bigger cams for a jeep liberty

[BlueJeep07]

Forced induction, are you serious? I hope he's gunna at least put in forged pistons and rods first. But if you're gunna take apart the entire engine why not just swap it with a more powerful engine to begin with? I don't think longtube headers are made for the KJ - would probably need to custom make some. I beleive JBA makes some shorties though.

Yeah, I was only talking about the easy things to do on the outside of the engine. If you want to move to FI then you would need to break open the engine and the pocketbook. Maybe with the simple stuff you might get enough horsepower to be satisfied. You might want to leave the internals alone for the sake of reliability on the road or trail.

Whatever you do have fun.

 

[_UnLiMiTeD_]

IF you are doing a supercharger then i would hold off on the cams. You cannot run the same type of cams on a engine that is N/A compared to a turbo or supercharged motor, you could kill it.

 

[indieaz]

IF you are doing a supercharger then i would hold off on the cams. You cannot run the same type of cams on a engine that is N/A compared to a turbo or supercharged motor, you could kill it.

Kill hte motor...how so? The cam timing is only going ot affect how beneficial the forced induction is. Besides - he could go with cams that have an FI oriented grind now...and still reap the benefits of some power gain, then install the blower later.

 

[Bashgod]

My jeep is "light kaki".

I have remomved the air box and put on a K&n filter.

I have the full Magnaflow catback exhaust.

I will be buying a Jet II chip in a week or so.

The cams will be next. The big horse power stuff wont be for a long time so until then these cams should be fine.

Then ill get a throttle body from a 4.7 and see it it will fit on my engine if not i may go with the Fastman TB.

I am aware of the amount of work i will have instore with these plans, everything you guys have brought up I have already considered. I haven't heard anything about ****** issues and frankly am not really worried. I read in a street racing magazine that did an article on a 1000+hp integra was running with the stock transmission.

 

[Atrus]

My jeep is "light kaki".
I read in a street racing magazine that did an article on a 1000+hp integra was running with the stock transmission.

OK, here is where I do see a major problem. You should definitely be worried. People built up the GM 3800's enough to where the starter ring gear bolts were backing out. Input shafts snapped. CV joints were exploding.

FWIW - a supercharger is going to add more torque off the line and will be harder on the transmission. A turbo kicks in as RPM's build and are easier on hardened components in the transmission. The trans needs to be capable and designed to hold up to the demands you're going to put on it. I'm not saying the KJ trans can't handle it - I don't really know. I am just saying that you can't say because an Integra did it that anything can. Sometimes (the majority of the time) it's just not going to be possible or feasible.

You'll need to look at fueling - is the stock fuel pump enough? Injectors? You will definitely need a tune, and you'll also need the ability to scan/log constantly for knock and such (tool such as Autotap is critical). You're going into unchartered territory, therefore there's no cookie cutter approach. It'll be very easy to detonate.

I'm not trying to sway you, just really think it all out before you start going down that road. Think about how many miles you'll have on the KJ before you're ready. I was going to drive my Grand Prix forever, I was going to turbo it (yes, there's a pre-fabbed kit to bolt on a turbo and run 11's). Well, plans change - look where I am, on jeepkj.com. Hell, 6 months ago I was still planning on getting it cleaned up and working on it some more this summer. PLans can change, IMO have your daily driver that you mod slightly to your liking that can still be reliable, and then have your fun car. I have my KJ now that'll receive minor mods, and my '68 Austin Healey that will soon be torn down to rebuild into a custom classic. All I am saying is you'll love it dearly and think you're going to keep it forever, then life plans change. The Prix isn't useful to me anymore. It's a two door, my friends don't want to climb in the back. It's a car - I am a homeowner now and I need to have some cargo room for various things. Life changes, really plan the whole project out before you dig yourself into a hole.

 

[_UnLiMiTeD_]

not every car is the same, just because one cars ****** can handle it, doesnt mean yours can. They are using a mini van ****** in a 5000+ pound vehicle and it is already weak. And sorry i did not mean kill the motor, i meant kill performance, if you put a NA cam in with a supercharger, thats a big waste of money.

 

[tjkj2002]

1000+hp integra was running with the stock transmission.

