[mhayes]

I am glad to see here that someone has the guts to really build an engine from the oil pan up in order to squeeze as much mileage out of it as possible. I like your general idea, and the Firebird is a great platform for a build such as this. Anyway, the ideas about the pistons and cylinder heads are intruiging, but I wonder why is it necessary to fork out $1k on a set of heads that will likely not gain you anything in economy. You can buy a lot of fuel for that much money. It seems that your funds would be better spent cleaning up the factory heads with a normal bowl blend and long radius clean up and then a valve job (30 degree) that will allow more flow at low valve lift. We want to reduce parasitic losses and restrictions to flow where it will do the most good. Consider having the block true decked to 9.00'' and having the piston stick out of the bore by .010'' in order to increase quench and detonation resistance. The LT1 already has a CR of 11:1 from the factory, and this will give you about a half a point increase. The reverse cooling is a nice feature, and you should have no trouble staying out of detonation provided that you select a cam that does not have too tight lobe separation, causing dynamic cylinder pressures to get too high. The engineers were not idiots, and I would not stray too far off the target of a 117 degree centerline. That is already a pretty wide separation.

As for the TPI on the LT1 heads, I do not see how that will benefit you in terms of port velocity or fuel distribution over the stock TPI that is already there. Again, this is likely to be wasted effort and money. You already have a port injected intake. The older TPI runners are longer, but I bet that there is comparable inertia in the newer design to fill the cylinders effectively at low speed.

As for suggestions to improve on your plan, think thermal management. Have your pistons, valves and combustion chambers thermal barrier coated to retain as much heat in the cylinder as possible. Have your headers coated as well. This will keep exhaust pressure wave velocity as high as possible due to the higher temperatures in the primaries. Consider a port mismatch on the bottom of the exhaust ports to create an anti reversion dam. This will minimize reverse flow back into the cylinder during overlap.

Also, always run the longest connecting rod you can. The reason for this lies in the geometry of the crankshaft. With the longer rod, the crankshaft will rotate more degrees before the piston starts to come down in the bore, therefore the crank sill be closer to 90 from TDC as the cylinder pressure rises to maximum. This allows for more mechanical advantage. Try to get a 6.2'' rod.

Also, you didn't mention transmission or axle ratio. A combination like this should be geared as high as possible. A T56 would be the best, offering a 50% overdrive. This is a cool project. I hope it turns out well.