Maybe just PM the ONE single individual that made the comment? Pretty obvious that no one else agrees so I`m not sure what you`re looking for??
Is it because Bob pushes AFR so you have to make it a point to let everyone know that it`s all good?
Not sure what the point of this thread is. Everyone agrees with you

Brian some of us do appreciate the technical insight from the guys that don't cut corners and do things right. It's a real shame with all the experience and appreciation we all have for marine performance engines we can't have better technical discussions rather than pissing matches and vendor bashing. If your have trouble with something instead of calling it junk why not bring it to the table and see if there is a fitment/ installation issue or whatever. Now don't get me wrong there is some real garbage out there but in the case with this thread I don't see it being the case.

Its not just the case with the AFR stuff. The comment about the AFR exhaust port just kinda pushed it over the edge. AFR knows how to make a head. So does Brodix, Dart, CFE ect. Ect. Many times over I think there are installation / combination issues and someone's product gets blamed for it. Then everyone jumps on the band wagon and b4 you know it you minus well have bought the Chineese stuff and went with that.

is minus well anything like might as well,lol,

Sorry tryin to du 5 things at once

I believe this thread started over a 4 year old thread, that was discussing an 8 year old head. And like every great company out there I'm sure they are always updating their product. (Staying stagnant will put you out of business) There is no need to get personal and worked up over internet opinions. We as consumers are fortunate that we have so many options to choose from when making decisions on how to build HP. It's funny we are splitting hairs over, "Do I want to make 643HP or 651HP?"

This is definitely a 1st Word Country problem. Now I'm off to remove some Teflon strips from my blowers. Peace!

no problem,sometime i think one thing and type another.it,s all good.

This morning I was reading this article posted on AFR's website. They did a comparison of several bbc heads, on a 496 stroker. Although the shortblock was untouched, they swapped heads. Something to keep in mind is the compression ratio differences as well.

http://www.airflowresearch.com/artic...t/shootout.php

GM Rect ports with 123cc chamber, roughly 9.8:1
630HP @ 6600
577FTlbs @ 5300

Summit (dart) cast iron 308. 9.9:1
688HP @ 6600
607 @ 5400

Pro comp chinese 369cc 9.8:1
690HP @ 6300
600lbs @ 5500

Trick flow 360cc 9.9:1
691HP @ 6500RPM
603lbs @ 5400RPM

Brodix 332 rovals 10.5:1
705HP @ 6500
624lbs @ 5200

Dart 335 Pro 1 9.9:1
717HP @ 6500RPM
619lbs @ 5600RPM

Edelbrock 355 CNC 11.28:1
723Hp @ 6500RPM
627ft lbs @ 5600RPM

AFR 290/300 Magnum oval 11:1
729HP @ 6500
639FT @ 5400

Its a no brainer, that stepping up to almost any aftermarket head, is where the big gains are found, in comparison to the GM head. The AFR head made the best power in that shootout. I would have liked to see what the 335 Dart head would have done, had it had the same compression ratio. It was down 12hp at peak, and 20ftlbs, but also had a full point less compression.

Even the budget summit racing head, was not a bad head. An as cast iron head, that picked up 58HP over the GM iron head? Pretty sweet.

What else I thought was interesting, was the torque at 3500 in the graphs on the setups.

At 3500RPM,
GM 540 FT lbs (9.8:1)
Dart 335 560 FT lbs (9.9:1)
Brodix 580 Ft lbs (10.5:1)
AFR 570 FT lbs. (11:1)
.

Lots of choices out there for the consumer. Many variables. I don't agree with a one brand is best mindset. Also, cost is a factor. Look at the darts. You have a set of 308 irons that retail for say 1400 a pair bare. Then you have the 335 cnc ported aluminum, for 3200 a pair bare. On this build, there was a difference of 29HP at peak. That gap would probably be even less, on a milder build like say an HP 500 upgrade. Is it worth the extra 1800 bucks for that 29HP? If a twin engine boat, x2=3600 dollars? That might net you 2mph speed gain? I think that 3600 dollars may be spent towards prop work, shorty lowers, better rods, better carbs, or things along those lines.

