Melted Piston.

Discussion in 'Workshop Forum' started by lookforjoe, Sep 6, 2013.

  1. lookforjoe

    lookforjoe True Classic

    That is correct. Either LH2.2, which requires neither, or LH2.4, which requires both. I just want to be prepared for either possibility. 2.4 will be more refined, and has greater tuning potential - more free support for chipping, calibration, etc; which I will need due to the difference in stock injector flow (14lbs vs. 21lbs for the 2.3l Volvo application).
     
  2. lookforjoe

    lookforjoe True Classic

    Adaptor plugs to fit knock sensor in OP port (14x1.5), and Thermal timer in coolant port (since there is only one port in head). This in case I have to run L-Jet initially.

    [​IMG]

    Thermal timer, EGR flange ground & welded closed

    [​IMG]
     
  3. lookforjoe

    lookforjoe True Classic

    Horrible cold weather today, so no outside work. So, I made a setup for measuring combustion chamber volume, following Steve C's outline.

    CD case cover, with two holes drilled for fill/vent.

    [​IMG]

    First time i just used Vaseline - it leaked around plate once I got almost full

    [​IMG]

    After a couple of attempts, I clamped the plate in place, using a little more Vaseline to seal.
    Trying to completely fill & remove the smallest air bubble resulted in pressure between the cover & chamber, causing seepage

    eDIT : next two pics are reverse order - the one with almost no bubble is the final

    [​IMG]

    So, I did three tries following the same steps, shifting the head off level once over 3/4 full to aid in bleed off, and came up with 31.5ml, allowing approx -.2ml for spillage.

    [​IMG]

    Piston pop up is .025", HG squished is .055-060" (variance is depending on where I measure)

    [​IMG]

    New HG is .070" - 1.8mm

    [​IMG]

    So, how so I compute overall chamber volume & clearance? :)

    Seems like I may need a thicker HG - with only .035" (or less) approx that is .9mm - too tight?
     
    Last edited: Dec 5, 2013
  4. petex19

    petex19 True Classic

    I think your combustion chamber volume may be calculated on the low side. I don't know what your piston valve relief volume is, but assuming that it's like mine at 2.4cc(ml) then with your calculated CC volume at 31.5cc, your piston pop-up at .64mm(.025") and a compressed head gasket of 1.5mm(.060"). According to "Summit racing" compression calculator, you're sitting at 11.43:1 compression:shock: in theory.

    'PeteX1/9
     
  5. lookforjoe

    lookforjoe True Classic

    Valve relief pockets are pretty large, given the 39mm intake valve.

    I'd have to say the CC volume is pretty accurate. I used a 1ml syringe to fill the chamber, and the last three fills all came out at 31 -31.5ml. I'm going to have to look at thicker HG's.
     
    Last edited: Jun 4, 2016
  6. petex19

    petex19 True Classic

    A thicker head gasket would certainly get your compression down. My intake valves are 39mm so I'm familiar with how much the intake flycuts had to be enlarged.

    Good Luck :),

    'PeteX1/9
     
  7. fiatfactory

    fiatfactory Steve Cecchele

    Location:
    Western Australia
    I just got home from work last night, so let me get my math brain into gear and work this out for you...remember the piston isn't 87.0 right at the top it's smaller and the volume between the piston and the bore above the top ring land matters, and the 0.65mm of plus deck comes off the capacity of the cylinder too... it doesn't end up 67.4mm down the bore anymore... it's now 66.75mm down the bore at BDC....head gasket is 87.2mm ish inside the fire ring too...

    If you could measure your flycut volumes Hussien, and later today I'll gladly run thru the calculations with you.

    You would be better to open up the chambers a little and deshroud the valve and lay the plug side wall over a little more than open up the SQ...only takes a couple of CC to drop it a quite few points

    31.5cc could easily be right for the chamber volume, looks like you did the measurement in a precise enough way to be within 0.5cc for sure... if the head was skimmed in a previous life before you got it, and you skimmed it just a little again... a nice thick valve margin (that the exhaust looks like it has) occupies a bit of volume too...small is good though, gives you scope to play with.

