Re: xkcd: Good and Bad Ideas

On 5/8/2024 4:09 PM, Scott Dorsey wrote:

In article <v1eb3l$3gva7$1@dont-email.me>, Alan  <nuh-uh@nope.com> wrote:

On 2024-05-07 15:21, Lynn McGuire wrote:

xkcd: Good and Bad Ideas
     https://xkcd.com/2929/
>
We would have lost WWII without leaded gasoline.  The bombers and
fighters both required 100+ octane gasoline which was only achievable
using massive quantities of tetra-ethyl lead in those days.

>
1. You're such a tedious pedant.
>
2. You're wrong on the facts.
>
While having 100+ octane gasoline made more power possible, if they
hadn't had it, engine manufacturers would still have built very
effective engines.

 Not to the same extent, although we DID know about things like alcohols
as octane improvers at the time.
 Lead made for MUCH more powerful aircraft engines with much higher
compression, and because the only octane improver we had at the time
was lead there were a lot of crazy volatile engine fuels that were
mostly casing head and lead.
 BUT... the point should be made that if we didn't have ethyl back then,
the Germans and Japanese probably wouldn't have had it either.  Although
the Germans did some some pretty amazing performance features that we
didn't know about (like nitrous), keeping a secret like ethyl would
be difficult.
--scott

It was not just the higher compression of the engines, the superchargers and turbochargers compressed the air going into the cylinders.  The act of compressing the inlet air also raised the inlet temperature of the air by some 150 F to 250 F which also caused preignition problems of the gasoline mixture.
The lead also plated out on the engine exhaust valves and did the dual job of lubrication and hardening.  So, the exhaust valves also lasted longer in temperatures approaching 1,000 F.
Lynn