Re: AFR heads: Anyone else interested in buying?
 

The first column shows the intk/exst flow numbers in JimV's post #28 are from an 357 AFR CNC ported head out of the box. The second column shows the same AFR heads only with a chamber port done by JimV. The third column shows the Dart heads (don't know the size but probably comparable in size to the 357 AFR's).

The reason I know this is because the AFR heads JimV is speaking of are [/B]MY heads[B]. I took them over to his shop because I looked Jim in the eye and told him I wanted to know the truth about the AFR head flow numbers, and also without any 6 inch "cheater pipe"---nothing more...nothing less, and Jim flowed them for me while I stood over his shoulder. My first reason for doing a chamber port was because I wanted to reduce the comp ratio of my engines to 9.3, so I had JimV do a chamber port to the heads to increase more volume in the combustion chambers. Jim also told me that the added bennifit was that a chamber port would also most likely increase the flow numbers as well without even going into the ports----and he was right! However, as Jim points out the exhaust flow numbers don't increase much after .500" lift.

I only plan on using a smaller .578"/.578" lift cam---and I am not exactly sure if I will have him port the exhausts any further yet or not . I really like the mid-lift flow numbers---they are very impressive the way they are now especially after he chamber ported them, and if I were to have Jim further port the exhaust ports I am not so sure that those mid-lift numbers would stay the same or shift to higher lift flow numbers which I really don't want, and neither am I quite sure I really need it. I am quite confident with Jim's talent and experience/abilities that he would get more of a gain out of the port rather than a loss, and when asking Jim about it I really appreciated Jim's honesty when he told me he could not honestly tell me how the flow numbers would truely end up. I have to wonder at what expense---from my wallet ("bang for the buck") and also the expense that the MID lifts might suffer for a HIGHER lifts gain especially with the cams I am using. I can just hear how old Foghorn Leghorn would put it;

"BOY, I---I SAY, BOY!!! ONCE THAT METAL COMES OWFF---I--I SAY, ONCE THAT METAL DUN COMES OWFF IT'S OWFF FOR GOOD SON, YA HEAYA ?" :D

Re: AFR heads: Anyone else interested in buying?
 

I could offer a big discount on Dart heads. Jobber price (bare head) is $912.00 each. I could do a lot better than that. I'm not hooked up with AFR. I did ask AFR for a head I could experment on. They said yes but that was two years ago.

Re: AFR heads: Anyone else interested in buying?
 

well it looks like the afr cnc 315 kicks most the other heads a--,even bigger ones but if they are inflating there numbers then what is the best choice. The local head porter (he is talented) in our area says he has flowed afr's and they are no better than a pocket ported stock head? I'm not sure what to believe, If afr's claims are true then basically up to .700 lift a dart pro1 345 won't come close to there 315 cnc head or will it even beat there as cast 305 cc intake head (i do find this hard to believe). I plan on purchasing a set of heads this winter,but i don't want to spend 2500 0r 3000 just to take my heads in to be flowed to hear they need another 1500$ worth of port work,they aren't close to their claim. I'm have no problem spending money, i just don't like paying TWICE. Smitty

Re: AFR heads: Anyone else interested in buying?
 

articfriends/Smitty,

Well said! Yes, I like to go fast, and I like running decent performance equipment, but there will always be someone faster. I supposed if I wanted to go faster I could put a supercharger on it as a forced induction engine can cover a lot of the mistakes, and are much more forgiving than mistakes made by a naturally aspirated engine where I suppose air flow numbers are more critical. I am blessed enough with what I can afford, and for what I have got, and the money spent I believe my heads are good enough. Besides, my life isn't dependent upon how fast I go on the water and I have other financial commitments and I certainly don't want to pay twice either. I just want to be in the "ball park" and my own .02 is that I think I am close enough.

Re: AFR heads: Anyone else interested in buying?
 

Ahhh the numbers game .the is no set way to get the flow #'s. different vac and diff plates etc.


