[KEV]

** NOTE: Jim i posted this here as well as under another thread. One thing i dont like about the new boards is that you cant reply to a reply if you know what i mean. you are really only replying to the main thread and unless you watch the number count next to the thread its hard to know if someone commented on your reply. at any rate this is under the thread i started about flow #s for 670s.

hey Jim! first thanks for the formula on flow and thanks for the examples. Your
examples hit home as im going to build a 406 here shortly.

i think im getting this but i have a few more questions...

the way i calc it (and you did as well) to make 450 HP i need about 219 ish flow at
28". that gives me a peak HP @ 5185 shift @ 10% above that gives me approx
5700 rpm. i understand all that. what i dont understand is why porting would not
help or show a benefit at the same RPM?

here is my goal, a 450 hp motor on pump gas running a '66 Tripower. i posted on
the old board as to the flow coeff of a '66 Trips and did not get any info. i have
heard it is not that great an intake. im guessing high 80s???

here is what i dont understand. im going to make the assumption that i am not
running at 100% VE and i am not fully filling the cylinder. if my heads are flowing
212 (stock) and my tripower intake is only flowing 89% then my total flow would
only be 188 (which would calc out to max HP of 386 HP). now if i port the head to
240 and i run 89% im now flowing 213. so by porting the heads i compensate the
poor flow of the intake. the unfortunate part is that im still shy of my 220 mark i
need. how do i know if i am totally filling the cylinder and need more flow with a
test such as yours?

now lets say i use the 220 flow and an intake that flows 92% (think that is what
your other post stated) that give me 202 flow. now im looking at the issue of PHR
that has your car in it. im using 3900 lbs (think im a little low on your weight but
will suffice for what im trying to explain) and the 11.880 1/4 time and 112.34 mph.
i calc you at 462 HP. 462 HP should need 462/.257/8 = 224 cfm (im assuming that
this is a TOTAL flow calculation not just head flow) that is a 22 cfm diff which is
about an 11% diff from what the formula "says" you need and what you are
actually running with intake attached. this may even be less with the carb and air
cleaner on. why the large difference???

i re-read my Pete McCarthy book where he posts some flow #s for a set of 96
heads. they were measured at 10" and were 120 @ .500 if i conver that i get 200
cfm. im confused by the fact that this car was running in the 120 MPH range.
Another set of 96 heads measured at 10" 131 cfm at .500. converted gives me
218. these heads were on a car running 10.38 at 128 mph. i dont know the weight
of the car but the flow #s dont seem to add up. i would have expected these
numbers to be much higher. hmmmmmm.... maybe that is the point your trying to
get me to understand.

just trying to get a better understanding. i already have a set of 670 that are
supposed to flow in the low 220 range, maybe i dont need much port work???

thanks again for your help!
(sorr so long)

------------------
Kevin Swaney
Gold '66 GTO, 389 4 spd with Trips
13.042 @ 106.64 mph