engine compartment suggestions needed

[ruthi]

Ok, me again, with yet another question. What is the best thing to use in the engine compartment area for insulation. We want to make it as quiet as possible, and as little heat inside as possible. We already coated the area with tc ceramics, but what else can we do? 

[John316]

We used EHP (engine heat protection) for ours. Works VERY well. No heat, no noise. We used their rollboard, and their 1 inch insulation. We have ours on the top side. We also have one inch of pink foam board over some of it...

FWIW

God bless,

John

[luvrbus]

Ruthi, the best way I can find is cover the floor in the bedroom with rollboard from EHP 949-661-8482  for heat then cover it with a 1/8 lead sheet for quietness then the flooring
They also sell exhaust wraps and insulation for the engine and the compartment very helpful folks.
The 60 series is a very loud engine but I guess you found that out on your own LOL

[ruthi]

Where would you find lead sheeting? We will give ehp a call. All suggestions are apprecialted. Thanks

[JackConrad]

Where would you find lead sheeting?  Thanks

check with a local roofing supply place.  If I remember correctly it comes in 2 different thicknesses (sized by pounds per square foot).  Jack

[John316]

Where would you find lead sheeting? We will give ehp a call. All suggestions are apprecialted. Thanks

I will forewarn you. They are expensive. Expect a hefty price tag....

God bless,

John

[luvrbus]

 John they are expensive but she heading in the right direction just like you get it right the first time, their bus is a little more challenging that most the way it was built 




good luck

[John316]

John they are expensive but she heading in the right direction just like you get it right the first time, their bus is a little more challenging that most the way it was built 

good luck

I agree, Clifford. She is absaultly heading in the right direction. I was just warning her about the price, that's all. We sure like the piece that you sent us, and then we ordered a lot more. Thanks...We haven't regretted putting that stuff in at all. Works VERY well...

We have been thinking about wrapping the exhaust....

God bless,

John

[ruthi]

You are right about the price, but, you only get one shot, and we are doing everything extra that we can do to make it the best we can. Getting all the exhaust stuff tore out of the back is going to help a lot to. It really opened up that area for the bedroom. We are going to have 2 stacks coming out of the back..The back and the front end have had a lot of modifications. We got all the insulating done yesterday, and we are about to start the electical stuff. Hubby has been working steady since we got home, just a few hrs sleep, and back at it.  Thanks all.

[Tim Strommen]

I swear by this Gold Thermal Barrier...

But like John316 warns - it's also expensive (most "good" thermal/noise control products are).  If you are really worried about focused areas (like the firewall right next to the turbo, or the incoming fuel lines) a couple of square feet will be enough to wrap braided hoses, (etc) without breaking the bank.

If you can, you will get the best performance from a sandwich of materials - a "loaded" paintable skin sprayed on the metal inside the engine compartment (frame, skin - not the block!!), then a 1/4" to 1/2" layer of closed-cell foam, then a "loaded" layer of heavy vinyl or lead, then another layer of closed-cell foam or rock-wool (aka mineral-fiberglass) and finally the outer cover (some kind of heat reflecting barrier).

The outer barrier will reflect most of the radiated heat from the engine, the rock-wool will absorb some of the higher frequency noise from the engine (turbo whistle, valve rattle, fan whir) and slow sown the passage of thermal energy (insulation can't stop heat it only resists it), the lead sheet floating on the closed cell foam will absorb a lot of the airborne low-frequency noise (hum, combustion noise) by deforming upon collision with the sound-waves, the closed-cell foam should absorb a bit more of the low frequency sound energy and slow down a majority of the remaining heat energy that gets past the rock-wool (but some will still get through) - and the loaded paint will add a bit of mass to the sheet-metal/framing to reduce it's resonant frequency.

To explain that last part a bit more, if you tap a piece of metal with a coin - the sound you hear after the coin makes its initial impact, is the metal resonating until the impact energy added to the material dissipates.  It will sound kind of like a “clink” that runs out for about a second or two – but with a pliable-load on the surface and the same impact, after the coin hit and makes its “tap” the resonance should sound more like a low “thump” and it should die out almost immediately (the loaded paint is a bit flexible and will deform as the metal vibrates, converting the mechanical energy into a little bit of heat).