Most of the drag racers I see use the dart 360 and some are starting to use the Pro 1's reason?mayby there cheaper?

Re: AFR heads: Anyone else interested in buying?
 

I was thinking about adding aluminum AFR 315 cnc heads to my 5000efi's but want to run 87 octane, what compression ratio should I use? would you recommend a cam change?

Re: AFR heads: Anyone else interested in buying?
 

Man, this is one confusing thread. This is a perfect opportunity for one of the mags (Hotboat?) to do a build up series on. There are enough of us with 500efi's who want more power, but it seems no one has really done any extensive dyno work on one to see what bolt-ons will give a good power increase besides boring to a 540. I would love to know what the limitations of the stock fuel system are.
Anyhow, back on topic, have we decided what AFR head will work best?

Re: AFR heads: Anyone else interested in buying?
 

I should have a customer with some dyno numbers real soon on 502 CID that just underwent a head and cam swap. It has a set of the small canfields, unported with factory valve job and a mild hyd roller stick designed for 5400 max rpm. I'll post the numbers as soon as he gets the dyno problems lined out. This package is conceived to be a bolt on type kit for carbed 502's and HP500 equiped boats. Dyno numbers are with 89 octane and wet CMI's so should be pretty close to running conditions.

Chris

Re: AFR heads: Anyone else interested in buying?
 

I have not personally used these pieces yet, but know some reputable builders making very good #'s with these heads. I dont sell Profiler Heads, nor am I affiliated, but they are worth a good look.
http://www.profilerperformance.com/bbc-heads-174.html
Bob

Re: AFR heads: Anyone else interested in buying?
 

I will be having my naturally aspirated 565" engines dyno tested with the 357cc AFR cnc ported heads that have been chamber ported by JimV sometime between November and Febuary by Dave Wessledyke of WESCO. I will be able to use my Stellings full length tubular headers during the tests.

Re: AFR heads: Anyone else interested in buying?
 

Kaama: Looking forward to seeing your results. How's Dave doing? Did he get the Supercat together?

Re: AFR heads: Anyone else interested in buying?
 

I went to lapouttres shop today (he is our local head pro -head porter). On the phone last week he said he had flowed a set of afr 305's a customer brought in that had chamber work and pocket porting done to them by afr(I'm going to assume that this mean't afr's cnc chamber option). He said they barely flowed better than a set of stock heads with a pocket port job,he also flows his heads without a "cheater pipe" on the exhaust for copmarison reasons at 28" water column press. He showed me the sheet for those afr's today and personally they still looked pretty good:
intake exhaust
.200-162---131
.300-233---184
.400-291---219
.500-317---239
.600-326---248
CANFIELD 310 w/full CNC? I don't know what size they actually were cnc'd to
.400-268---203
.600-356---268
Anyways,he showed me flow sheets for several cnc'd heads (darts,canfields etc) and NONE of them ouflowed the 305's under .500 lift,were close to equal at .500 and had about 40 cfm at .600 and increased steadily from there on up. Now,i explained to him again, i have a 540 that i run a .620 lift cam in, it has to idle and make good torque when not under boost (cruising rpm's-2500-4000) and not have ports that will create a LACK of velocity or reversion,He did admit the afr's actually did have some excellent low lift flow #'s in comparison to most the rest and also said the cnc ones would probably compare to the bigger cnc'd competing brands. I plan on buying the cnc 315 afr's,i will have them flow tested,they might flow 30-40 cfm less than what they claim but they should still have around 350/270 at .600 if they gain 10% compared to the ones he flowed,Smitty

Re: AFR heads: Anyone else interested in buying?
 

Check out the cylinder head database that chevy hiperformance mag is putting together. The idea is same bench/operator/techniques. The numbers for a particular head might be different from what others have measured but should be comparable with the numbers for other heads in the same database.

