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  1. #41
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    Quote Originally Posted by Bobw View Post
    Just to throw some fuel on the fire.. What is an "Ideal" port shape..

    WHAT is the GOAL? What are we trying to achieve here?
    Simple, to maximize the flow throughout the range of valve lift with the given constraints. If you were starting from scratch then many of the constraints would be eliminated.
    Four valve heads have a narrow included angle to straighten the bend of the port at the valve and minimize the combustion chamber area. If not constrained by height you could leave the valves with a wider angle and bring the port in from the top, eliminating most of the flow going out the exhaust valve on the overlap.
    If you are not constrained by using poppet valves you could go to rolling sphere valves to eliminate the float.

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    Quote Originally Posted by magno_grail View Post
    Simple, to maximize the flow throughout the range of valve lift with the given constraints.
    Good thing you are not building race motors.

  3. #43
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    Quote Originally Posted by snowshooze View Post
    Well...
    I know this.
    But, once a design has been proven...
    After that, it is just production.
    If you really believe that, I have a bridge to sell you.

  4. #44
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    Quote Originally Posted by magno_grail View Post
    Simple, to maximize the flow throughout the range of valve lift with the given constraints. If you were starting from scratch then many of the constraints would be eliminated.
    Four valve heads have a narrow included angle to straighten the bend of the port at the valve and minimize the combustion chamber area. If not constrained by height you could leave the valves with a wider angle and bring the port in from the top, eliminating most of the flow going out the exhaust valve on the overlap.
    If you are not constrained by using poppet valves you could go to rolling sphere valves to eliminate the float.
    I've got a Fiat with "multi-air"... Which is a really stupid name, but its really cool. And the mechanical side
    of it is really simple. Its basically a big giant hydraulic lifter that can be bled off. Its only on the intake valves.

    But its cool, low rpms, the duration is very short, torque builds quick, and then from about 3000rpms up to redline,
    which is 6600, the torque curve is just flat. It feels really weird, and you have no clue when to shift.. Normal car,
    truck, as you are running through the revs, your power is building, and you can feel the increase in acceleration, and
    when that starts to slow down, you can feel when you need to shift. Not with this thing, its just flat, the acceleration
    is constant.. Its kind of cool..

    Also doesn't have an EGR valve, when its cold, it will burp the intake valves and let some burnt stuff back into the
    intake. And when you have the cruise control on, and heading down a big hill, it will just completely shut the intake
    valves down to increase engine braking.. And apparently, when just cruising, it leaves the throttle plate wide open, and
    adjusts speed and power using just the intake valves..

    Neat little system. Though it does require a second oil pump since you are using the engine oil as a hydraulic fluid,
    and it requires keeping your oil CLEAN.. The mechanicals are simple, but I couldn't imagine the difficulties in
    programming it, that had to be a nightmare.

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    Quote Originally Posted by snowshooze View Post
    Hi guys;
    I have been doing some cylinder heads, and there is call for porting and polishing.
    Well, that gets too far off track for me, unless I could come up with proven CAD models, I just don't have the time or inclination to start doing port designs and doing all the dyno work and tail chasing...
    I make chips.
    Does anyone know if there is a source for proven cylinder head port cad models?
    It doesn't look like it so far.
    Thanks!
    Mark

    Maybe I missed it...Might help to narrow it down to type of engine, cylinder head type, and intended use.

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    Quote Originally Posted by Bobw View Post
    Are we just looking for PEAK HP.. OR.... are we looking for a big wide power band,
    a ton of torque all throughout. Something that is FUN to drive, and probably faster,
    even with a lower peak HP number.
    .
    Which is where the art part comes in.
    Drag race, offroad, short track, Daytona, boat, street car?
    All these like different porting and this comes from many trials and errors.
    CFM is only the start. Heck even changes to piston dome changes the best porting.
    As I said it it easier to loose power and driveability doing this than get a gain.
    I too was at "open up the ports", match and polish them mirror smooth. Lessons learned.

    Not sure what the OP has but cnc porting a head needs a bit of a fancy machine and very fancy tooling to get inside.
    Bob

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    Quote Originally Posted by CarbideBob View Post
    I too was at "open up the ports", match and polish them mirror smooth. Lessons learned.
    Do you mind sharing.. I'm curious. What did you do, and what happened?

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    Quote Originally Posted by CarbideBob View Post
    Which is where the art part comes in.
    Drag race, offroad, short track, Daytona, boat, street car?
    All these like different porting and this comes from many trials and errors.
    CFM is only the start. Heck even changes to piston dome changes the best porting.
    As I said it it easier to loose power and driveability doing this than get a gain.
    I too was at "open up the ports", match and polish them mirror smooth. Lessons learned.

    Not sure what the OP has but cnc porting a head needs a bit of a fancy machine and very fancy tooling to get inside.
    Bob
    Lots of new (young) guys in the performance cylinder head game. Bottom line is it takes good cylinder heads to make horsepower. Lots of people have flow benches now to develop cylinder heads and other equipment to build heads.

    Here's a link to one builder. One man shop which means he has a lot common with other machinists. Pricy equipment that needs to be paid for. Niche business maybe but there are a lot of players.

    Shop Tour and other useless info - YouTube

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    Quote Originally Posted by Bobw View Post
    Do you mind sharing.. I'm curious. What did you do, and what happened?
    If he's like the rest of us he 'ported' his small block and then it went slower, didn't idle as well, burnt more fuel, and was generally worse off than before he "improved" it

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    Take care to not use an electric die grinder..and burn it up.

