looking for more torque and hp

[my07kj]

I recently purchased a cold air intake and throttle body spacer for my 07 kj and they say that the spacer and the cold air intake each are good for 20 hp What does that do for my torque numbers? Also I was thinking of porting and polishing the heads and intake manifold buying jba headers and i really like borla exhaust . What do you guys think?

 

[tommudd]

Honestly?
both should be returned as you will never see that type of horsepower or anything from them.

Not being rude just the facts of life with a 3.7 in a KJ

 

[my07kj]

what will i see?

 

[Dave]

what will i see?

Just less money in your wallet.

Not too much you can do to the 3.7L to give it more hp/torque.

Dave

 

[my07kj]

not even a cam and rollar rockers?

 

[05kj6spd]

Cam and rockers should do something, as well as porting and polishing heads and intakes. A motor is a motor and anything you do to improve air flow in and out of an engine is going to increase the amount of HP and Torque it can produce. Now how much you gain differs based on engine size and design. But the fact is if you improve flow into the engine with intakes, spacers, cams, port work anything that allows more air in and following that you have to move that same air out with headers, port work, cams, larger exhaust you will see a performance gain. Good luck and I hope you find something that will make you happy within the price range you are willing to pay.

 

[huntbuggy]

Dump the tb spacer for sure (or if you haven't bought it already...) consider getting a ported throttle body made by Fastman instead.

Perhaps just getting more air into the stock airbox (I think if you search here the LongTallTexan modification might be what you're looking for - a hole in the airbox with tubing to the front grille) it's cheaper and pulls in a lot less dust and crud into your engine than an overpriced CAI.

Headers, well, a lot of money for questionable gains given the cats on our Liberties unless you're going to do some serious modifications and/or are an o2 sensor wizard. Just a less restrictive muffler is probably a better investment no?

Search through the 4x2 performance section there are lots of members posts on the above and other mods like chips, lowstall torque converters, transmission tunes etc...

Another recommended favorite here is regearing to 4.10 if you wanted low end or are going to offroad any with larger tires.

 

[J-Thompson]

Regear to 4.10's
will cost the same and out perform all the listed mods
if it is 2wd then a regear to 4.10's should cost less than $500
and you could go 4.56
highway mpg will be in the tank but 0-60 will be close to V8 sports car

 

[tjkj2002]

Cam and rockers should do something, as well as porting and polishing heads and intakes. A motor is a motor and anything you do to improve air flow in and out of an engine is going to increase the amount of HP and Torque it can produce. Now how much you gain differs based on engine size and design. But the fact is if you improve flow into the engine with intakes, spacers, cams, port work anything that allows more air in and following that you have to move that same air out with headers, port work, cams, larger exhaust you will see a performance gain. Good luck and I hope you find something that will make you happy within the price range you are willing to pay.

None of that will net you anything without the correct PCM programming,you actually might loose power if you do all of that and leave the stock PCM programs in place.

 

[05kj6spd]

I agree that you will want to look at PCM programming to change timing, to take advantage of any drastic changes. But the fact remain that if you increase flow in and out of a motor you get more power. Small modification such as intakes and better exhaust might not warrant a PCM flash, and probably not major power gains but they do help. In fact I just buy better gas and see a slight improve it. No I don't know the numbers and it's not a wheelie popping monster but the fact is my gas mileage went up and I down shift as much for the hills. My point was that he was looking for performance gains and everyone seems to think there is nothing you can do. But slight changes like intakes and throttle bodies will make a difference just not sure if they will justify the cost is all. And the PCM measures the air in and add fuel to meet those needs so unless you have drastically changed something the stock PCM should keep up with slight modifications.

 

[J-Thompson]

Still can get more bang for your buck out of gears
Correct me if I am wrong
CAI = $300
TB Spacer = $100
complete exhaust =$1000 ,including headers
Same price as a regear and fore a few more $$$ a locker
out back
And if we are talking 2wd then you are ******* away
nearly $1000

 

[diyman]

I agree that you will want to look at PCM programming to change timing, to take advantage of any drastic changes. But the fact remain that if you increase flow in and out of a motor you get more power. Small modification such as intakes and better exhaust might not warrant a PCM flash, and probably not major power gains but they do help. In fact I just buy better gas and see a slight improve it. No I don't know the numbers and it's not a wheelie popping monster but the fact is my gas mileage went up and I down shift as much for the hills. My point was that he was looking for performance gains and everyone seems to think there is nothing you can do. But slight changes like intakes and throttle bodies will make a difference just not sure if they will justify the cost is all. And the PCM measures the air in and add fuel to meet those needs so unless you have drastically changed something the stock PCM should keep up with slight modifications.

