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Thread: The Official Engine Building Thread

  1. #1
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    The Official Engine Building Thread

    You got engine questions, we got engine answers... or at least that's how it's supposed to work. Keep it on topic; this thread will be long anyway. Strictly engine building and rebuilding talk here. Ground rules: only engine-related posts. That means internals, head/block work, and forced induction only. No air intake posts, no header posts, no exhaust posts, no transmission posts. No question is too stupid. Post away my friends.
    By the way, any engine that has found its way into your e30 can be discussed.
    Last edited by iamane30m20nut; 01-14-2004 at 09:06 PM.
    1992 Nissan 240SX Track Rat
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  2. #2
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    For the inaugural post:
    1. I'm rebuilding my M20b25 and am thinking of stroking it on the cheap. This immediately discludes stroker kits from any company. The two options I've heard of are making an "ita" motor or dropping in a 524td crank. What work is associated with each? I'm not going to ask questions like "how much power should I expect?" but if you've dynoed your ita or 524td-crank-equipped M20, feel free to post the numbers.
    2. Also, what parts constitute a rebuild? I've posted this question before with little success, so I'm hoping someone will answer this time so the information is made available to everyone. Thanks in advance for your answers. Edit- I have found out what I need from an old post by UD///M:
    Standard rebuild: New rings, bearings, valve stem seals, valve seats recut. (make sure they maintain the three angle cut that is standard on BMW's) New oil pump. Hone cylinders. If a ridge exists then a full rebuild will be needed. (not a carbon ridge but a metal ridge.
    Full rebuild: All of the above plus new pistons +1 size, valve springs, valve guides (no knurling), bore and hone. And more if your budget can afford it.
    Has he missed anything?
    Last edited by iamane30m20nut; 01-12-2004 at 01:29 PM.
    1992 Nissan 240SX Track Rat
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  3. #3
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    That list should cover it. I don't know anything about the 524 crank though. Sorry.


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    Alex Grabau

  4. #4
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    This is a dumb question... I've always been confused at to what a stroker motor was...
    The whistles go "woooo woooo!"

  5. #5
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    A stroker motor is made when one increases the piston stroke beyond that of the normal specification of the given engine.

    For example, if i have a 2 liter engine and I want to increase the displacement to move more air I can either "overbore" the cylinders which isn't ideal given that you reduce serviceablity and weaken the block, or leave the bore and increase the crank's stroke by replacing the crank.

    Some companies sell longer throw cranks, even BMW as seen in the 2.5 liter S14. (which increases the displacement .2 liters) Stroker kits are expensive, ideally one could be made with other stock parts but weight is an issue as factory parts aren't necessarily performance parts.

    Stroker kits sometimes come with lighter connecting rods and pistons as the weight is being thrown about a larger axis causing more stress on the parts.


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    Alex Grabau

  6. #6
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    I don't know anything about the 524 crank though
    It is basically a forged 81mm crankshaft. To the person asking about a TD crank it is nice to have but not really necessary. The "i" cranks are cast as well, and you will have no worries spinning an "e" crank...........

  7. #7
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    The turbo-diesel crank is now obsolete with the E36 M3 crankshafts available for the same price....and with 5mm more stroke.
    Stu

    Jochmael; vhere is zee wasserpumpen!?"

  8. #8
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    So the E36 M3 Crank is forged as well I take it? Nice idea on that one Stuey.

    AL


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    Alex Grabau

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    Again, what would be necessary if I were to use one of those ideas? "i" head on "e" block, custom pistons, or what? I want to make these ideas as out in the open as possible because I want people like me to start making faster e30s so we can rep the old Bimmers. I know many people have made stroker e30s... I want them to post. Tell us what you did. Stu, see if your dad can shed some light on the subject.
    1992 Nissan 240SX Track Rat
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  10. #10
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    Originally posted by E30 Stu
    The turbo-diesel crank is now obsolete with the E36 M3 crankshafts available for the same price....and with 5mm more stroke.
    Ahem, word
    -Ted

  11. #11
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    ted: post your setup, might be of some use
    Rob

  12. #12
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    Lets see some more good stuff on this thread! I'll sticky it.
    Bryan K.
    1988 ///M3
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    Texas A&M Formula SAE

  13. #13
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    I apologise if this typing is terrible, I dislocated my shoulder last night and am typing with my left hand while hihgh on perscription heroin.


    When it comes to additives trust only the "Lucas" brand and "TK7 upper

    cylinder lubricant".


    After 250h of independent dyno testing with and w/o TK7 comparing bore

    wear the TK7 motor showed a minimum improvement in bore wear of %600

    comparing the best-to-worst cylinders.

    break-in will take %50-100 longer, but a smoother lower friction

    bore results. 1-1.5% hp improvement can also be seen.

    block/internals

    Check summit for their comp cams rod balancing fixture when rebuilding,

    if the motor's ripped apart balance your rods for smoother runnung and

    higher rev capabilities.

    if you have your crank balanced also get your crank pins drilled hollow,

    the reduced inertia will allow freer revving. usu when this is done the

    counterweights will also need to machined down B4 it can be balanced.

    fab a windage tray/crank scraper.

    while your machining, chamfer and slightly enlarge the crankshaft oil

    passages on the crankshaft.

    while the motor's apart and you're replacing the oil pump, like one ALWAYS should when tearing down a motor : chamfer and machine away as much casting flash as you can around the block passage.

    porting

    Whenever porting remember to concentrate on the area from right @ the seat to

    slightly up past the valve stem.

