Jeep 4.0L engine mods - what mechanic told me, need opinions...

[iGas]

Again, you're suggesting a $10,000 purchase to get $1,200 in savings on gas. That $1,200 savings is going to be much less, possibly close to zero, once you factor in the cost of insurance and maintenance.

I'm not sure what the insurance is like in the US, but for me a second car for pleasure use only add $500~$600 more per year. And, maintenance would be the same on 1 or 2 cars because both scenario would be the same mileage per year (possibly less because the cars that I mentioned are much more reliable than the Jeep).

IMHO, it is stupid to screw around with mods on a car and it is ended up costing you money to lower the performance of the car & make it unreliable.

It is not like I haven't mod cars in my youth.

 

[ponyo]

I'm saying keeping both. The Jeep for the weekends.

And pay for 2 insurance, tag, upkeep, garage space.

 

[LTC8K6]

The 4.0L in the Grand Cherokee only had 195 hp. He'd be in the ballpark of a 10% increase in hp and some improvements in throttle response. The change would be noticeable.




I fail to see how that would make modifications suddenly not have an effect. It's not like the 4.0L is a crappy engine that wears out after 6 years. If anything, that would make the benefit of an aftermarket exhaust header even greater because it increases the chances that his already manifold is already cracked.

Most of the parts were for much older engines.

His engine is already "upgraded" by Chrysler.

4.0 liter I-6 (242 cu in., 195 bhp)
The standard in-line 6 cylinder engine was significantly reengineered in 1999. Upgrades included new cylinder heads with reduced-area exhaust ports, new exhaust manifolds, a new 50% more efficient slitter-vane water pump that added two horsepower, a new elastomer-coated steel intake manifold gasket, a two-piece high silicon-molybdenum alloy cast-iron exhaust manifold, automated belt tensioner and a new laminated oil pan. These refinements added more power (10 bhp), a 5db quieter operation with an enhanced lower "throaty" sound quality, and cleaner emissions.

Nice torque curve:

 

[iGas]

And pay for 2 insurance, tag, upkeep, garage space.

2004 Jeep Grand Cherokee reliability rating is be low VW Jetta.

 

[Bignate603]

Most of the parts were for much older engines.

His engine is already "upgraded" by Chrysler.



Nice torque curve:

Indeed, the torque curve is awesome on the straight 6.

I didn't know they had done so much by 2004. My cherokee is a '97 so I haven't spent too much time thinking about the newer engines. I wonder if the new exhaust manifold address the cracking issue. I would still bet that there is some room to improve with those components but I concede that some of the updates may make the difference less.

 

[Bignate603]

2004 Jeep Grand Cherokee reliability rating is be low VW Jetta.

On that page you linked I'm seeing that they rated the reliability as 5 out of 5. All the issues that they said sometimes need attention have a low repair cost. How is that bad?

 

[ponyo]

2004 Jeep Grand Cherokee reliability rating is be low VW Jetta.

I support having multiple cars. I have 4. But it definitely cost more when you have extra car(s). Here in Georgia you also pay annual ad valorem tax on the vehicles too. Depending on the value of the car that can mean additional x,xxx dollars a year.

 

[iGas]

On that page you linked I'm seeing that they rated the reliability as 5 out of 5. All the issues that they said sometimes need attention have a low repair cost. How is that bad?

Moderate problems: Engine and Steering & Suspension.

MSN Auto Rating: 7.2 out of 10.

And, adding mod is not going to make it a better car.

 

[iGas]

I support having multiple cars. I have 4. But it definitely cost more when you have extra car(s). Here in Georgia you also pay annual ad valorem tax on the vehicles too. Depending on the value of the car that can mean additional x,xxx dollars a year.

And, I though Komunist Canada is bad with taxes.

 

[Bignate603]

Moderate problems: Engine and Steering & Suspension.

MSN Auto Rating: 7.2 out of 10.

And, adding mod is not going to make it a better car.

The engine problem is a TPS sensor. Estimated cost of repair, about $100. Hardly major.

The steering/suspension problem is the shocks (most likely from people using their jeep like a jeep) and the cost is also quite reasonable. If it is a recurring problem you can easily switch to higher quality after market shocks.

