what to order or where to start any help would be appreciated.
 

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Thanks for the quick reply and i looked on their website and there are 4 different models for my year what would be the best one to purchase? Predator 2 (custom tuning), Intune l3 (custom Tuning), Intunel3 (50 state legal) and Predator 2.
 

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Discussion Starter #4
Thanks for the quick reply and i looked on their website and there are 4 different models for my year what would be the best one to purchase? Predator 2 (custom tuning), Intune l3 (custom Tuning), Intunel3 (50 state legal) and Predator 2.
 

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A steeper rear end gearset / Getrag LSD will do wonders and likely be the most effective mod short of a supercharger.

I started with a 3.55 and then jumped to a 3.91 and I enjoy every second of it.

Sent from my SM-G950U using Tapatalk
 

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Thanks for the quick reply and i looked on their website and there are 4 different models for my year what would be the best one to purchase? Predator 2 (custom tuning), Intune l3 (custom Tuning), Intunel3 (50 state legal) and Predator 2.
Which ever you can afford, if you would like a custom tune get one that has CMR capabilities. You should probably contact them and they can answer your questions regarding the differences.
 

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All true above. First, what is your budget? Second, how much power and how much faster do you want? Are you just interested in performance, fuel economy, or both. On both my 5.7 Hemi's (05 Magnum and 06 Jeep Grand Cherokee) I've spent almost 10 years, a little at a time so as not to upset the wife, doing mods in what I considered a logical order. Definitely start with a tuner and, if you desire a custom tune. I've never done that with mine, but I have all the tuners for both....Superchips, Diablosport and HPTuner and I have a pretty good handle on what needs to be done tune wise.

Since yours is an 05, I am sure you're aware of the dropped valve seat problem with the early Hemi's. If you're not familiar with it, do an internet search on, "early Hemi dropped valve seats" and you'll see what it is all about. IMO, the next thing you should do it insure the cooling system is in top notch condition.....a cooler thermostat (I run 190* ones) and, with your tuner, reset the cooling fan start temperatures to lower settings. Here's what I use on all 3 of my Hemi's: Low: 200*; Medium: 205*' High 210*. Also make sure you use nothing but the factory recommended HOAT type anti-freeze mixed 50-50 with DISTILLED water. Not necessary, but I also use a lower pressure cap, about a 15 pound one. This takes a little of the load off the cooling system, especially the cheapo radiators. Set up this way, I've never seen any of mine past about 215*, even in 105* temperatures and idling for long periods of time. Also, be aware that this IS NOT a cure all, but it may prevent a drop, since most happen with an overheat or excessive heat soak condition. A typical scenario is you stop for gas (5-15 minutes) and then when you try to re-start it, it either won't start or it starts, runs very rough, makes a lot of engine noise and/or stalls. The more you try to start it, the more damage you do to the engine. Repair prices run from $1500-10000, depending on damage and extent of rebuild desired.

I've been running the cooling setup above for many years and reworking the heads on both of the 5.7's was the last thing I did. I finally pulled both apart and had all new valve seats installed, ported and polished (doesn't help that much) and .030 in. milled off them to raise the compression ratio to about 10.2:1. On Maggie, when the machinist was cutting out the intake seats (the ones that fail the most), he said one started spinning in its bore when it was only about half cut out. All the others had to be completely machined out. He said that the one that spur could have been a candidate for a drop......no way of knowing though.

Back to the mods.... the LX Hemi's log manifolds are not all that bad, so doing the whole thing isn't necessary right away. When you do, the best way to go is long tube headers and a good straight through cat. back exhaust. I have JBA Shorties on Maggie and ARH Long Tubes on the Jeep. My Chrysler 300 SRT exhaust is completely stock and works fine for me. Other less expensive stuff that helps is listed in my signature in the approximate order I did them. For both of my 5.7's, I've gained about 120-130 hp. and my fuel economy is now about 25% better than stock......Maggie, 27-30 mpg, Jeep, 20-23 mpg. Oh, not listed is I do have a Getrag 3.06 LS Differential in Maggie, as it is mostly our highway cruiser.

Good luck and happy modding. Keep us posted on your progress.
 

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Discussion Starter #8
I'm interested in performance and fuel economy. My budget i'd say anywhere from 1500-2000. I'm glad you mentioned the radiator and cooling part because i just had to replace it due to a small crack in it and bought a new thermostat but not a 180* etc. I would love to do a valve seat and head upgrade but that would be later in the future. I purchased the car used but in very good condition and it had 174k and now has 189k (daily driver) so not looking to keep the car to long due to miles and wear and tear but i'd like to keep it till the wheels fall off so don't want to dump a ton of money on like cam, headers etc ( only if needed) just small things if possible. My first purchases will be a tuner and then another thermostat but anything else reasonable in price far as bolt on things I'm willing to purchase.
 

