392 6.4L Hemi Recommend Engine Break-in Procedures?

[70sKid]

Thank you for the detailed write-up. How does your break-in process differ from what’s in the manual? By no means am I being sarcastic; I really want to get this right before mine is delivered (est end of Jan). Thanks again!

Hi,
Others will likely have other details to add, but I believe the single, most significant detail left out of the manual (and all break-in manuals to be honest) is this idea of gradual acceleration/deceleration followed by a cool down period. Other details to be mindful of:
1-When starting up from cold, it's important to allow the engine/oil to warm up for a good 5 minutes minimum before putting your foot into it.
2-Regarding the mileage intervals/speed limits, I'm not sure how critical these are, but honor them at your own discretion. Some will swear that the ring seal must be performed in the first 100 miles, so don't drive it too lightly. In other words, give it a handful of light pulls with plenty of cool down time in between them on that first trip home from the dealer. With a brand new vehicle, those MPH limits are probably there to give the driveline a chance to break in without overheating. With that said, brief, gentle pulls shouldn't hurt anything as long as your sustained speeds are aligned with the manual.
3-Keep the transmission in manual mode in order to slowly accelerate/decelerate using the engine. This is your biggest insurance policy against "catastrophic engine damage" aka cylinder head overheating.
4-I believe it's important to avoid loading up the engine at low RPM's. So, to avoid this, downshift into a lower gear when initiating a pull. Engine loads at low RPM's place more stress on the internal components as compared to higher RPM's. At low RPM's, the power stroke is spread over a longer period of time. Higher RPM loads, by contrast, have quicker power strokes, which is better for the main and con rod bearings. So, when on the highway, simply downshift from 6th into 5th or even 4th to place the RPM's somewhere around 3K. This 392 has no trouble pulling nicely from 3K, so I have been using this as my minimum RPM when initiating my pulls.
The manual seems fairly reasonable about the time it takes to break-in the motor. 5-While I describe this process as "hard", its by no means irresponsible or negligent. Rather, it's highly controlled and scientifically based. Some would argue it's necessary in order to avoid a leaky, underpowered motor that will ultimately have a shorter lifespan. By 500 miles, it should be fully broken-in, especially if you practice this accelerate/decelerate/cool down procedure.
6-Good articles on this topic are abundant, but here are a couple that spell things out. I especially like the second one as it's very detailed. Engine builders seem to honor these guidelines from what I have found.

Dispelling Engine Break-In Myths With High Performance Academy

Engine break-in is one of the most widely misunderstood processes in the automotive world. High Performance Academy seeks to change that.

www.enginelabs.com

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

New Engine Break In Procedure For Cars, Motorcycles, Motocross, Snowmobiles and Boats

www.mototuneusa.com

 

[HearHear]

My 392 break in procedure is pretty basic and common sense- under 55mph and easy on the gas until 300 miles. After 300 miles, let 'er rip!

 

[Fast-n-Furious]

Picked up mine two days ago and it had 26 miles already. The paperwork stated 17 miles, so I guess someone at the dealership had some fun. No biggie.

The first day I drove 80 miles, lots of local drive with stop signs and traffic lights. I also tested the cruise control on highway. I have to admit that I didn’t really pay attention to the rpm and gear number until the second day I set up the gear display on the dash. Now it has 150 miles, I feel I’m driving a tank, and I’m very gentle on the skinny pad.

It’s very interesting so far the acceleration doesn’t feel fast at all, especially compared to my Audi A4. It feels very heavy, like King Kong. Maybe because I never really pushed to that extend?

The exhaust note is just so sexy.

 

[Proptrash]

