How High on Stock Engine?

I'm planning on buying a 1965 Mustang. It's 289 ci 2V V-8 with 200hp stock. I'm planning on installing an EFI. How much horsepower would be safe to run on it without worry? I'm looking at a turbo and possible nitrous.

Thanks :)

well if you're going to go through all the work to upgrade it to EFI (which I think is kinda stupid, but whatever) you might as well rebuild it with a 302 crank and low compression forged internals. If you did the engine would easily be solid over 500 hp.

well if you're going to go through all the work to upgrade it to EFI (which I think is kinda stupid, but whatever) you might as well rebuild it with a 302 crank and low compression forged internals. If you did the engine would easily be solid over 500 hp.

I havn't completely decided on it yet.

Without the crank and forged internals?

Thanks

On a stock cast 1965 assembly? I might go as high as 275. I'd go 350 on a fully rebuilt fresh 289. Your problem is a weak lower end, wimpy rods, and a pathetically high compression height on heavy pistons.

Keep in mind that the 200-hp rating on that 289 is gross HP, so to compare it to today's ratings, that is only about 150 hp in real life.

If you're going to sink thousands into EFI and turbos, start with something better than an engine who's internals are only designed to handle 150 hp. 87 and later 302s came stock with forged guts and beefier mains and could easily take 400 hp, more if you do some very modest upgrades like main and rod studs.