In recording studios we do the same thing – but then in the sound-stage, we will even “float” the floors and walls (mechanically isolate the room from the structure).  While you could do this in a bus, it’s probably impractical – but “floating” the engine and drive-train is not (these are usually vibration isolators that the engine/tranny are mounted to).  Let me tell you, you haven’t driven a quiet vehicle until you’ve driven one with the drive-train properly isolated!!! (just think of all the things in your rig that wouldn’t be vibrating and adding to the perceived noise of the space)

You can pick up a little more sound isolation if you carefully separate all radiated sound energy from the passenger space (it has to go somewhere, so absorb it, diffuse it or direct it).  For a “pusher” bus, adding a mud-flap that goes all the way across the back right about there the transmission meets the engine, and then down along the sides of the bus towards the back near the bumper will help to “direct” the sound energy out below the bumper (not forward under the bus towards the passengers, or out to the sides to bounce of buildings and passing cars/trucks back to the side windows).  Adding the above mentioned sound treatments will help with absorption of sound energy, and adding structures in the engine compartment and under the bus that have pyramid shapes or random surface features will help to diffuse sound energy – much like light waves, when a sound wave hits a surface it either passes through (some of it can be absorbed, the amount depends on the type of treatment), and some of it reflects.  Think of a mirror, a hard flat surface will reflect sound energy with enough uniformity to retain a lot of the fidelity of the sound (i.e. you can hear what the source sounded like through the reflection).  And again, much like a rough/jagged surface (even if made of a hard “mirror-like” material) breaks-up a reflection, you can’t make out the image that was reflected as clearly since not all of the energy was reflected in the same direction (this is diffusion).

Hope this helps…

-Tim

[belfert]

Part of the reason Ruth's Dina is noisy is because the engine cover in the back of the bus is not there.  Now, I don't know if it was driven home that way or not.

My Dina is way too noisy in rear.  It was a bit better this year with no changes, but last year I didn't know how they could haul passengers with the amount of noise.  I think the noise is coming mostly from the cover over the top of the Series 60, but I really don't know.  I've been thinking how I could build a better cover and still allow mechanics with easy access to the valve cover.

[ruthi]

Brian, our bus is not missing the engine cover. The cover that was on it was not the best, it wasnt sealing good. So,,,,,,, we used the old one for a templete, and built another one.  The new one is much better then the original. It is insulated very good now, as well as sprayed with the ceramics. It isnt any louder than anyone elses, we just want to make it as quiet and heat free as possible. And, no, we didnt drive it home that way, it had the cover on it. Ken, my hubby, worked on rvs for 25 yrs before we started doing the work we do now, so, we know a little about this, but, there are always others who know more, had more experience with a particular application, etc. We are always learning.

[belfert]

Brian, our bus is not missing the engine cover. The cover that was on it was not the best, it wasnt sealing good. So,,,,,,, we used the old one for a templete, and built another one.  The new one is much better then the original. It is insulated very good now, as well as

Sorry, I wasn't sure if you had the engine cover on when you drove the bus home.  I know you or Ken said bus was somewhat stripped out when you got it.

Any chances of a photo of your new engine cover?  I need to make a new one or something to cut down on the noise.  I have some ideas, but I would like to see other ideas too.

[PCC]

I am adding a diesel generator under the floor directly behind the steering axles.

It has its own frame with rubber mounts, and I am putting a strip of teflon between the generator frame and the steel mounting frame being built into the coach.

There is little more I can do to deal with any vibrations during the generator's operation, and it a smooth and quiet running unit, for which I am quite pleased.

Should I additionally place some sound proofing above the unit?

I have built a steel frame across the bus both for support and to be able to remove the unit for servicing, but this issue of noise has me curious, so my request is for some suggestions.

I have opened the access way between this bay and the front end of the engine (which sits under the bus in the middle) to move the operating heat into the engine area.

The engine compartment seems to be well heat and sound insulated, because there is little engine/transmission heat or noise transferred into the passenger compartment.

[Old Scool Bus]

Spray foam insulation then have the clear hard coat sprayed over that. Probably the most affective way for the money.