I would say the 400 hp 460 would get better mileage than the 400 hp 302.Depending on what you want it to do, I'm assuming to accelerate as fast as possible you would have to gear the 302 pretty low as it would probably have to rev fairly high to hit 400hp.The 460 with all that torque could loaf along at a much lower rpm and still accelerate well so you could go with a higher gear ratio.I had a 429 thunderjet in my 1982 pickup and it got better mileage than the original 302 although both engines were stock.
I agree your mileage would probably be the same. But I would go for the 460. The torque would be much higher than the 302. You wouldn't have to turn it a hard, and the seat of pant feeling would be awesome.
I have a good article on a 460 intake shootout.The engine is a 9.4.1 compression 460 with old style 76cc heads JBA shortie truck headers,750 holley,a crane353942 camshaft with .518L on intake .513L exhaust and 216 and 228 degrees duration at .050. The baseline dyno pull with stock intake and unported heads made 396.5 hp at 5000 rpm and 512.9 ft/lbs of torque at 3250.So theres your 400 hp without any headwork or trick parts.If your curious removing the bump in the exhaust port was worth 13hp and the best intake for this combo was the edelbrock performer although the stock intake was tough to beat.The performer made 25 more hp and a hair less torque than the stocker
frdnut: What other intakes were in the shootout? I've got a Performer on my 460, but I was thinking of swaping it out for a Weiand Stealth. I've heard they're really good intakes, but I'm worried with the larger volume intake that it wouldn't make as much bottom-end torque, and I definitely don't want to loose any of that.
I rechecked the article and it says the exhaust has slightly less lift as I stated before.Maybe this is a error as I agree the exhaust side usually has more and it does have more duration.You could phone crane with the number to find out for sure.I'll give you the intakes tested.The motor is the same as above with the exhaust bump removed.Stock [email protected]/[email protected] Offenhauser Port-O-Sonic 6157 single plane made [email protected]/lbs of tq @3500 Weind Stealth [email protected]/lbs of [email protected] Ford Power Parts 4250 highrise dual plane made [email protected] and497.7 ft/lbs of tq @ 3500 basically the same manifold but with the divider in the plenum cut down(known as 4250B)made433.4 [email protected] and [email protected] ft/lbs @ 3500 The Edelbrock performer made 434.6 [email protected] 5000 and 518.9 ft/[email protected] Both the stock intake and the performer made very flat power curves making over 450 ft/lbs of torque from 2500-5000 rpm.Keep in mind that this is a pretty mild motor and the intakes would perform differently with more cam ,compression ,carb etc.As you can see the cam was all done by 5000 rpms
Wow, thanks for the info. My 460 is pretty mild, it's got the next smaller cam than the one they tested in it, but other than that it's pretty similar to my engine. I think I'll keep my regular Performer intake now