For the average mercruiser marine upgrade with stock pistons, its kind of a no brainer, that going to a head like the AFR 290, with its smaller chambers, is a great pick. The stock mercs are lacking compression for most performance builds, so bolting a set of those on, not only give you much better airflow, but the gains from bumping the compression as well. Its a win win. Just an article, and just some thoughts on it.

procomp all the way.:D

and that was an AFR OVAL head. it was a rect head comparison and AFR sent them an oval...and won. boy those exhaust ports must really suck!!!! Air Flow Research? i guess they do a little.

you may find this hard to believe, but that procomp head isn't a bad head... just buy the empty castings and do the work and put proper parts in them... as for the head it works well for a budget build... just my $.002

I made the post and stand behind the data and my flow bench. I don't know why would you ask a question you don't want an answer to. I'm sorry your flowbench dosen't tell you how to port a head, build a motor and what prop to use, mine dosen't either. My flowbench provides data, period. It's up to the operator to desifer the numbers and decide were to go from there. For those of you who don't know I flowed the stock cnc exhaust port, modified it and got an average gain of 26 cfm from .200 to .700 lift. Peak gain of 38 cfm at .500. To answer your question: AFR uses a cheater pipe when they flow there exports. A cheater pipe is a 6" pipe that does nothing but enhance the numbers on there flow bench, my flow bench and your flowbench if you were to dig it out of the trash. I'm not sure where they get there advertising numbers on the web site... hmm... maybe a FLOW BENCH. A flowbench is to provide a measurement
The data from my flowbench tells me how efficient a port is. Example, I know from flowing more ports that I can remember that a 1.880 exhaust valve can flow in the 330+ cfm no cheat pipe on a old style Dart Pro One head. The new ones wont do it, different story. It's obvious on the video's, the port volume, crossectional area and area at the flange are different than the much smaller AFR's Flag up excessive exhaust pressure. The piston has to evacuate the cylinder, a choke in the port means more pressure on the piston along with other potentiual problems. Maybe one of those engineers can give you the psi. I don't have that number. The second video shows the modified afr port. There is an editing error, at .500 It should read 286 cfm. The multiplier is .318 times the percentage
The second part of reading data is airflow increase between the lift points. The stock cnc'd head shows near peak flow at .500 lift whereas the modified port at .600. The data from my flow bench data also shows if the flange size is correct for the application. Reading the curve, if the venturii, bowl, short turn is correct the higher lift numbers will flatten out considerably. It really pisses me off hearing of the few broom stick cowboy internet engine builders out there that don't have a flow bench, or do have one and do not know how to use it, or even worse owning one for a status symbol and are giving advice and BS because the profit margin. I got one down the street from me. I was in his shop a couple of years ago looking at what he said flowed 300 cfm on a fluffed up set of Darts. He backed himself in a corner and was able to bring him back his 260 cfm heads he sold as fully ported. I did ask one of the members here on OSO to dyno one of his sets of the cnc'd afr's he had up for sale, against a set of my heads, appearantly he drank the kool-aid too and declined.

Video 1: https://www.youtube.com/watch?v=lefrYoaVsCk
Video 2: https://www.youtube.com/watch?v=9SP9vzIFifc

Video 3: cheater pipe racing : https://www.youtube.com/watch?v=C9AQzI-pfdo

You obviously know heads and flow, ... but how can you possibly call any exhaust fitted to the head a cheater?
In the real world isn't said cheater going to end up perhaps being the limiting factor?

Buck, some heads are flowed with a pipe, and some not with a pipe, when publishing flow numbers to help sell their heads.

As for JimV, he does know heads and flow. And knows engines as well. Having worked for Roush, Dart, been involved in development of cylinder heads for big companies, modified tons of head for oso members over the years. I personally feel his resume makes his words worth listening to. He is by no means, a ''monkey with a dremel tool". He is a guy worth having around on oso in my opinion.

I totally understand that and give him all my respect, but heads are designed to have an exhaust bolted on. I've never seen a set of cheaters , be they dry or wet.
absolutely no disrespect intended .

