Looking for motor advice - 6.1 hemi or eagle 5.7

[Jayb22]

Hi, new member here.

Im in a predicament here and hoping you guys can help me choose the correct path. 2 days ago I purchased a 2011 Grand Cherokee with a 5.7 in it. I heard the Jeep accessories worked a bit better so I figured that was the way to go. Yesterday a 06 SRT8 Chrysler 300 popped up. It’s going to be $3000 more then the Jeep I bought but has a little less km on it.

My question is this - for those of you that have experience is there any benefit to one of the motors over the other outside of the hp bump the 6.1 gives? With the money I’d save with the Jeep I could do a full rebuild on the motor and maybe squeeze a bit more reliable power out of it to come close to the 6.1. But I feel the 6.1 has a cool factor to it and more potential down the road.

The car is currently a 318 with a 727 trans. I was debating if the Nag1 trans is a positive or not as I searched a few threads on here and it seems it complicates the wiring and there are other trans that make more sense.

Any insight would be greatly appreciated. I’m trying to figure out if I should just go with what I have or try to flip the Jeep and grab the 300 srt8.

Thanks

 

[scar426]

Hi, new member here.

Im in a predicament here and hoping you guys can help me choose the correct path. 2 days ago I purchased a 2011 Grand Cherokee with a 5.7 in it. I heard the Jeep accessories worked a bit better so I figured that was the way to go. Yesterday a 06 SRT8 Chrysler 300 popped up. It’s going to be $3000 more then the Jeep I bought but has a little less km on it.

My question is this - for those of you that have experience is there any benefit to one of the motors over the other outside of the hp bump the 6.1 gives? With the money I’d save with the Jeep I could do a full rebuild on the motor and maybe squeeze a bit more reliable power out of it to come close to the 6.1. But I feel the 6.1 has a cool factor to it and more potential down the road.

The car is currently a 318 with a 727 trans. I was debating if the Nag1 trans is a positive or not as I searched a few threads on here and it seems it complicates the wiring and there are other trans that make more sense.

Any insight would be greatly appreciated. I’m trying to figure out if I should just go with what I have or try to flip the Jeep and grab the 300 srt8.

Thanks

5.7/6.1 potatoe, potato, lol. pretty close to each other. you can put a 6.1L intake and coil covers on a 5.7 if ya want for a lot less than $3000. NOW for the real opinion on the matter. go with a 545rfe transmission. The NAG1 is a great transmission, but it does require a lot more to use it in a swap. (i.e. components and money) I swapped a 545rfe for the nag1 on my 6.4l swap, works fine. my 2 cents.

 

[Jayb22]

5.7/6.1 potatoe, potato, lol. pretty close to each other. you can put a 6.1L intake and coil covers on a 5.7 if ya want for a lot less than $3000. NOW for the real opinion on the matter. go with a 545rfe transmission. The NAG1 is a great transmission, but it does require a lot more to use it in a swap. (i.e. components and money) I swapped a 545rfe for the nag1 on my 6.4l swap, works fine. my 2 cents.

Thank you for the reply. That was kind of my thoughts as well. I could completely overhaul the 5.7, MDs delete, slightly better cam, maybe upgrade the intake as you mentioned and be right there on powder for the same dollars and have a fresh motor.

I’ve searched around a bit for 545rfe trans and up here in Alberta they don’t seem too common. Almost everything we have here is for 4wd applications. I’d really like to do a manual trans swap but that may be a down the road plan due to budget.

 

[scar426]

Thank you for the reply. That was kind of my thoughts as well. I could completely overhaul the 5.7, MDs delete, slightly better cam, maybe upgrade the intake as you mentioned and be right there on powder for the same dollars and have a fresh motor.

I’ve searched around a bit for 545rfe trans and up here in Alberta they don’t seem too common. Almost everything we have here is for 4wd applications. I’d really like to do a manual trans swap but that may be a down the road plan due to budget.

Might check with a transmission shop on swapping out the tail shaft section to a 2wd unit.

 

[Buckminster]

Hi, new member here.

Im in a predicament here and hoping you guys can help me choose the correct path. 2 days ago I purchased a 2011 Grand Cherokee with a 5.7 in it. I heard the Jeep accessories worked a bit better so I figured that was the way to go. Yesterday a 06 SRT8 Chrysler 300 popped up. It’s going to be $3000 more then the Jeep I bought but has a little less km on it.

My question is this - for those of you that have experience is there any benefit to one of the motors over the other outside of the hp bump the 6.1 gives? With the money I’d save with the Jeep I could do a full rebuild on the motor and maybe squeeze a bit more reliable power out of it to come close to the 6.1. But I feel the 6.1 has a cool factor to it and more potential down the road.

The car is currently a 318 with a 727 trans. I was debating if the Nag1 trans is a positive or not as I searched a few threads on here and it seems it complicates the wiring and there are other trans that make more sense.

Any insight would be greatly appreciated. I’m trying to figure out if I should just go with what I have or try to flip the Jeep and grab the 300 srt8.

Thanks

I'm going through this swap now and have not yet completed it, but have done a lot of work and have the engine and trans hooked together on a run stand (pre-Eagle 5.7 and 8HP70 Trans) to work out all the wiring kinks. What rearend ratio are you running? The 545RE, NAG1, 8HP70 all have overdrive which is great if you're running a tall rear end. The 545RE has a .67:1 OD, the NAG1 only has a .86:1 OD and the 8HP70 has a .67:1. The trade off is they all have a fairly tall first gear, so if you have a high numerical ratio rear end, you may find that first gear is useless.

The NAG1 requires wheel speed sensors and a sensor for the driveshaft to work properly. Hotwire, Sound German have kits that can adapt it. You will need a custom driveshaft as you would with any of the choices you list. The 8HP70 also needs a TCU in my application because the Pre-Eagle 5.7L never came with an 8HP70, so the factory ECU needs to be supplemented with a TCU.

As far as the engine goes, the parts are different between the pre-Eagle engine and the post-Eagle engine, so things like the pans need to be specific to the engine you choose. (the post-Eagle engine has Variable Valve Timing).

The jeep engine comes with the 45 degree oil filter adapter which clears the K-frame. Not sure if that's necessary if you're running a Bill Oreilly tube front end, or a QA-1 front end or one of the other conversions. It also comes with a different timing cover that re-locates the other accessories, so it clears the chassis. I used the smaller jeep alternator, so it clears the frame (I'm using the stock K-frame).

Hope that helps and that your project goes well.

 

[marksmopars]

I would note the 6.1 is the base for the blown motors, assume this means it has stronger inner components.