grabbem88

i'm using 185's....and i still get 20+ mpg on the road.very streetable.

FullAuto

Not that I disagree with the theory behind this statement, but since this thread is primarily over AFR heads I thought I'd say something. Are you familiar with the differences in the AFR chambers? It is more than just 3cc. Your advice may have been intended for the heads you market.

There is a good thread on the corral about it. Here is a stolen post from the thread:

QUOTE-
u should get the 61cc heads that afr sells if ur seeing a blower.

RESPONSE-
This is not very good advice. The AFR 61cc head has a different chamber than the 58cc head- the diff is not just 3cc's. The 58cc head has two quench pads, while the 61cc is more of an open design. Go with the 58cc head for sure, even in a blown motor. It is a far superior performer.

The 3cc's barely make a difference in compression, and you can use a slighly bigger head gasket if you need to. Plus, you will have to flycut the pistons anyway, and you will gain 1-2 cc's in volume by cutting the pistons.

promustanperformance

Can you explain what a quench pad is? Thank you

FullAuto

It's not a "pad" per se, but that was just in the guys quote and I'm not going to change wording in a quote for my benefit. It doesn't change the fact that they are 2 different chamber designs which is the point I was trying to get across. And in this specific instance choosing a 61cc chamber AFR 185 over the 58 cc chamber AFR 185 for a boosted application is the wrong choice.

grabbem88

^that is somewhat true,cause when i called AFR when i purchased my 185's 4yrs ago.they kinda said the same thing
but with awhole lot more jargen than i'm used to.

tokinGLX

heh. i dont even get 20 mpg right now. maybe freeway driving, but as for street driving, i average about 130 miles per 20$(around 9 gallons). so 13-15 mpg.

thanks for the input, by the way. being that in the future i am going to need to buy some forged pistons anyways, as us pre 85 stangs got stuck with the cast aluminums, i think ill stick with a head where i dont have to cut the pistons, and comparing to the rhs, the afrs are a tad bit cheaper.

another question....my engine came with a flat tappet cam, what are the benifits of going to a roller cam, and do i have to buy a block made for the roller¿ or should i just stick with an upgraded tappet¿

tinman

Yep, TW's are what I'd do with the stud mount and TW roller rockers.
185's to big for daily driver carbed car? Maybe and maybe not........
Flat tappet blocks ( like an '82) can be converted but it's spendy. If the shortblock is one that you are goung to rebuild in the near future you may want to get a roller block as a core and rebiuld that....

promustanperformance

Hi FullAuto,

I understand they are two different designs, they would have to be different for one to be larger than the other. I don't know about you or anyone else here, but I am not one to simply accept some words that I or the person saying them don't know what they mean. I'd like to know why they aren't good for a boosted application. I mean if you're saying that the 58cc is better either way, why would they even offer a 61cc? Can anyone explain the difference as to why the 61cc are worse for blown applications than the 58cc? Thanks

promustanperformance

Are you saying a set of AFR's with 2.02 valves won't recquire you to notch the pistons?

tokinGLX

the afr165s with 1.90 dont require notched pistons, the 185s im sure do. the tw tho, is the one head that doesnt require the notched that does have a 2.02 intake valev. how about the rhs, does anyone know, for certain, whether it does or not¿