Originally Posted by 305mouse
V8 super beetle, belive me this is no disrespect,im just learning all this,but on that 305 build they use a set of slightly under fed 350 heads. So why not just use 350 heads to start with or port & polish the 305s? Why is the 305chevy such a dead dog compaired to the 302ford? Both 5.0s kinda. My class mate did a"bolt on build" to his 85gt.foxbody & he eats SBCs all day!,why the big diff?
Those are "350" heads they used, well, they're best suited for a 350 anyway. Can be used on a 305 or 400. Depends on what you're after. The intake runner size (180 cc) and chamber cc (64 cc) are a little large for a 305. A 305 with these heads would be soggy down low and you'd have to wind it up to produce power, which is the case in the article.
If you read the article, you'll see they machined the heads by .040 to arrive at a 58 cc chamber vs. the 64 cc size, which was necessary to bring the compression ratio up to around 9.5:1 with the dish pistons.
A 305 can be built to perform, as you see in the article, but the same parts on a 350 would produce about 15% more power and torque due to the larger displacement of the engine. Engines are just air pumps. The more air you can pump in the more power you will get in return.
If you go to the drag strip, you'll notice most of the cars are chevy's or they're running chevy motors. That's cause you get the most power for your buck due to the popularity of chevy's.
Fox body mustangs are light and it's easy to get some decent power out of a 302 for cheap. Again supply and demand. It's all about power to weight ratio. I would be glad to run him in my bug with my 383 SBC. It'll be a tough one for him to swallow.
Gearing and converter size make a big difference too.
305's were really never meant to be a race motor. It was built for torque and fuel economy, well, that's my understanding anyways. They tend to run out of power after about 4500 rpm due to their heads.