What's wrong with AFR's exhaust port?
#181
Makes sense to me Mark. I really have no dog in the fight, I just like FACTS, not politics.
Its funny, I was just sitting here drinking my evening coffee, and reading a thread on another boating site. The thread consisted of a flow test on a new set of AFR heads, tested by an independent engine builder, along side a pair of out of the box dart heads. In that thread, the AFR's did not flow what they were claimed to, on this particular persons bench. And it was a repeat of the oso debate.
Its funny, I was just sitting here drinking my evening coffee, and reading a thread on another boating site. The thread consisted of a flow test on a new set of AFR heads, tested by an independent engine builder, along side a pair of out of the box dart heads. In that thread, the AFR's did not flow what they were claimed to, on this particular persons bench. And it was a repeat of the oso debate.
#182
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Joined: Jul 2004
Posts: 11,332
Likes: 73
From: chicago
Heres the flow numbers from that thread I'm speaking of
Next: AFR 305 as-cast, assembled from AFR with their valves, 2.25 intake with backcut (angle unknown) AFR 1.88 exhaust.
AFR as-cast advertised:
right/ex
.2 154/131
.3 223/176
.4 287/219
.5 335/251
.6 363/276
.7---------
Truth:
right/left/ex
.2 146/143/109
.3 209/210/144
.4 268/276/185
.5 324/327/223
.6 366/336/250
.7 361/343/262
.8 ---/345/271
The bowls are nicely CNC blended but transition from the seat to the chamber is terrible. The exhaust port I believe suffers far worse because of this than the intake.
Now, he didnt have the advertised flow numbers from the darts. Dart doesnt have the flow numbers on their site, but I do have their master catalog here, that does. So, heres what my catalog shows for the 310's.
.200 147/136
.300 219/175
.400 275/210
.500 318/233
.600 347/249
.700 364/258
.800 .369/266
Here is what that builder got on his bench with the out of the box dart heads
Left/Right/Exhaust
.2 140/141/111
.3 207/207/151
.4 271/271/192
.5 322/312/227
.6 351/329/254
.7 365/329/271
.8 341/335/281
Next: AFR 305 as-cast, assembled from AFR with their valves, 2.25 intake with backcut (angle unknown) AFR 1.88 exhaust.
AFR as-cast advertised:
right/ex
.2 154/131
.3 223/176
.4 287/219
.5 335/251
.6 363/276
.7---------
Truth:
right/left/ex
.2 146/143/109
.3 209/210/144
.4 268/276/185
.5 324/327/223
.6 366/336/250
.7 361/343/262
.8 ---/345/271
The bowls are nicely CNC blended but transition from the seat to the chamber is terrible. The exhaust port I believe suffers far worse because of this than the intake.
Now, he didnt have the advertised flow numbers from the darts. Dart doesnt have the flow numbers on their site, but I do have their master catalog here, that does. So, heres what my catalog shows for the 310's.
.200 147/136
.300 219/175
.400 275/210
.500 318/233
.600 347/249
.700 364/258
.800 .369/266
Here is what that builder got on his bench with the out of the box dart heads
Left/Right/Exhaust
.2 140/141/111
.3 207/207/151
.4 271/271/192
.5 322/312/227
.6 351/329/254
.7 365/329/271
.8 341/335/281
#183
Platinum Member
Joined: Dec 2002
Posts: 2,195
Likes: 2
From: Dallas, TX
On a different thread back in 2011, Articfriends/Smitty, posted a link to a website that shows several flow bench tests of several different head designs and companies, etc...including AFR and all their BBC head designs and ports, etc.....were done by what looked like several or at least a few different flow bench shops. (I tried copy/pasting the link to this thread, but it doesn't work for some reason) Although some of the tests varied from flow bench company to flow bench company, it never showed the AFR Exhaust ports as being a lagging port as JimV has claimed.
Last edited by BenPerfected; 03-11-2015 at 08:07 PM.
#184
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Joined: Jul 2004
Posts: 11,332
Likes: 73
From: chicago
Kaama, I know the site youre speaking off. Heres some numbers I got off there.
Dart 335 CNC 4.5 bore no pipe and AFR 335 cnc 4.6" bore, no pipe . Then AFR 335 cnc 4.6'' bore, WITH 2 1/8TH PIPE. Dart is top numbers
.200 .300 .400 .500 .600 .700
174/136 245/178 306/235 353/265 383/282 401/296
170/133 249/178 313/230 362/259 396/268 405/273
164/144 240/197 304/257 352/285 385/311 404/319
Without the pipes, looks like darts ex ports flow more? Would have been interesting to see the darts port WITH the 2 1/8 pipe. Couldnt find any flow data with a pipe on a dart head on that site.
