Anybody hand-port their NPI heads?

Discussion in '96-04 - 2V Specific' started by Burninrock24, Jun 5, 2013.

  1. lwarrior1016

    lwarrior1016 Moderator Staff SN95 Supporter

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    I know this isn't the "show us your f250" thread but I'm posting 2 irrelevant pictures anyway lol.

    Tear down
    [​IMG]


    This is what I found, and the only picture I have before the port work. It's kind of hard to see the difference because this one is so filthy. Thank you dinosaur oil and crappy pcv system.
    [​IMG]

    After porting
    [​IMG]

    Buttoned up
    [​IMG]
     
  2. 96blak54

    96blak54 Legend

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    Wow! This thread has all kinds of good tech!

    Justa wanted to throw this bit of info in here. Im sure you guys will appreciate.

    The modular 2v heads compared to pushrod heads excel in every way. Chamber design, plug placement, overhead cam efficiency, and lastly but the biggest improvement is valve angle. While pushrod heads valve angle is nearly perpendicular to the port or angled towards the intake entry side of the head, modulars are the opposite towards exhaust. Why is this a major contributor to performance? Straight shot flow! A pushrod valve interfers with the incoming blast shooting through the port while modular allow the shot to skim over the valve.
     
  3. 96blak54

    96blak54 Legend

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    Chatting with a fellow modular enthusiasts yesterday brought on some curiosity of intake valve seat dimensions, such as valve seat o.d., I.d., and thickness. Poking around on different 2v heads I find the I.d. of npi and pi heads very different. One could classify a significance better than the other through the opening of the hole itself. Although from the factory more art work has been applied to the pi intake seat, the npi head has a .050" bigger I.d. seat. Your probably thinking like me, "i thought the intake valve for both heads are the same size?"......well....they are. A 4" valve will do no better than a 1"valve if the seat I.d's are of the same size.

    Im not stating one head is better than the other based on valve seat I.d. hole size. Either head comes with their strong points and weaknesses, but in the world of performance bigger generally is better. Its a proven fact that a hole will only pass a certain amount of air freely within its means and that a bigger hole naturally will pass more. Although this holds truth, the pi heads valve seat shape can pass equal amount despite that its I.d. is .050" smaller all because the art work of the seat. 3angles and back cuts on the seats bottom, port shape, dips crevices, sharp edges allow the air to slip through more efficiently by using the science that air does when flowing over such scenarios, were as the npi head is just one angle and one back cut, a few diverts, and depressions before the seat. So is their a benefit opening up the pi seat like the npi size? Good question, but their is a huge improvement doing a valve job to a npi head! Ive read more than 20cfm just by adding 3angles to the seat. Pi heads do not require valve jobs. Only cleaning the mating seat surface.

    In conclusion here,....adding this once again....when both heads are set up in the same scenario (same cam, intake, compression) neither out performed the other by any significance. Lets remember, its the pi compression bump on the npi shortblock that everyone see's.
     
  4. 96blak54

    96blak54 Legend

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    Adding to this post

    I failed to leave out some very important info about the straight shot flow. Since the valve tulip is not in the way and the rush skims over the valve, this maximizes the in cylinder swirl. Having this valve angle creates an awesome in cylinder swirl that never slows down, keeping the mixture more active throughout the chamber as the piston intake strokes. If the valve were an interference to the port, like in 95% of heads(old dinosaur engines), the rush gets walled at low lifts and needs to disburst 360* around the valve causing more interruptions, until the valve is at full lift were the shot is straight. Not to mention valve shrouding as its one down fall of the valve angle. Also including different flow patterns as the valve opens and shuts. This kills low lift flow, low lift cylinder swirl, homogenous condition and a wall to Helmholtz resonance flow when piston is past BDC.
     
  5. 96blak54

    96blak54 Legend

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    Once again adding more to this thread

    I wanted to add a link to this npi head thread about being able to use a 1.900" intake valve. I watch this threads view count often and seems to get traffic. I can appreciate good tech especially when its organized.

    So this link shows how a 1.900" valve can be installed into a npi head on top of a stock bore engine with the proper modifications. No modifications when using a big bore.

    http://www.sn95forums.com/showthread.php?70998-Stock-bore-1-900-quot-intake-valve-)
     
  6. DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    Sticky?
     
  7. 96blak54

    96blak54 Legend

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    SWEET!
     