Who cares what's bolted on? Find out how they're flowed at the factory and take that into consideration.

The pro comp head can be worked to flow good numbers.

IMO the cheap casting can not reliably handle a lot of power though.

Even with the best parts installed, shaft rockers etc, the casting will fail.

The steady, low pressure airflow testing described for intake valves often fails to adequately predict the performance of exhaust valves/ports. Inconsistences frequently occur where enhanced flow bench performance leads to decreased engine performance. This is a result of the considerably different exhaust port flow environment, which includes higher pressures, compressible flow, and products of combustion. Early gas exiting occurs under high pressure as critical, or choked, flow then transitions to sub- critical flow under lower pressure ratios. Normal practices are to ensure the exhaust port flow capabilities are at a minimum of 60-80% of the intake. This however does not ensure the most efficient geometry and can lead to larger than required valves/ports or a restrictive exhaust. Excessively large diameter exhaust valves leave less room in the cylinder head for the intake valves, while a restriction can significantly lower the capabilities of the engine regardless of intake flow improvements. Other general findings include maintaining a minimum area throughout the port or increasing exhaust port volume can often increase engine performance. It would be desirable to have improved methods of analysis specifically designed for exhaust ports during critical flow to understand these findings and produce more efficient port geometry. This would be of particular interest to high performance engine designers within the motorsports industry.

Copied from a research study Unniversity of Miami. And the main reason why I began the thread the way I did. The flow bench is a poor piece of equipment to be using on the exhaust port. My question is was the flow bench the final test done with the exhaust port? Was there and kind of dyno testing before and after? Track, water whatever kind of testing before and after the work was done to the port?

With page upon page of combinations putting up big numbers AFR's port with the cheater pipe seems like it has done very well. I'd really like to see some more real world testing cause as stated the flow bench testing doesn't really mean anything. Maybe the port wasn't fixed and instead broken.

When I looked into them I was told if going over 600 lift to use Girdles.

I would recommend running stud girdles on about any high performance engine regardless of the cam profile, stability is key, heck I use to run them on 450 hp small blocks back in the day, jmo

I think a lot off the problems with pro comp come from lack of material ...thin deck.. A good quality head is 3/4" or so at mating surface .I don't think pro comps are near that thick........

Amen, Unfortunetly the flow bench is the only reletively enexpensive tool that I know of for testing before it goes to dyno. I heard of some equipment that can measure combustion pressure but not export pressure in front of the valve. If there is a question on the dyno I will put extra lash on the exhaust valve to see if theres a loss or gain. My opinion there needs to be a buttload more r/d for marine engines starting with exhaust valve size and port size.To say it again, there are four or five options for intake runner volume with only one choice for exports. I cringe when I see a 310ish volume intake runner 2.250 valve with a 1.880 export. If someone wants to fund it I'd like to start with a 1.750 valve with a port size to fit and increase combination including looking at a stepped header design, primary tube diameter and an up to date collector. I did find a better flowing export dosen't need as much duration on the cam lobe. I'll bet theres enough talent on this board to bring the technology forward.

We will have to agree to dissagree on the importance of flowing exports no hate here. Thanks, Jim

The steady, low pressure airflow testing described for intake valves often fails to adequately predict the performance of exhaust valves/ports. Inconsistences frequently occur where enhanced flow bench performance leads to decreased engine performance. This is a result of the considerably different exhaust port flow environment, which includes higher pressures, compressible flow, and products of combustion. Early gas exiting occurs under high pressure as critical, or choked, flow then transitions to sub- critical flow under lower pressure ratios. Normal practices are to ensure the exhaust port flow capabilities are at a minimum of 60-80% of the intake. This however does not ensure the most efficient geometry and can lead to larger than required valves/ports or a restrictive exhaust. Excessively large diameter exhaust valves leave less room in the cylinder head for the intake valves, while a restriction can significantly lower the capabilities of the engine regardless of intake flow improvements. Other general findings include maintaining a minimum area throughout the port or increasing exhaust port volume can often increase engine performance. It would be desirable to have improved methods of analysis specifically designed for exhaust ports during critical flow to understand these findings and produce more efficient port geometry. This would be of particular interest to high performance engine designers within the motorsports industry.