They often test the exhaust both ways; with and without the pipe. It's not a cheater pipe. Since the head will be used with pipes in real life maybe you should port for the best flow with a pipe.
Unfortunately they have not tested the AFRs.

http://chevyhiperformance.com/techar...98/index9.html

Here's an example:

Re: AFR heads: Anyone else interested in buying?
 

He showed me the sheet for those afr's today and personally they still looked pretty good:
intake exhaust
.200-162---131
.300-233---184
.400-291---219
.500-317---239
.600-326---248


Here are some numbers from a ported Dart head with and without a pipe @ 28"
......Exhaust.......W/pipe

.2.......149..........156
.3.......203..........216
.4.......288..........262
.5.......265..........295
.6.......281..........318
.5.......297..........327
.7.......308..........344


Somthing you guy's may be missing is that the venturi areas are very close to the same in the AFR and Dart heads. The Canfields may be bigger I don't remember. The valves are the same size. So at this point we are compairing apples to apples. Because of valve overlap and piston speed (or lack of) checking airflow is not that important at lifts below .200.
Im running out of time, more to come

Re: AFR heads: Anyone else interested in buying?
 

Hi Jim:

Good point about venturi and valve size. I was trying to visualize this idea. When you have time could you comment on the following:

There are two ways to reduce resistance to airflow and they apply to cylinder heads like anything else.

1) Make the hole bigger. The hole can be venturi area or the area between the open valve and the seat. For lots of reasons we don't want a bigger hole than necessary, so the second method is usually the one we want.

2) Reduce losses through the hole. In my business we call this reducing the loss coefficient. In practical terms it means preventing flow from detaching from the wall and going turbulent.

Nowhere is this more important than between the valve and the seat, and in the area immediately before and immediately after the seat. Correct me if I'm wrong but isn't this where it's at for lower lift numbers and the main benefit of porting?

Once the valve to seat area is wide open at high lift, then maybe the "small" venturi becomes the restriction.

One thing I don't understand; do smaller venturis always give better low lift numbers than large venturis? Is this because the larger venturi creates a sharper radius into the valve seat on the floor of the port?

I like the idea of your wedges because raising the floor makes the short radius bigger. I never understood why Edelbrock/GM didn't raise the floor of the "square-oval" aluminum heads. If you're going to keep port volume small it makes sense to do it by raising the floor vs lowering the ceiling of the port.

Tom

Re: AFR heads: Anyone else interested in buying?
 

Two years ago when I was shopping for heads I talked to AFR & told them about my motor. (bbc540, procharged with 10-12lbs boost 8:1 compression, crane 741 cam, & cmi elbow tops) Who ever I talked to said that they felt the 315's were too small, the 335 were what I wanted for a boat motor & that the 357's were too big. Don't know if they changed their mind but I do not feel like I am lacking any HP. On plane at 2200 rpm when I go WOT the motor instantly goes to 4400rpm & then starts pulling from there to max rpm. Could not ask for any more low end torque.

Re: AFR heads: Anyone else interested in buying?
 

Turbojack,i talked to afr today and they also told me out of their lineup of heads the cnc 335's were the way to go on my 540 too,Smitty

Re: AFR heads: Anyone else interested in buying?
 

Smitty,
I'll be more then happy to fax you a couple of dyno sheets on marine engines with small square port heads, a 540 and 572. Just for reference if you would like. Cylinder head mfgs are good guys, but most think power begins at 5000 and doesn't stop till 8500.

Chris

Re: AFR heads: Anyone else interested in buying?
 

Hey Chris:

I'm looking for a good base engine to put my system on and sell as a package. I would be interested in hearing about your dyno tests.

Tom

(416) 709-8714

Re: AFR heads: Anyone else interested in buying?
 

