Suggestions needed: getting more torque and power from 5.7Hemi - JeepForum.com

 
LinkBack Thread Tools
post #1 of 6 Old 03-20-2017, 04:46 PM Thread Starter
Matt5791
Registered User
2007 XK Commander 
 
Join Date: Feb 2011
Location: Birmingham, England, UK.
Posts: 30
Suggestions needed: getting more torque and power from 5.7Hemi

Hi all,

I have one of only 160 Commander 5.7 Hemi's currently on the road here in the UK.

Does anyone have some simple suggestions as to get a bit more torque and power from this unit? Especially torque, and ideally lower down torque. I find it rather frustratingly "revvy" this engine and would prefer more flexibility.

I appreciate that getting more low down flexibility may be into the electronic re-mapping arena.

But, for starters, any suggestions for simple stuff like breathing (air intake, exhaust etc.) would be interesting. This would be a good starting point for me.

I am prepared to look at importing parts from the USA to the UK.

Matt5791 is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old 03-20-2017, 05:41 PM
90grandoneer
Web Wheeler
 
90grandoneer's Avatar
2006 WK 
 
Join Date: Apr 2008
Location: City of Trees
Posts: 2,986
Anything that will improve the volumetric efficiency will improve the performance. The most restrictive part of the combustion cycle in the 5.7 Hemi's is the exhaust system. A good header back low restriction exhaust system is worth about 30-40 hp. on these, when done with headers and a 3 in. straight through (piping/muffler/resonator) cat. back setup. You can also advance the cam one tooth (will give you about 7* advance) which will move your torque curve to a slightly lower RPM. You could also opt for an aftermarket cam but, generally, they will kill some of your low end torque. Choosing the right one for your purposes is important. I use FRI Engineering Sidewinder cams in both my Hemi's. They have been around for over 10 years and are noted for being torque strong cams. The one in my Jeep is advanced a total of 6* and the one in my Magnum is advanced a total of 10*. Other things that will help somewhat are a good tuner, slightly larger throttle body, under drive crank pulley, etc., but only after the exhaust system is addressed. A good low restriction air filter and a modified airbox and SRT or Airaid Jr. intake tube probably won't give you much more horsepower or torque, except maybe at higher RPM, but is still a good, inexpensive mod.

06 GCO, Dk Khaki, QDII, Flshing Hi 3rd Bk Lt, MDS "ON" Lt, Airtab Vortex Gens, Debadged, Fumoto Drain Valve, BT Catch Can, Chopped EGR Tube, SRT8 CAI, K&N Filter, Sonnax Trans Line Press Booster, SC Tuner W/Adv Trans Tune App, DS Tuner, Cust tubular hdrs w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Springs/Sways, Cust Eng Cvr, SRT8 frt/rear bumpers, FRI Sidewinder Cam/6.1 valvetrain, SLP 25% UD Pulley, BBK true 90mm T-Body, SOS Ign Coils w/.060 spark plug gaps, SRT Reps with 265/45&295/40X20's.
90grandoneer is offline  
post #3 of 6 Old 03-20-2017, 07:59 PM
Hemicuda61
Registered User
 
Join Date: Sep 2015
Posts: 90
Use a tuner like Superchips to do flash remapping. This is the easiest mod to do.

Sent from my HUAWEI MT7-TL10 using Tapatalk
Hemicuda61 is offline  
 
post #4 of 6 Old 03-21-2017, 12:21 AM
SavageSalad
Registered User
2008 WK 
 
Join Date: Aug 2015
Posts: 146
Garage
Different headers would be a good choice. Most restrictive part on the 5.7 imo aside from the atrocious stock muffler


Sent from my iPhone using Tapatalk

'08 Black WK Limited | 5.7 HEMI | QD-II
MODS: SRT Intake Tube - Flowmaster Super 44 - BT Catch Can
SavageSalad is offline  
post #5 of 6 Old 03-21-2017, 12:23 AM Thread Starter
Matt5791
Registered User
2007 XK Commander 
 
Join Date: Feb 2011
Location: Birmingham, England, UK.
Posts: 30
Quote:
Originally Posted by 90grandoneer View Post
Anything that will improve the volumetric efficiency will improve the performance. The most restrictive part of the combustion cycle in the 5.7 Hemi's is the exhaust system. A good header back low restriction exhaust system is worth about 30-40 hp. on these, when done with headers and a 3 in. straight through (piping/muffler/resonator) cat. back setup. You can also advance the cam one tooth (will give you about 7* advance) which will move your torque curve to a slightly lower RPM. You could also opt for an aftermarket cam but, generally, they will kill some of your low end torque. Choosing the right one for your purposes is important. I use FRI Engineering Sidewinder cams in both my Hemi's. They have been around for over 10 years and are noted for being torque strong cams. The one in my Jeep is advanced a total of 6* and the one in my Magnum is advanced a total of 10*. Other things that will help somewhat are a good tuner, slightly larger throttle body, under drive crank pulley, etc., but only after the exhaust system is addressed. A good low restriction air filter and a modified airbox and SRT or Airaid Jr. intake tube probably won't give you much more horsepower or torque, except maybe at higher RPM, but is still a good, inexpensive mod.
Thanks very much for that, really helpful - I'll start with the exhaust.

Can anyone recommend a good supplier for exhausts? As I say, I don't mind looking at importing from the USA to the UK because there is limited choice on this sort of stuff in the UK.
Matt5791 is offline  
post #6 of 6 Old 03-21-2017, 08:26 AM
PolkaPower
Registered User
1998 ZJ 
 
Join Date: Aug 2011
Location: The Abyss
Posts: 20,258
I put on a MBRP and it sounds great.

Biggest gains in power will be from

1. Custom tune. I have a HPtuner and hired this guy to tune it. https://www.frptuning.com this will give you the biggest power increase for the money. This is not a "canned tune".
2. Long tube headers
3. Ported throttle body
4. Cam
5. Heads
6. Oil catch can. A lot of oil is sucked back into the motor and over time that causes a reduction in power and mpg. The can will catch the oil and cleaning the intake will improve everything over all.

A tune up including new oxygen sensors can also improve performance if the current ones are old and lazy.

Good luck, it's not cheap.
PolkaPower is online now  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome