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[Alloytec] Designing tuned length alloytec 190 extractors

Discussion in 'V6 Development And Modification' started by OS-Mike, Dec 6, 2012.

  1. OS-Mike

    OS-Mike New Member

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    So iv got a few weeks of holidays coming up and i know ill get board not working on cars all day so im going to make some extractors custom made for my engine to learn something new iv never really looked at the science behind extractors and iv spent 3h a night for the last 3 nights collecting raw data calculating and designing and its making my head hurt so i give up for tonight lol. But i can tell you there is not one set of properly made extractors for an alloytec 190 not even the pacemaker "tuned length" ones they dont even look close and what exactly are they tuned for? i have seen one nice set for a 335hp camaro but the dimensions are to big for alloytec190's ill add a pic at the bottom of post.

    Is there any engineers out there (not the welding or fabricating kind) or exhaust gurus that can help with some numbers i think iv got it right but this engine is a nightmare to calculate the ideal length for the pressure wave's due to cam phasing.

    Design goals: Its a street car so broad torque curve with peak pressure wave efficiency at 4500rpm-5000rpm in theory about -3 to -5 psi at the exhaust valve.

    Extractor design: Mild steel material, laser cut flanges port matched, 3 into 1 primaries, custom made venturi style merge collectors, secondaries meeting at a siamese crossover pipe.

    Data: 594cc per cylinder, 94mm bore x 85.6 stroke, Exhaust cam specs that come from a GM workshop manual and i can tell there is an error in these and i cant be bothered degreeing my ex cam. all values at 0.150mm lift: Duration 238, opens -229btdc = 69bbdc, closes 9 atdc, centerline 111, overlap 0, cam lift 42.5mm, valve lift 10.8mm, Ecu controlled phasing upto +50 but my ex cam phase map shows +20 across the rev range at wide open throttle . I would love to know the ex valve size anybody have this also has anybody actually degreed an alloytec i only need ex cam specs the error from the GM manual is the degreeing dosnt match the duration FAIL!

    Calculations: Primary pipes 1.5"dia x 40" length for 4500rpm 38" for 5000rpm, Collector 6.17" length 2"dia venturi tapered out to 2.25" exit, secondaries 2.25"dia 37" lenght to crossover.

    Thats about where im at so far ill probly put flanges on collectors where they get to 2.5" so i can take out the venturi and experiment with length, venturi size and taper for fine tuning. Also another science experiment i would like to try is using a tuning fork and microphone and watching how sound waves travel through each pipe if i make them right all pipes should be in perfect harmony its just a theory because sound is just a pressure wave if i record it and watch it on a pc it will be like a pressure wave scope well see how this goes im not holding my breath for this to work.

    And to make things a little easier i have access to a really nice engineering workshop and dyno. You need a really fancy cutter to make the cuts for the merge collector im not even going to try and bother explaining it ill take some pics when i make them and i priced up materials to make them today worked out about $600nz.

    Im open to ideas and suggestions so fire away if you have any advice.

    [​IMG]
     
  2. Tree cutter

    Tree cutter Tree cutter

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    You say this is for a street car at 4500 to 5000RPM. Where i come from you will end up in serious trouble with the law if you are revving your engine that high on the streets. You will only be revving to about 2000RPM at 110Kph so i think you would be better off tuning your pipes for a lower rev range where you will use it most. Your setup will probably work for a track car that is running at high revs most of the time but i cant see much benefit using a setup like this on a street car. Most off the shelf designs will be for normall street use at low revs and will be a lot shorter than your design.
     
  3. Dr HaxZaw

    Dr HaxZaw New Member

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    the whole problem with tuning it the way you want to is that it will work wonderfully well in that specified rev range but terribly elsewhere
    as you said the pacemakers arent up to that standard but they are more deigned with exhaust pulse in mind not so much for the frequency harmonics... this means they work well over more of the rev range than those tuned to a much narrower rpm range
    to be honest i dont think you'd see any gains over the pacemakers with your custom made set but i would love to see some dyno results proving me wrong :)
     
  4. OS-Mike

    OS-Mike New Member

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    The shorter the header primaries the higher the tuned rpm most off the shelf stuff is made to bolt on so compromise is made. And i think 4500 is right for street use ill gain low down torque and make more top end power if my calculations are right.
     
  5. OS-Mike

    OS-Mike New Member

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    I hope they preform across the whole rev range thats why im making fancy collectors. ^Dr HaxZaw
     
  6. OS-Mike

    OS-Mike New Member

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    Finally parts turned up to day so had a few beers and had a play with mock up this is not my final design just getting started.

    [​IMG]

    [​IMG]

    [​IMG]

    And here is a half finished merge collector i started making last week.

    [​IMG]

    [​IMG]

    Ill do a proper update if i get time tomorrow explaining design how to work it out etc.
     
  7. OS-Mike

    OS-Mike New Member

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    Update: Had way to many parties over christmas and new years still haven't got round to welding them up yet iv got most of the pipes cut and the hard parts made just need to pull my exhaust system off and tack them up on the car. Trial fitted PVC mock ups and measured each pipe length and volume and cut up bends etc.

    How i got the measurements for these extractors

    Length:

    Primary Length=850xED/RPM-3 ED=180+degrees before bottom dead center Exhaust valve opens RPM=revs your tuning for

    ED. for alloytec was tricky ex valve normally opens 131* (* means degrees) but with VVT at full throttle =20*retarded so 131+20= 29*before bottom dead center. ED=209

    RPM. I chose 4500 because the inlet manifold changes to single plenum at 4000rpm and my dyno graph shows torque drops off around 4500-5000 its a good compromise good mid range and shouldn't be restrictive high in the revs.

    Here is the equation (850x209)=(177650/4500)=(39.48-3)= 36.5 inches from the exhaust valve to the collector.


    Primary diameter:

    There is a fancy calculation: cc of 1 cylinder 594cc, divided by (p+3)x2 which is 79 so 594/79=7.52 then x2.1=15.79 so the inside diameter of the primary is 1.57"ID =1 5/8" tube

    But generally 1 1/2" OD tube is good for 25-40 hp per cylinder 1 5/8" for 35-50 hp so 1 1/2" is good for 240 hp and 1 5/8" is good for 300 hp and the car already made 211 hp at the wheels.

    Primary tubes = 1 5/8"ODx36.5" long


    Venturi merge collector:

    Normally its just one diameter and that's the area of the 3x1 5/8" primary tubes with a 1.4-1.7 in/out relation so mine starts at just under 1.4 and tapers out to 1.7 with 4 valve heads its all about air speed not how much it flows example Twin 2.5" exhaust systems are too big you'll probably lose power.

    Area of 3x1 5/8=3400.62mm squared divided by 1.4= 2429mm2 convert it back to diameter and imperial = 2.18"ID and divided by 1.7 =1.98"ID so im using a 2" out to 2.25" taper.

    Im sick of typing now ill explain the rest of the exhaust system next time.


    Here is one side iv made a template for test fitted and matched the volume of each pipe there not all 33.5" close to it but they all have 950cc volume.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Tapered 2" out to 2.25" flanges for the collector.

    [​IMG]

    [​IMG]

    Inside the collector

    [​IMG]
     
  8. OS-Mike

    OS-Mike New Member

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    One more

    [​IMG]
     
  9. Drawnnite

    Drawnnite Obviously Unsensible

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    liking the effort youve put into this.
    awesome job and keep it up.

    should be interesting to see how they go.

    also loving the PVC pipe test pieces.
     
  10. WogBoyz

    WogBoyz 435rkw/590rwhp

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    comming along great mate! deff a good read
     
  11. AirStrike

    AirStrike Administrator Staff Member

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    Props for giving it a go, but on a N/A V6 is it really worth the time/effort? I say no. If you drove it with your custom setup or a set of off the shelf pipes I doubt you could pick the difference.
     
  12. SJM38S

    SJM38S New Member

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    Good on ya for having a go! Why not use your skill, time and resources to do something which interests you! Can't wait to see dyno results :)
     
  13. chargedvx6

    chargedvx6 Active Member

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    Supercharge it and see if the stock manifolds are adequate.
     
  14. 0081

    0081 New Member

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    What is worth it???? Supercharged or turbo v6 supercharged or twin turbo v8??? Lambo v12 conversion. If you want to do it it's worth it in my opinion. Everyone has there reasons for what they do and so be it.

    I'm keen to see the results and i don't even have that motor in my car..
     
  15. AirStrike

    AirStrike Administrator Staff Member

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    Whats that got to do with a N/A 6:s
     
  16. kuzman89

    kuzman89 Active Member

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    Loving the effort on this so far, have you got facebook man? Would love to have a bit of a chat. Dont see why its not "worth" it either, its a hobby, worth as much as you want to put in to it.
     
  17. Not_An_Abba_Fan

    Not_An_Abba_Fan Exhaust Guru

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    I don't know how I missed this thread originally.

    Props for giving it a go. Although 'm of the opinion that you won't notice any improvement over an off the shelf set.

    Extractors, to be 100% effective, only work to their maximum efficiency at the rev range they are designed for. Even then, on a dyno, changing the length of the primaries makes very little difference on a stock engine.

    Building the extractors to suit your rev range is one thing, as soon as you bolt up an exhaust system to them, you negate all that work. Not only do you have to take into account exhaust pulse, but also the effect of heat loss. You will need to keep the extractors as hot as possible to aid flow, and the further the exhaust gets from the engine, the cooler it gets and the less volume it has. Even as little as the length of the primaries will affect flow due to heat loss. The merge collector and reduction at the flange are the best compromise to this as it helps keeping the gas velocity up. What you really need to do though is measure the percentage loss of heat from the outlet of the exhaust port to the merge collector at your specified rev range and match the pipe size accordingly. EG if the exhaust loses 15% heat, the pipe size has to be 15% smaller to maintain velocity.

    You also need to take into account intake temps and velocity. A change in intake air temp will affect exhaust velocity as well. As the temp rises, the exhaust velocity will reduce as there will be less bang due to less a dense O2 charge.

    Vehicle engineers have very specific software to calculate all this to make the engine run as efficiently as possible on the street, race applications are completely different. What you are doing is more of a race application where the revs will be consistent, on the street this will never happen.

    Well done on a good exercise though, they will look impressive.
     
  18. OS-Mike

    OS-Mike New Member

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    Sorry for the late reply yea iv got facebook youll find me under Michael Jarden or mike@drifta. co. nz Im always keen to chat about cars and making parts for them at the moment im trying to design pressure wave termination boxes to get the most out of the extractors but with vortexes in the end so the sound waves hit each other and hopefully it works like a noise cancelling muffler as well.
     
  19. OS-Mike

    OS-Mike New Member

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    Cheers for your input iv taken a few notes and yea im making a proper exhaust system to go with them. Im still trying to workout the best position to place the 4 o2 sensors there must be some way of working out where they will work best any ideas?
     
  20. OS-Mike

    OS-Mike New Member

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    Quick update

    To those asking is it worth the effort HELL YEAH just to learn something new and there's plenty of other reasons like being able to sit back and say yip i designed and built those from scratch. I must say though it is a lot of effort but well worth it.

    finally got some welding done L/H side almost done R/H side just started hopefully i get them finished this weekend iv got some good pics but cant find my camera cable at the moment so heres a couple off my phone.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    And i might have to start another thread for the exhaust system its starting to get interesting.
     

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