Chris,in your opinion what head would you reccomend for my application? Currently 540 ci,.600 lift hyd roller,lightning headers,8-1 compression,procharger w/intercooler 9-10 psi boost,502 merc efi plenum and intake,merlin vr heads that are supposed to flow around 300cfm in/200 cfm ex at .600. On dyno last year w/ 5-6 lbs boost and 4 degrees less ign timing it made 600+ft lbs torque from 2800-5400,peaked at695 at 4300,hp was flat 630- ish from 5300-5500. Since installing in boat w/dissapointing results i have lowered base fuel pressure 5 psi,increased total timing 4 degrees and raised boost 4-5 psi gaining 8-10 mph,i'm guessing it is now around 800 ft lbs/725-750? hp. I didn't look at the merlin flow #'s when building the motor,the intake to exhaust ratio is only 65 % or so,when i freshen it this winter i am thinking a set of better flowing heads (or at least ones w/a intake to exhaust ratio around 80%) would give me more topend horsepower. The boat will already accelerate thru the midrange like it has nitrous but i would(like everyone else on this board)like more top end with out giving up ANY midrange. I am also planning to ditch the fuel injection as i am at the limit of what it will do and go w/a carb,aluminum open plenum intake etc. The afr cnc 315's with 20 % more intake flow and 30 % more exaust flow are looking pretty good to me but afr says the 335's are the way to go.So when you say small square port heads, what yours mindset of size and flow you would use,what kind of flow #'s did you have and dyno results? I may even have this motor dynoed when it comes out this winter(its not hurt) so i have before and after results of what i build,Smitty

Re: AFR heads: Anyone else interested in buying?
 

Articfriends/Smitty,

I have heard from several engine builders that an engine with a supercharger usually needs or will allow for a larger cc runner sized head just by the mere air volume that a supercharger puts through an engine.

I bought my 357cc AFR cnc ported heads as USED because I got a half way decent deal on them. Yes, a 335cc head would work great on my engines. I'm sure there are exceptions to the rule as this can get to be very controversial and create a lot of arguement, but I have asked about 4 professional marine engine builders all with several years of experience if a 357cc runner sized head is too large for a naturally aspirated 565 cubic inch engine for a marine application in the 3000-5800rpm range---they all said "no". I only have a 32' boat---it isn't real heavy---maybe 8000lbs or so. It is true that torque is the name of the game for a marine engine, but with my boat I don't need a ton of torque to get it moving. I believe that one of the factors in choosing a specific size head will depend on how heavy your boat is. There is a member on OSO by the name of "Bad to the Bone". He has a 35' Cig Awesome---VERY HEAVY boat---probably 11,000-12,000lbs! He built a pair of naturally aspirated 540 inch engines with GM ported rectangle heads on it. He bought some 315cc AFR cnc ported heads and a maybe a cam change and he said the difference was like night and day---he was very happy. If he had superchargers on it then he would probably get more favorable results with some 335cc heads vs the 315's. Yes, torque is good, and I want the boat to have good throttle response, but I would think that you'd want the engine to breath a little and move some air too. Besides, I don't exactly need Bravo drive killing torque.

The trouble is that there are 1001 different combinations and all of us has an opinion, therefore with a supercharger on a 540 inch engine (if it was me) I would lean towards the 335cc head. But what do I know? I am just an exterminator---I only kill bugs for a living, so I will probably get some rebuttal on this post, but that is kinda what this forum is for.

Anyway, I wish you the best in your decisions as you journey on your endeavor for torque and horsepower. Have fun! :D

Re: AFR heads: Anyone else interested in buying?
 

Kaama,maybe i'll run into you at hardy pond.I want to upgrade my heads,i just don't want to lose midrange,it's a toss up!We all know what its like to spend all winter redoing something and not get the exact results you want. Good luck on your motors too,Smitty

Re: AFR heads: Anyone else interested in buying?
 

Arcticfriends,
I have a polished Procharger box with a dual carb setup that I would be interested in selling. If interested shoot me an email and I will give you my number so we can talk. I would like to sell the box, carbs, and intake. This setup came with my M-4, so it should work well for your application. I ran it with 13 lbs of boost.

