Silver95bird
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- Sep 5, 2016
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Thanks to the threads and discussions of some of 96blak54's discoveries on porting of modular heads, it lead me to looking at flow ratios of various modular heads (stock, ported, npi/pi/svo, 4.6vs5.4, etc). For lack of a better starting point, I started comparing modular heads to a few 5.0L heads to see where we're at and what directions make the most sense to look into. I'll start with stock heads. Going with average flow from 0-.500 and using the numbers from shm, here's where the modular starts at:
NPI: 86.9% exhaust/intake
PI: 82.3%
SVO: 77.5%
Next I did the same thing for a few types of pushrod heads:
E7TE (stock GT heads): 70.1%
1969 351W Heads: 71.5%
gt40 (93 cobra): 75.7%
x306 (FRPP heads): 77.8%
I've tried trying to figure out what an "ideal" ratio is, but it's like asking about politics - everyone has a different opinion and no two agree. However, from both sets it appears the Ford engineers on both engines seemed to want to get somewhere between 75-80%. That's good enough for me. That means stock for stock, especially N/A, that the real restriction seems to be the intake side. It also explains why the modular engines love supercharging so well.
The next thing then becomes looking at cams. One would expect the patterns of cams to be much different considering the head flow characteristics are so different, but overall that's not seeming to be the case. Aftermarket cams for the 5.0 tend to favor the exhaust valve by 4-6 degrees, and favor the exhaust some times even on lift. Notably there's also the SVO letter cams, which are single pattern cams, though they're admittedly not the best by today's standards.
Now going to modular cams, with 12-17% more exhaust flow bias, we'd expect a lot more camshaft lobe bias toward the intake side. Nope. The cams really don't look that much different, though the pushrod cams are able to make it work with less duration on both sides. What gives? Even the stock PI cam favors the exhaust even more than the stock NPI cam. Perhaps from Ford they're more pushing for fuel mileage and emissions, but I'd expect the aftermarket to have picked up the slack. Ironically, I'd expect the letter cams to perform better in a modular than a pushrod. That is, except for the fact that Ford has shown less than zero interest in 2v cams in general.
The whole thing leaves me scratching my head. It looks like they aren't even looking at the modular before specifiying their "stages" of cams on the aftermarket. What gives? :shrug:
NPI: 86.9% exhaust/intake
PI: 82.3%
SVO: 77.5%
Next I did the same thing for a few types of pushrod heads:
E7TE (stock GT heads): 70.1%
1969 351W Heads: 71.5%
gt40 (93 cobra): 75.7%
x306 (FRPP heads): 77.8%
I've tried trying to figure out what an "ideal" ratio is, but it's like asking about politics - everyone has a different opinion and no two agree. However, from both sets it appears the Ford engineers on both engines seemed to want to get somewhere between 75-80%. That's good enough for me. That means stock for stock, especially N/A, that the real restriction seems to be the intake side. It also explains why the modular engines love supercharging so well.
The next thing then becomes looking at cams. One would expect the patterns of cams to be much different considering the head flow characteristics are so different, but overall that's not seeming to be the case. Aftermarket cams for the 5.0 tend to favor the exhaust valve by 4-6 degrees, and favor the exhaust some times even on lift. Notably there's also the SVO letter cams, which are single pattern cams, though they're admittedly not the best by today's standards.
Now going to modular cams, with 12-17% more exhaust flow bias, we'd expect a lot more camshaft lobe bias toward the intake side. Nope. The cams really don't look that much different, though the pushrod cams are able to make it work with less duration on both sides. What gives? Even the stock PI cam favors the exhaust even more than the stock NPI cam. Perhaps from Ford they're more pushing for fuel mileage and emissions, but I'd expect the aftermarket to have picked up the slack. Ironically, I'd expect the letter cams to perform better in a modular than a pushrod. That is, except for the fact that Ford has shown less than zero interest in 2v cams in general.
The whole thing leaves me scratching my head. It looks like they aren't even looking at the modular before specifiying their "stages" of cams on the aftermarket. What gives? :shrug: