Editor’s Note: This article was originally published in the March 2001 issue of BCM but is worthy of reprinting as it has been a while and this information is still very helpful to many, as hot engines are a problem in many bus conversions.
The engine installation in my Eagle is a standard truck motor. To explain the difference; a truck motor has the turbocharger mounted on top of the air box, whereas the typical bus installation has the turbocharger mounted at the rear with a flat horn to the air box. This way, the bus will have lower headroom and thus maintain a flat floor under the bed. One might ask, “Why use a truck motor?”. The answer is, “There are more bargains to be had in take-outs from trucks, than from buses”.
Two problems arise from these bargains.
1) The additional height of the truck motor must be accommodated. The height is a result of the top-mounted turbocharger.
2) Some form of insulation must be provided to keep the turbocharger-generated heat from invading the living space of your coach as it will be very close to your bedroom floor.
The first problem is customarily solved by opening the floor under the bed area. A typical raised bed support framing reinforces the opening cut into the floor to allow the turbocharger and other accessories to occupy this space. This has the additional advantage of permitting easier access for engine maintenance.
The second problem has not been quite so easy to solve until recently. In the past, many have added urethane foam insulation to not only the side wall of the structure but the bed platform also. One layer of an inch-and-a-half urethane foam didn’t do the job, so we added another layer. A total of three inches of foam just wasn’t adequate to solve the heat problem and we were running out of space.
When we had a 6V92 engine installed we had the motor wrapped with typical sewn fiberglass, fiberfrax, silicone, and stainless-steel wire installation. These insulation wraps are typically $500 to $800 and require an experienced installer to add to the engine.
They were originally developed for yacht installation to minimize the heat in the engine room. I have also been advised that an exhaust wrap will add power. This may be true, but I couldn’t perceive any difference in my bus.
After installing my larger 8V92 engine,, most of the original engine wrap would not fit, so I opted to simply go with the added urethane insulation as mentioned above. This was not a good idea. After several trips, my co-pilot complained of the high-temperature build-up in the bedroom. Since this was once the source of a coach fire, paranoia syndrome became pretty intense.
Since my genes are rife with thriftiness, (being a cheapskate, that is), I was not prepared to spend another $800 for an engine wrap, but I did get an ultimatum from the co-pilot, “Do something about that heat or fly solo hereafter!”
After commiserating with one of my mechanic friends, he mentioned a material that was applied wet and molded over the manifolds and turbo to dry and was cured by the engine itself. He promised to find out what it was called and let me know.
In the past, I have used a material called Rollboard, which is a form of ceramic insulation like blotter material, so I called Engine Heat Protection (EHP), the company that sells Rollboard. Bingo! They had the material I was looking for! Later I learned that they advertised in BCM. (I’m going to hafta start lookin’ at that magazine…duh.)
I called Penn Lenson, the owner of EHP, and found out the characteristics of this magic material. It comes as a wet blanket, two feet by three feet, by one-quarter inch thick, in a polyethylene sleeve. And its price is nearly $100 per unit. I was also advised you could put your hand on a wrapped exhaust pipe with the motor running without being burned.
After pondering this information, I figured this was a bargain compared to the fiberglass engine wrap, so I ordered two blankets. This material also has the added advantage of being fireproof.
Since Penn is almost a neighbor, he delivered them in person and gave me a few pointers on how to install the material. The next day I began the job.
The bed platform was raised, and I began the application. First, however, I used masking paper and mashed it around the parts I was wrapping in order to approximate a template. I then used this template to cut the EHP blanket to the necessary size and shape. It cuts quite easily with just a pocket knife. A sheetrock knife would also do the job.
One of the cautions was to place paper beneath any area where the material might drip to avoid a whitish stain on the part or on any cement floor below.
The material molded pretty easily around the straight section, but there were shapes where it had to be pieced together because of the compound contours. The material has no adhesive properties so masking tape was used to hold it in place until it dried overnight. After drying, it hardens into the molded shape.
In order to ensure it remains where it is placed, EHP supplies stainless steel band clamps to wrap around the insulation.
As an experiment on my own, I used metallic duct tape which can be seen in the picture of the finished installation. Our experience is the Wet Blanket as installed, is as effective as the fiberglass wrap, less labor intensive, less money, and may be done by a rank amateur, (well almost ranked.) Bottom line, I highly recommend it.
One of the neat things about EHP is that it is for do-it-yourself kind of people, i.e. most Bus Nuts, and is an easy and relatively inexpensive solution to keeping the heat out of the bedroom area so you can sleep in a cooler environment.
If you are interested in learning more about EHP’s Wet Blanket or Rollboard insulation, visit: https://engineheatprotection.com/.