  8. Silver95bird

    Silver95bird Active Member

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    5.4l heads different?

    Okay, I hope nobody minds me joining in the conversation here. I joined this forum directly to reply to this thread, it's that good. I got searching into 5.4L things because I'm going to be acquiring a 5.4L engine soon (for free), so I'm learning as much as I can about them. The engine has F75E heads with "5.4L" stamped into them (NPI).

    I knew that there were revisions in NPI heads, such that some things like high-lift cams won't go into the older F1AE/F4AE heads as easily as the F5AE's, but I kind of assumed development basically stopped there. Since there are at least 2-3 different NPI Windsor heads, how many/ which ones have the more open exhaust ports? Has anyone flowed a set of these different castings? It's kind of hard to tell from some of the pictures, but how much more open are we talking?

    One of the long standing NPI/PI relationships was that the intake/exhaust flow ratio was a little better for NA from the NPI heads, and the PI heads were a little more favorable for supercharging. Is that now in question? Then there's the whole what happens if we try 5.4L heads on a 4.6L, and vice versa. Oh, and if this isn't enough, let's ask those questions all over again once we start porting the heads. I know it's a lot to throw out on a first post, but this got me curious.

    Are we having fun yet?
     
  9. 96blak54

    96blak54 Legend

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    Who is this? What is your screen name on tccoa forum?
     
  10. 96blak54

    96blak54 Legend

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    1st question
    We all are glad you are here! Dont be shy to represent your bird over in the build thread.

    2nd
    My findings of 5.4l npi head is revised with bigger water cavities, opened exhaust bowl and port, and thicker deck surface. Intake port is the same, valve seat cut is the same, bowl contours the same. Chamber shape the same. Nearly all the same except exhaust port, water cavities, thicker deck.

    A 4.6l npi crutch is the pinched exhaust port and can wake up a npi engine just by carving it open. The 5.4l head already has the opening needed, plus the port has a ton of material if more area is desired. Why baffles me, but options to the builder.

    Nearly 98% of all heads ever made were designed with the valve angle towards the inside of the engine, making the intake valve tulip an obstruction / obstacle for the incoming blast of air.....needing all 360° of the valve opening. Not to mention flowing caracteristics over the valve at different valve lifts. Modular heads valve angle is towards the outside making the valve tulip non-obstructive to the port angle allowing the blast to skim directly over the valve backside regardless of any lift....not needing 360° of valve area. Heck, the valve is shrouded 75%!! Chamber shape along with plug placement flowing along with cyclonic action(better known as swirl) Couple all this with a tiny bore means a nasty swirl that is uniformly stratified (meaning the same action through out the bore during incoming stroke). Detonation resistance. Preignition is truly eliminated.
    This is why the mod 2v is so mighty!

    With all this said, porting a set of npi heads is almost fool proof. Pi heads,...different story. A little more tricky.
     
  11. 96blak54

    96blak54 Legend

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    A ported exhaust port isnt much better than a tiny port, unless its pinched like the 4.6l npi head is. What im getting at here is the port size is ample enough to support the valve diameter. The valve diameter really determines camshaft exhaust duration. Story short....a tiny exhaust valve will need more open camshaft duration to allow ample cylinder bleeddown(not a bad thing here). A big exhaust valve doesnt require long exhaust valve opening for bleeddown, allowing for a short duration. Equally meaning a tight lobe seperation angle.
     
  12. Silver95bird

    Silver95bird Active Member

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    Same name over at tccoa, I just don't visit as often over there these days. Having kids really does it to you. lol.

    If I read between the lines right, you're basically saying that the 4.6L's port gives up a ton in flow, even considering the tiny valve. The 5.4L port at the very least (in stock form) can basically make the most of the stock exhaust valve arrangement. I was working in towards the camshaft duration aspect (and I agree), but how much the cam duration should change I would expect would really vary depending on how different that exhaust port flows. I'd still love to see some flow listings to compare them to the other 2v heads, stock for stock. Do the PI heads for a 5.4L vary at all from their 4.6L counterparts like this?
     
