Could anyone tell me how the Aussie heads stack up against the 4v American heads? Also what kinna HP increase would I be looking at over the stock American 2v heads going to Aussie heads. Can the Aussie heads ever create the power that the 4v American heads can?
Could anyone tell me how the Aussie heads stack up against the 4v American heads? Also what kinna HP increase would I be looking at over the stock American 2v heads going to Aussie heads. Can the Aussie heads ever create the power that the 4v American heads can?
Teh 335 series forum is a good place to ask this particular one.
The Aussie heads make good power. They are not 4v heads though and won't ever flow or have the same power potential. They are popular heads however because since they have smaller ports than the 4v they produce torque at a lower RPM than their big american brothers the 4v. They also have the beneift of a smaller combustion chamber than the 2v american ehads which if you do nothing else to the motor ups the compression.
I see alot of people going to the assie heads for street cars simply because you can make the power at a lower RPM.
The Aussie heads are a 2v head with a quench combustion chamber. You will pick up horsepower due to the pick up of about a point to a point and a half of compression (10-15HP). They are good heads, but it is my belief that 2v's need porting to work well. Having said that, with the right supporting pieces this could work very well for your set-up without having to port them. It all depnds how fast you want to go.
It is my opinion that 4v heads are better, but they need work, too. Like extensive porting, and stuffing the intakes. And an expensive intake manifold. And you have to be willing to make a commitment to the right parts to make them work. We've given you advice on how to make a good performing set-up it is now time for you to choose which route you would like to take.
The good part is that either choice is a good one, both heads are proven performers. It might be cheaper for you to go down the route of the 2v since you already have the exhaust for the 2v. Give Scott at MPG a call, his number is 303.762.8196. He'll setyou straight about Clevelands, and you don't have to buy his products if you don't want to. Some people don't like him, but he has always steered me in the right direction when I've accurately told him what I've wanted to do. Give him a call, you might learn a thing or two.
one thing about the aussie heads is, the ones that are usually ordered by people here are acutally 302c heads. the 351c 4v heads are also available as well. as for adding power, no they dont unless you have a compression increase by going from an open chamber to a closed chamber head. the other thing is using the 302c head is you gain low end power at the expense of both top end and maximum power.
Check these out. Aussie heads, increased flow velocities, increase compression, increase swirl, increase squish (over standard 2V cleveland heads), and good for 700hp, they make plenty more power over the standard heads, check out the articles on the same website. I can't see anyone needing 4V heads on a street car, unless it's going to be a VERY large capacity motor, or a large capacity that revs very, VERY high.
I'll add more, I have read from Aussie mags and tech sites that 4V are overkill and 2V will work better for a street car, giving better overall power, and lots more low rev power. I have never read that 4V are any good for street motors, and the guys talking about these motors are building 500+hp 2V motors, so I'd say they know their gear.