Water Injection Thread

[Greg Hermann]

Hi again--

One more thing about insulating headers--

Already said the headers need to be made out of 321 SS if you are gonna
insulate them and want them to live for any length of time.

Another aspect of this is that once you have insulated the header tubes,
obviously, they will get hotter, and therefore experience a bunch more heat
expansion than uninsulated header tubes do. And stainless has a somewhat
higher coefficient of expansion than plain carbon steel, so you will be
fighting a double whammy with insulated 321 SS headers in terms of tube
growth from cold engine to fully hot, sustained WOT header tube operating
conditions.

Specifically, you had better allow for about .080" of growth in length per
foot of tube length. If you do not allow for it, this is MORE than enough
growth to cause things to disassemble themselves!!! (NASTY ways of doing
it, too, like breaking bolts off at the head, breaking flanges off of the
head, breaking turbine housings, breaking turbo mounting brackets, etc.!!
The 321 SS is tough, stiff, and strong enough at high temps, even in only
16 or 18 gauge thickness, to vent its wrath at captivity on almost anything
else foolish enough to be in its way!!

Also, cuz of the differential in thermal expansion between stainless and
plain steel and/or iron, the older boys have told me that the best plan is
to fab the header flanges out of carbon steel (min. 3/8" thick, I would be
inclined more toward 7/16" or 1/2"). They have also told me that the wire
of choice for welding the 321 SS tubing to the carbon flanges is 308 SS.
(347 wire for welding 321 tube to 321 tube.) These same older boys did not
mention what to use for header flanges meant to mate with them thar
new-fangled aluminium heads----

Now, as for the expansion joints that you are almost bound to need to make
the fool things work without breakin' sumthin':

Any creative thoughts on this subject are more than welcome!

Best idea I have come up with, so far, is to use a regular tube into the
second tube swedged larger slip joint, just like on stock exhaust pipe
joints--but no clamp, and be sure that the inner tube sticking into the
swedged part of the other tube is NOT QUITE bottomed  (1/8" clear end
play??) in the final assembly position.  Then weld a rolled bellows looking
device on over the outside of the slip joint to seal it. Such bellows are
available (IN 321 SS!!) in  an innumerable variety of appropriate sizes and
thicknesses (and with plain tube ends) from, for one,  an outfit by the
name of Hyspan.

This is all obviously a LOT of effort to get more out of a motor, but
hey--why do we spend our time here if not for just that reason???

Regards, Greg