Re: AFR heads: Anyone else interested in buying?
 

Smitty,
For your combo, you are missing about a 100HP/150#/ft of torque somewhere. I have missed all this time you are positive manifold pressure. . .sorry. In this case a 320 to 335cc runner head would be fine on a blower engine. I would suspect camshaft is not in sync with the rest of your combo and is fighting the induction system. Based on the ratio of the intake flow to exhaust that you posted. The cam should have about a 12 to 14 degree split favoring the exhaut. Based on the the CID and rpm range. . . now is when I will get called NUTS. . .cam duration at .050" shoud be about 226/238 for a max rpm of around 5500. Lift would be greater then what you have. I think you got the parts you need to make some power, they just need a little tweaking.

Chris

Re: AFR heads: Anyone else interested in buying?
 

Hey Smitty:

The heads and/or the Merc intake must be the problem; you were at least 100 ft-lbs short when you were running 9-10 psi boost. With a single plane intake and ported GM heads we see 800 ft-lbs @ 5500 RPM with 8.5-9 psi on 500 CID.

Why don't you buy the Holley EFI universal kit? You already have the computer, wiring harness and injectors. All you need is the manifold with fuel rails and a throttle body. You really only need the 1000 CFM throttle body but you could use the Dominator flange intake and the 2000 CFM throttle body.

Of course, this would now fit a supercooler under the hatch. :rolleyes:

Chris:

I agree with keeping the cam small, especially for a centrifugal blower. And I wouldn't be afraid to use the 315 CNC heads. This would make great torque down low without boost, then let the supercharger do the work on the top end. Midrange will be awesome.

Re: AFR heads: Anyone else interested in buying?
 

Chris, Most fellas usually like large cams, but I sure don't think you're "nuts"----I agree with you! Unlike most guys, I kinda like the idea of using a smaller cam as well. In fact, more and more I try to get away with using the smallest camshaft allowable.

Re: AFR heads: Anyone else interested in buying?
 

Chris, Most fellas usually like large cams, but I sure don't think you're "nuts"----I agree with you! Unlike most guys, I kinda like the idea of using a smaller cam as well. In fact, more and more I try to get away with using the smallest camshaft allowable.

Re: AFR heads: Anyone else interested in buying?
 

Chris,my cam is a cam motion hyd roller,.228 deg at .050 intake,236 ex,.593 lift intake,.612 lift ex 110 intake centerline,118 ex centerline.
Tomcat,the 695 ft lbs torque and 630 hp was at 5psi boost w/4 degrees less ign timing on dyno,the boat with motor in it exactly that way off dyno was 3 mph SLOWER than my old 502 w/stock merc cam but all the other topend components i'm currently running. After turning IGNITION timing up 4 degrees and upping boost to around 9 i picked up roughly 8 mph. To gain 8 mph i'm guesing the torque and hp to be around 800 ft lbs and 725 hp but its only a guess.Are you saying if i didn't run the merc manifold/efi i could pick up another 100 ft lbs or am i in the ballpark of what it should be making? The motor just started burning a few puffs of oil on startup so i'm thinking the guides are getting worn,so i'm planing on freshening the motor and figured it would be a good time to optimize the topend (higher flowing heads w/better i/e ratio). Also like we were talking about on a thread a few months ago i just got some real nice bourdon tube vacuum /pressure gauges and i'm going to rig them temporarily on my boat this weekend and post a thread showing inlet press vs outlet press vs intake manifold press w/aw504 intercooler on my boat,ive always wondered where the pressure really was and where the drop will be,Smitty

Re: AFR heads: Anyone else interested in buying?
 

Arcticfriends,
I have a polished Procharger box with a dual carb setup that I would be interested in selling. If interested shoot me an email and I will give you my number so we can talk. I would like to sell the box, carbs, and intake as a package and give you a deal on all of it. This setup came with my M-4, so it should work well for your application. I ran it with 13 lbs of boost.