    SteveC
     
  8. lookforjoe

    lookforjoe True Classic

    Did two things today. :)

    Determined true TDC, and measured the flycut displacement.

    1ml for the intake, .5ml for the exhaust.

    [​IMG]

    Bar with adjustable stop for setting TDC pop up. 5.25" on center for bolt holes in plate. I used the flywheel bolts to secure it.

    [​IMG]

    Rotated CW until piston touched bolt tip (rotated over center a couple of times to check and adjust bolt contact point), and marked the gear and cover at that juncture. Then rotated CCW, and marked contact point

    [​IMG]

    Split the difference as true TDC, and adjusted crank marker to align with the pulley notch

    [​IMG]

    Then I removed the pulley, and noticed that there is a marker on the gear, and that aligns exactly with a cast pointer on the front cover that I hadn't noticed before. so, true TDC is accurately marked from the factory :)

    [​IMG]
     
    Last edited: Nov 27, 2013
  9. fiatfactory

    fiatfactory Steve Cecchele

    Location:
    Western Australia
    Let's figure out your true static CR, now you have all the numbers.

    A basic compression ratio calculation looks like this:

    Volume at BDC is (swept volume - pop up volume )+ flycut and ring land clearance volume + gasket volume + chamber volume.

    Volume at TDC is (volume in gasket - pop up) + flycut and ring land clearance volume + chamber volume.

    Volume of BDC over Volume at TDC is expressed as a ratio to one (xx:1)

    Your bore is 87.00
    Your Pistons are 86.50 above the top ring land and the top ring groove is 6.5mm down from the crown.
    Your Valve Flycut measured volume is 1.5cc
    Your Piston sits at 0.65mm plus deck
    Your Combustion Chamber measured volume is 31.5cc
    Your head gasket is going to be 1.5mm compressed and has an inside fire ring diameter of 87.2mm (assuming a Felpro 21195-PT2)

    So lets do some math...

    Swept Volume of the cylinder.
    Pi x R squared x Stroke
    3.14285 x (43.5 x 43.5) x 67.4
    3.14285 x 1892.25 x 67.4
    400.831cc

    Volume of the piston 'pop up'
    3.14285 x (43.25 x 43.25) x 0.65
    3.14285 x 1870.5625 x 0.65
    3.821cc

    Volume of the head gasket.
    3.14285 x (43.6 x 43.6) x 1.50
    3.14285 x 1900.96 x 1.50
    8.961cc

    Volume of the ring land clearance.
    [3.14285 x (43.5 x 43.5) x 6.50] - [3.14285 x (43.25 x 43.25) x 6.50]
    [3.14285 x 1892.25 x 6.50] - [3.14285 x 1870.5625 x 6.50]
    38.655cc - 38.212cc
    0.443cc

    and then put these numbers into the equation,

    Volume at BDC = (400.831 - 3.821) + 1.5 + 0.443 + 8.961 + 31.5
    = 439.414

    Volume at TDC = (8.961 - 3.821) + 1.5 + 0.443 + 31.5
    = 38.583

    V at BDC / V at TDC = 11.4:1 (11.389)

    If you add just 2cc to the chamber volume you get 10.9:1
    If you add just 3cc to the chamber volume you get 10.6:1

    I think you should do a little deshrouding on the plug side wall, and around the inlet valve, or scoop a little out of the inlet valve head, to enlarge the combustion chamber volume to around 34.0 to 34.5cc... and you'll be good to go. IMO the SQ at 0.9mm is good (provided you have adequate V to P clearance)

    Scooping a little out of the inlet valve would be good as you'll drop valve weight too.

    TDC marker cast into the front seal cover can move a tiny bit depending on bolt and seal alignment, so it's best to check... not all front gears (aftermarket) have the TDC scribe mark either.

    I notice you have a two groove front crank pulley... can you find a single groove 1500 one, a little lighter ... even a 1300/1100 one will fit if you want to re align the water pump and alternator pullies inwards a little, that's lighter again.

