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WK GC 3.7 performance

6K views 13 replies 11 participants last post by  tjkj2002 
#1 ·
Hey guys I have a Grand Cherokee Laredo 3.7 and was just wondering if there's anything extra any of you have added that made a major difference in either gas mileage or acceleration. Please share your finds!
 
#2 ·
It's debated a bit, but a general concensus is you won't see many large gains with the 3.7L. The $$ it would take puts you into the realm of just buying a wk with a 4.7 or 5.7.

They do have a tuner out that I haven't really heard of anyone using. Not sure if no one here's tried it or if it just doesn't perform.
 
#4 ·
A K&N may help and may not. A 3.7 doesn't have that much performance mods and the ones that are out there ar probably not worth the money for the gains. But one guy on here has added a Throttle body, CAI, headers, and I beleive a chip to his 3.7.

I compare the 3.7 to the Toyota 4 cylinder. Very little power but ultra reliable.
 
#5 ·
A K&N may help and may not. A 3.7 doesn't have that much performance mods and the ones that are out there ar probably not worth the money for the gains. But one guy on here has added a Throttle body, CAI, headers, and I beleive a chip to his 3.7.

I compare the 3.7 to the Toyota 4 cylinder. Very little power but ultra reliable.
Yeah that is Ill, he said with a combination of those mods he has had significant gains. (Not sure if he has headers though)
 
#6 ·
1. the factory exhaust flows very well. Folks trying catbacks report no diff in mpg and little if any performance boost.

2. CAI typically sound better, however nobody out there has any proof that the aftermarket offerings actually flow more air than the stock systems. CAIs are only a benefit if the factory system is restricted. CAI may offer snappier throttle response. the 3.7 is slow to respond-- IDK if it's because of intake tuning or drive-by-wire. I suspect it's the DBW.

3. A chip can yield some gains.... advance the timing and run a higher octane fuel. better power and likely mpg, but pricier fuel.

4. a header will def add power, and potentially mpg, but WHERE in the powerband? the JBA shorty headers come alive above 3000 rpm or more, and are known for a modest boost. But jeeps aren't racecars... they like to live down low... and you need long-tube headers for that. Short headers actually reduce low-end torque... and JBA has quit production IIRC.

5. head porting and a cam would honestly probably be the best way to get the 3.7 to breathe better, dollar per pound. I've heard the plastic intake manifold has trash in it that can be ported out too.

6. otherwise put 3.55 gears in it for more immediate power, tho at reduced mpg.

basically, by now the 3.7 is very refined and there aren't a lot of options out there for modding it. It's a great engine for what it has to do. WKs are NOT lightweight machines.

M
 
#8 ·
1. the factory exhaust flows very well. Folks trying catbacks report no diff in mpg and little if any performance boost.

2. CAI typically sound better, however nobody out there has any proof that the aftermarket offerings actually flow more air than the stock systems. CAIs are only a benefit if the factory system is restricted. CAI may offer snappier throttle response. the 3.7 is slow to respond-- IDK if it's because of intake tuning or drive-by-wire. I suspect it's the DBW.

3. A chip can yield some gains.... advance the timing and run a higher octane fuel. better power and likely mpg, but pricier fuel.

4. a header will def add power, and potentially mpg, but WHERE in the powerband? the JBA shorty headers come alive above 3000 rpm or more, and are known for a modest boost. But jeeps aren't racecars... they like to live down low... and you need long-tube headers for that. Short headers actually reduce low-end torque... and JBA has quit production IIRC.

5. head porting and a cam would honestly probably be the best way to get the 3.7 to breathe better, dollar per pound. I've heard the plastic intake manifold has trash in it that can be ported out too.

6. otherwise put 3.55 gears in it for more immediate power, tho at reduced mpg.

basically, by now the 3.7 is very refined and there aren't a lot of options out there for modding it. It's a great engine for what it has to do. WKs are NOT lightweight machines.

M
Thanks for the detailed info.

Greg
 
#10 ·
X2.....meep is completely right on in all regards.
 
#11 ·
I realized that the 3.7 was weak before I coughed up up the cash to buy a WK that had one. I ended up spending a little more and getting the 4.7. No regrets.

Sorry I know this comment doesen't answer you question in any way shape or form ;)
 
#12 ·
lol thanks for the responses guys! I havent taken my jeep up to the mountains or anything so i was also curious if any one knows how they run up in the snow and trails... I know these are questions i shouldve asked before i bought the 3.7 but they made me an offer i couldnt refuse lol
 
#14 ·
I've taken my 3.7 in a 6000lbs Jeep well over 12,000' in the mountains here in CO without issue.Have to run premium gas but would anyways.Since your WK does not have low range I'd keep to the pavement or very mild trails(gravel roads) at high elevation to prevent the trans from overheating.
 
#13 ·
Actually I have a magnaflow cat back exhaust and a k&n intake. It actually made quite a bit of difference. The exhaust instantly added more low end torque and I bought it for less than half of retail off eBay. About an aftermarket air filter like k&n letting dirt into your engine that's just ignorant. The cai kit adds hp and the kit comes with a dyno sheet to prove it, it's not break neck hp but it's a filter designed to keep out as much dust and dirt as possible on a micron scale and last for 1,000,000 miles. I bought a new tuner for my 3.7 wk but it hasn't come in yet, i paid 240.00 for it off ebay also. I plan to cut out and weld in high flow cats this springs.
 
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