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  1. #51
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    What is? You mean strictly OEM, correct?
    I'm talking about peak potential, not the untouched OEM casting.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Respectfully disagree, the S85 would be IMO.
    The S85 is a smaller engine with lower VE than the S70/2. Why would you chose an engine that makes less power and is less efficient?

  2. #52
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    What is? You mean strictly OEM, correct?
    s38
    Click here to enlarge

  3. #53
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    Click here to enlarge Originally Posted by bluejeansonfire Click here to enlarge
    I think aluminum bores are an inferior option. Displacement is also win. As are solid lifters.
    Displacement is fairly close as an S85 can go to 5.8 and even more. Aluminum block just means you need sleeves, not a big deal and the weight makes a difference.

    V10 is not inherently balanced but who cares? We aren't building a smooth tugboat motor. Plus, which S70 version are we talking about? If it is the S70/2 that does change things a bit although I still believe a 5.8 liter S85 twin turbo would win out. We have seen this from the V10 with turbos: http://www.bimmerboost.com/showthrea...Turbo-COMPLETE!

    I would not mind hearing more about the blown S85....

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  4. #54
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    Click here to enlarge Originally Posted by bluejeansonfire Click here to enlarge
    s38
    The S38 head outflows the S54 head? The B38 S38?

    Edit: I see this was mentioned based on potentially, not on actual OEM flow.

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    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    I'm talking about peak potential, not the untouched OEM casting.
    I see, that makes more sense. Why does the S38 head have more potential?

    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    The S85 is a smaller engine with lower VE than the S70/2. Why would you chose an engine that makes less power and is less efficient?
    The S70/2 is a different beast. S70/1, or S70B56 aren't the same thing.

    Everything changes based on which motor we are talking about as the S70/2 really has nothing in common with the M70 like the other S70 variants.

    I would choose the S85 because it revs higher, is lighter, and has great potential for increased displacement.

    How do we know the S70/2 has greater VE?

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  6. #56
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    How do we know the S70/2 has greater VE?
    iirc, the s70/2 head is identical to the s50b30 head. The 850csi motor wasnt a real s70. It was sohc. It was a hopped up m20x2. where as a s70/2 motor is a s50b30x2, i mean, the m20-based motor can't compete.
    Click here to enlarge

  7. #57
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    Click here to enlarge Originally Posted by bluejeansonfire Click here to enlarge
    iirc, the s70/2 head is identical to the s50b30 head. The 850csi motor wasnt a real s70. It was sohc. It was a hopped up m20x2. where as a s70/2 motor is a s50b30x2, i mean, the m20-based motor can't compete.
    This is all correct and makes sense as the S70/2 has been said to be basically two S50's. But, I do not believe that means the VE is on its side vs. the S85? I don't know the VE of either motor anyway but it would seem to be close either way?

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    This is all correct and makes sense as the S70/2 has been said to be basically two S50's. But, I do not believe that means the VE is on its side vs. the S85? I don't know the VE of either motor anyway but it would seem to be close either way?
    i don't know either, that's some pei information. Looking down from canada, he will strike us with lightning bolts he holds in his hands in the form of extremely unavailable information
    Click here to enlarge

  9. #59
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    Click here to enlarge Originally Posted by bluejeansonfire Click here to enlarge
    he will strike us with lightning bolts he holds in his hands in the form of extremely unavailable information
    I like that...

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  10. #60
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I see, that makes more sense. Why does the S38 head have more potential?
    Because the S38 has a HUGE bore allowing larger valves to be used.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I would choose the S85 because it revs higher, is lighter, and has great potential for increased displacement.

    How do we know the S70/2 has greater VE?
    HP/L

    Tq/L

    That's the tell of the tale right there.

    Please keep in mind, this is just my personal preference. The S70/2 is still the most powerful engine BMW has ever built for a road car; and it's got a racing heritage the S85 can only dream of.

    The S85 in a number of technical areas would definitely be my choice for a big HP twin turbo race car, but the S70/2 comes from a $4M supercar. (Current market value) How do you top that?

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    Click here to enlarge Originally Posted by bluejeansonfire Click here to enlarge
    i don't know either, that's some pei information. Looking down from canada, he will strike us with lightning bolts he holds in his hands in the form of extremely unavailable information
    He he...good one.

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    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge

    HP/L

    Tq/L

    That's the tell of the tale right there.
    that really wasnt that unavailable, rofl
    Click here to enlarge

  13. #63
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    I've thought about a TT S70 in a 1M............ would be quite the car.

  14. #64
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    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    HP/L

    Tq/L

    That's the tell of the tale right there.
    Yes, that is roughly what I was going on. We are still roughly guessing the volumetric efficiency and thermal efficiency.

    102.7 for S70/2 vs. 101.4 for S85 hp per liter.

    78.68 torque per liter for the S70/2 vs. 76.8 for the S85.

    The S85 has an advantage that it has so much displacement it can gain due to its shorter stroke while still revving much higher. For me, this is the deciding factor.

    Both have aluminum blocks and heads.

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    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    ease keep in mind, this is just my personal preference. The S70/2 is still the most powerful engine BMW has ever built for a road car; and it's got a racing heritage the S85 can only dream of.

    The S85 in a number of technical areas would definitely be my choice for a big HP twin turbo race car, but the S70/2 comes from a $4M supercar. (Current market value) How do you top that?
    I completely understand your perspective, just providing my own Click here to enlarge

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    I havent read the whole thread yet because I'm at work. But I rep this because the guy likes data, what can I say; it gets me hard too.
    Some people live long, meaningful lives.

    Other people eat shit and die.

    I'm not racist, I hate everybody equally; especially fat people.