    SteveC
     
    Last edited: Nov 27, 2013
  10. lookforjoe

    lookforjoe True Classic

    Thank you for all the calculations, Steve!

    I'll start by removing some material around the spark plug aperture.

    Any valve work will mean going back to the machine shop -I guess I should have asked about scooping out the valve centers before the head was assembled.

    The front pulley has to be double channel - I have AC.

    [​IMG]
     
  11. fiatfactory

    fiatfactory Steve Cecchele

    Location:
    Western Australia
    If you can get your combustion chamber to look like these, then your in the ballpark for volume.

    [​IMG]

    and a picture of the same combustion chamber before any work was done.

    [​IMG]

    see how the machine cut around the inlet valve is blended right in, and the chamber is right out to the fire ring (the bore on this engine was 87.2) so you should scribe a line and keep 0.1mm inside it for your bore size. From memory this was 34.0cc chamber volume...and smooth out all the sharp edges from the head reface, they will get hot and pre ignite... not good.

    SteveC
     
  12. lookforjoe

    lookforjoe True Classic

    Thanks for the pics, Steve.

    Looks like 1 step forward two steps back. :(

    It's going to take me a while to get the chamber work done - I'm going to do it myself with hand tools, which means very careful marking to insure consistency across all four cylinders. This type of work is definitely labor intensive, and the machine shop costs for all the piston & block work & custom mods required to make the head useable, became more than I had anticipated by a significant amount. 3cc's is quite a bit of material, given the intake flycut is 1cc for comparison.

    For anyone considering a BVH, they should plan on doing this up front, while the head is apart, since we know that 34-35cc is the appropriate chamber volume for the 1600 stroker setup with 87mm bore.
     
  13. fiatfactory

    fiatfactory Steve Cecchele

    Location:
    Western Australia
    Every 0.2mm thicker you go in head gasket when crushed is 1.2cc
    (1.195)

    Volume of the head gasket.
    3.14285 x (43.6 x 43.6) x 1.50
    3.14285 x 1900.96 x 1.50
    8.961cc

    3.14285 x (43.6 x 43.6) x 1.70
    3.14285 x 1900.96 x 1.70
    10.156cc
    SQ is now 1.1mm which is still very good,
    CR is 440.609/39.778 = 11.08:1

    3.14285 x (43.6 x 43.6) x 1.90
    3.14285 x 1900.96 x 1.90
    11.351
    SQ is now 1.3mm which is about as large as you want for good performance, CR is 441.804/40.973 = 10.78:1

    I always do that chamber mod... taking away the machined edge and enlarging the area on the inlet side of the plug wall is one of the basic mods described in my P&P thread. If the head wasn't assembled it's an easy job to scoop some material from the valve head too... there's another 0.5cc straight away.

    Some of the chamber volume reduction could be from the exhaust valve recut too...the valve head is sitting up into the chamber a fair way. I usually try and drop the exhaust valve down into the head a little more than the inlet, as this has some benefits with less draw thru of the incoming charge at overlap ... the usual downside is it increases the chamber volume, but in your case it would make it about right.

    with a 33.4 valve recessed a further 0.5mm from where it currently sits
    3.14285 x (16.7 x 16.7) x 0.5
    3.14285 x 278.89 x 0.5
    0.438cc

    I usually try to set the exhaust valve about 1.0mm lower in the head than the inlet, so there's around 0.88cc

    like I said before, most times it's a struggle to get the chamber small enough for good static CR, all the little parts of a CC add up...some people think I'm overly anal working to two or three decimal places, but it does make a difference to the final numbers.

    If your going to leave the valves in and be die grinding in the chamber, make up a plate that drops into the bottom of the chamber to protect the valves, you could also make up a guide plate (using an old head gasket as a template) to protect the machined head face. Most times the chamber mods would get roughed out before the head skim was done, and then the final evening up of the volumes is done very carefully after the head has been skimmed and you can get accurate measurements.


    Stick with it, your actually almost there. :wink2:


    SteveC
     
    Last edited: Nov 28, 2013
  14. lookforjoe

    lookforjoe True Classic

    Thanks, Steve.

