[Diy_efi] RE: Timing and dyno pulls
Adam Wade
espresso_doppio at yahoo.com
Fri Dec 20 00:04:34 GMT 2002
--- William Shurvinton <shurvinton at orange.net> wrote:
> No: dave's point: Best power is way off detonation
> in a race engine. My question, why does a modern
> road car gain 10HP when run on high octane (real
> test, think it was a BMW) when all it has to go on
> is the knock sensor.
> Inference: it must be running close to knock all the
> time.
Often, that is the case. With the lean mixtures
reguired for current emissions, lower-octane fuels
often require retarded timing to prevent detonation,
IME. Usually in cars like the BMW, you will find a
recommendation in the manual for a higher-octane fuel
in any case. Just because you CAN run it on a
lower-octane fuel doesn't mean it's a great idea. As
a rule, I tell people to run the lowest octane they
can without pinging; if the car retards timing on a
knock sensor, use what the manual recommends, in
general.
> I quoted F1 because it is an extreme case. The
> engines are run at riduculous coolant temps and revs
> and until recently were billet unobtanium.
I like to think in many ways they still are. ;)
> I like beryllium in space apps, but not sure I want
> it in my car.
Sure makes repairs a bit more difficult, I should
think. ;)
> However the coolant temp in this case is due to not
> being able to get the heat out, not because the
> engine liked the heat.
True, although again I think they are primarily
concerned with components failing when they get too
hot over anything else. As I'm not a design engineer
for an F1 team, I can't say for sure. :D
=====
| Adam Wade 1990 Kwak Zephyr 550 (Daphne) |
| http://y42.photos.yahoo.com/bc/espresso_doppio/lst?.dir=/ |
| "It was like an emergency ward after a great catastrophe; it |
| didn't matter what race or class the victims belonged to. |
| They were all given the same miracle drug, which was coffee. |
| The catastrophe in this case, of course, was that the sun |
| had come up again." -Kurt Vonnegut |
__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com
_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi
More information about the Diy_efi
mailing list