Engine Noise Questions - Diesel vs Gas

[jwiltx]

I picked up my 67 M715 a few months ago, and I've been doing tons of reading on what to go with for my drivetrain. This is going to be a "daily driver" type vehicle that I plan to use on and off road (80% on, 20% off for hunting). I've looked at several different options for engines (LS-gas, 6.2 Detroit, 5.9 cummins-Diesel, Tesla swap-electric), and I ran across someone who yesterday who does diesel swaps that said I should steer clear because of the noise in the cabin.

I plan on insulating the whole cab to quiet things, but my question is how loud each engine is in the cab? I've searched the forum and can't find much on noise levels, unless you're talking about the 4bt. I'd like to be able to have a conversation at normal levels, which is pushing me towards the LS, but I like the economy and power from the 5.9.

I'm already planning to replace the NP200 to reduce the noise, but I'm just wanting to know what to expect. If there's anyone near Houston with any of the engines listed above that would let me come see their truck I'm more than happy to make the drive. Thanks in advance.

[Barrman]

I have run stock engine, 396 Big Block gas and 6.2 diesel in my truck. My NP200 has had the center output swap. My exhaust is out the back in the stock location.

There is a lot of mechanical noise in this truck. I can drive with the 6.2 down the road at 52-56 mph with the top off and still hear the radio. Conversation is ok but phone calls through the phone are kind of tough. Phone calls through the radio kind of work.

Adding the bikini top traps a little more noise inside. The hard top makes it even louder inside.

You are welcome to come listen and drive some time.

[kwai]

LS swap is the easiest and will give you the quietest truck. Dynamat-like material on the floor and firewall and the inside of the doors will help reduce the noise.

[jwiltx]

I have run stock engine, 396 Big Block gas and 6.2 diesel in my truck. My NP200 has had the center output swap. My exhaust is out the back in the stock location.

There is a lot of mechanical noise in this truck. I can drive with the 6.2 down the road at 52-56 mph with the top off and still hear the radio. Conversation is ok but phone calls through the phone are kind of tough. Phone calls through the radio kind of work.

Adding the bikini top traps a little more noise inside. The hard top makes it even louder inside.

You are welcome to come listen and drive some time.

I just saw you're from Giddings in your signature, right? In March I'll be headed out that direction and might see if you're available for me to stop by for a few minutes. I really just have no frame of reference on this, other than the stock engine while driving around the neighborhood, so hearing it should make a difference. Thanks for the offer.

[jwiltx]

LS swap is the easiest and will give you the quietest truck. Dynamat-like material on the floor and firewall and the inside of the doors will help reduce the noise.

I was planning on doing as much insulation as the firewall will allow, undercoating, padding under a vinyl floor, insulating the walls, and I've got an idea for deadening some of the noise from a soft top, but I'll have to wait to get one to try it out.

That guy that I was talking to kept saying that the LS will be simple, quiet, and cheap. I know at some point, I'll want to swap it out, but it'll get me driving quickly. I'm currently looking at the 5.3 (LM7 with turbo it should give me enough power) or 6.0 (LQ4). Any other recommendations on which ones I should look at?

[kwai]

FYI, vinyl floor mats and padding are a sure-fire formula for rusty floors. The M715 is kinda leaky.

With the LS you can also put in an automatic trans. Use a Lokar shifter and linkage and the missing clutch pedal is the only way to tell it's not a manual.

[jwiltx]

I'll be doing everything in my power to seal it up and giving the whole body and undercoat after I replace the floor pans, but that's good to know.

I'm ok with the idea of an automatic, but something feels wrong with not having a stick shift in this truck. I've got a lead on a VERY cheap NV4500 that's probably going to be going in.

[Barrman]

Just give me a heads up a few days before you are headed through town. I work right off of 290 and can even drive to work in it that day.

[jwiltx]

I'll be doing everything in my power to seal it up and giving the whole body and undercoat after I replace the floor pans, but that's good to know.

I'm ok with the idea of an automatic, but something feels wrong with not having a stick shift in this truck. I've got a lead on a VERY cheap NV4500 that's probably going to be going in.

[Barrman]

It was nice to meet you twice this weekend Jason. Your project sounds like fun.