Hello...

Thought I might share some data I recently acquired that is very "typical" of what I have seen in the past when I compare a factory re-worked head against the new clean sheet of paper AFR design. What I will reference as "Brand X" was a ported "243" casting that featured 2.080 / 1.600 valves, a 242 cc Int. port and an 87 cc Exh. port (one cc larger than our 225's, 2-3 larger than our 205's). The workmanship and execution of this particular head was actually quite good....very neat....and was in fact one of the "better" ported factory castings I have had the oppurtunity to flowtest and evaluate. I can count on one hand with a couple of fingers chopped off how many LS heads have gone legitamately over 320 CFM on OUR testing equipment.

The AFR "philosophy" is easily witnessed below....and what I mean by that is good peak flow, strong low and mid-lift flow, and a small, highly efficient cross sectional area which provides high airspeeds thru the entire lift curve.

Intake @ 28' (4.125 Bore)

ValveLift......200....300....400....500. ...550....600....650

Brand "X".....137....207....252....290....306. ...318....326
AFR "225".....151....221....269....306....31 5....322....325


Exhaust @ 28'' (4.125 Bore w/ 1.875" Pipe)

Brand "X".....114....145....179....211.... N/A....237....242
AFR "225".....120....177....219....240.. ..N/A....251....255


Note: AFR 225 #'s are not our advertised #'s. They were recorded the same day on the same equipment from a 225 head I had upstairs in my office. Depending on what liftpoint you are comparing, the #'s might be one or two CFM off of what we advertise in our catalog and website.


Another "interesting" comparison is the same Brand "X" head versus our 205 on the smaller "stockish" 3.910 bore. I will be using the AFR 205 advertised #'s as they are very accurate and I didn't have a head easily accesible to flow at the time. Keep in mind the following comparison is a 205 cc head with a 2.02 valve versus a 242 cc head and a 2.080 valve. It starts to become clearer why the AFR 205's have been able to put down some of the larger numbers of late that have been documented on this forum as well as others...


Intake @ 28" (3.910 Bore)

ValveLift......200....300....400....500. ...550....600....650

Brand "X".....136....200....243....276....290. ...302....310
AFR "205".....140....200....251....281....29 2....300....N/A


Exhaust @ 28" (3.910 Bore w/1.875" Pipe)

Brand "X".....114....151....179....205.... N/A....230....233
AFR "205".....112....170....203....221....22 6....230....N/A


The best part of this comparison is that it actually is a "viable one"....same flow equipment, same bore fixturing, radius plates, exhaust tubes, etc.

Keep in mind guys that this test was against one of the better ported factory castings we have seen....I have flowed many others that would have showed a much larger "delta" when compared to the AFR piece.

Regards,
Tony M.

 

Thanks Tony for your information. I read about your car in one of the Vett mags. Very impressed. I have a 04Z and the AFR heads with LG headers and maybe a little hotter cam are in my plans. I have been told to think about a clutch soon after.

 

Tony,
I have heard talk of tuners buying your heads and then porting them.
My concern is that they are using their prior experience and perhaps even their existing CNC programs to modify AFR heads for more flow.

I have followed your ads for many years (in my blown 5.0 days) and most recently of course on your LS1 heads, and I genuinely believe your claims of consistently higher low and mid lift flows with approximately the same peak flows at .600" to .650" lift.

For my F1-R blown 427 with mild 224/228 Xer Comp cam how can I assure myself that I am getting the best AFR "225" heads for my purpose and not somebodies hogged out 340-350 CFM claimed AFR wonder heads without the benefical low and mid flows that you design into your heads?

Does AFR modify heads for the larger cube blown LS1 engines?

Also many CF menbers are reporting "head lifting" and gasket failures on their blown LS1's...have you any data indicating that your thicker 3/4" head surface casting may resist these failures?

Roy

 

Andy,
We have AFR upgrade the Compression and the Springs on the 205 heads. We also plan on getting the 225 compression and springs upgraded by AFR.

We have seen great results with the 205 heads, and we expect to see the same great results from their 225 heads.

Stay tuned this week.

LG

 

Tony the AFR's are clearly the bar. I cannot wait to order mine up.
Are the standard AFR 205 valves lighter than the stocker LS6 valves ? Also do the 205's come w/ titanium retainers?

 

Tony-
Those cyl. heads you have labeled as "brand X" look very much like a set of LS6 castings prepared by E.T Cylinder Heads...yes? Just curious.

Regards,
DTE

 

now i wonder what those brand x heads would cost vs. the AFR's

dave

 

The Brand X heads would be pretty decent if thats what they flowed on a 3.9 bore but they are pretty anemic for numbers on a 4.125 bore.

 

Comparison with the 5.3L heads?

 

Phil,

I don't think they were, we've done very few with a 2.080 intake valve, and the flow numbers don't look like ours. Our 2.080 valve ls6 on a 4.125 bore will flow well into the 330's at .600

 

Gotcha. Thanks for the clairification.

See you folks at P.R.I.

Best Regards,
Phil- DTE

 

Is the AFR price worth it???? They don't say what castings they use, do they?

Intake @ 28" (3.910 Bore) 2.02" Intake
Valve Lift.....200"...300"...400"...500"...550 "... 600"
AFR "205".INT..140....200....251....281....2 92.... 300.
Patriot.. INT....140....202....244....280....291.. ...304...

Exhaust @ 28" (3.910 Bore w/1.875" Pipe) 1.57" Exhaust
AFR "205".EXH..112....170....203....221....2 26.... 230.
Patriot...EXH....124....160....196....22 0....226.....229.

Patriot Flow data:
http://sites.reachtheworld.tv/waterN...05234&DID=1225

 

those are advertised, id like to see em on a flowbench to compare. Sometimes advertised #s are skewed.

Dave

 

Were those PP numbers on the same bench, and the same operator as the AFR heads? If not, they are basically not a valid comparison with one another.

I have an extensive spreadsheet with all sorts flowsheets posted by various shops.

You can only use data like this as a general reference, and not as an absolute. I use it mostly to "trend a port" not as a compariosn to another bench which is not apples to apples.

With that said, you need to look at cross section, port size, etc... when considering heads. The AFR is a better head.

The casting they use is their own. Not a ported stocker. More material in all the places it needs to be stronger.

 

Can anyone confirm what componants AFR uses as standard for that much cash & how they compare to stock?

 

 

I don't follow your question. AFR uses their own castings - what information are you looking for?

 

If you start a group purchase for the 205 AFR heads count me in on a set.