menlatin

Alright, my heads wereflowed @ 8" and 10" of water, and the shop converted them to 25". Now i was wonder if there is some kind of formula for going from 25" to 28" so that i could get an accurate compairison to other heads. my numbers were -

Intake:
.1 .2 .3 .4 .5 .6
@10" 77 110 140
@8" 163 165 170

Calculated to 25"
122 174 221 258 261 269

Exhuast:
.1 .2 .3 .4 .5 .6
@10" 74 102 126 137 141 142

Calculated to 25"
117 161 199 216 223 224

Anyone know how to convert?

menlatin

damnit ok i guess that didnt work too well. The intake was split between 10" and 8", the first 3 are 10" and the other 3 are 8". All the rest are 10"

Mindgame

According to David Vizard:

Flow at new pressure drop = square root of (NPD/OPD) x Flow at original pressure drop

NPD = new pressure drop
OPD = Old pressure drop

Example.... you want to know 25" #s but the heads were flowed at 28".

25/28 = .89286
The sq root of .89286 is .945

Take .945 and multiply it by each at-28" flow bench reading for the #s at 25".

Hope that helps.

-Mindgame

menlatin

muchos gracias.. that means that my heads flow 284/237 @.6". Thats pretty F-ing good, for a first time home port. Oh yea, they do have 2.05 and 1.60 vavles. maybe that helps too.

NightTrain66

to convert a 10" # to a 28" multiply the 10" # by 1.67.
to convert a 25" # to a 28 " multiply by 1.06
These are the #'s from Superflow conversion chart.

As the depression raises so will the cfm and if a head flows XXX amount at 10" you can use the math to get a 28" # to compare to but if you flow the head at 28" the head may not flow that #.

The added depression and cfm makes every little bump show up and shape is ALOT more critical. At 10" the port may NEVER go turbulent but flowing at 28" it may go turbulent at .500 lift because the air is going so fast across the shortside it can not stick to the port and will fly off and hit the back side of the valve.
Your heads may flow those #'s at 28" but there is no way to know until ya flow it at 28".

NightTrain66

menlatin

hmm... so i need to find someone with a sf-600. These guys flowed em on an sf-120. anyone know of a place near denton, tx (25 mi north of dallas), that has an sf-600??

NightTrain66

I am in Red Oak Tx, I have a SF300 and it can handle that.

E-mail me if ya need it flowed.

NightTrain66@msn.com

menlatin

I'm assuming it doesnt since he had to breakup the intake pressures, when the numbers picked up. I dont think im going to get em flowed again. I need to get this truck running. School i starting soon and i have no car.