Is there a such thing as to big of heads for an application. Im building a supercharged 383 with about 15# of boost that will see strip/street. More street time. Im looking at the afr227's. My machine shop thinks i should stay around 195ccs. Says 227 is too big and it wont run right. What do yall think?

 

Boosted motors don't gain as much as n/a motors do from better flowing heads.

 

The short anwser is, bigger is not always better in certain applications. From the little bit that iv have read, the higher the rev's the bigger you will need. As for it not running 'right' no clue why they are suggesting that.

 

Yes you can easily over do it on the heads. If the velocity of the air slows because of the oversized runner volumes, HP goes to crap. A boosted stroker will be moving a larger volume of air, therefore you would be looking at bigger heads than you would have on a NA stroker.

Heads are where the power comes from. Dont get it wrong.

 

So do yall think the afr 227's are to big for me? Would hey be ok on the street?

 

Not too big, but be ready to spend some cash on the right shaft rockers to fit the things. Boosted engines pick up as much and more than n/a engines when it comes to head flow. The afr heads imo have a very small pushrod pinch for thier volume and flow. If I was doing it I would talk to somebody about ported darts or trick flows over the afr shelf stuff. The afr heads I have used recently have made good power n/a, but when it comes to a blown engine i'll stick to my old ways.

With a boosted engine and even an n/a engine you'll never know the difference other than the power at high rpm. When you're cruising around on the street you're using a very small percent of your engines potential, basicly at a loaded idle. Air speed doesnt come in until you have your foot on the floor and the revs have come way way up because until then the air speed is basicly nothing.

 

i just ran across a good deal on a set of afr 227's. I was looking at the trick flows. I just need a head that has a combustion chamber in the 60's. Why would the price of rockers be different from other roller rockers?

 

The AFR 227's require offset rockers I believe.

 

I think your builder was suggesting that your intake velocity will slow down due to the larger runners and make the car feel sluggish around town. It isn't as bad of a problem with injected cars like it would be for a carbureted application but it might affect efficiency of low speed driving and cause you to have less torque when you're bypass valve is open and the blower isn't doing anything (along with the lower compression and bigger cam). You can build a killer top end car but then suffer driving it around town, so it matters a lot how exactly you will be using the car. Again, the larger engine will help a bit there too, but 227cc is considered a race head for a reason.

 

Oh he aint my builder, im building it. He just done the block work. But i reckon ill just go with the 195cc's

 

this #15 pounds of boost is going to come from what blower?
The head unit will play a large role in selecting the right heads.

 

Or maybe 210 cc head would be a good compomise for a 383.

 

I hope to get close to 15#s with a ati d1sc. I thought about the 210cc but i cant find a descent deal on any of those.

 

I know a guy happily using the AFR 227. thing is it is a 434ci smallblock turning 7200rpms and feed boost with a little nitrous to cool it too. If they are the right choice there then they probably are not for an engine as small as a 383 held to the same or lower rev limit.

 

+1, I think TFS makes a 215 which would be good for your setup. Look at AI and LE's TFS castings, both are very proven.