Copied from a research study Unniversity of Miami. And the main reason why I began the thread the way I did. The flow bench is a poor piece of equipment to be using on the exhaust port. My question is was the flow bench the final test done with the exhaust port? Was there and kind of dyno testing before and after? Track, water whatever kind of testing before and after the work was done to the port?

With page upon page of combinations putting up big numbers AFR's port with the cheater pipe seems like it has done very well. I'd really like to see some more real world testing cause as stated the flow bench testing doesn't really mean anything. Maybe the port wasn't fixed and instead broken.[/QUOTE]

AFR stands behind all of our advertised flow numbers (to account for production tolerances, we guarantee our numbers within 2% of advertised). While some of our competitors seem to take some liberties in that department, we try our best to meet or exceed all our published data. In fact, a handful of our products actually flow notably higher than we claim. Read More A lot of engine builders rely on our heads to deliver the power they guarantee. It is important we provide them with a head that delivers and flows as promised every time. It’s also important to note that some manufacturer’s flow their heads on different types of equipment and conveniently don’t include that information in their test results. Cylinder head flow testing equipment is no different than dyno’s; some read higher than others and a few types of equipment tend to read a lot higher. All of our heads are tested on an accurately calibrated SF600, what most still consider to be the industry standard although the SF1020 has gained a lot of popularity in recent years as well. The newer 1020 benches read very close to an SF600 model while some of the older 1020 units were a little stingier. Note all our intake data is obtained using a proper fitting radius plate with the appropriate corner radius’s (clay is not consistent), and all our exhaust data is flowed thru a curved pipe that directly simulates a typical header installed in a production vehicle (a pipe about 10” long that has an immediate curve off the exhaust flange and straightens out).

That was copied from there website for those that think they use the cheater pipe just to market/ sell heads.

I believe I heard a build that they made 1000-1100HP. Not to extreme of a build. Moderate boost, decent cam similar to what you would expect from any aftermarket head.

[/QUOTE]

The Technology is there for improved exhaust port testing I don't understand why it's not mainstream yet. For a high volume/ production based company a piece of equipment thAt could simulate combustion and measure it's flow out of the chamber/ port in my eyes would be priceless.

The AFR intake ports flow very close to there claims on my 600superflow the exhaust dont on all heads that I tested. All the exhaust ports were very consistant. Without the pipe and with. My bench is in good working order.

ok jim. what IS wrong with the AFR exports? i am not calling you out. i am at best a backyard a$$hole who just started playing with port work. apparently lingenfelter might have known a little more than you about cyl heads-but not much. what IS it about the ports that could be done better and can it be corrected with a die grinder? or does the casting need to be redesigned?

"apparently lingenfelter might have known a little more than you about cyl heads"

really,,I know my friends vette's heads were port so much that water pressure blew right into the port and Hydro-locked the motor.Good news is Lingenfelter replaced his engine w/ a 427sb,twin turboed it too(at owners expense) 760hp to the ground.yahoo.car still runs perfectly after 9yrs now.

I don't believe anyone said the port is wrong. For different applications it can be improved.

I am only a weekend warrior boater. I may know a few things, but I am certainly no engine "expert" and I am not here to throw anyone "under the bus".

Anyway, I still have my 565cid N/A engines sitting in Dave Wesseldyk's shop....been sittin' there since 2008. They were built back in the Spring of 2005 with the AFR 315cc full cnc ported heads. Back during that time I had JimV flow test those AFR heads and modify the exhaust ports mainly for the reason he has stated within this thread. They had machining marks just below the seat area on the exhaust side and a slight "ridge" where the seat meets the casting---I didn't like it so, I had JimV go in there and fix it. Plus he also did some work on those exhaust ports to improve them over the AFR factory based on JimV's opinion. He also slightly massaged the combustion port immediately near the exhaust valve for some un-shrouding and he slightly increased the size/volume of the AFR factory exhaust port. We ran the engines on the dyno---it is difficult to say if the additional massaging work made an increased power improvement over the AFR heads that came out of the box from the factory.

