Engine 3.7L and what It could handle

hrogi · **Posted:** Tue May 17, 2011 6:19 pm

Ok I am looking for some input.

I want better power from the Liberty. So Adding a Super charger will give me what I want.
Lets say 3 to 5 PSI... Yes, I know no one makes a real kit...

BUT I read on here the Piston will not allow for this.
The Piston have ring groves that are to High up and the extra Pressure would make them collasp.
SO My thought is, change the Pistons out.....

Lets say that is possible.

Would the Computer be able to work with 3PSI and or more?
Or would you need to add in a helpers to get more Fuel when needed.

My over idea is if this 5K pound Jeep has more Power,it could get 19 to 22 MPG gallon around town.
THen maybe 25 to 27 on the High way or more...

So i am farming out the Idea to you all....
What is possible and still State and Ferdaly Legal here. I care about the Envoriment enough to stay Legal...
I am not looking to Light up the tires are get better ET time at the Track..

I just want to have more power for moving this Jeep around...

:POPCORN:

tjkj2002 · **Posted:** Tue May 17, 2011 6:44 pm

All said and done your looking at spending a big chunk of change for little gain.Just off the top of my head most likely looking at $4000 for the supercharger,another $500-$1000 of mods to make it work(brackets,bolts,belts,and all the little things),$2000+ to get forged pistons and install them(if not doing it yourself),$300-$500 for PCM programming to actually have any effect,then you got exhaust mods,and possibly powertrain mods to handle the extra power.

If your looking for mpg's this is not the way to do it,you will get worse and all that listed above buys alot of gas even at $4 a gallon.Your never going to see what mpg's you want from a KK with the 3.7 which only weighs about 4000lbs-4200lbs stock depending on options.Start modifying it with a lift,bigger tires,and heavy armor and kiss that good mpg's goodbye,the best bet is to almost get back to stock by regearing.Your best bet is to regear the diffs and slow down some.Regearing alone will make a world of difference,will make it "feel" more powerfull without having to over stress the drivetrain,will actually reduce the stress on the engine and trans.

hrogi · **Posted:** Tue May 17, 2011 7:56 pm

I fully understand the Cost Factor... YOu did answer my question... It is possible...

But you bought up a new route that is safe and easy as well... GEARs.....

Umm now to look in this new direction, as this might happen...

Spending $7K is not happening, but I did know that before I made this post.....

Thank you for the Input... Now to see what Gears would be better for Daily driving, and might also help on Freeway driving...

tjkj2002 · **Posted:** Tue May 17, 2011 8:10 pm

Well your lucky as the KK uses the same front gears as the JK's front D30 which are easy to come by.If you have a auto trans you have 3.73's so 4.10's would make a different and if your well modded and big tires(31"+) then 4.56's would be a great choice.The 4.10's would be more highway friendly but the 4.56's would be great for city driving.

hrogi · **Posted:** Wed May 18, 2011 4:52 pm

The Jeep is an Auto tranny with Command Tract 2 4X4 system.....

I will need to look into the D30 gear in a 4.10 ration for both Front and back then..
If I am reading your post Right. I can get away with buying 2 front gear set from a JK D30 diff system?

DirtyKK · **Posted:** Wed May 18, 2011 5:14 pm

kk front is the same as jk front. aftermarket 4.10s are outrageously priced for that diff, so buyin used would be cheaper but good luck finding them. i searched for a while and everytime some would pop up they would be gone immediately. the rear is a chrysler 8.25, not the same as any jk axle but aftermarket theyre readily available for a good price.

i agree with tearing into the motor to replace the pistons would be a waste of time. i would go turbo over supercharger for cost but turbos will leave your engine bay running very hot and that would not be ideal for low speeds like wheeling. tons of headaches with trying to boost an NA motor.

hrogi · **Posted:** Thu May 19, 2011 12:14 pm

To fix the heat issues, you go with a Turbo at the Tail pipe end..
It also helps to Bypass the Smog issues in most states....

Yes it is not perfect, but most issues can be over come with adjustments...

But I do not have the money or time, do it just yet.
If I did it would be cool and work well....

Truely when it comes to adding Power, It is never about being wise with my money. I only care about the outcome.
I do not look for a Retrun on Investment when it comes to my toys.... It is all money badly Spent.....

The gears is a better faster fix for my issues, I can not deny that.. Hands Down the best way to go.....

The reason for the post was to get new ideas like Gears.. So I am supper happy about that....

$1500 to $2000 spent on gears is better then $7k to $9K on a turbo system....

Engine 3.7L and what It could handle

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