I know Chrysler uses the same 3.8 ltr. engine in the JK as in the Caravan, Did you know they also offer an all aluminum OHC 4.0 ltr. w/250 hp in the same vehicle. It is alittle taller but it does'nt look like it would an issue, it's probbaly lighter weight, and has an extra 50 hp. Both engines use the same 6sp auto transmitions. Courious that this is not offered in the JK as it a production engine with the same applacation.

Ken G.

 

Then you "know" something that everybody else does not. Although the JK engine is based off the 3.8 Caravan engine, the two are nowhere near the same. They have different blocks, heads, induction and exhaust systems. Not to mention a host of other things. They are quite different.

 

Yes. Not the same at all, just because they are both 3.8L doesnt mean anything

 

If they are that different then you will need a lot parts to integrate it into the JK (a kit of sorts), plus you still have all the labor involved. Even if you do it yourself, time is money.

So why not invest a bit more cash and get a HEMI instead of a souped-up minivan engine?

 

Umm same block and same heads...
Also our engines are based on the 3.3l platform except our 3.8L is overbored & re-inforced (unless that is what you call different).
We also have the same rocker arm issue but it's been beefed up but still the weak point once you go FI.

Intake, exhaust and the compute that controls all is very very different then the minivan counterpart.

 

Yes I understand they not excatly the same, but I doubt Chrysler would would make a compleatly seperate block casting of the same engine for a different applacation, the intake and exhaust systems are different because of the front wheel drive layout in the van. I have looked at both the 3.8, and the 4.0 engines in the van, they both use the same 6sp auto. So assuming, and I could be wrong, the block/bellhousing interface is the same they (Chrysler) could make the same modifcations to the 4.0 as they did to the 3.8 to work in the Jeep and the drive train could remain the same. If the block castings are different then too many things would have to be changed.

I have driven a Caravan with the 4.0, they are very smooth and have a bit more push than the 3.8. and at about the milage

Ken G.

 

Then you doubt incorrectly. They are completely DIFFERENT. You really need to do some research on it. It's out there in abundance.

 

Are you kidding? This certainly would explain a lot. I used to have 2 mini-vans. An '02 with the 3.8 and an '06 with the 3.3. We traded the '06 in on the JK. It never felt like it could get out of its own way and always pissed me off driving it. Now the '02 on the other hand.... we still have it and at 127k miles still feels like a V8 and not a mini-van. I have no idea why they would pick that motor as the basis for a JK. It's not like it was a "torque" motor or anything.

 

compared to any other engine in the world it is very close to the mini-van motor.

 

I'm not sure who wins the debate as to it being "different" from the minivan 3.8 but below are some facts:

The 2007 JK engine is the 3.8L (231 cu in) V6, producing 202hp @ 5200 RPM and 237 ft-lb torque @ 4000 RPM. It is a direct derivative of the 3.3L Chrysler minivan engine introduced in 1990 and the only remaining Iaccoca-era power plant still seeing active duty. The 3.3/3.8L series has a traditional cast-iron block, aluminum head, overhead-valve with timing chain design along with sequential, multiple-port fuel injection (SMPI) and an integrated electronic ignition system supplanting the mechanical distributor systems of the past. It has been continuously revised, receiving intake (including variable length manifold), exhaust, compression ratio, and piston head improvements. The 3.8 liter engine was retuned and fitted with electronic throttle control technology in 2007, yielding a flatter torque curve and more “punchy” feel. Compared to the previous AMC 4.0-liter inline six-cylinder engine, the 3.8-liter is lighter, quieter, shorter, maintains higher torque at speeds above 3400 rpm, and offers similar fuel efficiency.

The 4.0-liter engine, offered in Wranglers for the past 15 years, was discontinued due to:
1. Its production volume diminishing to only Wrangler application.
2. It requiring significant modifications to meet current emission standards.
3. The manufacturing plant needing retooling due to its advanced age.
4. Its length, relative to “V” cylinder arrangement engines, is long. This hampered efforts to obtain a 5-star frontal impact rating, which was achieved in 2007 with the new engine.

The following modifications were required on the 3.8L engine to apply it to the Jeeps in-line engine compartment mounting application:
1. A new exhaust manifold
2. A redesigned intake lower manifold to add bosses for the ignition coil and air inlet
3. The addition of cylinder block motor mount bosses as part of impact energy management strategy
4. A new front engine cover to accommodate accessory drive
5. The relocation of the oil filter from the side of the block to the chain case cover
6. A new aluminum and steel oil pan to allow a structural tie to the transmission for noise mitigation and impact resistance. Oil capacity was increased to six quarts for Jeep lubrication requirements.
7. A new one-piece rear crank seal assembly instead of three parts.