That 100% is anything but. I haul fuel. The so called alky free has less than 5% alcohol. A good way to tell is to put some in a pan and set it outside when the weather is humid. If it turns milky white, it's got some alcohol in it. Or just add a little water to the pan and see if it turns white. Around here the alky free premium is 91 octane. 10% blend is 93. I alternate fillups at both making the mix around 92 octane and the alcohol content at around 5-7% This I'm running in my 10.4 to 1 compression 331. And it's completely fine at that octane level. Your 429 should be OK as well. I too add in a lead substitute to cushion the valves. Been running this 331 now for 14 years like this.

 

The owner's manual references the research octane number or RON. Pump gas in the US is rated using an anti-knock index, which is the average of the RON and MON (motoring octane number). Premium fuel will have a RON much closer to what the owner's manual specifies than the number shown on the pump. Also, ethanol has a higher octane number than gasoline, so if the quality of the gasoline remains the same and ethanol is added, the anti-knock index and octane rating will increase.

 

 

Have you ever heard of a Webster Heise Valve? From what I have read, it is a way for a wet manifold vehicle use a mechanical system to sheer the fuel. Invented before any type of fuel injection was on on everything, it was quite interesting. Documented to do a bunch of stuff, its true claim to fame was for the octane requirement to be reduced on anything. I assume it would also work to a degree with TBI to some degree as well.


https://www.washingtonpost.com/archi...=.c9a16adc73e3

David Lindahl: The Webster-heise Valve ~ Congressional Research Service Resport 82-176 ENR

Sherwood Webster, Richard Heise: Fuel Atomizer (Thermocharger); US Patent #4187820, #4285320

https://digital.library.unt.edu/ark:/67531/metacrs8512/

https://patents.google.com/patent/US4187820

 

It sounds interesting, and I'm sure improving fuel atomization with carburetors can make improvements to combustion efficiency, but I think these features are being achieved with modern fuel injection systems. I think if someone continued developing TBI systems, they could achieve the same improvements.

But modern EFI systems have a lot more advantages over any wet intake manifold systems, the most significant of which is very precise control of fuel delivered to each cylinder. Or in the case of direct injection systems, fuel delivery into the cylinder at exactly where it needs to be at the exact time it needs to be there. This leaves the engineers to optimize the intake manifold for the best air flow, without worrying about fuel condensing out of suspension while the wet mixture goes through the runners. The wall-wetting effect of a wet manifold system is much stronger than a port injection system, as the acceleration enrichment has to shoot a lot more fuel on throttle opening to compensate for the fuel condensing on a lot more surfaces from the increased manifold pressure. All this extra fuel is then sucked out and wasted when the throttle is closed again. With direct injection that delivers the fuel right into the combustion chamber, it doesn't need to compensate for wall wetting, just what the engine needs for additional power, so that saves a lot of fuel.

Of course, as long as engines use PCV and EGR, there is the build-up behind the valves that the DI system can not clean off, so some newer DI engines still use a port or throttle mounted injector for that purpose.

 

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​I have not heard of this. I'll have to read some of the links when I get more time. I certainly don't want to make my fuel economist worse, so that would be a downside for me.

 

If you want to suppress knock look to Snow Performance water/methenol injection. It solve my problems