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Old 04-18-2006, 09:32 AM
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head flow velocity and port size

how much does the slower head flow velocity of a 230cc port hurt the torque/hp over a smaller port 190cc head with a street grind cam? motor is a 400CI with a cam in the 230@.050 and .550 lift range. would a 230cc port rev slower and thus make your ET's slower?

i've got another question. one set of heads flow 260@ .550 lift with a 190cc port and the other heads flow 290@ .550 lift with 230cc port. with the cam above the smaller port head 190cc 260@ .550 lift would make more power right because of port velocity? since the small cam can only allow so much air into the chamber. i would take it that the cam would be the bottle neck?

anyone willing to fill me in on how this works. i've done google search for a few days on it.

a airgap would make more velocity in the intake but it would slow down when it hits the 230cc heads, right?

PS the motor is a 401 with 10.5 compression.

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Old 04-18-2006, 11:36 AM
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Try this article...it might not answer all your questions but is will answer a few:
http://chevyhiperformance.com/tech/e...n/0601ch_head/

Here is another link to flow charts done by a 3rd party rather than the head manufacturers:
http://www.chevyhiperformance.com/te...598/index.html

Your cams manufacturer might be able to point you to the best theoretical head for your application or intended use.
Good luck!
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Old 04-18-2006, 11:53 AM
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You may want to look at this thread....it just died a couple of days ago. About 1/3 in it starts talking about after market heads and flow data.
Port CFM vs. Valve Size vs. Port Velocity...Data WANTED!
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Old 04-18-2006, 12:25 PM
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sorry, i knew i should of done a search.

thanks for the links.

i've got a 401 to build for the wifes car. i just wasn't sure if i wanted to use the indy heads 230cc ports or the edelbrock heads 190cc ports. since i would like to use a 2500 stall and highway gears in her car. i can get a deal on a set if indy heads that just around 200 bucks more than the edelbrocks.
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Old 04-18-2006, 12:37 PM
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I'm going with the AFR 195 street heads. They look to out flow just about anything in the 190-200 cc port catigory and maintain high port velocity. You can find them for about $1225 or so if you shop. They also make a 210 cc head....The nice thing with AFR is they fully CNC port the entire port and also the chamber. Elelbrock only hits about 1/3 of port with the CNC machine. Also, AFR will mill the head to hit your chamber size if its not either 74cc's or 68cc's. Sallee Chevy has em in stock with custom milling already done.
You have a lot of cam there...what's your CR?
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Old 04-18-2006, 01:03 PM
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If you think about it, your valve is spending more time at lifts between .100 and .400 than any other. You want to go with the most flow between these lifts (for a mostly street driven car) at the smallest port volume. The chevyhiperformance web site has an excellent flow comparison chart of all most all heads. Two heads that come to mind and have the most modern up to date port designs of their company is the AFR 180 cc head and the Dart Pro 1 180 cc head. I talked to Jim Grubb of Grubbs Motor Sports and he said the AFR 180 head was the best street head he had ever tested, better than the 195 as the 195 design was a little long in the tooth. I also had an opportunity to talk to an engineer from Dart and he too said that they were putting all their knowledge into the 180 cc head first as it was a new product and the other lines would follow. Just food for thought.
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Old 04-18-2006, 01:09 PM
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Cool rockin daddy is right. What I failed to mention was the AFR will release a new version of the 195 street head in about 2 months. I'm ginding on them for details but have yet to hear back. I'm told the price and part numbers will stay the same but there are numerous changes in the castings themselves.
I actually got those two links above from Cool Rockin Daddy! Good stuff.
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Old 04-18-2006, 02:05 PM
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Eleventy' lives at 5,000+ ft.....whole different world....and he is shooting for 500hp with a 350....

the second link article he posted is packed full of great details of how changes to flow affect driving characteristics and performance.....read it carefully

wife's street car,
"KISS"....Edelbrock RPM "package" intake, cam, and (small runners) heads....proven results combo....or use those (intake, cam and heads) AMC 400 spec's as a base line to closely match the vendor of your choice

just for general reference:
it takes 100+ additional HP for a 3400 lb street car to drop 1.0 seconds ET,
so good heads can drop it "maybe" .4 sec,
a little better yet heads can drop it "maybe" .5 sec
get my point?
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Old 04-18-2006, 02:26 PM
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Javelin,
What cam are you using? You're talking about stall speed already. What stall speed does the cam you are using need? Pick a head based on how you (or wife) is actually going to drive the car and MATCH the CAM to the head! Red is right, heads are a huge investment. Be honest with yourself on how the car is actually going to be driven and buy your parts accordingly. If this is going to be driven mainly on the street, by the wife, you might be happy with an carb/manifold change, a rear gearing change, possibly a cam change (one that will work with the heads you have now). All of these are a lot cheaper than a $1200 set of heads. Good luck and happy hotrodding.
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Old 04-18-2006, 03:06 PM
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since i have a amc i'm stuck with three chioces. stock ported amc heads wicth out flow Edelbrock heads. but the problem is finding a porter that knows amc heads. you can get 280cmf @ .500 lift 250 exhaust with a small port (best choice)

