Boost limits with EFI

[Charles]

Someone wrote:
> I've lean burned down twice, and a 3rd time
>via detonation.  Learn from me, you absolutely MUST run 116 octane fuel
>at all times if you run more than 8lbs boost.  Also, spend the 75 bucks
>to ceramic coat your pistons, another absolute must have if you don't
>like swapping pistons with holes in them.  Other MUST haves are EGT
>sensors in each pipe, a good boost/vacuum gauge, and fuel pressure
>guage.  For me burn down occurs at 1250 degrees, with ceramic I've been
>over 1400 with no damage. =20

	My daily driver is a 1981 BMW 745i (factory intercooled turbo and
L-Jetronic fuel injection). It is rated for 8 psi, on US 93 octane
pump gas.
	I have built an additional injector controller (8748-based)
running two 50 lb/hr injectors in the intake tract. Having disabled
the mechanical "vacuum" retard mechanism in the distributor, and
adding an MSD Boost Timing Master, I now run 15 psi on 93 octane. Need
a bigger intercooler though - higher boosts just give a hotter exhaust
due to the needed retard, but no more hp.
	EGT runs around 1200 cruise and peaks at 1600 or so under WOT
with a small (30 hp) nitrous squirt for quicker spool-up. This is
upstream of the turbo in the manifold. Tens of thousands of miles with
no damage. The pistons are flat-top forgings.
	You shouldn't be melting things at 1250 F EGT unless inaudible
detonation (or something else) is killing the engine...keep it RICH!
-Charles