Comparing 4.6l head flow and cams to the pushrod 5.0

Discussion in '96-04 - 2V Specific' started by Silver95bird, Sep 12, 2016.

  1. Silver95bird

    Silver95bird Active Member

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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:
     
  2. DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    These are the types of posts that were going on back from 1999-2004 on the forums. Most of that info is long gone especially since the better tech forums like modular depot and modular powerhouse are gone.

    The corral and stangnet had good info but server changes etc wiped out early stuff.

    This place came along a bit late for the 2V revolution.
     
  3. JerZeyStangz

    JerZeyStangz Well-Known Member

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    Thank for this post. I like learning more than the average knowledge on modular platform, heck all engine platforms. On the NPI head when the percentage goes up does that mean its good or bad? because you said the head likes a ration between 70/80 +/- 10%.
     
  4. Nighttrain

    Nighttrain Well-Known Member

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    If you can even find a cam manufacturer thatll give you real cam numbers. With the head design the only thing really limiting a 2v head is the valve size. Blak went over that as well....i dont know off the top of my head but unless you change that a larger lift intake lobe may not help because of this. Shroud is already minimal because of port design.
     
  5. Silver95bird

    Silver95bird Active Member

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    I agree. I was never on modular powerhouse, but i was more a lurker than a poster at MD. It was a real shame that got wiped out. Tccoa is about the only place that might still have all the original work by JL and kdanner from the early NPI days. Corral and stangnet just have too much bad information to sort through. MD was a bit better, but not always. There was this constant uphill battle that all NPI heads were boat anchors, despite JL's Tbird (which is equal to an sn95 with a 500lb gorilla riding shotgun) going low 12s N/A. After reading their PI cams/intake post, I did the swap to my 97. The intake alone was night and day. I even had a post where I had figured the cross-sectional area of the NPI intake runners, and they weren't even close to the NPI port size at the head. That damn intake is probably 75% of the reason PI headswaps caught on in the first place, lol.

    Jerzeystangz,
    It's not that there's a magic number. It's about getting a combination of parts that are all aimed at making power the same way. Running supercharger cams on an N/A car might be better than stock, but they're not going to be optimal. The difference in the flow ratio between pushrod and modular heads isn't necessarily a problem, but I personally wouldn't use the same type of cam profiles for both. In the modular's case, it's high enough to explain why it seems so hard to make power N/A, but so easy to do well supercharged. Keep in mind, the shm numbers I used are the 4.6L heads, and the 5.4L heads 96blak54 found have even better ports on the exhaust than the 4.6's do. That means on those heads the percentage would be even higher.

    Personally, if I were going to do some experimenting, I'd start by flowing the 4.6L head and the 5.4L head back to back. Then I'd flow them both with just the offset dowels, to see how much the exhaust shrouds up, and the intake frees up. You wouldn't think much, and maybe it wouldn't be on a 302, but the 3.55" bore makes it tougher. If I were going farther, I'd probably try 2 or 3 different increased size intake valves and see what each gives, but it looks like 96blak54 is going right for the throat the first time. lol. I was a little skeptical at first, but I'm coming around to his conclusion the exhaust isn't the main problem - and it's made worse by not having decent off the shelf cams that are meant to work with the head flow patterns. Without a little more research on the subject, I'd love to see what a cam like the cms stage 1 and 2 NPI N/a would do if the intake/exhaust lobes were swapped out for each other. Keep the lobes tight, keep the overlap the same, just swap the durations around.

    Nighttrain,
    I agree the intake side is the bigger limitation, especially after the data I've posted here. The cam problem becomes one where PTV can't be ignored either. If we stick to off the shelf cams, to get more intake charge into the cylinder we have no choice where we can leave the exhaust alone and only increase the intake side. This means we either end up increasing the lobe separation (like the Comp cams) or increasing the overlap to get more intake flow. Either of those changes in my opinion distorts the peak and the width of the power band and makes the situation worse. Look at the Comp back-to-back magazine article and you'll see what I mean. Degreed properly, it appears lobes far bigger than the XE270AH can be made to fit, though much bigger than that would likely be too much for a street car. I think I've basically made the case for the custom ground cams route. Otherwise, you end up trying to make up for the cams by trying to port the heads to work with the cams on the market. That's crap. I really gotta build a flowbench, lol. All it takes is cubic money.
     
