Jesse, I kept forgetting to answer that. The #'s are from an independent guy in my area with no rhyme or reason to inflate or undercut. We never spoke of trying to get a certain # or doing any porting. I trust the #'s.

 

Now THIS is a good thread! More, please!

 

steve i say if those heads come in at 240 cc or less they will work very good on the larger motor

 

Cool, after seeing the #'s and comparing to what is out there in terms of flow/volume seems like that would be a good size. I was thinking somewhere between 245-250.

91tpi-zf brings up a good point that I will need to inquire about. If the runner is longer, how much does that effect the measured size? Maybe a 245cc 18* runner has the same cross section of a 23* 220/5/7 head.

J or C, Why didn't you guys go with the AFR raised runner? Lots of air for a 215cc

 

OK that is a very good sign.

The 215s you mentioned have their own demons, with the use of shaft rockers, special headers (which we mentioned you will have to deal with) - for these reasons we avoided them. Seems that everything has its cost.

 

to get the 215 afrs on the car would have been over $5000 instead of $2150
$3000 difference for maybe 10-20 hp is very expensive

 

here are some numbers 215 cc 23% head 2.248 crosssection
here are some numbers 231 cc 23% head 2.318 crosssection
here are some numbers 240 cc 23% head 2.362 crosssection
here are some numbers 256 cc 18% head 2.548 crosssection

as you can see the the 18% is pretty large

 

To get a good idea I guess maybe comparing cross section to flow might be useful

 

If you want to be a bear be a grizzley. now..........nuff said.

 

 

I have a column on my chart called Valve velocity.

Is that the speed of the air at the valve?

Next to it is Port Velocity, which is of course a bunch of 0's

 

Where are you seeing these values at? Valve velocity I would take as "valve opening and closing speeds due to cam profile"

Do you have an engine analyzer program your looking at?

 

Yes, it's the program the shop uses to design their cam profiles. If we had taken a couple more measurements, runner cc for instance, put in an intake profile etc. we would be able play with profiles and see where the power would be. This is not anything new, as you know, but it seems to be a Pro version of desktop dyno type software.

The columns are...
vlv area sq. in.
Corrected CFM
CFM/sq in
Flow area sq. in.
Flow coef.
Valve velocity
port velocity
% exh/int

Valve velocity reads...
.025 379.6
.050 375.9
.100 368.6
.200 380.3
.300 357.2
.400 313.7
.500 270.8
.600 275.1

Any chance that's feet per second of air velocity entering the chamber? There is no unit given to the measurement so I don't know what to think....

 

Get me as many of the measurements as you can off the heads. What brand are they Brodix or something else?

I will put them into Engine analyzer pro, using my 434 specs and see what it yields.

Those values you are lookig at are valve speeds, probably ft/sec, that is why they slow up around max lift. Most cams snap the vavles open pretty quick and then their profiles allow the valves to slow up towards the top, to allow more "dwell at max lift" this is important cause the valve is also changing directs at max lift, and if it were and abrupt change in speed and direction, it would eventually ruin the valve train.

 

They take a 1206 int gasket, I know that doesn't mean much but for intake port matching.

Valves 2.15 int 1.6 exh

add to lift chart in first post

.025 17.5
.050 34.9
.700 336.9 ===>
.750 337.2 ===> I doubt I'd run a cam over.630

Chamber is 54.4cc

What else? I will try and scan the sheet...

 

Flow test printout



I got the name wrong in the first post, he said they were probably by Keith Dorton Auto Specialties (ists) in Texas.

Be back in a ~hr

 

on a side note the flow numbers on the m2s that are on brodixs site are a little inflated the numbers i got from ron at m2 were right on the money for what the heads actually flowed
here they are again

int
100.......76
200.......153
300.......215
400.......261
500.......297
600.......304
700.......307



exh
100......55
200......114
300......159
400......198
500......221
600......232
700......240

 

Steve it appears to me that with your printout those are infact velocities. Now the question becomes, compared to say a baseline heads like AFR 190s how does that port velocity compare. That would really be the ticket here in this analysis. Perhaps the shop may have some information on AFR heads, something we can all argree flow well and work on most setups - you can compare to them. In other words if the AFR 210 flow 290CFM and have a velocity similiar to yours, but your flow 330CFM, you probably have a killer head. Since your flowing more and not giving up port velocity.

I have not been to a bench that has this information also available,. The software is part of a series of programs, one of which I have to see how different setups perform. I am not sure how accurate the results are, cause for mine it says I am making over 600fwhp, but I don't think I am there yet - with the new cam it gained roughly 50hp across the boards- again not sure I 100% agree with it.

The information if its accurate they gave you would be very helpful in porting work or comparing different heads. As in the example corky gave with the BBC and SBC 454s, I would bet if both those heads used on the respective engines were flowed on a bench like your heads were, the BBC heads would have shown a huge decrease in port velocity

Really all they are doing to get the velocity off the top of my head is using taking the following:

ft^3/min x min/60sec x (1/(port area or valve area in ft^2) = ft/sec of airflow.

So if you had the CFM reading of a given port you could work backwards through and get the velocity that given area is flowing, but it would be a averaged area reading, unless you could take CFM reading for different areas through the port. Again that was all just off the top of my head - real key here would be to get some "baseline" velocities off a good known performing head, like our M2s for comparison.

Interesting information - I wish I was closer to you, I would be happy to go to the shop with you and see how exactly how these heads compare to other heads. I would call them and see if they can give you some other readouts of some AFR brand heads, or brodix 23* stuff. They should have some in their database for comparison purposes.

 

Guess my head porter did a great job from looking at those #'s

 

Just for comparison purposes, here are the numbers Bob Jones gave us after he finished porting the heads for Steve's 434 SB. Bob is in CA and use to work at Extrude Hone before striking out on his own. He's worked on just about all the heads (factory and after-market) available in the market. Bob's also the guy that got right at 400CFM out of a TPIS MiniRam intake.

We had the flow verified on Dennis Wells' Racing flow bench here in TX.

Steve’s 15* Brodix Heads
29 Mar 01

Intake Port Height = 2.45”

Exhaust Port Width = 1.415”

Intake Port Volume = 262 ccs
Exhaust Port Volume = Not Given

Exhaust Port Height = 1.67”

Exhaust Port Width = 1.55”

Intake Port Length = 5.5”

Exhaust Port Length = 4” (Uncertain on this)

FLOW NUMBERS

CFM Measured @ 28 Inches of Water


15* BRODIX HEADS

Intake Exhaust

.100 67 57

.200 156 113

.300 227 163

.400 279 195

.500 317 221

.600 334 240

.700 340 249

Jake