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....315....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....292....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....226....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.

 

What brand name of valves do you guys use in the 205's and 225's? Also, will the 225's ever be offered in a configuration with a smaller intake valve and combustion chamber that would be more suitable to a 3.9 bore?

 

Tony,
I am curious, you show the 225 AFR as having a 4.125 bore. I thought this head could be used as a "max effort" stock inched apllication. But the stock bore is a 3.900 or 3.905 "refreshed". I was pretty poor in math growing up but wouldnt that leave a overlap of about .125? Wouldnt that be asking to kill your head gaskets on a stock inched car?

Not trying to trash on you, just curious because I am looking into purchasing a set of 225's

 

The AFR "LS" line of cylinder heads will come with premium one piece stainless steel valves. They will either have a Ferrea part number on top or an AFR part number on top. They are "race quality" valves and we don't offer an upgrade except for a longer stem for taller, solid roller spring set-ups (actually, we do offer an inconnel exhaust material for turbo and other extremely high heat situations).

As far as the chamber goes, it simply warrants the use of a larger bore head gasket as per our instructions. The lip does not pose any problems for numerous reasons....you will find very little airflow that close to the chamber wall (or any wall for that matter), and air is very "compressible" and easily finds its way around the "lip" anyway....What air WON'T do is find its way out of a valve that has no room around it (shrouded) no matter how big or how small a lip might be under it. Every standard bore BBC (4.250) running an aftermarket head has the same "lip" situation due to the majority of the aftermarket performance cylinder heads having large 4.500-4.600 bores incorporated in their chamber design. It doesn't pose a problem there and it certainly won't pose a problem here either (unless the wrong head gasket is used!).

Also, the 225 works very well on the smaller bore with the same exact "lip" on the flowbench (with the use of a 3.910 bore fixture) simulating the exact conditions as they would be on your stock shortblock. The 225's will not be offered with a smaller chamber bore or a smaller intake valve.....They were designed to be very effective on all bore sizes in their current configuration and a lot of time was invested to make that happen.

Tony M.

 

I'm just curious, were those 'out-of-the-box' 205's you flowed?

If so that means good news for my budget

 

For what it's worth the heads I got from Jay at AS are 5.3 Stage II's with 2.02 intake valves flowed on a 3.9 hole (just have intake flow numbers). Yes I did wait for 6 months, but there are other heads out there that flow just as good. The point is that for 1,000 dollars more do the AFR's actually buy the average Joe anything? I can see it if you need the added thickness for Nitrous or FI, but could not justify it for plane Jane N/A me.

200 147
300 206
400 257
450 277
500 294
550 307
600 312

 

can you do flow numbers of that same set of 225 same test procedure on a 3.90 bore? Wed be very nterested in seeign those results, as well as insure people that it wouldnt hurt anything

 

I only know a couple vendors that use a large 242cc port volume on the intake.

Interesting comparo!

 

I have tried to address this entire situation in other threads....You are comparing apples and oranges. Flowbench #'s are useless to compare unless taken off the same equipment with the same fixturing. It has been our experience that many of the claimed #'s you guys think you are buying don't pan out on OUR testing equipment....and some are off HUGE.

I'm not naming names....Just trying to get you guys to at least CONSIDER that what you might have paid for might not be what you have actually received. Anyone seriously wanting to know they did in fact get what they paid for should inquire around and find a quality shop that actually uses radius plates (NOT clay entrances) and professionial fixtures to INDEPENDANTLY flow test and evaluate your cylinder heads. Isn't that a much better proposition than building the entire engine, paying for dyno testing and tuner time, and possibly coming up short of expectations in power output? At least if you KNEW your heads were as good (or close to as good) as you expected, it would certainly be one variable to cross off the list when trying to search for the power that a similar combination "typically" produces and you feel you might have come up short.

And then there lies the whole "Different Dyno" controversy, but thats a whole different topic in itself. If you guys had the oppurtunity to flow test and see what I have in the last 18 months of this LS program, trust me when I tell you that you would be in for quite a few surprises...

Tony M.

 

You might actually be suprised. I, too, have the AS stage 2 5.3s with almost the same flow numbers with a 2.055/ 1.60 valve and the BIG 238+ runners... AFR kills these IMHO. Ive been thinking about getting a set.

 

Hey Tony. I bought a set of 225's from Jason last month. Can't wait!! Would a no brainer explanation be a short and sweet something like this: The 225's #'s at low to mid lift/ R.P.M.'s make it act very much like a non-ported head, while acting somewhat like a fully ported race head at higher lift/R.P.M.'s?! Kinda like a turbo motor without the lag, but while not capable of turbo horsepower on top, it still holds its own or surpasses anything else N/A.? Having the cake and eating most, if not all of it, too? I have been around high performance a long time, and it is VERY rare indeed when you can increase low and mid lift flow AND velocity while giving up what, 1 c.f.m., to the BEST "other guys head' at max. I think you guys did an awesome job. I think it is logical to assume that everyone knows AFR's reputation is excellent. That said, throw away the flow numbers you printed along with what lift they were at. Logic tells me that when a company that has the reputation yours does takes 7 (SEVEN!) years, give or take, to come up with the first aftermarket head for our motors, how in hell CAN'T it be better than anything else??? Anything less would be unacceptable from anyone....ESPECIALLY the top brass at AFR!! Just my .02. Maybe it's me. Been wrong before, just ask her!!

 

i wish i would have waited for the AFRs to come out and got the 205s.when i'm done replacing my heads this winter i'll have spent as much money going thru 2 sets of heads to get the results i was looking for last year.most of my friends run SBC cars and the fastest run AFR heads.yes,they are expensive and not everybody can afford them but their heads have always made power.

 

who runs 242 cc intakes? Ive seen old style GTPs at 235-237 cc

 

See you at PRI Tony

 

What kind of cams do you have in the works Tony?

 

Tony, what is the best way to get in touch with you with a couple of questions? I'm not a hard-core race guy like many here, but I am doing a heads, cam, headers, intake build up this spring. Actually, LT1DAVE will be doing the work. I serve merely as a conduit to write checks. Anyway, I do like what I am hearing about your products and think they will meet my needs and goals.

 

Hello Steve...

I welcome you or anyone else for that matter, to contact me directly at AFR. You can reach me by telephone @ (818)890-0616 Ext. 109 or you can email me direct using tony@airflowresearch.com.

If all else fails feel free to PM me here on this website.

Thanks for your interest in the product. The workmanship and quality of these heads are truly outstanding, and more importantly, they work as good as they look.

Regards,
Tony Mamo

 

Tony, I'll shoot you an email later today with what it is I would like to accomplish with my ride.

 

Tony,

Why do people always talk in terms of port volume, and not cross-sectional area? Obviously the later is responsible for velocity. I know the cross section is mostly fixed by the factory intake manifolds, but I'm still confused as to how port volume is so important. When porting heads, do people remove most of the material from the bowl area or do they increase cross-sectional area after the port inlet? It seems to me like removing material from the bowl could increase port volume without really effecting velocity at all.

 

Say hi to my man Kevin Gass there at PRI...from holley...i guess hes my Kentucky state representative...lol