IHRA S/S engine ?

[Bench Racer]

Depends on if you are talking "IHRA superstock production" or" IHRA super stock" the production engines are simular to the old modified production engines and run at weight per cubic inch. In the early years they were classed as formula 1 through formula 4. Formula 1 was multiple carb, formula 2 was single 4bbl, formula 3 was 2bbl. limited to a 650CFM Holley, and formula 4 was NHRA legal engines that run at a horsepower to weight class. I think the multiple carb class has been eliminated, and unless memory serves me wrong all you are limited to in production superstock is a carb of 500 CFM in the two bbl class. and the only thing checked is stroke and cubic inch. I am not sure what the "formula 4 NHRA" engine cars are called, I assume just superstock. IHRA does not always keep up with NHRA with horsepower changes when the lead foot prevails at a NHRA track. Hope this confused rambling helps. Don Jackson