For like 5 seconds,or unless he never got on it more then idle.Sorry to say unless you have the 45RFE ****** you will need major upgrade,and there not a whole lot you can do to a 42RLE.You may get the 42RLE to live behind maybe 350-375ft-lbs of torque but that's really pushing it big time. Just adding cams will not gain you much,the stock PCM will override it and it'll just run rough with no power gain.OBDII ***** that way.Until the computer learns the new cams,your only looking at maybe 20hp,then zero when the computer overrides what the cams are trying to gain you.It's just life,the 3.7 was never made or will be any type of HP or torque engine,heck there is very few options for the 4.7 V-8.

Heck when money allows(after SFA first) I'm even trashing the 3.7,going to put a bone stock 4.7HO in.That will actually get me better mileage then the 3.7 since the engine won't have to work as hard to move my 5400lbs hog.Not doing anything fancy to the 4.7 besides maybe headers and intake.300 ponies in a KJ is plenty,it's all in the gearing,to bad you need to scrap the front D30A before you can really take advantage of gearing,heck even the 8.25 is limited to 4.56 gears.I'm going to 5.13 gears that should make my KJ feel like it has 400HP even with running 35" tires(should be running 4.88's for back to staock feel).

 

[_UnLiMiTeD_]

obd has tuners out there available for it, obdII became available on 96 berettas and became the most popular computer to use on them because there are tuners available so you can override the computer with a few buttons

 

[tjkj2002]

obd has tuners out there available for it, obdII became available on 96 berettas and became the most popular computer to use on them because there are tuners available so you can override the computer with a few buttons

But non are availeable for the 3.7,let alone the KJ,I've checked with them all,non are even considering making one.

 

[_UnLiMiTeD_]

well that *****...lol oh well, liberty was never even thought to be a street machine for performance

 

[Bashgod]

I meant, in general, certain things may not be as weak as you think. 1000 hp and 11-10 sec 1/4 is impressive with the stock transmission.

I have been looking at the sts universal turbo as it looks much cheaper and i would rather have a turbo any way. I read somewhere the the stock pistons can handle up to 5 lbs of boost (don't know if I believe that) which can be up to 80hp. for the near future I may use that setup until I really am certain of what I want to do.

what do you guys think of the stock pistons holding up to 5 lbs of boost? I may get forged pistons and just run with that for a while.

 

[_UnLiMiTeD_]

deffinately go forged, i would never trust stock pistons out of an suv for any forced induction setups. Besides, why spend all that money just to get a lousy 5 lbs of boost?

 

[tjkj2002]

I meant, in general, certain things may not be as weak as you think. 1000 hp and 11-10 sec 1/4 is impressive with the stock transmission.

I have been looking at the sts universal turbo as it looks much cheaper and i would rather have a turbo any way. I read somewhere the the stock pistons can handle up to 5 lbs of boost (don't know if I believe that) which can be up to 80hp. for the near future I may use that setup until I really am certain of what I want to do.

what do you guys think of the stock pistons holding up to 5 lbs of boost? I may get forged pistons and just run with that for a while.

The stock pistons can't stand any boost,the top piston ring is to close to the top lip of the piston,under boost that lip breaks off and frees the top piston ring severly damaging the engine.$3000+ for a messly 80hp and decreasing the reliability? sorry rather spend $5000 and put in a stock 4.7 and get 90+hp,better mileage and no turbo lag and the lose of being to offroad.

 

[icarl]

Heck when money allows(after SFA first) I'm even trashing the 3.7,going to put a bone stock 4.7HO in.That will actually get me better mileage then the 3.7 since the engine won't have to work as hard to move my 5400lbs hog.Not doing anything fancy to the 4.7 besides maybe headers and intake.300 ponies in a KJ is plenty,it's all in the gearing,to bad you need to scrap the front D30A before you can really take advantage of gearing,heck even the 8.25 is limited to 4.56 gears.I'm going to 5.13 gears that should make my KJ feel like it has 400HP even with running 35" tires(should be running 4.88's for back to staock feel).

wow tjkj2002! Are you doing all that to your daily driver or do you have another vehicle you use?

 

[Bashgod]

I know about the stock pistons and will not run boost with them.
I probably will never go off road nothing serious anyway.
The turbo setup im looking at is not really that expensive.

 

[tjkj2002]

wow tjkj2002! Are you doing all that to your daily driver or do you have another vehicle you use?

Yep my KJ is my daily driver,no use building it not to drive it.