Interesting that you quoted the MSN auto rating of 7.2 (which isn't that bad) rather than the user rating of 8.9. The people that actually own and drive them like them really like them.

 

[JulesMaximus]

The 4.0L in the Grand Cherokee only had 195 hp. He'd be in the ballpark of a 10% increase in hp and some improvements in throttle response. The change would be noticeable.

195hp to 210hp in a 4000lb vehicle isn't going to make much difference.

 

[LTC8K6]

http://www.angelfire.com/my/fan/stroker.html

 

[Throckmorton]

Indeed, the torque curve is awesome on the straight 6.

I didn't know they had done so much by 2004. My cherokee is a '97 so I haven't spent too much time thinking about the newer engines. I wonder if the new exhaust manifold address the cracking issue. I would still bet that there is some room to improve with those components but I concede that some of the updates may make the difference less.

Your 97 is about the same 195hp. The 4.0 had 195hp in the early 90s (or late 80s?) when V8s has measly horsepower numbers like 150hp

 

[KDOG]

Thanks for all this info guys. Still wondering what can be done. Some people on the Jeep forums I frequent recommend flowmaster exhaust and a "cat-back". I *MAY* do the airbox mod just for shits n' giggles. My mechanic offered to put on a Flowmaster for $100 installed so that might be fun even for just the sound. Still thinkin'.

 

[Throckmorton]

I don't think a cat back is going to do anything

 

[angry hampster]

Thanks for all this info guys. Still wondering what can be done. Some people on the Jeep forums I frequent recommend flowmaster exhaust and a "cat-back". I *MAY* do the airbox mod just for shits n' giggles. My mechanic offered to put on a Flowmaster for $100 installed so that might be fun even for just the sound. Still thinkin'.

don't do a flowmaster. They sound raspy and irritating on a Jeep 4.0. Get something with a smoother tone like a Borla or Magnaflow.

 

[KDOG]

Interesting article on this matter:

http://www.jpmagazine.com/techartic...iter_engine_myth_busting_true_lies/index.html

 

[Bignate603]

Interesting article on this matter:

http://www.jpmagazine.com/techartic...iter_engine_myth_busting_true_lies/index.html

That's the article I gave my information from.

 

[Viperoni]

don't do a flowmaster. They sound raspy and irritating on a Jeep 4.0. Get something with a smoother tone like a Borla or Magnaflow.

Plus shitty flow.

 

[9thvacavcoe]

just found this web site. what problems the person started with in 2011, have surely been solved by now. i have a few changes to my
2004 grand cherokee se 4.0l that i am pretty happy about. though nothing major, it does add some spunk.

stock block:
- k & n cold air intake
- borla cat back exhaust system (not mind blowing by itself)
- magnaflow high flow catalytic converter (great with borla)
* this alone gave it a little life and didn't cost me a bundle.

- superchips power programmer (avoid the highest performance setting.
absolutely no difference to me except the cost at the pump.)
- new injectors
- pulstar plugs (i was skeptical because of the cost. surprisingly, they
eliminate all hesitation. it jumps at throttle. happy.)
- rancho shocks (big mistake. they're great for a truck. have used them in
past for good reason. my cherokee will vault off the road.)
- moog stearing stabilizer and suspension parts (always a good bet.)
i run mobile 1 synthetic and the max additive advertized on tv. i will not run down my '69 gto ra4 with certified rw dyno 647 hp, but it pulls pretty steadily from about 45 mph up. strangely, it's really subtle. you don't realize that your moving until it's too late. don't ask. highway passing and long hill power is pretty good.
about the mileage... i have tested continuously since the first change. on the highway, i can get an average of 2.5 mpg with the air conditioner on.
just my observations.

 

[Pacfanweb]

2004 Jeep Grand Cherokee reliability rating is be low VW Jetta.

Not because of the engine, that's for sure.

 

[Pacfanweb]

Well a lot of people report better gas mileage with a snorkel. I have no idea why... it's more restriction and cooler denser air, so gas mileage should go down.

Don't know how a snorker is routed on one of these cars, but I'm guessing it gives a bit of a ram air effect?