Hotfooting It (Post # 135)

Wrapped headers on chassis *01909*.

 The Heatshield Products exhaust armor's
inner ceramic fibers layer is capable of
withstanding 1800 degrees F continuously.

Now we're back to the exhaust system, following Post # 129. The Alfatross has a hot engine. No, really, I mean HOT! And the exhaust gasses are the hottest part.  Alfa engineers knew this, so 1308 SS engines came from the factory with aluminum and asbestos heat shields protecting the starter, generator, and part of the steering column from the intense heat radiating off the headers.  A dedicated aluminum scoop and shroud ventilated the entire exhaust side of the engine when in motion, but was of little help otherwise. We need to get those hot gasses away from the car as fast as possible while at the same time keeping the decibels down to a civilized level. Alfa engineers put the first of three pairs of mufflers or resonators right under the driver's seat. At this point in the system the gasses are still at a few hundred degrees F. This might seem like a dumb thing to do, but if you look around under the chassis there really isn't any other place to put it, given that the chassis is short and you still need to find space for two more muffler pairs. 

The corrugated metallic outer layer keeps the
inner layer together and allows it to be shaped.

We discovered this "engineering compromise" during the 2016 Arizona Concours d'Elegance. Positioning the cars on the field in the wee hours took a long time, with a lot of stopping, idling, and waiting.  Even though the pre-dawn January morning was quite chilly the cabin became uncomfortably warm very quickly.  Fellow 1900C SSZ owner David Smith experienced the same phenomenon while preparing his car (*01947*) for Pebble Beach this year. During road testing the floorboard got so hot it started to melt his shoes! The only viable solution is to add more insulation between the first pair of mufflers and the floor under the driver's seat.

The Heatshield Products "Exhaust Armor" installed on 
top of the insulation previously fixed to the bellypan creates 
a good two cm total insulation between the exhaust system
 and the floorboard directly under the driver's seat. 

The third muffler pair hides in a recess in
the bodywork with no more than half an 
inch of clearance on either side.  

Trial fitting the Quicksilver exhaust system in preparation for tack-welding.  Altogether there are 10 joins, 2 hanger tabs, and a brace to weld.

Now that The Alfatross' new Quicksilver exhaust system is welded up and almost ready for installation, it's time to beef up the insulation in a discreet manner that does not detract from its originality. There is no question that insulation materials and technology available today do their job quite well, and some 1900 owners have gone so far as to wrap their headers, but some authorities think this practice may be damaging to the headers themselves. In any case use of header wrap for The Alfatross would be an inappropriate anachronism. On the other hand, replacing the traditional asbestos insulation attached to the bellypan beneath the driver's seat with modern materials is easy to do and should make a big difference without even being visible. 

Another place where the exhaust system could stand additional insulation to keep it from damaging the body paint is the muffler recess in the trunk area where the last pair of mufflers reside. On Zagato bodied SS cars like The Alfatross this space is only about 7 inches wide, leaving about half an inch of space on either side of the twin mufflers--too close for comfort!  

The Lava Shield mat material looks like carbon fiber and
is only 0.008 thick, but is said to reduce radiant heat by up
to 80%.  

After some online research I ordered two different kinds of insulation for the two applications, both manufactured by Heatshield Products (https://www.heatshieldproducts.com/): "Exhaust Armor" for the area under the driver's seat and "Lava Shield" for the last pair of mufflers in the recess. "Exhaust Armor" is a mostly fibrous ceramic material 0.50 inch thick bonded to a dimpled metallic sheet said to be able to resist 1,800 degrees F continuously, while reducing radiant heat by 60%. "Lava Shield" is a completely different material ("made of crushed volcanic rock" according to the manufacturer).  It comes in the form of a self-adhesive mat only 0.008 inch thick but capable of reducing radiant heat by 80%.

At this writing the Quicksilver exhaust system is back on the workbench following a test fitting to make sure everything is still in alignment after welding. The next step is prepping it for coating with the same high-temperature flat black paint I used on the first system.  I won't know how effective the heat shields are until after the whole system is back on and the engine fired up. One thing I can say for sure is this better be the last time anything having to do with the exhaust system needs attention--I'm tired of living under a car!