guys this is going to be a ongoing review to help and guide other members with there future HO projects. If you have specific questions or advice please feel free to comment below. So let's get into it.
The 4.7 HO and standard 4.7 are physically almost identical externally. The HO block has 2 spots under the intake manifold for knock sensors. The High output heads are clearly stamped with a HO on both the passenger and driver side heads. The HO might not be visible if the engine has all of the accessorys on it since the AC and alternator tend to cover HO up.
On the inside things get interesting.
CAMS
Standard 4.7
Duration 244/254 deg
Lift 0.443/0.429"
Lobe separation angle 115.5 deg
4.7 HO
Duration 236/250 deg
Lift 0.472/0.429"
Lobe separation angle 112.5 deg
Notice the lower LSA on the HO cam. I would speculate this is why the HO cams make better mid range power over the standard 4.7 cams despite having slightly less duration.
Pistons
The HO piston has a nearly flat top on it that brings compression to 9.7 to 1 compared to 9.3 to 1 of the standard 4.7. its also worth noting that the HO uses a stronger floating wrist pin design vs the pressed in pin used on the standard motors.
CRANK
The HO has a stronger forged crankshaft vs the standard 4.7s cast crank. The bearing material is also different to accommodate the stronger material. Interesting enough the HOs harmonic dampener is also specific to the HO to minimize vibration and reduce crank wear.
Injectors
MYTH!!!!! The 4.7 and 4.7HO use the same injector!!! I have looked at a few web sites that say the HO 4.7 uses 25lb injectors compared to the standard 4.7s 22lb injectors. In my experience this is false since both injectors use the exact same part number. I suspect the diffrence in flow is from the PCM commanding more fuel pressure.
More coming soon. And pictures!
Ok now for the swap portion of this Thread.
Swapping the 4.7 and 4.7HO is very simple but a few miner issues may come up.
OIL PAN. The oil pan from the Grand Cherokee Overland is slightly different from the Dakota and Durango oil pan. The Cherokee pan will hit the front differential on the dodge and will need to be swapped out for the Dakota pan. I highly recommend replacing the oil pan gasket when doing this. If you install your oil pan correctly it should be leak free for many years and is cheap insurance.
MOTOR MOUNTS: You will reuse the Dakota/Durango motor mounts. The Cherokee mounts are slightly different and mount to the block differently. Don't worry the bolt holes for the Dakota/Durango mounts are there and you simply install the dodge mounts in the same locations as you normally would.
INTAKE MANIFOLD: Depending on what manifold you use you may need to make miner adjustments. In my case I used the 04 HO manifold and the hose running to the oil fill tube for the crank case depression system had to be slightly modified. In addition my throttle cable needed a small rubber shim behind the pedal to take up some slack in the cable. This was not a huge issue and could be from normal wear and tear on the cable. I took the time to replace the intake manifold O ring gaskets since I had every thing apart however they are reusable and its personal preference.
IAT (intake air temp sensor): Different 4.7 intake manifolds use different locations for this sensor. In my experience the factory sensor wiring was long enough to reach the sensor location on the HO manifold. I elected to extend and relocate my IAT sensor to the intake tube a few inches in front of the throttle body. This lowered by intake air temp reading by about 15F.
IACV: I noticed a slight difference in the dodge and Jeep IACVs. Both can be used and seem to work with out issue. What I did notice is the truck seems to idle a little better with the jeep control valve. I do recommend cleaning both the head of the IACV and TB because they tend to build up carbon and can cause miner issues.
Exhaust Manifolds: It appears that the exhaust manifolds on the jeep and dodges are different and will probably need to be swapped out for the vehicle specific manifold. I installed a set of JBA headers that fit perfectly and bolted to the stock exhaust Y pipe. A year latter they are holding up well and are leak free.
OIL Pressure Sensor: The Dodge and jeep oil pressure sensors are different one being a single wire sensor and the other being a two wire sensor with both using a two pin plug. I found this out when I plugged the factory plug into the Cherokee oil pressure sensor and was terrified when the oil pressure gauge was reading 0 while cranking. Fortunately I checked the sensors are sure enough one has a two wire pin in the plug and the other is a single. Simply unscrew the oil pressure sensor and re install the stock one off your old 4.7. Problem solved.