Dart 335 CNC 4.5 bore no pipe and AFR 335 cnc 4.6" bore, no pipe . Then AFR 335 cnc 4.6'' bore, WITH 2 1/8TH PIPE. Dart is top numbers
.200 .300 .400 .500 .600 .700
174/136 245/178 306/235 353/265 383/282 401/296
170/133 249/178 313/230 362/259 396/268 405/273
164/144 240/197 304/257 352/285 385/311 404/319
Without the pipes, looks like darts ex ports flow more? Would have been interesting to see the darts port WITH the 2 1/8 pipe. Couldnt find any flow data with a pipe on a dart head on that site.
#185
MT, I did not want to reprint your entire post, but in a previous post within this thread, I had said I am willing to contribute one of my 565cid engines that have been sitting since 2008 at Dave W's shop that have the AFR 315cc fully cnc'd ports that were modified by JimV back around the month of March or in 2005. JimV modified the exhaust ports on my/those AFR heads and I have also already posted the CFM numbers within this thread.
I will supply the JimV modified Exhaust port, AFR cnc'd heads and test engine (one of my 565cid engines), Mike Tkack supplies the AFR 315cc heads untouched,...then with all due respect to JimV, if he truly believes his own porting techniques with his own hand on a set of AFR cnc'd heads can increase a reasonable amount of HP/Torque output on a dyno, then let him pay Dave W for the dyno time. My engines stay at Dave W's shop...if any work needs to be done to conduct the test such as new valve springs, installed spring height, head/intake gaskets, valve job, etc, etc. then it will be done in Dave W's shop. If anyone else wants to contribute towards the cause of the test, then I suppose they can, but I don't think it would be fair without a contribution from JimV....at least he or we can save money on the "plane tickets" as we can conduct the test right here in his living area.
And if the test comes out in JimV's favor and there is a significant increase in HP on the dyno, then JimV may reap the rewards from selling the porting projects from future customers he may gain from the results of the test---and people can go to him for the port work. Again, with all due respect to JimV, he is the one making a public claim on this forum about the AFR cnc'd Exhaust port not being as good as it could or should be, then let him be the one to put his own money where his mouth is by fronting and contributing towards the costs of the test. And if it his modified port work on a set of cnc ported AFR Exhaust ports turn out to be what he says it will be, then he can tell us all that he told us so.
From what I remember, JimV has not proved once in a back to back dyno test how much increased HP his port work has done/will do on a set of heads. If he has, then from what I know he has not made it public to prove his point on here.
I will supply the JimV modified Exhaust port, AFR cnc'd heads and test engine (one of my 565cid engines), Mike Tkack supplies the AFR 315cc heads untouched,...then with all due respect to JimV, if he truly believes his own porting techniques with his own hand on a set of AFR cnc'd heads can increase a reasonable amount of HP/Torque output on a dyno, then let him pay Dave W for the dyno time. My engines stay at Dave W's shop...if any work needs to be done to conduct the test such as new valve springs, installed spring height, head/intake gaskets, valve job, etc, etc. then it will be done in Dave W's shop. If anyone else wants to contribute towards the cause of the test, then I suppose they can, but I don't think it would be fair without a contribution from JimV....at least he or we can save money on the "plane tickets" as we can conduct the test right here in his living area.
And if the test comes out in JimV's favor and there is a significant increase in HP on the dyno, then JimV may reap the rewards from selling the porting projects from future customers he may gain from the results of the test---and people can go to him for the port work. Again, with all due respect to JimV, he is the one making a public claim on this forum about the AFR cnc'd Exhaust port not being as good as it could or should be, then let him be the one to put his own money where his mouth is by fronting and contributing towards the costs of the test. And if it his modified port work on a set of cnc ported AFR Exhaust ports turn out to be what he says it will be, then he can tell us all that he told us so.
From what I remember, JimV has not proved once in a back to back dyno test how much increased HP his port work has done/will do on a set of heads. If he has, then from what I know he has not made it public to prove his point on here.
#188
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Joined: Oct 2007
Posts: 8,439
Likes: 93
From: yorkville,il
brian,he said it would need to happen at wesseldyk,s shop.i doubt dave would have a problem with mild being at his shop but a phone call would be the first thing to do.that was a very generous offer on your part.
#189
Although they say nothing about seat widths they do mention vgc in the literature as follows : Our typical valve guide clearances are .0013 - .0016 . In some severe applications ( nitrous , marine endurance racing or blower usage ) looser guides might be required . Check with your engine builder .



