Valkyn71

Planning on having my heads done in the near future.

One port jobs keeps the stock vavles, and flows aprox 255/180.

The next level uses larger Ferrea 2.00/1.56 valves and flows ~270/190.

So im curious if you all think that ~15cfm is worth the extra $500? What kinda performance gains do you think i would see from the better heads?


Also would the 270/190cfm heads support a 383? in the distant future i might be doing one.

95_LT1_6SPD

I would go for the stock sized valves with 224/230. But if your planning to step it up to a 383, i would want all the flow you can get.

jkipp84

I could be wrong, but I don't think taking the two peak flow numbers and comparing them is looking at the whole picture. The stock valve size may be fine for your particular application, I don't know, that's a different story. But I think there's more to it than just those 2 numbers.

scoobysnax83

not really. Flow number are everything in heads. What matters is the cam. Heads that flow better won't flow better if not utilized by the cam. The only differences would be the actual porting technique. Since he is talking about the same company, that is out of the question.

Valkyn71

Do you guys think the 2nd set would support a 383?

I dont wanna spend the extra money now, then find out i will need AFRs later.

Dave88LX

2nd set will support a 383. Do it all out now, spend the extra. Don't put the engine back togother, drive it, and say "I wish I spent the extra $500 when it was apart".

besz28

spend the extra 500

scoobysnax83

o yea, spend the extra $500... I meant to say that

LilJayV10

I think what he was trying to say is, peak numbers aren't the whole story, under the curve and average numbers are important, it's like a dyno graph, yeah peak numbers are good, but I would rather have a graph that looks like a table and not a moutain, if that makes any sense to anyone.

Jason

disco192

Well if your flow sheets look like mountains and your cam look like a table it can be ok too Solid roller cams with HUGE duration can make use of high peak #s.

Dave Feerst

ditto

it all boils down to what cam you are using, With a small cam the first set of heads would probibly be better because 250 CFMs will fill the cyl till 6000 or so. With a bigger cam which would go to 6500 or more, or if you stroke it, you would want the extra 15 CFMs to fill the cyl, at those higher RPMS.

Valkyn71

When i do the head swap im also going to put in a custom cam which is a little larger then the 224/230 and should be making around 400 RWHP.


I think ill spring for the extra $500, since its the "under the curve" area that im disapointed in with my 224/230. The custom cam is supposed to have much better under the curve power.

Its a similar design to the guy who just ran the 11.7 N/A

1 Nasty Bird

Dont forget about the combustion chambers and ports, flow #s arent everything, velocity is pretty important too. Theres alot more to it then peak flow #s!!!

kmook

Good point runner size. I could have some nice 380cfm sb2.2 heads right now but i dont think a 300cc runner would act nice.

Peak #s are of little importance at least to me. I spent $3k on my current set of heads which only flow 28X cfm at .600, I could have had a set of AFRs that flow 300cfm, but my low/mid lift #s kick huge ***, and since you hit every lift point twice in one valve opening except your peak which is only hit once, i'll take the low/mid lift.

As far as 15cfm for $500, I'd do it.

SStrokerAce

Yep