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Guide on Head Porting

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  • #16
    Ahh OK - a trusted source then... not some geezer daan the pub
    Paul Nugent
    Webmaster http://S2central.net
    Administrator http://S2forum.com

    1994 S2 Coupe ABY - aka Project Lazarus
    2001 A6 allroad 2.5TDi - family tank
    2003 S4 Avant 4.2 V8 - daily burble

    Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

    There are only 10 kinds of people that understand binary - those that do, and those that don't

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    • #17
      ^^^^ @ S2central

      The head on my car is spec'd as follows.

      Intake valves backcut and swirl polished, Exhaust valves swirl polished, Intake seats 30, 45, 60,75 degree cuts of varying widths blended into the bowl. Exhaust seats 30, 45, 75 degree cuts of various widths blended into the bowl, fitted with tapered guides on the intake.

      I've only got dyno results of the engine with the 3" exhaust system fitted but no other headwork other than the above. Obviously the comparison being with that of the standard factory results it made a 10+% power gain with improved throttle response and midrange driveability.
      UrS6 Stroker + HTA3586 =

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      • #18
        TBH I didn't do much reshaping. Just getting rid of the casting marks and making the ports smoother. I didn't bother with the multi-angle valve cut either.
        I too was concerned about heat conducted by the guide boss, but I was told that most of the heat travels up the valve.
        SS

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        • #19
          @RWD - see I reckon most of that 10% comes from the 3" zorst... wouldn't you reckon ?

          If you had fitted the head to an otherwise standard car you would have a more objective result... But I know its not always possible to do things that way.
          Paul Nugent
          Webmaster http://S2central.net
          Administrator http://S2forum.com

          1994 S2 Coupe ABY - aka Project Lazarus
          2001 A6 allroad 2.5TDi - family tank
          2003 S4 Avant 4.2 V8 - daily burble

          Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

          There are only 10 kinds of people that understand binary - those that do, and those that don't

          Comment


          • #20
            i wish i'd kept the flow info from my 10v.it was the most interesting thing i've ever done with an engine.i even chopped the practice head in half to see where i got so close to the water jacket.i did,however,have a rolling road result of 148bhp.it was a 2226cc.
            Last edited by philS2; 30 January 2009, 18:25.

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            • #21
              ~150bhp is good for a KV engine... versus its 136bhp stock output... NIce gain from head work. Always wondered what you could squeeze out of one with an ECU controlled injection and ignition system on one. As much as the K-Jetronic is cool and ingenious and utterly bereft of any chips (in its simplest form) - its just not as efficient as a modern EFI system.
              Paul Nugent
              Webmaster http://S2central.net
              Administrator http://S2forum.com

              1994 S2 Coupe ABY - aka Project Lazarus
              2001 A6 allroad 2.5TDi - family tank
              2003 S4 Avant 4.2 V8 - daily burble

              Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

              There are only 10 kinds of people that understand binary - those that do, and those that don't

              Comment


              • #22
                your right there.once i'd put a cam in that kv,i got bored after a while so i was running a kg with an extra 4lbs of boost and a cam on standard js k-jet.i did eventually change the metering unit for a later one with potentiometer so i could see how much the plate was raising. it didn't get to the end of it's travel,but i didn't know where it ran out of fuel,but it was the best i could do without a AFR meter.the only trouble i've ever had with k-jet was when a needle fell out of the injector.it burnt two pistons out in that pot.i used to like it when people said 'did you put that braided hose on?'.i was interested in the weber alpha system when i first saw it years ago.
                Last edited by philS2; 30 January 2009, 22:58.

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                • #23
                  Jamo, which edition is that article from?
                  S2 Avant......fully loaded :rock: :bow: Slipper Wagons Rule !!!!!

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                  • #24
                    Originally posted by S2central.net View Post
                    @RWD - see I reckon most of that 10% comes from the 3" zorst... wouldn't you reckon ?

                    If you had fitted the head to an otherwise standard car you would have a more objective result... But I know its not always possible to do things that way.
                    As a reference on a different motor but pretty much the same port workup.


                    Standard rebuild KR 16v balanced but not lightened according to race series rules. Rebuild head with hiden seat and valve work as it was not allowed in the race series nor was any porting.

                    So the headwork consisted of:-

                    Swirl polished and back cut intake valves, refinished to look like OEM valves.
                    Intake seats original 75 and 45 degree cuts where kept and an extra 30 degree cut was added.
                    Swirl polished exhaust valves, refinished to look like OEM. Exhaust seats same configuration as the intake.
                    Cams where standard KR items.

                    Rest of the setup consisted of standard factory intake manifold and throttle body and kjet fueling setup as per race regulations. Standard factory exhaust manifold mated to a 2.25" exhaust system consisting of a centre and back box.

                    Factory hp is 137 not sure of factory tq. However the car made 166hp and 130ft/lb tq on the rollers after a short 400 mile break in period.

                    I can't believe knowing that flow figures where up over 10% on the head from standard proven on a flowbench that just the exhaust and tune up was good for 20% hp gains.
                    UrS6 Stroker + HTA3586 =

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                    • #25
                      Originally posted by RWD19T View Post

                      Factory hp is 137 not sure of factory tq. However the car made 166hp and 130ft/lb tq on the rollers after a short 400 mile break in period.
                      Standard Kr lump 126lb ft/4600rpm
                      s2 new project

                      On going !!!

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                      • #26
                        Does anyone have the rest of the mini series by vizard? His articles seem to be the best online and I have downloaded his diy flow bench article outa an american mag from way back in 80s judging by the pictures.

                        I have been giving a 20v head ago recently, the one thing I have done which I think will increase flow is in the exhaust ports, the opening in the head seems to be machined out to size. In doing so the cutter left a 90 degree step at ends of the divider (knife?) between the valves and the sides the ports dont marry up well with the hole end either. Other than that all thats been done is smoothing out the bumps.

                        Anyone got any good tips to follow? and is a 3 or 4 angle job kinda thing machine shops would deal with regularly?

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                        • #27
                          You can find more Wizard's writings at http://www.gofastnews.com/board/technical-articles . It kind of was his site, but he's not posting there anymore.

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                          • #28
                            Originally posted by Jamo View Post
                            I've been told the biggest gains can be had from going to a 7mm valve stem from the OEM 8mm
                            There is a 5,5mm steam (34mm head) inlet valves too....
                            800HP 800++Nm

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