    Click here to enlarge

  17. #67
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    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    I havent read the whole thread yet because I'm at work. But I rep this because the guy likes data, what can I say; it gets me hard too.
    YES I was so happy to see flow bench data for the N54 vs those other motors! I knew that BMW had the N54 bottlenecked in the head! I'm curious what the stock turbos could do if someone really opened up the head...... and what Unfor's and Ar's setups could do with headwork.

  18. #68
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    I glanced at the N54 data, super cool to finally see someone get flow data. I don't think the heads are a huge restriction, could you pick up power from porting? Yep. But how much and for how much.
    Some people live long, meaningful lives.

    Other people eat shit and die.

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    Click here to enlarge

  19. #69
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    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    I glanced at the N54 data, super cool to finally see someone get flow data. I don't think the heads are a huge restriction, could you pick up power from porting? Yep. But how much and for how much.
    Depends how extreme you go. Click here to enlarge I'd like to see an N54 with Unfor's turbo/fuel rail setup plus an opened up head, bigger valves, aggressive cams..... I'm confident it would be 600whp+ capable even at just 7000RPM.

    I wonder how fast the N54 could spin reliably with a solid aftermarket valve-train setup and stock bottom end......

  20. #70
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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    I wonder how fast the N54 could spin reliably with a solid aftermarket valve-train setup and stock bottom end......
    You really need to spin some RPMs to take advantage of that kind of cam, and the stock rods aren't going to like it.

    I've worked directly with Schrick to design a solid lifter valvetrain for a project I'm working on. Here's what a 300 degree intake cam looks like:

    Click here to enlarge

    With all the flow-bench work I've been around, we didn't really see the need to go beyond 11.7mm of lift. You really need to put the engine on a Spintron once you go above 12mm lift....

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    The S85 has an advantage that it has so much displacement it can gain due to its shorter stroke while still revving much higher. For me, this is the deciding factor.

    Both have aluminum blocks and heads.
    the other thing is that when you start increasing bore while keeping stroke the same, the rod ratio gets affected in a little way (good). If the rod ratio is already good (I prefer over 1.80:1) then a lot of gain can be seen with displacement increase without affecting longevity of the rings. Also since you have more surface area, now you can use the energy caused by combustion more efficiently.

    When you have a motor with poor rod ratios (1.50:1 or lower), increasing displacement can actually cause piston ring wear in as little as 3k miles, with scuffing of the bore. since the engine already puts more effort side to side on the piston rather than up and down, increasing bore size gives you more surface area to be affected.

    For example, back in the day when i used to do DSMs, everyone was trying to put a galant 2.4l block in their car with a 2.0 turbo head, and then spin it to 8-9k.

    Almost everyone killed their rings within 6k miles. Why? Because the rod ratio was 1.51:1. Maximum efficient redline was 6k, yet people were trying to spin it 2k higher and expect nothing bad to happen.

    I on the other hand, built a 1.6l bottom end with a 2.0 head. Rod ratio was 2:1...pretty much like a bike engine. The piston spent more effort going up and down, not side to side, and is really slow in movement around TDC and BDC. i could use less timing to achieve the same results. Sure it was a little gutless below 2k rpm but i built the gearbox with short 1st-4th gears, and it was a real screamer to 9k with no issues....i could keep boost on a boil in each gear and make up for the displacement loss over a 2.4 with a bit of a big turbo.

    Having it in a dodge colt hatchback helped in the weight department as well LOL...


    Sorry for the tangent, carry on Click here to enlarge

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    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    You really need to spin some RPMs to take advantage of that kind of cam, and the stock rods aren't going to like it.

    I've worked directly with Schrick to design a solid lifter valvetrain for a project I'm working on. Here's what a 300 degree intake cam looks like:

    http://www.bimmerboost.com/images/im...10/12/1711.jpg

    With all the flow-bench work I've been around, we didn't really see the need to go beyond 11.7mm of lift. You really need to put the engine on a Spintron once you go above 12mm lift....
    Can you tell us what project that is for? Click here to enlarge

  23. #73
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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    Can you tell us what project that is for? Click here to enlarge
    Same one this head is for.

    I'll get around to posting more about it soon, but it's certainly been fun so far.

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    1 out of 1 members liked this post. Yes Reputation No
    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Displacement is fairly close as an S85 can go to 5.8 and even more. Aluminum block just means you need sleeves, not a big deal and the weight makes a difference.
    Cast iron blocks also seem to quelch harmonics a lot better (which manifest in proportion to torque, rpm, and crank length).

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    Click here to enlarge Originally Posted by spdu4ea Click here to enlarge
    Because you are limited on the camshaft lift you can run on a 996tt head before interference. The GT3 heads have a lot more clearance (among other things -- like larger valves)
    For some reason, the above statement stuck out in my mind recently, and I thought I'd address it.

    Increasing lift isn't necessarily going to increase static flow. (Ignoring the increase in duration from moving the lift curve up which increases dynamic flow) Look at the graphs I've provided earlier in this thread, and you'll see a flow plateau for all the heads. From a valve-train dynamics point of view, you are better off running as little lift as you can and increasing the peak lift duration.

    The GT3 head may offer the ability to run more lift, but that is because there is an advantage to doing this with the port design. Quite simply, it flows better at all points including lift values above the TT head's.

    For reference: The engine analysis software I have points to running much less lift than we all seem to pursue. For example, under 10mm of lift even @ 8k rpm. Why don't we do this? Valvesprings...or more to the point weak valve springs that aren't compatible with the "jerk" required with agressive cam profiles. (BTW, aggressive cam profiles in the racing world have very little to do with duration and lift, and all to do about how fast the valve is opened and closed)

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