Drove the new 2025 Ram 1500 SST today and have questions

[Xman]

I drove a 2025 Ram 1500 Lone Star (Big Horn) today with the 3.0 SST standard output. The engine was very smooth and had a nice progression of power and torque. I had been concerned with how much heat build-up there would be in the engine bay on the driver's side with both turbos and catalytic converters tuck together on that side of the engine. When I pulled off the highway and directly into the dealer's lot, I popped the hood to check for heat buildup. There was no felt temperature difference between either side of the engine bay. I could stick my hand down by the turbos an not feel penetrating heat like I do with my V8 exhaust manifold. The turbos and CATs are very well insulated. My questions are.

There was a small 12 battery that looked like a motorcycle battery just aft of the primary battery. Does anyone know what its purpose is for? I could find no reference to it in the owner's manual.

The SST had a secondary cooling system for the turbos and I believe the intercooler(s). Does anyone have any info on that system and why the compressed air off the turbo's would be liquid cooled instead of air? (I've had 5 turbo vehicles so I am familiar with the turbo machinery) Again, not much info in the owner's manual except it takes 4 quarts. I couldn't find the heat exchanger for it.

Thanks in advance for any intel you can provide.

 

[SD Rebel]

I drove a 2025 Ram 1500 Lone Star (Longhorn) today with the 3.0 SST standard output. The engine was very smooth and had a nice progression of power and torque. I had been concerned with how much heat build-up there would be in the engine bay on the driver's side with both turbos and catalytic converters tuck together on that side of the engine. When I pulled off the highway and directly into the dealer's lot, I popped the hood to check for heat buildup. There was no felt temperature difference between either side of the engine bay. I could stick my hand down by the turbos an not feel penetrating heat like I do with my V8 exhaust manifold. The turbos and CATs are very well insulated. My questions are.

There was a small 12 battery that looked like a motorcycle battery just aft of the primary battery. Does anyone know what its purpose is for? I could find no reference to it in the owner's manual.

The SST had a secondary cooling system for the turbos and I believe the intercooler(s). Does anyone have any info on that system and why the compressed air off the turbo's would be liquid cooled instead of air? (I've had 5 turbo vehicles so I am familiar with the turbo machinery) Again, not much info in the owner's manual except it takes 4 quarts. I couldn't find the heat exchanger for it.

Thanks in advance for any intel you can provide.

Appreciate the info on your experience with the STT. I wonder if the cooler is for the turbo's bearings, water cooled instead of oil cooled, the Ecoboost for example uses a water cooled jacket over the turbo bearings to prevent oil cooking after shut-down .

 

[Magredvet]

The motorcycle battery is probably for the ESS system, like they have in the Jeeps (without Etorque) In the Jeep world they cause all sorts of issues due to the different charging capacities. Quite a few people bypass them, due to their location in the Jeep. At least in the Ram's it appears they are accessible................

 

[Xman]

Drove a 2025 Laramie today. Super impressed a second time - the 3.0 Hurricane SO is so smooth and quite. I've had 5 Volvo turbos but also plenty of big V-8s, e.g., 3 Suburbans, Camaro Z-28, GTO, and Charger. I appreciate the quite and smooth application of power so do not miss the fact it's not a V-8.

I did investigate the secondary cooling system by stopping in the parts department and asked them to show me the parts. Unlike the web where I found no information and every MOPAR parts didn't even list 2025 Ram parts. I wanted to know what to look for under the hood. The water-cooled intercooler is on the passenger side of the engine. I saw a pod cast that said this system also cools the turbo bearings, but I have not verified.



The secondary radiator (auxiliary #2 below) is sandwiched between the main radiator for the engine and the A/C condenser.



The over-flow tank is next to the primary radiator's over-flow. The secondary coolant system is 4 quarts while the primary is 16.

 

[Xman]

I have been searching the Jeep Wagoneer forums for 3.0 SST information as its been used in that platform for 2 years. The owners report being very impressed and pleased with the engine. There is one reliability problem that has recently arisen. The thermostat has been failing and causing overheating if it fails closed or no heating if open. Several owners have not stopped their vehicles soon enough and damaged their engines. Replacement thermostats are not available nationwide and may be out of stock for another month or two. It is not like the thermostats that we are used to. It is a new design. No intel if there has been any part updates making it into the RAM.

