[DeTomaso] pressure and overflow tanks

[JDeRyke at aol.com]

In a message dated 9/5/09 6:12:39 AM, LEVITT1946 at aol.com writes:

> I had a 13lb pressurized cap on each tank and car seemed to hold 
> its pressure and temp. Last night I changed to a 16lb on the pressure tank and a 
> non pressurized cap on the overflow. The car hit 250 degrees in traffic and 
> stop and  go.
> 
> Should I put a 13lb pressured cap on both tanks or a 16 lb pressured cap 
> on both?
> 
A pressure cap on the big collection tank will do nothing except slow down 
the transfer of pressurized water expanding out of the engine & surge tank. 
Depending on the altitude where you were driving, a 16-lb cap on the smaller 
surge tank will suppress boiling in the system up to 260F at sea level. A 
20-lb cap will increase that margin to 272F, but you better have a really 
tight cooling system made of very high quality hoses, clamps and a stronger 
than stock radiator. Look at the radiator cap article in the Sept 09 POCA News 
(now in the mail). 
It also tends to indicate that there's too little water in the system, too 
little fan air-flow at very low road speed and/or too-small a radiator in 
the car (e.g- a stock brass unit). Something we all sometimes overlook is, 
heat transfer is more-or-less constant in reference to ambient temp: a car that 
runs 180F at 80F ambient will run 200 (or more) at 100F ambient with no 
other changes.
A Fluidyne aluminum radiator specifically made for a Pantera, along with a 
Flexilite shrouded dual-sucker-fan system, will instantly drop the water 
temps by 30F or so under the same conditions. All the other cheaper mods are 
nice but none did anything noticable to the stabilized water temp except a 
bigger, better flowing radiator. FWIW- J Deryke