Re: AFR heads: Anyone else interested in buying?
 

:rolleyes:

Re: AFR heads: Anyone else interested in buying?
 

ttt

Re: AFR heads: Anyone else interested in buying?
 

Smitty: I didn't read your post carefully enough. But even so I think you're losing HP. I would expect about 625 HP with 4 psi boost. You needed 5 psi. I pulled out the dyno sheets I was referring to and read 844 HP and 806 ft-lbs @ 5500 with 8.5 psi boost. For you to get lower HP with higher boost just means that things are restricted after the intake plenum. I like your cam, so my money is on the heads not flowing as well as you'd like and the stock intake runners. If you look carefully at the lower intake you can see that the cross sectional area of the runners is reduced quite a bit below the flange. A single plane intake and some head porting would get you a lot in this case. I don't know about 100 ft-lbs, but a lot.

If you used the Holley EFI, you could eliminate a lot of intercooler plumbing pressure losses and get the same intake boost with a lower compressor RPM, lower temp, less parasitic loss etc. This is all good.

How good did you build the short block? You know if you get everything connected you're knocking on 1000 HP don't you? :D

Re: AFR heads: Anyone else interested in buying?
 

To all looking for some good head,
I will be running my 1998 gen VI HP 500's (carb) on the dyno before I tear them down, they are stock except I removed the choke horn. They have 250 hours on them not too many at wot. They are in a 382 Fastech formula weighing 10,450# dry approx 12,000# with fuel and people. It now turns un-labbed 28" bravo one four blades at 5,000 rpm at 75 mph. I will post before and after dyno results. Jeff

Re: AFR heads: Anyone else interested in buying?
 

Smitty,
Cam is part of the problem, you don't want any advance in a blower camshaft. . you don't need to open the intake valve early because you have a power adder. You need to retard the cam 4 degrees.

Chris

Re: AFR heads: Anyone else interested in buying?
 

I have a brand new Hirel/Holley manifold, fuel rails, and 1000cfm throttle body. Is it worth $1000 to you?

Re: AFR heads: Anyone else interested in buying?
 

Marty,i'm interested,sent you private message,Smitty

Re: AFR heads: Anyone else interested in buying?
 

Hi Jim:

Good point about venturi and valve size. I was trying to visualize this idea. When you have time could you comment on the following:

There are two ways to reduce resistance to airflow and they apply to cylinder heads like anything else.

1) Make the hole bigger. The hole can be venturi area or the area between the open valve and the seat. For lots of reasons we don't want a bigger hole than necessary, so the second method is usually the one we want.

2) Reduce losses through the hole. In my business we call this reducing the loss coefficient. In practical terms it means preventing flow from detaching from the wall and going turbulent.

Nowhere is this more important than between the valve and the seat, and in the area immediately before and immediately after the seat. Correct me if I'm wrong but isn't this where it's at for lower lift numbers and the main benefit of porting?

.......Yes, the area's closest to the valve/seat are the most sensitive. As far as low lift numbers (below .200) I don't believe they are as important because of piston position and cam overlap. There isn't much pressure in the chamber when the piston has moved a few degrees after TDC or BDC.

Once the valve to seat area is wide open at high lift, then maybe the "small" venturi becomes the restriction.

One thing I don't understand; do smaller venturis always give better low lift numbers than large venturis? Is this because the larger venturi creates a sharper radius into the valve seat on the floor of the port?

........Dealing in cylinder heads, usually the smaller venturi will flow more air because there is more distance between the valve and cylinder wall.

I like the idea of your wedges because raising the floor makes the short radius bigger. I never understood why Edelbrock/GM didn't raise the floor of the "square-oval" aluminum heads. If you're going to keep port volume small it makes sense to do it by raising the floor vs lowering the ceiling of the port.

........I don't understand that either. It shouldn't cost any more to make a high port oval port head. Thanks Tom!