PCM and tuning: As long as you have paired your toner wheel and PCM correctly (see below) your stock PCM will run the HO engine and you will notice a power gain however you will need tuning to capitalize on the new engine. DO NOT RUN THE JEEP PCM!!! I have tried and so far I have been unsuccessful. I am running hemifever tuning and it definitely woke up the truck and helped dial her in.
KNOCK SENSORs: They are simply not used. I have mine installed but the plugs don't have any where to plug into on the stock dodge wiring harness.
JTEC and NGC: It is important to know if your truck has a 3 plug JTEC PCM or a 4 plug NGC PCM. This is one of the most confusing parts of the swap. This is not as complicated as many people make it seem. Tone rings are interchangeable as long as you swap the hole timing set to do it. I highly recommend replacing your timing set any way while your motor is out. Its a small investment compared to dealing with it latter if your used one should fail.
***The 3 plug JTEC PCM uses a 16 tooth tone ring and has a separate 1 plug TCM located in front of the air filter housing next to the radiator.
****The 4 plug NGC PCM uses a 32 tooth tone ring and does NOT have a separate TCM.
NOW........................... For my impression.
THIS IS NOT A HEMI SWAP. It is definitely a noticeable upgrade with more useable power across the hole RPM range. This should be considered a subtle upgrade and is probably a excellent option for guys looking to go forced induction or nitrous induction who don't have the skills or budget to build a all out race motor.
For me the justification was simple. My truck had 140K on the clock and had been owned by a younger guy who beat the heck out of her prior to me owning it. I was going to overhaul the stock 4.7 however found a 4.7 HO from a wrecked overland with 92,000 miles on it locally for $600. The motor was in excellent condition but I elected to overhaul it while it was out including new timing set, gaskets, oil pump, water pump, bearings, valve seats, and so on. I feel very confident I could have dropped the motor directly into the truck and it would have been fine but I am hoping to get another 100K out of my truck so it really was a no brainer.
At the time I swapped the motor I was running 265/75 16 Duratracs and had just finished a 545RFE conversion. The truck is running 3.92 gears and is a 4 door tiping the scales at just under 5000lbs. I towed regularly with the truck and noticed that the extra high overdrive would bog down and hills at 55-65 mph do to the lower RPM's. This would not be a big deal except the truck would kick down from 5th to 3rd gear causing the motor to rev higher then I liked. Unloaded the truck didn't seem to have this issue.
The 4.7 HO and standard 4.7 are physically almost identical externally. The HO block has 2 spots under the intake manifold for knock sensors. The High output heads are clearly stamped with a HO on both the passenger and driver side heads. The HO might not be visible if the engine has all of the accessorys on it since the AC and alternator tend to cover HO up.
On the inside things get interesting.
CAMS
Standard 4.7
Duration 244/254 deg
Lift 0.443/0.429"
Lobe separation angle 115.5 deg
4.7 HO
Duration 236/250 deg
Lift 0.472/0.429"
Lobe separation angle 112.5 deg
Notice the lower LSA on the HO cam. I would speculate this is why the HO cams make better mid range power over the standard 4.7 cams despite having slightly less duration.
Pistons
The HO piston has a nearly flat top on it that brings compression to 9.7 to 1 compared to 9.3 to 1 of the standard 4.7. its also worth noting that the HO uses a stronger floating wrist pin design vs the pressed in pin used on the standard motors.
CRANK
The HO has a stronger forged crankshaft vs the standard 4.7s cast crank. The bearing material is also different to accommodate the stronger material. Interesting enough the HOs harmonic dampener is also specific to the HO to minimize vibration and reduce crank wear.
Injectors
MYTH!!!!! The 4.7 and 4.7HO use the same injector!!! I have looked at a few web sites that say the HO 4.7 uses 25lb injectors compared to the standard 4.7s 22lb injectors. In my experience this is false since both injectors use the exact same part number. I suspect the diffrence in flow is from the PCM commanding more fuel pressure.
More coming soon. And pictures!
Ok now for the swap portion of this Thread.
Swapping the 4.7 and 4.7HO is very simple but a few miner issues may come up.
OIL PAN. The oil pan from the Grand Cherokee Overland is slightly different from the Dakota and Durango oil pan. The Cherokee pan will hit the front differential on the dodge and will need to be swapped out for the Dakota pan. I highly recommend replacing the oil pan gasket when doing this. If you install your oil pan correctly it should be leak free for many years and is cheap insurance.