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IMO, if you don't plan on keeping the vehicle very long and your not budgeting too much for mods., I'd probably stick with less expensive things that will give you a little better performance and, hopefully fuel economy. I think, if it were me, the first few orders of businees would be, in this order, a cooler thermostat, a tuner that will allow you to reset cooling fan temps., perhaps an underdrive crank pulley, a catch can, and some sort of straight through (no switchbacks) muffler. For the thermostat I'd use a 180* if your in a warmer climate or a 190* if your in a cooler climate. Next with the tuner, first set the fan start temps. and then, if you're not going to get a custom tune, I'd experiment and find out which canned tune provides you with the best performance and fuel economy, taking into consideration the price of a good top tier fuel and price/availability of it in your area. Next, I'd probably do either the underdrive crank pulley or the catch can. The catch can won't necessarily give you much performance/fuel economy, but it helps keep oil and condensation out of the intake, combustion and exhaust tracts which may allow the PCM to add a little more timings. (While you're at this one, change the PCV Valve unless you know it's been recently changed. Finally, eliminate some of the exhaust restriction with a good straight through muffler. The stock "suitcase" that comes with the vehicle is quite restrictive. Doing these things could give you as much as about 50 more hp. and maybe a couple more miles per gallon. If you're able to do all this work yourself and not have to pay labor for everything, next I'd consider a cam. The parts.....cam, valve springs, push rods, etc. cost less than $1000....the labor to have it done is what would kill you. A mild high lift, longer duration cam can give you anywhere from 30-50 hp. depending mostly on your tune and your exhaust system.

Here's a couple references that'll show you what I mean. Disregard the bigger heads and note the difference just a cam and headers make:

This one will enlighten you on the benefits of a catch can. It was posted on an SRT Hemi forum by Mike at Diablosport, the tuner maker:
"No, this is where I comment on lost power due to oil contamination in the intake tract/combustion chamber. I will assure you that after having seen as many logs of as many HEMIs as we have here at DiabloSport, not to mention the numerous HEMI vehicles we have had on our dyno for R&D, I can say, without a doubt, that the HEMI's PCV/Oil Vapor control is the worst of anything we deal with. All you have to do is pull your intake manifold to see the puddles of oil collected in there, and realize that it eventually gets in the combustion chamber, and oil don't like to burn, thus, detonation occurs.

There is no gimmick here. HEMI's have KR issues. The KR issues are 99% of the time contributed to by oil contamination in the intake charge, reducing the effective octane in the combustion chamber, and leading to a loss of performance.

Plenty of people have seen solid power gains on even stock vehicles when getting rid of an oil issue by adding a catch can that works properly.
https://www.cherokeesrt8.com/threads/catch-can-billet-tech-vs-diablosport.50350/post-690577
 

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A couple other things came to mind that may be of interest to you. Before you go dumping a bunch of $$$ into it, do a compression check and a cylinder leak down test. These two tests will tell you everything you'll need to know about the condition of the engine. You have a little more miles on yours, 189 K compared to 170K on my 06 300CSRT8. I bought it from my Grandson with a slight engine noise. After doing all the preliminary tests, I decided the overall condition of the engine was sound. After extensive troubleshooting (don't want to tear into it farther than need be), I pulled the heads and front cover.and ended up doing a cam, valve lifters, valve job with new valve springs, and an 85 mm throttle body. Cost of all this was about $2000, but I had a set of 6.1 valve springs and the 85mm throttle body laying around from the 5.7's. The SRT now has about 460 hp. and gets 12-14 mpg in town (depending on stop and go) and 22-25 mpg on the highway. I did not advance the cam in it like I did in both 5.7's, because it has plenty of low end power.....amazing what about 25 more cubic inches in the engine will do..

Another thing you could do, if you don't want to go with a new cam is advance the stock cam by one tooth on the cam gear. This will advance it by just under 7* and slightly move the power curve (hp/torque) to a little lower RPM. The stock cam is already pretty good on the low end, but this should make it even a little better. On my two 5.7's, (modded almost exactly the same) the Jeep, with the performance cam, is advanced a total of 6* and Maggie, with the same type of performance cam, is advanced a total of 10*. As far as performance goes, the Jeep is about 600-700 lbs. heavier, has 4 WD, has worse aerodynamics (even with the SRT body kit on it), but does have slightly better gearing in 1st and 2nd. For about the first 100 ft. it is quicker than Maggie and about the same as the SRT, but beyond that both Maggie and the SRT leave it in the dust. Oh how nice it would be to have a 410 cu. in. stroker in all of them.....see the Hot Rod Network article above.
 

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Discussion Starter #11
Thanks for the replies well said my friend. Looks like I'm going to start with the compression check and cylinder down leak test, cooler thermostat, pcv valve, oil catch can, diablo tuner and Under-drive crank pulley. I think i'll be fine with those mods and esp when i get the tuner and add a costume tune and see how she feels afterwards to see if i want to go forth with cam valve springs etc.


I can do most of all repairs and bolt ons my self so that would save me a ton of money my next question is when purchasing a oil catch can is there a certain one you prefer i buy there is so many out there. Also once i do a compression test and down leak test i'll post results and see where to go next.
 
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