Perhaps we can do a comparison test on the dyno....my JimV exhaust port modified AFR 315cc heads vs a set of un-touched AFR 315cc heads.

that would be an interesting test.

Let's see if this spread sheet works here on the OSO system...I tried to post the head flow numbers from my Microsoft Word that I got from JimV that I had recorded 10 years ago, but the OSO system wants to bunch all the numbers together and make it difficult for reading and understanding. This was from back in 2005...Let me try it this way...

AFR 315cc CNC ported head, UNTOUCHED EXHAUST PORT as is out of the box from the factory with AFR premium exhaust valve VS on JimV's flow bench
.200 AFR advertised 146---JimV w/6" pipe 146
.300 AFR advertised 184---JimV w/6" pipe 206
.400 AFR advrtsd 238---JimV w/6" pipe 251
.500 AFR advrtsd 271---JimV w/6" pipe 280
.600 AFR advrtsd 296---JimV w/6" pipe 287

I cant remember what length of pipe that AFR uses for their exhaust port flow numbers (of if it matters), but JimV used a 6" pipe to test the heads in this test....so, I am not sure if that will make a difference or not on the numbers.

Here's the same UNTOUCHED AFR 315cc cnc'd head WITHOUT a pipe (raw port) VS JimV's final exhaust port work on the same head tested on JimV's flow bench within about a week or so of the previous tests prior to any port work---this was all back in 2005...

.200 AFR out of box, no pipe on JimV's flow bench: 140cfm---JimV's modified exhaust port work no pipe: 146cfm
.300 AFR/193---JimV/201
.400 AFR/232---JimV/246
.500 AFR/250---JimV/268
.600 AFR/254---JimV/279
Total 1069cfm vs 1140cfm = 71cfm difference

We only tested to .600" lift because the exhaust lobe cam lift was only at .620" lift or so on the cams I was using

I will say this in defense of AFR thus far.....the next 2 sets of AFR fully cnc'd heads I got a few years ago for the engines I am doing now, had NO cutter marks in seats or seat area under the valve....AND there were NO visible ridges where the seats meet the casting as was on my previous AFR 315cc cnc'd heads from about 7-8 years prior. I ran my fingers over the port work in the bowls, etc, and I could not feel any ridge marks, or flaws---they looked like pieces of jewelry---like pure art work!

The question remains, does JimV's Exhaust port work modifications on the BBC AFR cnc'd head actually an improvement over AFR's own factory Exhaust port??? It will either help it, hurt it, or create no change. And, if it does help it, how much HP/Torque will be gained or realized and if so, is the price worth $800 for let's say 15-20hp on an engine that is already making lets say 750+hp with forced induction? Is it too close?----Are we splitting hairs when the engine is already making that kind of power?

I think it's a valid question and I do not know if it is worth all the time, argument, money, and energy to spend on this subject, but I am willing to dyno test one of my 565cid engines if someone will help with the AFR 315cc cnc'd heads, dyno time, etc. My own thought's are that I am thinking we might be splitting hairs here---but who knows, maybe I'm wrong. I'd like to know the truth and just as curious as some of you other guys on here.

I think it be great to dyno first with your Jim v modified heads, then with out of the box afr 315s, then a set of JimVs own castings, on your 565s. If it were on a weekend, Id be willing to come up to michigan by you guys, help out with the parts swapping, and help chip in towards the dyno time/gas. I may even be able to get mike tkach to ride up there with me if i get him his favorite chocolate donuts he likes. :D

and i have a set of afr315s new in the box.

what I do know about exhaust,,especially on supercharger motors,is if its really restrictive,,it will aid in artificially increase the boost thru the engine.learned alot whippling the new 496 engines.

those are junk,,best send them to me.:D

Don't forget the beer.....lol

[ATTACH=CONFIG]537845[/ATTACH]

after last nite i may never drink again!