Hi,
Others will likely have other details to add, but I believe the single, most significant detail left out of the manual (and all break-in manuals to be honest) is this idea of gradual acceleration/deceleration followed by a cool down period. Other details to be mindful of:
1-When starting up from cold, it's important to allow the engine/oil to warm up for a good 5 minutes minimum before putting your foot into it.
2-Regarding the mileage intervals/speed limits, I'm not sure how critical these are, but honor them at your own discretion. Some will swear that the ring seal must be performed in the first 100 miles, so don't drive it too lightly. In other words, give it a handful of light pulls with plenty of cool down time in between them on that first trip home from the dealer. With a brand new vehicle, those MPH limits are probably there to give the driveline a chance to break in without overheating. With that said, brief, gentle pulls shouldn't hurt anything as long as your sustained speeds are aligned with the manual.
3-Keep the transmission in manual mode in order to slowly accelerate/decelerate using the engine. This is your biggest insurance policy against "catastrophic engine damage" aka cylinder head overheating.
4-I believe it's important to avoid loading up the engine at low RPM's. So, to avoid this, downshift into a lower gear when initiating a pull. Engine loads at low RPM's place more stress on the internal components as compared to higher RPM's. At low RPM's, the power stroke is spread over a longer period of time. Higher RPM loads, by contrast, have quicker power strokes, which is better for the main and con rod bearings. So, when on the highway, simply downshift from 6th into 5th or even 4th to place the RPM's somewhere around 3K. This 392 has no trouble pulling nicely from 3K, so I have been using this as my minimum RPM when initiating my pulls.
The manual seems fairly reasonable about the time it takes to break-in the motor. 5-While I describe this process as "hard", its by no means irresponsible or negligent. Rather, it's highly controlled and scientifically based. Some would argue it's necessary in order to avoid a leaky, underpowered motor that will ultimately have a shorter lifespan. By 500 miles, it should be fully broken-in, especially if you practice this accelerate/decelerate/cool down procedure.
6-Good articles on this topic are abundant, but here are a couple that spell things out. I especially like the second one as it's very detailed. Engine builders seem to honor these guidelines from what I have found.

Dispelling Engine Break-In Myths With High Performance Academy

Engine break-in is one of the most widely misunderstood processes in the automotive world. High Performance Academy seeks to change that.

www.enginelabs.com

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

New Engine Break In Procedure For Cars, Motorcycles, Motocross, Snowmobiles and Boats

www.mototuneusa.com

This is exactly how I’m going about it. Took a nice stop and go from the dealer today. 20 miles. Then took family for a spin around the block a few times. Moderate quick pulls, short 4K-rpm range or so. I’ll keep it below 50 and stay off the freeway until 100 miles and a few cool down cycles. This is for the gears. All good 4 wheel drive shops that do gear work will tell you the same.

 

[BenLandry]

Picked up mine two days ago and it had 26 miles already. The paperwork stated 17 miles, so I guess someone at the dealership had some fun. No biggie.

The first day I drove 80 miles, lots of local drive with stop signs and traffic lights. I also tested the cruise control on highway. I have to admit that I didn’t really pay attention to the rpm and gear number until the second day I set up the gear display on the dash. Now it has 150 miles, I feel I’m driving a tank, and I’m very gentle on the skinny pad.

It’s very interesting so far the acceleration doesn’t feel fast at all, especially compared to my Audi A4. It feels very heavy, like King Kong. Maybe because I never really pushed to that extend?

The exhaust note is just so sexy.

I think when you finally drive it like you drive your Audi you will be pleasantly surprised…it’s not an Audi tho. It will smoke most Audi’s even with 35’s or 37s, then turn off the highway, climb a mountain while pulling your Audi to the top then run over your Audi just to get a selfie. These Jeeps are seriously badass. And they sound so obnoxiously awesome.
But seriously, its only a sports car off the line and in a straight line and to 100mph. After that it’s just a Jeep.

 

[Fast-n-Furious]

I think when you finally drive it like you drive your Audi you will be pleasantly surprised…it’s not an Audi tho. It will smoke most Audi’s even with 35’s or 37s, then turn off the highway, climb a mountain while pulling your Audi to the top then run over your Audi just to get a selfie. These Jeeps are seriously badass. And they sound so obnoxiously awesome.
But seriously, its only a sports car off the line and in a straight line and to 100mph. After that it’s just a Jeep.

I’m in love with this Jeep 392! It’s the most unique vehicle I’ve ever had so far. I no longer have interest in those luxury cars/SUVs that I always wanted couple years ago. So I’m sure this 392 will change me.

 

[LTZ470]

At 80 MPH 8th Gear RPM's ~2000...so whats MPH got to do with breaking in the engine? The manuals (and several more I know of) can be oxymoronic...main thing "stay out of it" for 500 miles only periodically going WOT to pass someone if required or stay out of trouble on the freeway...while on cruise control periodically I would downshift to 7th for a few minutes with cruise control still on, and let it rev to 3400 rpms...going to change the oil at 1000 miles to Amsoil or Mobil-1 0-40 Full Synthetic....

