Those 99-01 cobra cams do even out the better head flow design of the newedge Mach1's!
____________________________________ 01 blk cobra coupe with s281 Saleen conversion. NX Wet Kit, 4.30 gears, pro 5.0 w MGW shift handle, Borla stingers, MRT catted H-pipe, U/D pullies, minor weight reduction. JLT CAI , predator, RWTD custom tune, 305/35-18 Nitto DR, 18x9 ,18x10 saleen wheels, H&R ss springs, MM isolator and cc plates,Hawks brake with slotted and dimpled rotors. Sub frame connectors, KB boost a pump. Aluminum driveshaft. Fidanza aluminum flywheel, Centerforce DF. HID. Tokico D-specs.
are there any ptv modifications needed to bolt on a set of 03/04 heads on a 99 shortblock with a set of fr500 cams?
No PTV issues with a stock shortblock and FR500 cams. The FR500 cam kits are no longer available...but I have one kit left if you're interested in getting one.
Here is the Dyno difference between the '01 heads and the '03 Mach 1 heads.
Same car, same dyno, same tune. Only changes are the cylinder heads and a Melling Billet Oil Pump. I can't imagine the oil pump making any real difference.
Note, the 2008 run is with the '01 heads and the 2009 run is with the '03 Mach 1 heads.
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Jeff White
2001 Cobra Coupe
NA Mod Motor 329rwhp/344rwtq
The stock 99/01 or 96-98 cams probably would have made more power.
It does look like the 03/04 heads outperformed the 99/01 heads when just looking at the dyno graph, but there are a lot of variables in the heads that could result in mroe or less power. Those are combustion chamber size, valve sealing, and lash adjuster preload. A good valve job alone can increase over totally stock heads. Were the 99/01 heads fresh? Were the 03/04 heads milled? Then there are the dynos, they were done a year apart. The tune itself could have had more or less timing, a/f could have been more lean or rich, etc.
The stock 99/01 or 96-98 cams probably would have made more power.
It does look like the 03/04 heads outperformed the 99/01 heads when just looking at the dyno graph, but there are a lot of variables in the heads that could result in mroe or less power. Those are combustion chamber size, valve sealing, and lash adjuster preload. A good valve job alone can increase over totally stock heads. Were the 99/01 heads fresh? Were the 03/04 heads milled? Then there are the dynos, they were done a year apart. The tune itself could have had more or less timing, a/f could have been more lean or rich, etc.
I am making no claims about which heads are better, I'm only posting my results. The 01 heads were stock with about 25k miles on them. The 03 heads had a minor clean up (mill). The tune had the same timing and the same moderately rich A/F of 12 - 12.5 thru 6500 rpms then 11.5 above 6500. The block is a 4.6L stock block bored 0.020" over with a stroker kit.
p.s. I didn't switch to 03 heads for the increased power but as a cost effective replacement to my 01 heads that got trashed when my oil pump died on track and f'd up my 01 heads.
I am making no claims about which heads are better, I'm only posting my results. The 01 heads were stock with about 25k miles on them. The 03 heads had a minor clean up (mill). The tune had the same timing and the same moderately rich A/F of 12 - 12.5 thru 6500 rpms then 11.5 above 6500. The block is a 4.6L stock block bored 0.020" over with a stroker kit.
01 blk cobra coupe with s281 Saleen conversion. NX Wet Kit, 4.30 gears, pro 5.0 w MGW shift handle, Borla stingers, MRT catted H-pipe, U/D pullies, minor weight reduction. JLT CAI , predator, RWTD custom tune, 305/35-18 Nitto DR, 18x9 ,18x10 saleen wheels, H&R ss springs, MM isolator and cc plates,Hawks brake with slotted and dimpled rotors. Sub frame connectors, KB boost a pump. Aluminum driveshaft. Fidanza aluminum flywheel, Centerforce DF. HID. Tokico D-specs.
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