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Thread: 12cm exh too small for 550whp ?

  1. #1
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    12cm exh too small for 550whp ?

    I have an e30 with Vanos M50b30 (m54b30 rotating assembly)stroker with S50 Cams,
    MlS 0.140 cr nearly 8.5
    Rapid spool exhaust manifold
    3"Exhaust
    Ebay Aluminum Intake
    M60 throttle
    0.9 bar on HXsuper40/Hx35 12cm (I guess this is equivalent to Percesion 6060 )
    With MSpro on 93 oct

    The virtual dyno is showing I m only around 400 whp (actually 380-400) which I think is too low
    Is the 12 cm exhaust housing holding me back ? was expecting 450 at least , or am I too optimistic ?

    now I m going to raise boost to 1.3 bar and add Water/meth shooting for 550 -600whp
    shall I go for bigger exhaust housing may be 14-16 ? or shall I upgrade for HX52 (70 mm compressor ) /16 cm housing ?

    its weekend street racing car , But I d like to have responsive turbo than a sudden rush of power at the very top end (rev limiter is 7000 )

    your input is highly valued
    Last edited by JOMARO; 01-06-2017 at 08:51 PM. Reason: Adding info

  2. #2
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    96 332IS 6466 turbo
    12cm is like a T3 .70AR I believe. I think you would benefit from a 14cm or .84 open. Do you have a link to your turbo ?
    1996 332IS
    Built 3.2
    CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
    Technique Tuning 80# tune.
    1/4 mile 10.84 @ 136.72
    Your 1 and only stop for all your BMW performance needs
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  3. #3
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    Quote Originally Posted by JOMARO View Post
    I have an e30 with Vanos M50b30 (m54b30 rotating assembly)stroker with S50 Cams,
    MlS 0.140 cr nearly 8.5
    Rapid spool exhaust manifold
    3"Exhaust
    Ebay Aluminum Intake
    M60 throttle
    0.9 bar on HXsuper40/Hx35 12cm (I guess this is equivalent to Percesion 6060 )
    With MSpro on 93 oct

    The virtual dyno is showing I m only around 400 whp (actually 380-400) which I think is too low
    Is the 12 cm exhaust housing holding me back ? was expecting 450 at least , or am I too optimistic ?

    now I m going to raise boost to 1.3 bar and add Water/meth shooting for 550 -600whp
    shall I go for bigger exhaust housing may be 14-16 ? or shall I upgrade for HX52 (70 mm compressor ) /16 cm housing ?

    its weekend street racing car , But I d like to have responsive turbo than a sudden rush of power at the very top end (rev limiter is 7000 )

    your input is highly valued
    400hp @ 14psi doesnt sound too far off from a holset. I say crank it up

  4. #4
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    - - - Updated - - -

    Quote Originally Posted by Butters Stoch View Post
    12cm is like a T3 .70AR I believe. I think you would benefit from a 14cm or .84 open. Do you have a link to your turbo ?
    Its a Hybrid turbo , that I did :-), took the compressor side from the HX super 40 (6 blade ) and the exhaust from HX35 12 cm
    I searched alot and got his :
    compressor :Ind 60mm/86 Ex
    Turbine: Ind 69/60 ex

    everywhere I search I found they claim that the 12cm exh =0.82-.0.89 (which is hard to believe :-))

    what shall I expct form a bigger Exh housing ?
    is it worth it go to HX52 (70 mm ) ?

    - - - Updated - - -

    Quote Originally Posted by Hofmeister View Post
    400hp @ 14psi doesnt sound too far off from a holset. I say crank it up
    I d be okay if i was an m50b25
    but with the extra capacity for the M50b30 , I think its a little bit on the low side

  5. #5
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    96 332IS 6466 turbo
    I think those #s are about right. 400whp from a holset 6060 is good power. Must hit hard.
    Maybe find a 62-64mm turbo and you will add a 100-150whp. Don't go too big, or your bottom end will suck.
    1996 332IS
    Built 3.2
    CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
    Technique Tuning 80# tune.
    1/4 mile 10.84 @ 136.72
    Your 1 and only stop for all your BMW performance needs
    WWW.CESMOTORSPORT.COM

  6. #6
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    Your results are about right for that size turbo. It will take a lot more than 1.3 bar boost to make 550-600 though. That's a pretty small turbine on that turbo to make more than 500whp. I would expect it to make 500 whp at mabey 1.5 bar or so. 600 might take a lot more due to the small turbine and compressor. I don't think going to a larger housing will do much for you.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  7. #7
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    I have a small .70ar housing on my holset, granted my holset is a 6764 hx40, but i doubt the housing is holding you back, I would crank it up to 17-18psi, shouldnt need meth for an 8.5:1 comp on 93 at 17psi.