 

[Bashgod]

We've come up with an eaiser/ cheaper setup, it will involve a garret T4/T3 hybrid turbo and it will be mounted under the back of my liberty. By being so far back, it might allow us to run without an intercooler. If we can find a way to cool the oil, it will lubricate and serve as a coolant. My magnaflow will have to but cut up, and possibly have to be run with out a muffler. I'm not worried about the ****** and I will be using forged pistons. Boost will be set at 5-6 lb for daily driving with the ability to switch to 12 lbs for fun (12 lbs of boost plus all of the other up grades should bring me close to 400hp). I'll need a better fuel management system too but as we progress and as funds become more avaliable we will see what happens.

Next up Jet stage II chip.

 

[indieaz]

If you actually manage 400 horsepower out of the engine your transmission is good as dead. That is assuming the transfer case doesn't grenade before the transmissino has a chance to.

And what is this "stage II" chip you are talking about? If you have a turbo setup with some custom ground cams you're gunna need to put the car on a dyno and get someone to custom tune the ECU with wideband O2 sensors - otherwise your A/F ratio will be *completely* out of wack - and you'll be lucky if the thing even starts/runs to begin with on 12 pounds of boost. You'll likely start/run on 5 lbs...but your A/F will be *way* out still and you'll end up with everything from bad O2 sensors (if you're lucky that's all) to holes in your cylinder walls and pistons.

 

[turbodave]

I can't comment on the ability of the drivetrain to handle the power - but the mounting a T3/T4 hybrid at the **** end of a liberty will be pretty crap...
These rear mounted turbo's have to use smaller turbines than is desireable to spool up at the rate considered 'acceptable' for a road car - which is great - but you aren't going to get close to enough turbine flow for close to 400hp (almost double the stock hp) at a measly 12psi.

T3/T4 units don't have enough efficiency to flow close to 400hp from 12psi either - not from a 3 litre engine at least! The GT stuff is better, but if you're going turbo - you may aswell aim for a PR above 2.0 to open up the field a little more.


I don't fully follow with the comments that the stock pistons won't take any boost - unless they are made of chocolate? The CR is (unless i'm mistaken) a paltry 9.1:1, which should easilly follow that this could take 6-8psi pretty easilly without opening up the motor.

I am not one of these who likes sticking with the factory ECU for boost however and adding injector drivers or 'bling chips' - I'm just saying that if you got an aftermarket computer on there, it'd be pretty easy to boost this engine.

Incidentally - I have very good experience of cast pistons under boosted applications. They might not be as forgiving as forged, but they are a lot cheaper and if you get the fuelling and ignition right, they are pretty easy to make work.

I'm not sure what the factory trans / TC would say about adding another 50% torque however? Maybe you could try a 25 or 50hp nitrous load coming in and see if this makes the trans throw a wobbly!

 

[tjkj2002]

I can't comment on the ability of the drivetrain to handle the power - but the mounting a T3/T4 hybrid at the **** end of a liberty will be pretty crap...
These rear mounted turbo's have to use smaller turbines than is desireable to spool up at the rate considered 'acceptable' for a road car - which is great - but you aren't going to get close to enough turbine flow for close to 400hp (almost double the stock hp) at a measly 12psi.

T3/T4 units don't have enough efficiency to flow close to 400hp from 12psi either - not from a 3 litre engine at least! The GT stuff is better, but if you're going turbo - you may aswell aim for a PR above 2.0 to open up the field a little more.


I don't fully follow with the comments that the stock pistons won't take any boost - unless they are made of chocolate? The CR is (unless i'm mistaken) a paltry 9.1:1, which should easilly follow that this could take 6-8psi pretty easilly without opening up the motor.

I am not one of these who likes sticking with the factory ECU for boost however and adding injector drivers or 'bling chips' - I'm just saying that if you got an aftermarket computer on there, it'd be pretty easy to boost this engine.

Incidentally - I have very good experience of cast pistons under boosted applications. They might not be as forgiving as forged, but they are a lot cheaper and if you get the fuelling and ignition right, they are pretty easy to make work.

I'm not sure what the factory trans / TC would say about adding another 50% torque however? Maybe you could try a 25 or 50hp nitrous load coming in and see if this makes the trans throw a wobbly!

Actually the piston issue is known,KenniBell was making a supercharger kit for the KJ and pulled it when they blew the pistons in the 3.7 with I believe 5psi boost.They have had similer problems with the 4.7 also.