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Thread: The E21 323i from the scrapyard.... <3

  1. #51
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    I have 2 questions, maybe you could help me.

    Would like to run a 4" downpipe and a 3" exhaust. There is not enough space to run the 4" down, but would you think i would gain a noticable spool & power benefit from just running like turbo back till the firewall in 4 inch (so maybe 1 foot or so) and then reduce it to 3" ? I would assume i could see some benefits but want to hear different opinions before i decide to do it.

    2.: could a open screamer wastegate pipe cause false AFR readings? i am still running enough exhaust gas to the sensor and would expect no false reading, and plenty of guys running open dump, but just wanted to hear if that could happen somehow?

    thanks. <3

  2. #52
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    IMO
    If the turbine outlet is 4" then starting with 4" will help organize the exhaust gas as the turbine was designed with that outlet size/shape in mind, it will also give the exhaust a chance to cool and condense slightly before being subjected to the smaller diameter, lower pressure, higher velocity tube downstream.

    I've never run a screamer but I don't see how venting one portion of well mixed exhaust gas would have any effect on O2 content in the exhaust tube since it isn't getting the chance to be sucked back in the way and exhaust leak would allow.

  3. #53
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    Quote Originally Posted by PowerKraut View Post
    I have 2 questions, maybe you could help me.

    Would like to run a 4" downpipe and a 3" exhaust. There is not enough space to run the 4" down, but would you think i would gain a noticable spool & power benefit from just running like turbo back till the firewall in 4 inch (so maybe 1 foot or so) and then reduce it to 3" ? I would assume i could see some benefits but want to hear different opinions before i decide to do it.

    2.: could a open screamer wastegate pipe cause false AFR readings? i am still running enough exhaust gas to the sensor and would expect no false reading, and plenty of guys running open dump, but just wanted to hear if that could happen somehow?

    thanks. <3
    1. What power level are you at? In general, bigger is always better (to a point)... but 4" is really big so if you're making <600whp then 3" is more than fine still... 3.5" is probably a better choice either way for you.

    2. No.

    E36 DYNO TUNING WIRING PARTS

  4. #54
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    Quote Originally Posted by Kingtal0n View Post
    IMO
    If the turbine outlet is 4" then starting with 4" will help organize the exhaust gas as the turbine was designed with that outlet size/shape in mind
    Its got a 3" Outlet, but i would go 3" to 4" with a smooth transition, then back to 3" to fit down there and 3" all the way back. I would think i could see gains from even that short bit of 4" pipe (approx 2 feet of 4" maybe?), as it offers a noticable bigger volume right after the turbine... not sure if thats just theory and not worth the cost of extra pipe and work.

    - - - Updated - - -

    Quote Originally Posted by NOTORIOUS VR View Post
    1. What power level are you at? In general, bigger is always better (to a point)... but 4" is really big so if you're making <600whp then 3" is more than fine still... 3.5" is probably a better choice either way for you.
    Shooting for daily 400-500 wheel and the sky is the limit on the dyno. or my stock pistons and rods.
    But improved spool up would really be nice of course.
    I will not buy 3.5 all the way thru, as i got a nice bit of 3" left, but a 3,5 Downpipe should be doable and maybe even fit thru the tight space between rack and firewall, what a 4" would not.... hmmm... unsure what to do.

    2. No.
    thanks

    - - - Updated - - -

    For everyone that is too lazy to klick thru this thread but still likes pictures. I will add more of those dia shows soon.



    Episode one of my build. The rescue from the scrapyard and welding.

    https://www.youtube.com/watch?v=E-Qx...ature=youtu.be

  5. #55
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    IMO

    Never increase and then decrease diameter of (turbocharger) exhaust gas plumbing unless you have an extremely good reason to slow it down (velocity loss), de-organize it (entropy loss)/ add turbulence, as this is surely going to negatively impact performance.

    Remember that mass flow in = mass flow out

    If you put a giant room in the middle of two small pipes it probably won't help with massflow on either end unless you've timed some kind of acoustic pressure wave (i.e. expansion chamber on a 2-stroke) in relation to an opening/closing orifice which a turbine does not... really have
    Last edited by Kingtal0n; 07-13-2018 at 05:08 PM.

  6. #56
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    Quote Originally Posted by PowerKraut View Post
    Shooting for daily 400-500 wheel and the sky is the limit on the dyno. or my stock pistons and rods.
    No need at all for larger than 3" in that case...

    E36 DYNO TUNING WIRING PARTS

  7. #57
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    Turns out the s300sxe Got a Strange Flange. No way 3" vband.. more like 3.5 but 3 inside diameter...

  8. #58
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    This is the one I used. 4.21 marmon flange if you want to search for others.