    Your numbers sound right but i would rev it to 7250.

    How big is your downpipe and exhaust? Are you open wastegate?

  8. #8
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    Quote Originally Posted by JOMARO View Post
    - - - Updated - - -



    Its a Hybrid turbo , that I did :-), took the compressor side from the HX super 40 (6 blade ) and the exhaust from HX35 12 cm
    I searched alot and got his :
    compressor :Ind 60mm/86 Ex
    Turbine: Ind 69/60 ex

    everywhere I search I found they claim that the 12cm exh =0.82-.0.89 (which is hard to believe :-))

    what shall I expct form a bigger Exh housing ?
    is it worth it go to HX52 (70 mm ) ?

    - - - Updated - - -



    I d be okay if i was an m50b25
    but with the extra capacity for the M50b30 , I think its a little bit on the low side
    Im building a m50b30 with s52 cams and will start off with a holset also. if it makes 500whp at 20psi id be really happy
    Last edited by Hofmeister; 01-07-2017 at 06:54 PM.

  9. #9
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    Quote Originally Posted by someguy2800 View Post
    Your results are about right for that size turbo. It will take a lot more than 1.3 bar boost to make 550-600 though. That's a pretty small turbine on that turbo to make more than 500whp. I would expect it to make 500 whp at mabey 1.5 bar or so. 600 might take a lot more due to the small turbine and compressor. I don't think going to a larger housing will do much for you.
    What do you suggest ?

    - - - Updated - - -

    Quote Originally Posted by E36 HateR View Post
    I have a small .70ar housing on my holset, granted my holset is a 6764 hx40, but i doubt the housing is holding you back, I would crank it up to 17-18psi, shouldnt need meth for an 8.5:1 comp on 93 at 17psi.

    Your numbers sound right but i would rev it to 7250.

    How big is your downpipe and exhaust? Are you open wastegate?
    I d be happy to get 500+whp
    would you think 17-18 psi would do it ?
    I ve 3" DP and exhaust

    - - - Updated - - -

    Quote Originally Posted by Hofmeister View Post
    Im building a m50b30 with s52 cams and will start off with a holset also. if it makes 500whp at 20psi id be really happy
    what Compression are you running and what hoslet ?

  10. #10
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    Quote Originally Posted by JOMARO View Post
    what Compression are you running and what hoslet ?
    Not running crap for now. debating on 10.5 e85 always or 8.5 and switching to e85 later. Turbo will be h1c 7 blade and 16cm housing

  11. #11
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    Quote Originally Posted by JOMARO View Post
    What do you suggest ?
    You should be able to make 500 whp with what you have now by just turning up the boost. If you want more than 500 whp I would look into something larger or upgrading the holset you have. I don't know what is available in Egypt but there are companies in the US such as turbolab USA that have upgraded turbine wheels and compressor wheels to go in your hx35 that will make a lot more power.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  12. #12
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    Quote Originally Posted by someguy2800 View Post
    You should be able to make 500 whp with what you have now by just turning up the boost. If you want more than 500 whp I would look into something larger or upgrading the holset you have. I don't know what is available in Egypt but there are companies in the US such as turbolab USA that have upgraded turbine wheels and compressor wheels to go in your hx35 that will make a lot more power.
    We have nearlly most of the holsets here
    I dont mind importing things from USA (Actually most of the turbo build was imported from USA )
    What turbine size do you suggest for 12cm hx35 for.550.whp ? (I m on stock m54rods ) 62 mm ? 64?
    I d rather have an efficient turbo than raising boost

  13. #13
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    Quote Originally Posted by JOMARO View Post
    We have nearlly most of the holsets here
    I dont mind importing things from USA (Actually most of the turbo build was imported from USA )
    What turbine size do you suggest for 12cm hx35 for.550.whp ? (I m on stock m54rods ) 62 mm ? 64?
    I d rather have an efficient turbo than raising boost
    For 500 whp import a 6262 or gt35r. Simple and effective . use a .81 or .82 AR back housing.
    1996 332IS
    Built 3.2
    CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
    Technique Tuning 80# tune.
    1/4 mile 10.84 @ 136.72
    Your 1 and only stop for all your BMW performance needs
    WWW.CESMOTORSPORT.COM

  14. #14
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    Would he be better off just going for a HX40? Not sure what the wheel sizes are on them (and there are a few variants). The turbine would be a lot better matched for the compressor though I think.
    -Nick
    91 E30 M42 on VEMS

    Turbo Camshaft Thread

  15. #15
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    A super 40 wpuld work perfect, the turbine is 64mm and they spool quick.