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    Quote Originally Posted by michiganbuck View Post
    Take care to not use an electric die grinder..and burn it up.
    That's what real guys use, buck. Dumore makes a honkin' hefty one that doesn't burn up, even after years of use.

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    Quote Originally Posted by EmanuelGoldstein View Post
    If he's like the rest of us he 'ported' his small block and then it went slower, didn't idle as well, burnt more fuel, and was generally worse off than before he "improved" it
    I do not do small blocks. Big block Bob is the street money and race name.

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    Quote Originally Posted by CarbideBob View Post
    I do not do small blocks. Big block Bob is the street money and race name.
    Bottle liked those too, but Mouse Motor Sammy was the next door neighbor, so I'll have to pick the opposing team

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    Hahaha when ever someone says polish in the same sentence as port I consider them FOS

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    Quote Originally Posted by wheelieking71 View Post
    Huh what?! Nobody ports heads to tune a lean spot. WTF does FI have to do with head porting.
    People port heads for one reason, and one reason only: more power. And the fuel delivery method has nothing to do with it in an N/A engine.
    In order to make more power, one needs more air. No way around it.
    In order to achieve stoichiometry in the quest for power, 99.99999% of the time, air will be the limiting factor. Fuel is the easy part.
    Add a power-adder (turbo, blower, supercharger), and that can skew the equation. And, FI can help with the tuning.
    But said tuning is needed because: more air. Just like modified ports can achieve.
    You seem to mget it.
    Look, the guys that make the good ones... they are grown-ups.
    Been at it 20 + years.
    I can't reproduce their work, in a week, a month, or 10 years.
    But... with a good CAD model, I could do it in an hour.
    If I could hire them, I would not think twice of it.
    Hey, I am doing a 426 Wedge.
    What you got?
    That much?
    Ok, well, I better get 3 of them to make her pay...
    That works.

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    Quote Originally Posted by barbter View Post
    Excellent book this!
    Also if you're interested, "twice lucky" by Stuart Turner.
    and then there's Gordon Jenning's 2 Stroke Tuners Handbook

    2 Stroke Tuners Handbook by Jennings, Gordon: Good Paperback (1987) | HPB-Red

    Personally I prefer 2-strokes over 4-strokes. More fun, cheaper to fix, sound better.

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    Quote Originally Posted by triumph406 View Post
    Personally I prefer 2-strokes over 4-strokes. More fun, cheaper to fix, sound better.
    RG500 or NSR250 ?

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    Quote Originally Posted by EmanuelGoldstein View Post
    RG500 or NSR250 ?
    Neither, I'm more into off-road 2-strokes. Current bike is a Suzuki RMX250, a semi-tamed RM250 with lights and a large tank.
    p1014248.jpg.69f71248866c5b025366403481eb69e9.jpg

    What I would like though is a bike I saw coming out of a Meon Valley (Hampshire UK) petrol station maybe 35 years ago. It was a Suzuki GT750 engined Dresda framed cafe racer. Made a racket that would raise the dead.

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  22. #59
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    Quote Originally Posted by snowshooze View Post
    You seem to mget it.
    Look, the guys that make the good ones... they are grown-ups.
    Been at it 20 + years.
    I can't reproduce their work, in a week, a month, or 10 years.
    But... with a good CAD model, I could do it in an hour.
    If I could hire them, I would not think twice of it.
    Hey, I am doing a 426 Wedge.
    What you got?
    That much?
    Ok, well, I better get 3 of them to make her pay...
    That works.
    Ah, the 426 wedge. Long, long time ago I played with one. A real Max Wedge. Crossram and Max Wedge heads, and not that they needed help, they were ported. Hemi 8 bolt flange crank, lots 'o compression, Milodon swing pickup--4 speed car
    -all the Super Stock stuff. Heavy engine--scary fast top end. Big dollar collector parts now-a-days. Am surprised that there would be enough demand for CNC ported "B/RB" motor heads. Anyone ever do Max wedge head castings?

    EDIT---"snowshooze"....Went down the "B" motor rabbithole...gonna have to broaden my horizons beyond SB Chev....The "B" motors are still a "thang".... Man, them "B" motor heads can flow...Stan Weiss' - Cylinder Head Flow Data at 28 Inches of Water -- DFW / FLW Flow Files for use with Engine Simulation Software
    Last edited by standardparts; 10-21-2021 at 07:51 AM.

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    Quote Originally Posted by wheelieking71 View Post
    Huh what?! Nobody ports heads to tune a lean spot. WTF does FI have to do with head porting.
    People port heads for one reason, and one reason only: more power. And the fuel delivery method has nothing to do with it in an N/A engine.
    In order to make more power, one needs more air. No way around it.
    In order to achieve stoichiometry in the quest for power, 99.99999% of the time, air will be the limiting factor. Fuel is the easy part.
    Add a power-adder (turbo, blower, supercharger), and that can skew the equation. And, FI can help with the tuning.
    But said tuning is needed because: more air. Just like modified ports can achieve.
    Huh what?


    Computerized fuel injection is more cost effective than playing with porting

    That is my point.

    Flow is important, but what flow. when?

    On a carbureted car large ports cause low velocity and poor fuel distribution at idle. Fuel injection and be programmed to eliminate that.

    You can add more horsepower with a good fuel injection tune than all the porting you want.

    Not saying porting is 'bad'[although as mentioned, much of it is done badly]

    Full emission cars are running much higher horsepower per cubic inch than the fanciest ported an polished carbureted cars ever did, and they idle, start from cold and don't stink.

    And they aint polished.


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