  6. JerZeyStangz

    JerZeyStangz Well-Known Member

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    Now I want to go do a PI intake swap until I have enough money for trickflow heads and a SVO blower. I still do not know what cams I should run with that setup. I am probably going to run the blower between 6-9 PSI to keep it in the optimal range for power. Moving back to the PI swap, would a ported PI intake benefit on NPI heads or you just should use stock PI intake on the NPI heads/cams.
     
  7. Thomas_W

    Thomas_W Well-Known Member

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    From experience.

    Dont spend the $$$ on the SVO blower. Since its non intercooled its limitations are pretty big. Save the $$$ for a KB. There also isnt enough material on the SVO blower to Port match the blowers intake ports to the PI/trickflow head ports without some substantial custom work and welding
     
  8. JerZeyStangz

    JerZeyStangz Well-Known Member

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    Understood, at the price point you can get them at they can become a great street blower as long as you do not crank them all the way, obviously any twinscrew is superior but that comes with a heavy price tag on top of TFS heads. I think the real benefit with this blower is the torque it makes and if it can give over 100ft lbs then i'm in. I am not looking to go past a certain limit because my engine is not built and wont be for a long time. I am aiming for more of a sleeper look with the power similar to big block. Anyways, you never know you can probably find KB 2.1 kits for sale for half the price these days.
     
  9. Thomas_W

    Thomas_W Well-Known Member

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    I made 400rwhp with the SVO blower on a PI motor with crower stage 2 blower cams. The car made that reliably, but on hot summer days, You could literally feel it was significantly underpowered.
     
  10. JerZeyStangz

    JerZeyStangz Well-Known Member

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    You make me want to cry Thomas, I probably have 200rwhp on a good day!
     
  11. Nighttrain

    Nighttrain Well-Known Member

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    400 is completely doable na. It may be quicker just boosting it but why not go for broke! Being in jersey salvage and used parts especially for our cars are numerous. Find yourself a forged rotating assembly and start the build!
     
  12. Thomas_W

    Thomas_W Well-Known Member

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    haha. We've all been there man. Ive had a bunch of different setups on different cars. Nitrous, motor, roots blower, centri-blowee, single turbo and soon to be a twin turbo car.

    Honestly of all those setup, the single turbo car was the most fun to drive. Then again it was throwing down about 700rwhp on low boost and a small turbo. Lol
     
  13. DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    They did make one for PI heads. Not many of them out there though.
     
  14. 07GtS197

    07GtS197 Well-Known Member

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  15. Thomas_W

    Thomas_W Well-Known Member

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    They did. In total, ive seen 3 PI head SVO blowers. All were complete kits and all were being listed for $6k+.
     
  16. Silver95bird

    Silver95bird Active Member

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    A PI intake manifold would be worthwhile until you gather all the parts for your supercharger setup, and they're always being bought/sold on corral so you could get your money back if you go SVO blower someday. Personally, I don't know if I would go changing heads if I were going SVO blower, but for expense reasons I've never really gotten that deep into the trickflow heads so don't base your judgment on me. I swear I remember nick mckinney saying something about the valves being moved changed the way the cam rides, and that most cams weren't meant to work with them. I'd have to dig that up if you're dead set on the trickflow route. As far as porting goes, you really can't port the factory PI intake or the later NPI intake. you could port the old aluminum NPI intake, but it still wouldn't be as good as a stock PI intake. If you wanted better than the stock PI intake, you'd go to the SVO (n/a) intake, or the Bullitt intake, depending on if you're going NPI/PI. Either one is fairly expensive, but on a max effort N/a engine they're worth it.

