1963SS

Shhhhhh!!! Don't tell, B-Body guy here, Impala SS

I'm wondering if anyone can enlighten me on flow numbers vs port size. I'm getting new heads and cam for the Impala (the big F-body with attitude) and am pretty familiar with LE and AI and even GTP to some extent.I've seen heads flow 280 that had 175cc ports and I've seen heads flow 260 that had 190cc ports and heads that flow 270 with 210 ports.

I imagine the larger the port volume the less velocity the mixture has going into the combustion chamber. Good top end, sucky low end torque.

I reckon my question is how do some get great flow numbers with so little ports. ("Smoke and Mirrors")

I'll be looking to buy a set of heads or send mine off when I get all this figured out. I know LE could tell me but without the advertising, what's the real deal?https://www.camaroz28.com/forums/ima...s/confused.gif


Thanks guys ---Bill---

Kaj

I'd be talking to AFR or AI if you got the money to do what you want. A lot of people go to Lloyd Elliot, his prices are reasonable, but I've seen better stuff come right from AI in my opinion. Just tell them what you want to do.

I'm looking into the AI 200cc heads w/ full head work, valves, supporting mods, with a custom grind cam. Which, I think a custom grind is always the better choice than that of something off the shelf.

It all depends upon your goals for the car and your budget Karl Elwein aka quickss is who you need to talk to here. He knows his stuff, and especially about the LT1 powered Impalas!

vette96

kind off the same of my problem.

i have a 195 AFR on my car, but cant squeez enough power from it..

and when i did the searching , i was confused by the same thing.

i think it depends on the person who do the porting.
The porting technique is important to shape the runner and get the desired flow numbers out of it.

i dont know if it worth get a new AI or Lloyd Elliot heads just to add a 20-30 hp on the wheel.???

i need to get to the 450 club, last time i dyno my car i got 380 only... i was so disspoineted.

Kaj

speeddemon recently added some 200cc AI heads w/ a custom grind cam on a stock 100,000 bottomed LT1 that dyno'd at 429 HP. That's with a stock intake manifold too. http://www.advancedinduction.com/AiProductsLTxDart.html
The new Dart Pro 1 is something wicked

Vette96, what cam are you running and what is the scoop on your car? Like supporting mods etc? I'm not seeing anything in your signature, and we know nothing about your setup other than the AFR 195cc heads you have...

96capricemgr

The AI 190s I have flow right around 275cfm, with awesome low lift numbers.

They are working for me.

AFR's old stuff is not good, a friend is selling his to go with something pretty close to what I have. Guess being around my little 350 in a b-body that is faster than his 383 in an f-body finally made an impression on him.

AFR's new stuff the jury is still out on, given history I would not hold my breath.

There are no aftermarket castings I would recommend for a NA street LT1.

The AI 200cc ported GM casting has proven to be potent on anything from a stock shortblock to a race built stroker putting over 500rwhp down NA. They have a turbo car out there at over 1000rwhp on the same porting I have. Given numbers like these from GM castings aftermarket castings should not even be discussed.

firebirdStud

I have AI's old 190cc ported heads, intake and their cam. with everything supporting, put down 438rwhp and 431rwtq. They know their stuff. I wish I would have waited for the 200cc's. Oh well, when they need refreshing ill prolly spend the cash then, why tear down a very strong, perfectly running motor? AI Gets my vote. Ron and Phil will get the job done!

firebirdStud

oh, sorry, almost forgot, you want to look for the best flow out of the smallest intake port size. Also, you need to look for low and mid lift flow numbers, your heads spend more time there then at the full open position. This is the rule of thumb for which to compare heads. You can compare max flow all day long, but its really the low to mid flow numbers where driveability and power coming on strong matter. Hope this helps, and hopefully others will chime in with what they think.