Forums
New posts
Search forums
Image search
Shop
Amazon Store
T-Shirts
Stickers
Members
Current visitors
Supporting Member Upgrade
Sponsors
About
Log in
Register
Search
Search titles only
By:
Search titles only
By:
New posts
Search forums
Image search
Search
Search titles only
By:
Search titles only
By:
Menu
Install the app
Install
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
Jeep Wrangler YJ
YJ General Discussion
2.5L upgrade...
Reply to thread
Message
<blockquote data-quote="machoheadgames" data-source="post: 433709" data-attributes="member: 18789"><p>It will never make a slow engine “fast” (4.0 included) but it definitely lets them open up their potential. Have to remember that Jeep sized the tires on these rigs with 27’s and street tires at that, so 31’s is like a 13-14% torque reduction by leverage alone, not to mention weight, especially once you get into the heavier aspects of all terrains or mud terrains. Do all that to a stock 4 cyl and it’s a big drain. </p><p></p><p>For me it makes the 4.0 good enough that I probably won’t ever bother to add any sort of power to it via V8 or stroker. Hard for me to speak on the 2.5 but I know in principle what works well because that engine likes rpm so I typically take what I like on the 4.0 and recommend one ratio lower for the 2.5. The 2.5 AX5 has a lower 5th ratio than the 4.0 AX15, so going one ratio deeper in the 2.5 is basically on the highway, about 2 gear ratios lower. This keeps the 2 engines in rpm ranges they like to work in. </p><p></p><p>Put another way, 4.88/31 would be similar to stock. Maybe a teensy bit higher rpm than stock was which helps make up for the heavier 31” tire and if anything, it’s not like stock was the perfect ratio to begin with so it adds back some zip you never had. Good upgrade all around. Not using 5th is a pretty normal solution for the tires you have on that ratio.</p></blockquote><p></p>
[QUOTE="machoheadgames, post: 433709, member: 18789"] It will never make a slow engine “fast” (4.0 included) but it definitely lets them open up their potential. Have to remember that Jeep sized the tires on these rigs with 27’s and street tires at that, so 31’s is like a 13-14% torque reduction by leverage alone, not to mention weight, especially once you get into the heavier aspects of all terrains or mud terrains. Do all that to a stock 4 cyl and it’s a big drain. For me it makes the 4.0 good enough that I probably won’t ever bother to add any sort of power to it via V8 or stroker. Hard for me to speak on the 2.5 but I know in principle what works well because that engine likes rpm so I typically take what I like on the 4.0 and recommend one ratio lower for the 2.5. The 2.5 AX5 has a lower 5th ratio than the 4.0 AX15, so going one ratio deeper in the 2.5 is basically on the highway, about 2 gear ratios lower. This keeps the 2 engines in rpm ranges they like to work in. Put another way, 4.88/31 would be similar to stock. Maybe a teensy bit higher rpm than stock was which helps make up for the heavier 31” tire and if anything, it’s not like stock was the perfect ratio to begin with so it adds back some zip you never had. Good upgrade all around. Not using 5th is a pretty normal solution for the tires you have on that ratio. [/QUOTE]
Verification
Post reply
Forums
Jeep Wrangler YJ
YJ General Discussion
2.5L upgrade...
Top
Bottom