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More Power from 5.7L ?

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DanaT

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Discussion starter · #1 ·
Has anyone sucessfully got more power from their 5.7L?

It seems that there are supercharger kits for every hemi except the 5.7L in the WK. I have also heard that the 5.7L hemis don't really like boost because of their piston rings being very near the top of the pistons.

So, that leaves heads/intake/exhaust/cams as the way to get more power. Some are much easier than others.

What have the results been with any of these mods that people make. Essentially, any modification that doesnt add a true 10% power probably wont make a difference in the feeling of the Jeep.

I am thinking..what does it take to make SRT8 power? Why not just buy an SRT8 you ask? In some stroke of genius, jeep engineers thought it would be good to leave out a dual range transfer case. And to think, they even try to compare an SRT8 without low range to competitors such as the Ranger Rover Sprot Supercharged or Porsche Cayenne Turbo (03-10) which actually have low range. Why can jeep make an SRT8 with a low range?

-Dana
 
#2 ·
I have been very pleased with the results of a good CAI, cat-back, and SC with the 91octane tune. The power increase more than made up for a lift and 32" tires. I used this combo for a couple of weeks before the lift and tires and it was a very noticeable power increase. I plan on playing with a cam swap and headers in the future. But for now this will do. I just wish some one made gears to help push these tire and relieve strain on the power train. Hopefully soon.
 
#4 ·
SuplexTreatment said:
Yea definitely. If someone made headers and a gear change for the WK they would sell no doubt. I need it especially for my 5.7L. The computer problem would have to be solved for the gear change too though.
Click to expand...
The SC would take care of that. You can modify your gear ratio just like you can your tires. If no one has started making gears for these by 2012 I am going to start talking to companies and at least get a set made. I know it won't be cheap, but I am hoping to convince them that there is a market for them and it would be worth their while to produce some.
 
#5 ·
As said above, headers, intake and tuner will do the most for the least $$$. I had custom header made for my 5.7 and it made the biggest difference by far. When you get into heads and cam the cost really climbs and requires partial engine teardown. I am hoping someone that doesn't want to spring the big $$$ for custom headers will try my suggestion here: http://www.jeepforum.com/forum/f67/better-exhaust-5-7-wk-1174042/ Here's the thread on my header build: http://www.jeepforum.com/forum/f67/headers-my-5-7-hemi-1161475/

As you can see by the pictures of the stock exhaust manifolds, you'd be wasting your time and money doing any serious engine work without first having a set of headers built. Those crappy things really put a damper on doing serious engine mods.
 
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#6 ·
intake manifold, throttle body, headers, *tuner* w/mds delete and trans tune, intake, injectors, head porting, pocket porting, piston swap, head milling (compression boost), alcohol injection, stroker kit, bigger valves, bigger exhaust, forced induction, etc... how much you wanna spend!?!?!

All that will make your Jeep haul ***, but take away the low end torque needed for wheeling...:(
 
#7 ·
SRT-8 power isn't that hard to achieve.... all you need is 70 hp.....more flow and fuel and more compression = more power
For more displacement, SRT engineers bored out the diameter of the cylinders in the HEMI by 3.5 millimeters each in order to increase the total displacement to 6.1 liters from 5.7 liters. Compression ratio was also increased to 10.3:1 from 9.6:1, increasing engine efficiency and power. Cylinders are honed with torque plates to ensure a truer bore, to reduce friction and increase power.

Engine breathing was increased with new higher-flow cylinder heads, a specially designed intake manifold, and exhaust headers with individual tubes encased in a stainless steel shell, all unique to the 6.1-liter HEMI engine. Larger-diameter valves and reshaped ports in the heads allow for maximized air flow. The intake manifold was designed with larger diameter and shorter runners for higher-speed tuning. Exhaust runners allow increased gas flow while maintaining fast catalyst light-off, while adding 12 horsepower over the 5.7-liter engine’s cast manifolds. Exhaust is routed through a large diameter (2.75-inch vs. 2.5-inch) exhaust system with 3.5-inch chrome tips.

To further increase horsepower, performance-oriented camshaft profiles were developed to allow more air in and out of the cylinders, as well as manage a higher engine speed. A billet steel, high-strength camshaft features more overlap and lift for better performance. Silent chain, 5-bearings. Bi-metal material except number 3 Babbit. Deep-fillet rolled journals for improved fatigue life, press fit damper to minimize torsional vibration.
 
Discussion starter · #8 ·
WK-916 said:
intake manifold, throttle body, headers, *tuner* w/mds delete and trans tune, intake, injectors, head porting, pocket porting, piston swap, head milling (compression boost), alcohol injection, stroker kit, bigger valves, bigger exhaust, forced induction, etc... how much you wanna spend!?!?!

All that will make your Jeep haul ***, but take away the low end torque needed for wheeling...:(
Click to expand...
I wanna spend $10 and do 145mph quarter miles...

-Dana
 
#10 ·
Add about 3 000 to the end of that 10 and you might get close, but I think it'll even run a little more.
 