  16. #16
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    Will Right now I intend to get back the 64 turbine wheel from the HXsuper 40
    with a T3 0.82 Housing
    and I ll get 64 comp with machined housing form turbo lab
    making a 64/64 turbo ....
    right now I have full spool at 3rd gear at 3400 ... how late approximately shall i expect spool to be ?

  17. #17
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    Time to revive this thread, I pulled the trigger and got a 67mm compressor wheel and housing from turbo lab ,
    will have that matched to a HX40 exh 14 , to finally have 6764 turbo ( was inspired by e36 Hater :-) )
    will update you once I get it settled
    Would I see any benefits going to from 3" to 3.5" Dp at my power goal ?

  18. #18
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    Sounds good, at 600 whp there will be a sizable gain going to a 3.5" exhaust. Probably 30 whp or more, and will spool slightly quicker. Even a 500 whp car will pick up quite a lot going from 3 to 3.5.
    Last edited by someguy2800; 05-27-2017 at 07:01 AM.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  19. #19
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    My Bad , I was asking if changing the Dp to 3.5" while still having the rest of the exhaust 3"?

  20. #20
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    Quote Originally Posted by JOMARO View Post
    My Bad , I was asking if changing the Dp to 3.5" while still having the rest of the exhaust 3"?
    The rest of the exhaust is where the gains usually come from. Exiting the turbo you have velocity, therefore you can get away with smaller DP, but at the exhaust expands and cools, you need bigger area + bends. You would be better off having a 3" DP and going 3.5" for the rest. Or 3.5 the whole way.
    1996 332IS
    Built 3.2
    CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
    Technique Tuning 80# tune.
    1/4 mile 10.84 @ 136.72
    Your 1 and only stop for all your BMW performance needs
    WWW.CESMOTORSPORT.COM

  21. #21
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    Its time to update this thread
    I got the Holset 6764 exh 16 installed
    And got a whole 3.5 dp +exhaust
    Open dump Wg
    And
    WE Reached 650 whp/577t
    I guess at 1.5 bar with 93oct +Meth inj
    I m getting some major boost creep bow with RS mani
    We dialed it back to 600 whp for now
    And I m happy
    My main concern now is I get full boost at 4500 which I think is kinda late

    I have an ebay Aluminum intake manifold
    Could that cause later spool ?
    It seems that e36 hater is getting earlier spool than me although the 2.8 rather the 3.0 (bearing he has smaller exh and Twin scroll )

  22. #22
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    Twin scroll makes a HUGE difference. Also, displacement helps for sure.

    Sent from my E6782 using Tapatalk
    1996 332IS
    Built 3.2
    CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
    Technique Tuning 80# tune.
    1/4 mile 10.84 @ 136.72
    Your 1 and only stop for all your BMW performance needs
    WWW.CESMOTORSPORT.COM

  23. #23
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    Quote Originally Posted by JOMARO View Post
    Its time to update this thread
    I got the Holset 6764 exh 16 installed
    And got a whole 3.5 dp +exhaust
    Open dump Wg
    And
    WE Reached 650 whp/577t
    I guess at 1.5 bar with 93oct +Meth inj
    I m getting some major boost creep bow with RS mani
    We dialed it back to 600 whp for now
    And I m happy
    My main concern now is I get full boost at 4500 which I think is kinda late

    I have an ebay Aluminum intake manifold
    Could that cause later spool ?
    It seems that e36 hater is getting earlier spool than me although the 2.8 rather the 3.0 (bearing he has smaller exh and Twin scroll )
    Cheese and rice. 650/577 on pump and meth at 1.5bar, I'd be happy with that. Can you Post up the dyno graph?
    WOT

  24. #24
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    Quote Originally Posted by hsvturbo View Post
    Cheese and rice. 650/577 on pump and meth at 1.5bar, I'd be happy with that. Can you Post up the dyno graph?
    Depends on where the power is.

    Sent from my E6782 using Tapatalk
    1996 332IS
    Built 3.2
    CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
    Technique Tuning 80# tune.
    1/4 mile 10.84 @ 136.72
    Your 1 and only stop for all your BMW performance needs
    WWW.CESMOTORSPORT.COM

  25. #25
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    Not the best photo but you get the idea

    21035259_10203761045062551_573505348_o.jpg

    This is what we settled at now

    21081957_10203761043622515_1569774159_o.jpg

    Is there any thing to be done to get full boost a little bit earlier ? like at 4000 RPM ?
    I m using EBC and MSpro3, with 13 psi spring

    Ignore the last attachment
    Attached Images Attached Images
    Last edited by JOMARO; 03-03-2018 at 09:06 PM.

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