5/5/05

Jay, Currently running a blown 355 SBC in my ’50 Stude. I can’t tell you much with regard to specs. I can tell you it has a 144 B&M blower, dished blower pistons, blower cam, and a 700 CFM holley double pumper blower carb. The weak link in the engine is the stock, low flow, 882 76cc straight plug heads. The engine dyno’d at 340 hp at 4700 rpm with nine lbs. of boost using a 3” blower drive pulley. I could put a smaller pulley on the blower drive and make the blower spin faster, but I think all that will do is create heat problems without much hp gain. The engine is a good all round street engine, but I’d like more punch at the track. I’d like to use aluminum heads from Edelbrock or equivalent, but I’m not sure of the cc and runner numbers I would require to gain some hp. Larger cc, lower compression, more hp when running a blower, correct? Can you offer me some advice as to what size head I should go with? Thanks, Darrell .

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Darrell, Apparently, this is a pretty mild blower engine judging by your posted Dyno numbers. It would have been interesting to know the amount of torque the engine produced and at what rpm. Without knowing your combination I can only talk in generalities, but, here goes. Considering this is a street car I would not get too carried away with buying a BIG runner volume cylinder head. The absolute largest runner volume I would go with would be 200 cc’s. Blowers generally will make GOBS of low-end torque so you can probably use a runner of that size and still have good throttle response. Any type of forced induction will tend to make a small head seem bigger simply because it is being force fed air. Also, by using an aluminum head you can actually run a higher static compression ratio than you can with iron heads and not have detonation problems simply because the aluminum heads will “sync” away more heat.

Hope this helps, Jay Roeder

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More Horses [4/8/05] Veteran engine builder and racer Jay Roeder solves your horsepower quest