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Discussion starter · #12 ·
I dont know if $30k would put it at 145mph in a quater mile....it would need about 1200hp to do that...

There comes a point when mods are worth it, and then there are mods that aren't it seems a good set of headers is one of the best bangs for the buck.

-Dana
 
#13 ·
X2, Dana. I can vouch for that first hand.
 
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#14 ·
90grandoneer said:
Add about 3 000 to the end of that 10 and you might get close, but I think it'll even run a little more.
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I'm trying to add as much HP to my 2009 Jeep GC 5.7L as possible, but I don't want to sacrifice offroad torque. I use it for day-to-day driving and want the HP, but primarily I want to turn it into some serious offload fun and for pulling my travel trailer. Any ideas?
 
#15 ·
Happy New Year to you and all of our fellow members.

Welcome to the forum. There are lots of things you can do to increase your power and torque but they almost all depend on how deep your pockets are and how much power you're looking to gain. Since yours is a 2009, it may or may not have VVT and the bigger "Eagle" heads. If this is the case, you're ahead of the game compared to the earlier 5.7 Hemi's.

From personal experience with the early (05-08) Hemi's, I can say that I got the biggest power/torque differences from a good header back exhaust system and a relatively mild aftermarket performance cam. IMO, these two mods. accounted for the majority of my approximate 100-125 hp. gain. The rest of my engine mods were less significant and gained lesser amounts of hp/torque.....See my signature below.

You'll probably still be running a single exhaust and should increase the cat. back size to 3 in. About the only game in town for the WK's/WK2's exhaust headers are some sort of SRT8 header, preferably long tubes, to go with the 3 in. cat. back. Your header primaries should be 1 3/4 in., not 1 7/8 in. You'll also want a muffler and resonator combination that is straight through (less restriction) and adequately reduces the exhaust drone, especially if you're retaining the MDS.

If you're going to go with an aftermarket performance cam and kit, you'll want to stay on the relatively mild side if you want to retain low end torque. There are several good cam manufacturers that make some nice grinds for the Hemi's. The cams I've installed in 3 Hemi's (Two 2 5.7's and one 6.1) over the years have all been ground by Comp Cams. The ones for my 5.7's still retain MDS and, with the other mods, deliver about 25% better fuel economy along with significantly better performance. IMO, the approximate key specs. you'll want to look for in a cam are ones with about a .525-.550 in. lift, about a 205-220* duration @ .050 in. and a lobe separation angle (LSA) of about 110-113*. A lower LSA slightly lowers the power band for each degree. On my 5.7's, I slightly advanced the cams (one 6* and the other 10* total) and the LSA's were 113* which, I believe, are the same as the stock cams. The 6.1's had an LSA of 117*, which is more of a mid-top end cam.

If you pull the heads, milling them .030 in. will raise the compression ration by about a half point. Cleaning up and port matching the intake and exhaust ports will also help a bit. Porting and polishing, like I did, isn't worth the $$$$, IMO, unless you're going to increase the engine displacement and/or add forced induction or NOS.

Remember, most well chosen engine mods. are cumulative and a good engine/transmission tune to suit your needs is a must. If you're both off roading and towing, you'll for sure want to do some minor mods to the transmission pressures and shift schedules to support the extra power and total weight. I would not recommend larger diameter tires....bigger size but not diameter. For towing, IMO, converting your 545RFE from a 5 speed to a 6 speed would be a must. For that you'd need an HP Tuner or pay someone with one to change it for you. Personally, I don't tow but I love to hot rod mine and the sixth speed makes it like a close ratio 4 speed through the first four gears. Fifth and sixth are the overdrive gears.

Good luck, have fun and safe.
 
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#16 ·
Thank you so much!! Really appreciate the advice...obviously based on a lot of experience.

The trans cannot be rebuilt. Metal shavings everywhere in the pan. Gonna have to start fresh. I like the idea of the 6 speed. How hard was it to mod?
 
#17 · (Edited)
The 545RFE is a pretty stout transmission but can benefit from a few "tweaks" to improve it a bit when you're adding more horsepower. Since you're going to rebuild, make sure they put better quality clutches in it, add a Transgo Shift Kit (about $50), a Sonnax Line Pressure Booster (about $70 ), and a Sonnax Oversized Lube Regulated Pressure Regulator Valve Kit (about $80). Be sure to read up on these on the Sonnax website and make sure it doesn't conflict with anything the trans. shop is going to do to increase the transmission operation and lifespan, or adversely affect your warranty.. Line Pressure Booster Kit - RFE-LB1. Most of this stuff is designed for "otherwise stock" transmisssions.

To convert the 545RFE into a 6 speed with all six speeds being in the normal upshift pattern requires a HP Tuner. All it entails within the Tuner software is a flip of a switch. With your 09, you can manually access all six speeds, but the sixth speed (2 Prime gear between 2nd and 3rd). So, if you want them all in the normal automatic upshift pattern, you need the HPT to turn that option on.
 
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90grandoneer
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