From Wagoneerfans.com

Hurricane Twin Turbo 510 Issue - stuck thermostat

www.wagoneerfans.com

 

[MT755]

I don't like plastic used for these situations

 

[Biga]

I drove a 2025 Ram 1500 Lone Star (Big Horn) today with the 3.0 SST standard output. The engine was very smooth and had a nice progression of power and torque. I had been concerned with how much heat build-up there would be in the engine bay on the driver's side with both turbos and catalytic converters tuck together on that side of the engine. When I pulled off the highway and directly into the dealer's lot, I popped the hood to check for heat buildup. There was no felt temperature difference between either side of the engine bay. I could stick my hand down by the turbos an not feel penetrating heat like I do with my V8 exhaust manifold. The turbos and CATs are very well insulated. My questions are.

There was a small 12 battery that looked like a motorcycle battery just aft of the primary battery. Does anyone know what its purpose is for? I could find no reference to it in the owner's manual.

The SST had a secondary cooling system for the turbos and I believe the intercooler(s). Does anyone have any info on that system and why the compressed air off the turbo's would be liquid cooled instead of air? (I've had 5 turbo vehicles so I am familiar with the turbo machinery) Again, not much info in the owner's manual except it takes 4 quarts. I couldn't find the heat exchanger for it.

Thanks in advance for any intel you can provide.

I believe you may be correct. I can hear a humming noise for about 15 mintues after the truck is turned off, I belive that the battery is used to run that cooling unit after the truck shuts off. I could be wrong.

 

[Xman]

makes some sense to use the smaller secondary cooling system to cool the turbos after the vehicle is shut down. There is a lot of heat stored in the primary radiator from the engine. With the quarter of the fluid, they should be able to cool the turbo bearings down quicker and more efficiently.

 

[PatriotLonghorn]

The JL Wrangler uses a similar secondary (electric) water pump to keep coolant flowing for the 2.0 for a while after shutdown when hot.

 

[HSKR R/T]

I drove a 2025 Ram 1500 Lone Star (Big Horn) today with the 3.0 SST standard output. The engine was very smooth and had a nice progression of power and torque. I had been concerned with how much heat build-up there would be in the engine bay on the driver's side with both turbos and catalytic converters tuck together on that side of the engine. When I pulled off the highway and directly into the dealer's lot, I popped the hood to check for heat buildup. There was no felt temperature difference between either side of the engine bay. I could stick my hand down by the turbos an not feel penetrating heat like I do with my V8 exhaust manifold. The turbos and CATs are very well insulated. My questions are.

There was a small 12 battery that looked like a motorcycle battery just aft of the primary battery. Does anyone know what its purpose is for? I could find no reference to it in the owner's manual.

The SST had a secondary cooling system for the turbos and I believe the intercooler(s). Does anyone have any info on that system and why the compressed air off the turbo's would be liquid cooled instead of air? (I've had 5 turbo vehicles so I am familiar with the turbo machinery) Again, not much info in the owner's manual except it takes 4 quarts. I couldn't find the heat exchanger for it.

Thanks in advance for any intel you can provide.

Water to air intercoolers are much more efficient than air to air. Which is why they are used. They do better at cooking he hot charge air.

 

[dammitbobby]

I have been searching the Jeep Wagoneer forums for 3.0 SST information as its been used in that platform for 2 years. The owners report being very impressed and pleased with the engine. There is one reliability problem that has recently arisen. The thermostat has been failing and causing overheating if it fails closed or no heating if open. Several owners have not stopped their vehicles soon enough and damaged their engines. Replacement thermostats are not available nationwide and may be out of stock for another month or two. It is not like the thermostats that we are used to. It is a new design. No intel if there has been any part updates making it into the RAM.

From Wagoneerfans.com

Hurricane Twin Turbo 510 Issue - stuck thermostat

www.wagoneerfans.com

View attachment 184076

Interesting. The hurricane engines in the rams are little different hopefully they fixed this issue.

 

[pensfan]

Interesting. The hurricane engines in the rams are little different hopefully they fixed this issue.

I'll pass on this engine for a while. Keep my '16 Ram Hemi as it runs great with no issues.

 

[dcchris311]

I prefer a water to air over a air to air, they take up less space. It held steady temps on my BMW until I started pushing the turbo outside of the turbo efficiency map and it was struggling to keep the intercooler from heat soaking. That's a simple fix though, just install a larger heat exchanger.

 

[Willwork4truck]

That little battery should be for the the start-stop. I forget which vehicle it was however when the starting battery got low it affected the S/S and vice versa. Seems like I remember the forum agreeing (!) that you should replace both at the same time else weird electrical things happened.