Jeep 392 Supplement Manual

 

[Jeepstin392]

At 80 MPH 8th Gear RPM's ~2000...so whats MPH got to do with breaking in the engine? The manuals (and several more I know of) can be oxymoronic...main thing "stay out of it" for 500 miles only periodically going WOT to pass someone if required or stay out of trouble on the freeway...while on cruise control periodically I would downshift to 7th for a few minutes with cruise control still on, and let it rev to 3400 rpms...going to change the oil at 1000 miles to Amsoil or Mobil-1 0-40 Full Synthetic....

Jeep 392 Supplement Manual

Regards to the oil.
Many manufacturers use an oil specific for breaking in. I couldn’t confirm this anywhere for the 392.
As for the 500 miles, avoid rapid acceleration, avoid sustained speeds at any speed, Vary throttle and speed. I can’t recall if there was a suggested top speed until 50 miles, 100 miles, etc. but it’s not a bad idea to limit your speeds and gradually incur ease after so many miles.

 

[LTZ470]

Extended idling is probably "the" worst thing you can possible do to these engines...

 

[LTZ470]

 

[scarab]

I'm always wondering if this procedure is really about breaking in the engine or maybe they are just trying to prevent fresh SRT owners from killing themselves They use pretty much the same engines in RAM trucks and afair break-in is not required there.

 

[LTZ470]

I'm always wondering if this procedure is really about breaking in the engine or maybe they are just trying to prevent fresh SRT owners from killing themselves They use pretty much the same engines in RAM trucks and afair break-in is not required there.

BAM! You win the internet today!

 

[LTZ470]

Interesting: Doesn't sound right, but only a fool doesn't listen with intent...

"The engine is broke in from the factory.

The manual recommendation is for the ring and pinion

Be sure to go onto read recommendation for towing also."

Ram Forum 392 Break In

 

[LTZ470]

I'm always wondering if this procedure is really about breaking in the engine or maybe they are just trying to prevent fresh SRT owners from killing themselves They use pretty much the same engines in RAM trucks and afair break-in is not required there.

And add to that full time 4wd feature as well...keeping the wild child's at bay...

 

[MDawg]

This break in is better than the standard Jeep engines. I broke 3 in on 800 mile trips last year. Try driving 45 mph through Nashville in a 65 mph zone. I had A LOT of people telling me “I’m number 1”.

My plan with my 392 is to drive in manual and when at highway speeds use the cruise control (even though they tell you not to). While in cruise, I’ll use manual shifters to run through range of rpm’s every so often. BIG side benefit of manual mode, NO cylinder deactivation! Why they even allow the engine to do this during their specified break in period is beyond me.

 

[LTZ470]

Interesting note: "Unlike most of the people on here who ran the factory oil for the first interval, mine was changed immediately. The factory oil is high in zinc which helps the break in process. Because the dealership removed it idk when my engine will break in. Generally the first interval with factory oil does the job. Not sure how long it'll take but im almost to 10k miles..but yes the manual has proper break in techniques..."

Ram Forum 392 Break In

 

[LTZ470]

This break in is better than the standard Jeep engines. I broke 3 in on 800 mile trips last year. Try driving 45 mph through Nashville in a 65 mph zone. I had A LOT of people telling me “I’m number 1”.

My plan with my 392 is to drive in manual and when at highway speeds use the cruise control (even though they tell you not to). While in cruise, I’ll use manual shifters to run through range of rpm’s every so often. BIG side benefit of manual mode, NO cylinder deactivation! Why they even allow the engine to do this during their specified break in period is beyond me.

That’s called the jeep break in Wave

 

[Bobo57]

That’s called the jeep break in Wave

So if you engage the paddle shifters the Jeep never uses 4 cylinder mode?

 

[LTZ470]

So if you engage the paddle shifters the Jeep never uses 4 cylinder mode?

4 Cylinder Mode

What is y'alls impression of 4 cylinder mode? I have noticed that if I paddle shift it doesn't go into 4 cylinder mode. I know in my 2017 corvette 4 cylinder mode was believed to cause some issues with the engine (I don't know if this was proven or not). are there any opinions on whether...

www.jeep392.com

 

[LTZ470]

Changed break-in oil out at 1369 miles...never has used a drop...oil was clean and clear...broken in at 80-83 miles per hour >3000 rpm....