    Started on the chambers today, trying to get one up to 34-35cc. Chambers are already right on the edge of the fire ring.

    [​IMG]

    [​IMG]

    Seemed to be around 34cc, so I took a little more off around the intake valve, and rounded the hard outer edge

    [​IMG]

    couldn't get an accurate measurement after that, I need to remake the cover tray - it kept leaking on me.

    Both valves do have greater height than the stock FI valves - those I measured at .042", and these measured at .050" in the same location.
     
  15. fiatfactory

    fiatfactory Steve Cecchele

    Location:
    Western Australia
    Looking good Hussien,

    getting the first one done is the most challenging, having enough faith that your not going to ruin a perfectly good head!!

    Now your over that hurdle, the next challenge is getting all four 'exactly' the same... and you should shoot for a variance of under 0.5mm across all four... that's the really tricky and time consumimg part I can assure you.

    If you get the static between 10.6 and 10.5, with that nice tight SQ clearance, your engine's going to sing. :wink2: ...

    the stock tipo head is good for 120cfm, cut back the guide and simple bowl work and it jumps to 140cfm. So your easily 30cfm more than the last head... perhaps more... that is a bunch more Hp and torque.

    The flow restriction is now going to come from the inlet manifolding and there's not a lot you can do about that unless you start fabricating... It's only just starting winter over there, so I'm guessing that's next on your agenda once the engine is buttoned up. :nod:

    SteveC
     
  16. lookforjoe

    lookforjoe True Classic

    Thanks for all the help, Steve - it is most appreciated!

    Started on the second chamber today. I'm going to measure the volume of each chamber as I go along, to ensure the volume is as close as I can get it. For whatever reason, I'm having more trouble sealing the chamber & accurately measuring the volume. I got a 3cc syringe, to speed it up a little, however sealing the chamber seems to be a challenge, so it can take several tries to get a reliable reading. I stopped with the first chamber at 34cc, in case I go slightly over on the others, I'll have a small margin to play with. The fire ring on the Italian HG is very close to the intake & exhaust chambers at their widest point - so no room to manipulate there - I'm trying to gently smooth and open up the valve seat area, and remove the bulk of the material to get to 34cc from the spark plug wall. I found your chamber pics & cross sectionals that I had previously printed when I did the port & valve guide reduction. Why I didn't think to do the chamber work then, I just don't know !
     
  17. lookforjoe

    lookforjoe True Classic

    3 down, 1 to go. got these three all at 34cc after several cuts/measuring

    [​IMG]

    Fire ring measured at 87.5mm - right on the edge of the chamber when centered over the two holes that align with the guide sleeves in the head...

    [​IMG]

    [​IMG]

    Not sure that won't be a problem? EDIT: Bayless has 88mm "heavy duty" head gaskets - but .059" uncrushed thickness
     
    Last edited: Dec 2, 2013
  18. mid79

    mid79 Youth Revisited

    Looking great!
     
  19. lookforjoe

    lookforjoe True Classic

    Thank you.

    All 4 chambers are now done - had to go slow, however all are 34cc even - within .2cc, based on the repeated measurements. Glad that's over - it was quite exhausting, having to be so careful not to go over the ideal sizing & keep the relationships similar across all four in terms of where the meat was removed. SO, with a 34cc chamber, my CR should drop to around 10.75.

    Next, I have to bolt up the head, cam box, t/belt, etc; then measure the V/P clearance.

    In the meantime, I ordered some .5"x2.5"x4' plate to make the flanges from, and some 1.75" OD tubing to make the runners from. Ordered injector bungs CNC'd for 14mm OD Bosch injector seal size.

    I'll enlarge the runner ID in the Plenum runners to 1.5", then taper the new runners down to mate with the smaller ID head ports

    stock port end
    [​IMG]

    stock plenum runner end
    [​IMG]
     
    Last edited: Dec 9, 2013
  20. petex19

    petex19 True Classic

    Great Job!
    I'm also sitting at 10.7:1 compression, do you think you'll be able to run on premium pumped gas or will octane boost be needed?

    Keep up the great work,

    'PeteX1/9
     

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