Afr heads with PAC 8002 spring upgrade.
01-22-2017, 10:31 PM
#72
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Yes. They actually made 1036hp at 6500rpm. 522ci , afr 315 heads, 1071 littlefields with blower shop intercoolers , twin 1050 carbs, 10lbs boost. Mike Tkach built them, bob M supplied the cam and heads.
I just wrote the 3d timing map for the daytona sensors boxes and helped out for the dyno session. It was an impressive combination of parts. I believe with 8lbs boost, they made 930ish, and around 870 with 6lbs . Air intake temps were around 115 degrees with 6, 8 and 10lbs. The intercooler was doing its job.
The cam was 245/253 , 681/663 113 LSA if i recall .
I just wrote the 3d timing map for the daytona sensors boxes and helped out for the dyno session. It was an impressive combination of parts. I believe with 8lbs boost, they made 930ish, and around 870 with 6lbs . Air intake temps were around 115 degrees with 6, 8 and 10lbs. The intercooler was doing its job.
The cam was 245/253 , 681/663 113 LSA if i recall .
01-22-2017, 10:40 PM
#74
01-22-2017, 10:43 PM
#75
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the 315 really flows well and imo they are the perfect head for the build.i have heard of 540s and 555s with them making good power.a lot of people think bigger is better but in the marine world where 6500 is a high revving engine the bigger port is usually not the way to go.imo a afr 325 head would have made less power on these engines.
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01-23-2017, 06:20 AM
#78
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.200 .300 .400 .500 .600 .700
315
Int 169 249 312 353 380 386
Exh 146 184 238 271 296 310
.200 .300 .400 .500 .600 .700
325
Int 170 242 304 342 372 390
Exh 145 195 244 266 274 280
.200 .300 .400 .500 .600 .650
305
Int 168 242 303 339 360 362
Exh 142 187 225 252 271 274
Its easy to see, why the cnc ported 315 would make more power than a 325 AFR with full cnc chamber. The ONLY place the 325 flows more, is at .700 lift. It flows a whopping 4 cfm more than the 315. Other than that, from the time the valve comes off the seat, the 315 simply flows more air, both intake and exhaust. And, it does so, with a smaller valve. Anytime you have a smaller port , flowing MORE cfm, its a safe bet, its gonna make more power, and have better velocity. The 315 was flowed on a 4.600 bore fixture, while the 325 was flowed on a 4.310 bore, but even still...
Then you have the 305 AFR, with with full cnc chamber and 2.25 valve, and 325 with 2.30 valve. Both flowed on a 4.310 bore. The 325 does flow a bit more air, past about .400 lift. The 325 and 305 cost the same money. My guess, is BOB M, supplied Tim with the 325 head, for that reason. Thats a tough call there. The 305 cross sectional area, seems to have a better fit for the rpm range tim runs. The question is, what will make more power? The head with less flow and a more textbook cross sectional area, or, the head that simply flows more air?
315
Int 169 249 312 353 380 386
Exh 146 184 238 271 296 310
.200 .300 .400 .500 .600 .700
325
Int 170 242 304 342 372 390
Exh 145 195 244 266 274 280
.200 .300 .400 .500 .600 .650
305
Int 168 242 303 339 360 362
Exh 142 187 225 252 271 274
Its easy to see, why the cnc ported 315 would make more power than a 325 AFR with full cnc chamber. The ONLY place the 325 flows more, is at .700 lift. It flows a whopping 4 cfm more than the 315. Other than that, from the time the valve comes off the seat, the 315 simply flows more air, both intake and exhaust. And, it does so, with a smaller valve. Anytime you have a smaller port , flowing MORE cfm, its a safe bet, its gonna make more power, and have better velocity. The 315 was flowed on a 4.600 bore fixture, while the 325 was flowed on a 4.310 bore, but even still...
Then you have the 305 AFR, with with full cnc chamber and 2.25 valve, and 325 with 2.30 valve. Both flowed on a 4.310 bore. The 325 does flow a bit more air, past about .400 lift. The 325 and 305 cost the same money. My guess, is BOB M, supplied Tim with the 325 head, for that reason. Thats a tough call there. The 305 cross sectional area, seems to have a better fit for the rpm range tim runs. The question is, what will make more power? The head with less flow and a more textbook cross sectional area, or, the head that simply flows more air?
Last edited by MILD THUNDER; 01-23-2017 at 06:35 AM.
01-23-2017, 06:45 AM
#79
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My rough guess, is the 305 would have possibly made a bit more low to midrange power, and the 325 would take over at some point. Where that tradeoff occurs, is unknown. Is it 3500, 4000, 500, or 6500rpm?
None of that matters though, if the cam is too short, or the exhaust is wrong, etc.
BCK had the 305s on his 540s . If i recall, out of the gate, he made around 670hp with the 4150 carb, with no accessories and huge dyno headers. Tims , had full wet exhaust, and accessories. I am pretty certain, tims would have got really close to 660-670hp if he dynoed with big dyno headers and no accessories. With an intake swap, and dominator, and some more tuning, maybe we could have saw 700hp from that combo.
Problem is, he doesnt have dyno headers in the boat, and needs to run alterator, sea pump, ps pump, etc. Imo, 700hp with all that installed on a 540, all in by 6000rpm, is not an easy feat, and isnt going to happen with a cam thats short on duration. Jmo
None of that matters though, if the cam is too short, or the exhaust is wrong, etc.
BCK had the 305s on his 540s . If i recall, out of the gate, he made around 670hp with the 4150 carb, with no accessories and huge dyno headers. Tims , had full wet exhaust, and accessories. I am pretty certain, tims would have got really close to 660-670hp if he dynoed with big dyno headers and no accessories. With an intake swap, and dominator, and some more tuning, maybe we could have saw 700hp from that combo.
Problem is, he doesnt have dyno headers in the boat, and needs to run alterator, sea pump, ps pump, etc. Imo, 700hp with all that installed on a 540, all in by 6000rpm, is not an easy feat, and isnt going to happen with a cam thats short on duration. Jmo
01-23-2017, 10:12 AM
#80
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I have 325s on my 502/575sci, bought them because of the price and they had already been checked/set up for Marine application. Have never fired the motor since rebuild so no idea how it will perform, maybe dyno this spring.
My 548s have Dart 360s which teague specd out...
My 548s have Dart 360s which teague specd out...