Well, probably the concept of 'closed loop' is a tough subject, but the bottom line is that the 'system' i.e sensors such as
IAT,TPS,O2S,etc., PCM and actuators like the injectors, EGR (does not apply to gas KJs) interact to maintain a given output,
not HPs but a pre-calculated combustion ratio, which represents the 'Required Output' of the system....
The 'system' will always try to 'keep-up' with it's own parameters, and any change made to the incoming air/gasoline flow
won't necessarily result in an increase in HPs output (though this might just eventually happen).

Anyhow the whole loop is not 'tight', therefore corrections cannot be made instantly, that's (among others..) the reason why
O2S sensor voltage, which represents the feedback, keeps on varying and will never stabilize itself on the 'goal value'...

IMHO money could be spent elsewhere ( sorry for the OT, but as everyone knows I'd buy spare parts but that's just me...)

Ouch, I'm beginning to speak like an old man.....again :happy175:

 

[05kj6spd]

All that means is your PCM and sensors adjust fuel levels to maintain a air/fuel ratio. The best ratio is 14.6 to 1 and you vehicle tries to maintain that. If you put more air in the the PCM puts more fuel in to get the ratio right. Means more power. Of course it will only go so far before the computer becomes confused because it shouldn't be seeing this much air....but the basics remain the same for all engines regardless of displacement, or engine management system.

 

[tommudd]

What 05kj6spd is correct
in books and on paper
in the real world of 3.7s
it doesn't work quite that way
The PCMs and sensors that you speak about only adjust so far
and its a fairly narrow band

and I agree with J-Thompson biggest bang for the buck with real seat of the pants feeling is gears

 

[05kj6spd]

Anyone ever call superchips about a tuner? I imagine someone had too. I was under the idea that the 3.7 is a lot like the 4.7, heck sure look the same. Any way they tune 4.7's and it makes a world of difference I would think it wouldn't be hard to do the same to the 3.7 assuming they are setup similar.


Oh heck I miss Carbs, and Distributors and tuning your car with a beer and screwdriver in your hand not a text book and laptop.

 

[tjkj2002]

All that means is your PCM and sensors adjust fuel levels to maintain a air/fuel ratio. The best ratio is 14.6 to 1 and you vehicle tries to maintain that. If you put more air in the the PCM puts more fuel in to get the ratio right. Means more power. Of course it will only go so far before the computer becomes confused because it shouldn't be seeing this much air....but the basics remain the same for all engines regardless of displacement, or engine management system.

It's 14.7:1...................

The OE programming has set charts,if the sensors are reading outside of those set charts the PCM will do what it can to get back into it's pre-set mode by reducing/increasing fuel and timing and if it can not the check engine light will come on.This means all that $$$ spent on internal engine mods will be for nothing.So increasing incoming air will do nothing as the PCM will not allow the engine to take advantage of it.

 

[Ry' N Jen]

I'm looking for more torque and horsepower as well.

I'm looking for an other engine option for our Heep.
Something to build up and drop in sometime between next winter
and nest spring.
Something with at least twice output as much as stock.

 

[flair1111]

i say to regear as mentioned already. or do the b&g pcm flash. i do have the open air filter set up and i can say that compared to the stock box it absolutely does give me quicker throttle responce and it take less pedal to excel past 60mph. way less!

im doing the pcm flash next and probably leave it alone after that.

 

[KYLiberty]

I'm looking for more torque and horsepower as well.

I'm looking for an other engine option for our Heep.
Something to build up and drop in sometime between next winter
and nest spring.
Something with at least twice output as much as stock.

For the price of reliably doubling your KJ's output, why don't you just buy a used GC SRT? It would probably be a similar price.


As far as making the KJ perform considerably better than stock, it isn't that difficult. Just regear to 4.10's if you have stock up to 245/75R16's on it. Get an aggressive flash for the PCM by B&G. You can also get a ported throttle body by FastMan for a little better throttle response. The exhaust can be upgraded for a little better power, but be careful since it could also drop power in areas. Also, for better transmission performance you can get a shift kit and even get a custom torque converter from APS.

 

[Ry' N Jen]

For the price of reliably doubling your KJ's output, why don't you just buy a used GC SRT? It would probably be a similar price.


As far as making the KJ perform considerably better than stock, it isn't that difficult. Just regear to 4.10's if you have stock up to 245/75R16's on it. Get an aggressive flash for the PCM by B&G. You can also get a ported throttle body by FastMan for a little better throttle response. The exhaust can be upgraded for a little better power, but be careful since it could also drop power in areas. Also, for better transmission performance you can get a shift kit and even get a custom torque converter from APS.

I thinking to getting rid of the 3.7 altogether.
Already have my eye's out for a wrecked SRT GC...
Yes, ail lockers and re-gearing will happen as soon as
the parts show up on my door step.