    What are your plans for the car? How much power do you want? An SVO blower can be ported to PI ports if it's not, but if you're looking into it I'd get over to tccoa. Here's the thread where cableguyjjs3 had his done. Doesn't look like it was all that hard.
    http://forums.tccoa.com/952-roots-type-superchargers/133238-porting-svo-blower-2.html
    If you want a fun street car and a lot more torque, the SVO and a set of blower cams will likely get you where you want to be. Dyno numbers aren't everything. The SVO blower is famous for not making big dyno numbers, but running well at the track. Talk to sneaky98gt, he had a lot more experience than I do with different combinations and how they run. Maybe this thread would help:
    http://forums.tccoa.com/952-roots-type-superchargers/144066-svo-pulley-would-you-run.html
    You can always add water/methanol injection later and it'll wake it up a bit. If you're dead set on 500hp, you'll want an intercooled blower.
    400 n/a is possible, but you'd have to hate your wallet to go that route. I'd get an intercooled blower if I were going that route, it's simpler and easier in the long run IMO. I'd run the SVO if I wanted more torque in a sleeper package, kind of like going 5.4L swap. If you don't point it out, a lot of people won't notice the difference.
     
  17. Thomas_W

    Thomas_W Well-Known Member

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    I do have to say, the SVO blower was great at being a sleeper. I had many a 4v guys talk crap on my slow NPI 2v car.

    [​IMG]
     
  18. JerZeyStangz

    JerZeyStangz Well-Known Member

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    My issue is that I dont have time or knowledge to put together a shortblock. If I were to ever go that route it would need to be assembled and someone help me put the heads/cams/intake, time it correctly, then button it all up. Something that I would pay a speed shop to do. I am DIY type of guy but I dont want to bite off more than I can chew. I wish some of you guys lived closer to me. :)

    I'm glad that the turbo setups were the most fun but I need to hit the first "iteration" of my car and that is some type of positive displacement blower with better heads/cams. Since my car is auto by default that would make it quite fun to drive.

    Coming from the man who knows his stuff ;)

    Honestly, I would get the blower inspected and pulled apart if there was a issue. I am betting that it is a isolated event but then again the blower is slightly ancient and things can go wrong when they are sitting around for a long time not being used.

    That's crazy I would of bought a Kennebell before I dropped 6k on SVO blower. I still love the cool factor and the sleeper status they give. If you paint the blower black forget about it. You will need a trained eye to even spot it from a quick glance.

    I'm really dead set on getting those heads because I really want maximum efficiency. I rather have heads the flow well so you do not need much boost to make great power. I remember L&M engines made statement about the heads not being properly matched to FORD oem PI cams. They needed cams specificially made "reverse grinds" so that the head is being utilized correctly. My goal right now is to have 380-430hp motor with the SVO blower and some mild cams, keep the shortblock happy until I can afford a built motor from L&M.

    Right now I have max bolt on's, only thing I am missing is the PI intake and a tune. I am very curious to see what my current setup would run at the track. I would be extremely happy if it pulled 14.1-2! I have exhaust, gears, pulleys, and t/b & plenum on a stock NPI tune.

    This is what I am going for! It looks like my car haha! Is your car pacific green or deep forest green metallic?
     
  19. Thomas_W

    Thomas_W Well-Known Member

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    If your looking for 380-430rwhp. You don't need a set of heads, you can do that with an SVO blower on 9psi with a set of Blower grind cams and basic bolt ons.

    That car was Pacific Green. I regret selling it, but its new owner has put a built 9" rear, forged/stroke Cobra 4v longblock, fast XFI, powerglide, cage and a 88mm turbo on it last i heard.
     
  20. JerZeyStangz

    JerZeyStangz Well-Known Member

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    It would be cool if he was on the board. Boost is a measure of restriction so if the heads can flow good I dont have to run 9psi, I would like to run something much lower like 6psi and see what I net.