    Don't ever "gasket match" the head to intake, DO however make sure

    the air doesn't see a "step-in", a "step-out" [as following the path of

    the air molecules] is fine.

    Always polish exhaust ports mirror-like shiny.
    Leave intake ports rough machined, polishing may actually reduce flow.

    deshroud your combustion chamber and then machine the head down to regain

    lost compression..... someone post a pic of a BMW combustion chamber and

    I'll show you where.

    enlarge the top and sides of your exhaust port to match your exhaust

    manifold, however make sure there is a step-out" on the bottm of the

    exhaust port.




    When creating an exhaust system, having one large pipe of the same

    x-sectional area as two pipes. The single pipe will have greater flow.

    If you love your motor always run fully synthetic oil and the largest

    filter that will physically fit. I run huge small block V8 chevy filters

    on my motor that are easily twice the size suggested by GM (I don't drive

    a bimmer)

    don't sweat oil ratings, I run 5W-50 %100 syn racing oil on my motor in

    the summer and a 5W-30 5W-50 mix in the winter.
    manual calls for 10W-30 year round.

    few tidbits i could think of.....
    Originally posted by Beau
    the turbo is the perfect garbage can....

  14. #14
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    Alrighty then. Here's my stuff,

    M20B25, bored 1mm to fit a
    -85mm, 9.8:1 Ross Racing piston
    -Pauter 4340 Chromoly Steel Connecting Rods (stock size)
    -'95 M3 crank, modified by Ireland Engineering to fit an M20.

    Cylinder head:
    -Mild Port job (see pictures)


    -Schrick 284/272 camshaft

    That's all the interior work that's been done on the motor, since all that stuff it's had some exhaust work, but you didn't want that so I'll leave it out until someone asks for it. Here's the engine's best dyno numbers to date:


    Hope that helpd some folks out.
    -Ted

  15. #15
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    "it's had some exhaust work"
    consider it asked....

    God those ports look nice (not just the porting but the fundamental shape).

    How are those cams? very streetable, correct?

    Do you have the size (in cc) of your ports?


    has anyone flowed the M20 intake manifold? is there a beefier aftermarket one available?
    Originally posted by Beau
    the turbo is the perfect garbage can....

  16. #16
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    Gotcha Covered Zenon

    Exhaust: (2) Borla Mufflers, inline; Borla "XR-1" race muffler replacing the catalyst, Borla "Turbo" exit muffler, 3" piping, Stahl 1 1/2" header.

    I love the ports too

    The cam rocks, VERY streetable, a little lumpy on the idle, but not bad at all.

    I don't have the cc's of the ports, sorry.
    -Ted

  17. #17
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    I've driven those cams in a 2.8 stroker, and yes, they are wonderfully streetable. Muscle Car idle rocks!
    Rob

  18. #18
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    Is there a stock-part-only way of making a stroker motor? I'm sure other people are kinda low on funds like I am, so cheaper is better.
    1992 Nissan 240SX Track Rat
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    1990 325i Manual Sedan Project

  19. #19
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    Complete "super eta" bottom end and an "i" head this would be your cheapest alternative..... I have 5 sets of Racing Dynamics Mahle 10.2 racing pistons with rings if you are interested. They work with any 81mm crank, "i" rods, and "i" head.
    info@creativeoptions.info

  20. #20
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    Just the "super eta" crank, or "super eta" crank, rods, and pistons?
    1992 Nissan 240SX Track Rat
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    1990 325i Manual Sedan Project

  21. #21
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    super eta crank or TD crank, super pistons and rods. A super eta is basically a "e bottom end with an "i" head but is made up of a
    "e" cam and "e" springs, 4 journal and single valve springs. You will still retain the 8.5cr unless you shave the head and deck the block you can obtain in the mid 9's cr............

  22. #22
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    I'm guessing using the "super eta" crank, rods, and "i" pistons would be out of the question? That would yield a better c.r., but then I wonder about piston/combustion chamber or valve clearance.
    1992 Nissan 240SX Track Rat
    1998 M3/4/5 74k mile daily driver
    1990 325i Manual Sedan Project

  23. #23
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    if you use a eta crank, standard i rods and i pistons then the pistons will crash into the valves................

  24. #24
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    Originally posted by zenon
    don't sweat oil ratings, I run 5W-50 %100 syn racing oil on my motor in

    the summer and a 5W-30 5W-50 mix in the winter.
    manual calls for 10W-30 year round.
    Sorry this is kind of off topic for the 'engine building' thread, but Zenon, what would you say about Amsoil's Series 2000 0W-30 oil? Have you seen
    the tests done by Bob ///M3?


    Also, are there any negatives towards a 'knife edged' crank? If it is dynamically and statically ballanced, I cannot see any problems in doing it. Here is a pic:


    Bryan K.
    1988 ///M3
    1997 E36 ///M3 Project
    Texas A&M Formula SAE

  25. #25
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    Kevin- but what if I put "i" pistons on "super eta" rods? Would that be motor-health-threatening? (I've heard that "i" pistons have a more efficient shape than "super eta" pistons. Or was that "eta" pistons...)
    Bry- you're the mod... everything's on-topic. Oil talk is cool here.
    1992 Nissan 240SX Track Rat
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    1990 325i Manual Sedan Project

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