Exhaust Pipe Size on Convertible

Q: Exhaust Pipe Size on Convertible

What is a good diameter exhaust for a convert WITH crossmember installed. Will have a shop work 400HP out of original 350 later on. Would like 2.5 Alluyminized. Will this help HP allowances, or will I have to get bigger to get that HP?

A: The real problem is getting anything bigger than 2.25″ past the convertible pan brace. Perhaps that’s what you meant rather than the crossmember. The exhaust has to share this tight space with the transmission tailshaft and the driveshaft. Some list members have reported getting 2.5″ to fit, and I’m sure it took some very creative pipe bending to do so. Or maybe ovalizing would be a better term.

400HP out of a 350? Is that flywheel HP, or rear wheel HP? Either is quite a bit to ask of that small displacement. But I’m sure it can be done. But how driveable will it be? 2.5″ probably won’t be too much of a plug for that HP.

It’s pretty important to keep the brace, by the way. Even if you get subframe connectors, the race car chassis builders like to keep the brace if the car isn’t given a tube frame.

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