What’s the size of the LT1 throttle body and can I use a larger one?
A stock throttle body inlet is 48mm in diameter. The matching inlet on the intake manifold which it’s attached to is about 52mm. Therefore, you can safely buy a 52mm one (like that from TPIS) and bolt it on in place of the stock one without any other modifications. Anything larger (like the 58mm from Lingenfelter) would require the intake manifold to be bored out to handle in the increased volume of air. The larger throttle bodies are not physically larger, they’ve just been bored out making the openings larger. The additional amount of HP from the 52mm throttle body is questionable. Some reports show little or no increase, yet others claim up to 10 more HP. And some air foils (to smooth the flow through the throttle body) claim to get another 5 HP. But even that, is questionable. A 58mm throttle body (in conjunction with the bored intake manifold) might provide a larger increase in HP, but once again, results usually vary.