MOTOR MOUNTS: You will reuse the Dakota/Durango motor mounts. The Cherokee mounts are slightly different and mount to the block differently. Don't worry the bolt holes for the Dakota/Durango mounts are there and you simply install the dodge mounts in the same locations as you normally would.
INTAKE MANIFOLD: Depending on what manifold you use you may need to make miner adjustments. In my case I used the 04 HO manifold and the hose running to the oil fill tube for the crank case depression system had to be slightly modified. In addition my throttle cable needed a small rubber shim behind the pedal to take up some slack in the cable. This was not a huge issue and could be from normal wear and tear on the cable. I took the time to replace the intake manifold O ring gaskets since I had every thing apart however they are reusable and its personal preference.
IAT (intake air temp sensor): Different 4.7 intake manifolds use different locations for this sensor. In my experience the factory sensor wiring was long enough to reach the sensor location on the HO manifold. I elected to extend and relocate my IAT sensor to the intake tube a few inches in front of the throttle body. This lowered by intake air temp reading by about 15F.
IACV: I noticed a slight difference in the dodge and Jeep IACVs. Both can be used and seem to work with out issue. What I did notice is the truck seems to idle a little better with the jeep control valve. I do recommend cleaning both the head of the IACV and TB because they tend to build up carbon and can cause miner issues.
Exhaust Manifolds: It appears that the exhaust manifolds on the jeep and dodges are different and will probably need to be swapped out for the vehicle specific manifold. I installed a set of JBA headers that fit perfectly and bolted to the stock exhaust Y pipe. A year latter they are holding up well and are leak free.
OIL Pressure Sensor: The Dodge and jeep oil pressure sensors are different one being a single wire sensor and the other being a two wire sensor with both using a two pin plug. I found this out when I plugged the factory plug into the Cherokee oil pressure sensor and was terrified when the oil pressure gauge was reading 0 while cranking. Fortunately I checked the sensors are sure enough one has a two wire pin in the plug and the other is a single. Simply unscrew the oil pressure sensor and re install the stock one off your old 4.7. Problem solved.
PCM and tuning: As long as you have paired your toner wheel and PCM correctly (see below) your stock PCM will run the HO engine and you will notice a power gain however you will need tuning to capitalize on the new engine. DO NOT RUN THE JEEP PCM!!! I have tried and so far I have been unsuccessful. I am running hemifever tuning and it definitely woke up the truck and helped dial her in.
KNOCK SENSORs: They are simply not used. I have mine installed but the plugs don't have any where to plug into on the stock dodge wiring harness.
JTEC and NGC: It is important to know if your truck has a 3 plug JTEC PCM or a 4 plug NGC PCM. This is one of the most confusing parts of the swap. This is not as complicated as many people make it seem. Tone rings are interchangeable as long as you swap the hole timing set to do it. I highly recommend replacing your timing set any way while your motor is out. Its a small investment compared to dealing with it latter if your used one should fail.
***The 3 plug JTEC PCM uses a 16 tooth tone ring and has a separate 1 plug TCM located in front of the air filter housing next to the radiator.
****The 4 plug NGC PCM uses a 32 tooth tone ring and does NOT have a separate TCM.
NOW........................... For my impression.
THIS IS NOT A HEMI SWAP. It is definitely a noticeable upgrade with more useable power across the hole RPM range. This should be considered a subtle upgrade and is probably a excellent option for guys looking to go forced induction or nitrous induction who don't have the skills or budget to build a all out race motor.
For me the justification was simple. My truck had 140K on the clock and had been owned by a younger guy who beat the heck out of her prior to me owning it. I was going to overhaul the stock 4.7 however found a 4.7 HO from a wrecked overland with 92,000 miles on it locally for $600. The motor was in excellent condition but I elected to overhaul it while it was out including new timing set, gaskets, oil pump, water pump, bearings, valve seats, and so on. I feel very confident I could have dropped the motor directly into the truck and it would have been fine but I am hoping to get another 100K out of my truck so it really was a no brainer.
At the time I swapped the motor I was running 265/75 16 Duratracs and had just finished a 545RFE conversion. The truck is running 3.92 gears and is a 4 door tiping the scales at just under 5000lbs. I towed regularly with the truck and noticed that the extra high overdrive would bog down and hills at 55-65 mph do to the lower RPM's. This would not be a big deal except the truck would kick down from 5th to 3rd gear causing the motor to rev higher then I liked. Unloaded the truck didn't seem to have this issue.