  13. 96blak54

    96blak54 Legend

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    Yes, even the pi 5.4l brothers are revised although I only know of ther water cavities are bigger. Ports appear the same, but that doesnt mean much. Hard measurements are needed. Im a npi guy...lol
     
  14. Silver95bird

    Silver95bird Active Member

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    This may turn out to be quite a discovery. Maybe not so much for the NA guys, since the ratio of intake to exhaust isn't as bad, but for the NPI SC crowd it may help a lot more. If the exhaust flow is noticeably better on the 5.4L heads, then someone grinding a custom cam for an SC'd modular with these heads would run the smaller exhaust lobes and tighter lobe separation, netting about the same overlap - but how much will that shift the shape of the torque/hp curves?
    Also, even if sticking with an off the shelf cam like the NPI comp 262s or a stage 1 or 2 MHS cam, the better exhaust flow should evacuate more of the outgoing charge before the intake valve opens. This should allow more fresh charge in, especially if there's boost pushing it in. Will the increase in flow help reduce the temperature inside the cylinder enough to lessen the risk of detonation, or make more power in that next cycle? Remember at WOT the incoming fuel helps cool the hot spots down, and effectively the more that happens the more of the liquid fuel vaporizes as it absorbs the heat. Not a bad deal. If that next cycle doesn't have to fight the outgoing charge, more air should come into the cylinder given the same blower pulley/rpm. Any chance that reduction in backpressure (boost) helps reduce the IATs?
     
  15. 96blak54

    96blak54 Legend

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  16. Silver95bird

    Silver95bird Active Member

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    That's fascinating. 1.90 is a serious valve even on a 302. Proving that it can be done opens a lot of possibilities. For me though, I have to wonder how much valve is overkill considering the tiny npi exhaust valve is now closer to the bore. Or is it not overkill? Most ptv clearance issues are on the intake side, how much does that situation change with larger, offset valves? I'm interested to see how the flow changes with the offset, even with stock valves. When does the offset/ larger intake become restricted by the changes in moving the exhaust side ?
     
  17. 96blak54

    96blak54 Legend

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    If you think about it.....Its not overkill when you consider stock npi performance compared to upgraded npi performance. And lets not forget....for both valves in that tiny bore, shrouding is guaranteed.

    70% of exhaust is evacuated directly as the valve cracks away from the seat.(thats why you hear the bang) The remaining 30% is the bleed down and 1.4" is adequate. Maybe not a 5.4l or for more rpm from a 4.6l, but adequate.

    The biggest 4.6l head restrictions are pinched ports. Opening the ports and grinding out the pinchs brings the heads to a little better than pi heads. Valve jobs, chamber work further improves, but who in their right mind will spend the coin on npi work? "Hey just pi swap it"....thats not me.

    Now lets crank it up and do this bigger intake valve and shift the head(or combo of both bigger bore and shift, reducing the needed amount of shift).

    Its the piston intake stroke choking the engine out. As one piston is in combustion,....7more are in limbo preparing or finishing out a cycle. That one combustion does alot ...and also propels the cars weight. If the engine cant make it self suck the air in easily, performance is compromised. Its true the power potential is within the exhaust bleeddown. Slow bleeddown coupled with reduced intake restriction can carry us to the next level with stock (junk) heads.
     
  18. Silver95bird

    Silver95bird Active Member

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    This is worlds away from where I started, which was simply looking into whether anybody goes gasket matching on the exhaust ports. I feel like we're down the rabbit hole now. How big of a difference in sockets are you finding it takes to pass through the 5.4 heads vs the 4.6? Back to my original query, it looks like gasket matching a stock 4.6 head really won't do much without opening around the guide, but there might be a little improvement on a 5.4L head from it. We really have to get access to a flow bench. I bet the results would be eye opening.
     
  19. Silver95bird

    Silver95bird Active Member

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    [​IMG]
    I know it's a small image, but it's what I could find. you can see how the intake port come in at a different angle than the old SBC/SBF does. Not a 90* turn, then another basically 90* turn when it hits the valve. It also demonstrates why it's crazy to just totally remove the swirl fin - the air mainly flows away from it anyway.
     
  20. 96blak54

    96blak54 Legend

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    Exactly about the swirl dam. Its there to keep the swirl swirling down and not re-entering into the rush