Edelbrock heads come with ok springs and valves and i believe .580 max lift. small ports and ok flow

indys have big ports but flow good number. nice valves and springs.


as you can see the indys out flow the Edelbrock all the way threw the lift. but i would think the Edelbrock have more velocity.

the motor is getting a small hyd roller cam 224/232@.050 543/564 lift. it should be around 500+hp 500 tq with the indy heads. but i'm just wondering if it'll rev slower because of the big intake ports.




Edelbrock 2.02 intake valve
Intake /Exhaust
.100-65/52
.200-130/96
.300-192/127
.400-235/163
.500-258/182
.600-260/190

indy 2.10 intake valve 230cc come with springs good for 650 lift. with a bowl port, light short wall work, blending and port match. PS: these are not indys #'s. these #'s are from the set of indy heads i have in my car.
Intake /Exhaust
.100-80/68
.200-155/130
.300-220/188
.400-265/220
.500-290/236
.600-315/249
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Old 04-18-2006, 03:47 PM
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what cam is in the car now with those Indy heads

the I/E ratio is 81% on your heads at .500, Edelbrock is 70%,

what is the ratio of the 230 heads at .500

I looked up the rpm cam, it's 234/244, .520/.544 112c....you chose a smaller cam 224/234 to use with higher flow Indy heads?????

it all has to work together!

Last edited by red65mustang; 04-18-2006 at 04:12 PM.
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Old 04-18-2006, 05:50 PM
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If those flow numbers are even close to correct you'd be crazy not to use the Indy heads. There should be no issues using a 230cc head on a 401 engine.
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Old 04-18-2006, 07:36 PM
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at first i was building a ten second car. but after thinking about all the upgrades i'd needed. since the motor killed my budget. i went with a smaller hyd roller 224/232 543/564 lift. until i install a roll cage, new trans, new axles...ect. the motor is built as a 10 second motor with a small cam. so when i'm ready it's just a cam and stall change away from being 10 second car. the car drives really nice and pulls hard if i can get it to hook.

http://www.cranecams.com/pdf/Page220-221.pdf
Roller HR-224/339-2S-12 power range from 2000-6000 needs a 2500+ stall

the cam i'm going to isn't on there site and is only a grind number. hyd roller 232/240@ .050 563/584 lift

i'm pulling the small cam out and putting it into the wifes motor and i'm stepping up to a little bigger cam. i do really like that small cam for the street but i have to have a faster car than the wife

here's my setup. i'm going to lower the compression to 11.1 to 1 soon and change the quench to 40 and hope i can run pump gas.
401, 20 over
indy sr heads
indy intake
crane hyd roller cam 224/232@.050 543/564
crane roller lifters
crane gold rockers
venolia flat top pistons 12 to 1 compression
perfect circle rings
rollmaster timing set
hooker sc 1 7/8 headers
msd dist and 6al box
quench 32

the rest of the setup is
727 trans
ati 10 inch 3200 tree master stall
63 ford 9 inch with 3.70 gears
caltrac's


but anyways it comes back to would the indy big port heads lose much over the small port heads. i used 230@.050 in the post since a 224 hyd roller makes a little more power than a 230@.050 hyd and more people run hyd than rollers. well at least the people i talk too.


red65mustang, the 230 head is the same indy heads i've got. they will flow around the same. there having the same work done to them.

rick WI those #'s are right. a max port job get's 350 and 340@.600 lift. but that also opens up the ports bigger.

Last edited by 71javelin; 04-18-2006 at 07:51 PM.
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Old 04-18-2006, 08:01 PM
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Good choice on the Indy heads. The quality of the mixture as delivered to the combustion chamber by the Indy heads have the potential to make more power than either of the other considerations. Flow numbers and volume don't tell the whole story.

BTW, I hope gat as big a laugh as I did about all the Chevy heads being recommended for your AMC.


Larry
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Old 04-18-2006, 11:14 PM
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I'd not think twice about which head to choose. The Indy head will smoke the smaller head. The 230 runner doesn't bother me a bit on a 401.
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