Why would it do that?

Surely it could withstand an extra degree or two with the better fuel if it was fine on 87?

Could it maybe have needed extra jet with the better octane?

Not doubting you.I know you turn some awesome results.Just puzzles me.

The octane rating of fuel relates to its detonation resistance, not its energy content. In fact, the higher the octane rating the lower its absolute energy content. Without increased compression and/or timing changes the engine will produce less power on higher octane fuel.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

Can you cut down exhaust valves like you turn down the intake?

Sure. The 1.74" and 1.81" Chrysler big block exhaust valves have both been used as slant intake valves. They are a little longer, but if the seat is higher in the chamber it makes up for a lot of the difference. When I had my 1.78" intake and 1.45" valve head built I used Ford 300 valves and the exhausts were cut down from 1.58" if memory serves.

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Joshua

If you get a chance, hang around a race shop with a chassis dyno and watch a real tuner work.

Any motor with good porting will make more power with less octane and timing than it will with more. Motors that want more timing usually have less than optimum flow characteristics.

We dyno'd a guys 14-1 BBC at the shop one night and showed him it made more power at 32* on 112 than it did where he had it at 38* on 116.

Guy still used 116 because he knew the dyno was lying.

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Official Cookie and Mater Tormentor.