    It's a little thin a warps but the clamp seems to bring it square.

    https://rover.ebay.com/rover/0/0/0?m...2F263578553284

    They sell it with and without a clamp

  9. #59
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    Thanks Kevin!

    Since the turbine got a 3,5" outlet, i decided to go 3,5 downpipe

    Plans are:

    All Stainless of course.
    Downpipe 3,5"
    On the Floor to the rear axle 3"
    Single Muffler right before the rear axle with single 3" inlet and dual 2,5" outlet
    Fit the dual 2,5" thru the rear axle somehow and back to the rear bumper, als the e21 323 came with duplex pipes at the back.

    And in my opinion the 2,5" pipes match the sleeper look better than 3"


    And flow-wise the dual 2,5" (9.81 square inch) offers almost perfectly the same cross area as single 3,5" (9.62 square inch)


    Cant wait to hear that thing run with a proper exhaust.


    What diameter for a proper open wastegate? does it even matter? Its a 38mm Wastegate, so i would of course not go any smaller than that... but would a bigger pipe give any advantage like less creep or stuff?


    e21 07_2018.jpg

  10. #60
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    Yeah that flange just gets cut down a little to get the 3.5" pipe in there.

    s300 flange.jpg
    Last edited by Kevin325i; 07-17-2018 at 08:07 PM.

  11. #61
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    Put a few things together today... looks promising already.

    e21 motor 23_07_2018.jpg


    one thing: first time with the tial blow off.. is it adjustable or do i have to buy a ton of springs to set it up? my chinese one on the other builds is adjustable and worked fine.. so why the tial... :|

  12. #62
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    If I remember they only have like two springs for them, the default spring for high vacuum engines and one for low vacuum. Unlike China, Tial knows how to make a blowoff valve work right without an adjustment screw.


    86 325es, 2.8L m50, S472sxe, MS3pro Ultimate, e85, solid rear axle, 4 link, spool, TH400 trans, Protorque converter, 28x10.5w slicks, zip ties
    Best = 9.43 @ 149.15 mph, 1.30 60 foot 28 psi boost

  13. #63
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  14. #64
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    I know you don't want to hear this now, but the bypass should be as close to the compressor as possible.

    And definitely not after any intercooler.


    The kind of bypass you are using:
    the kind of bypass you are using (non recirculate) is specific to MAP-sensor cars (cars without MAF sensors which would detect any minor leaks in plumbing) and furthermore being a 'china' replica is more prone to leaking and has a slower response time, and uncalibrated spring rates. The spring will likely need 'trimming' for best response. The heavy spring tends to open the bypass too slowly even on high vacuum engines and the lighter spring too often leaks.

    The single most important thing with any bypass is that it does NOT LEAK during high pressure situations. therefore it is IMPERATIVE that you test the system as-is at high pressure before attempting to run the engine there in reality at that pressure.

    If it leaks unexpectedly a couple things will happen. First the compressor will move to the right of it's map and could overspeed condition. Next, the exhaust gas pressure will rise dramatically and the exhaust gas will become higher temperature and the cylinders detonation prone. Finally of course if the leak is small enough that it does not overspeed or cause detonation, it nevertheless causes a loss in power so leaks are UNWANTED REGARDLESS.

    as to it's behavior:
    This type of bypass installed to a MAP sensor engine is OK to hang open at idle allowing high shaft rpm at off-boost situations, be tightly shut and leak free at WOT, and respond fast enough that there is little/no compressor surge when lifting from the throttle.

    The ideal strategy however is to use a recirculate bypass, especially for MAF sensor equipped cars. If you have a MAF I recommend recirculate kind of bypass. Place the maf sensor PRE-compressor and recirculate the bypass POST maf, pre compressor, thus raising pressure in this region pre compressor.
    Last edited by Kingtal0n; 07-25-2018 at 02:20 PM.

  15. #65
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    He is not using a maf so the placement of the blow off does not matter. Your advice is all stupid.


    86 325es, 2.8L m50, S472sxe, MS3pro Ultimate, e85, solid rear axle, 4 link, spool, TH400 trans, Protorque converter, 28x10.5w slicks, zip ties
    Best = 9.43 @ 149.15 mph, 1.30 60 foot 28 psi boost

  16. #66
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    Thanks man. Its not my first build so i am aware of the things you said. I will run a ECU Master Stand Alone with MAP of course.
    I sure disagree with the position close to the compressor you mentioned. Blow off close to the throttle body should be fine and give a fast response when the TB is shut, never had any problems on any build so far.

    But i must admit you seem kinda right, seems like i got f'ed over with a china copy.. did some research just now and i am pissed... but quality looks to be very very good.. sure gonna check if its working properly - going to check it when i am back in the garage to be sure.

  17. #67
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    Recirculate: It isn't my advice, it is the way all cars are all setup as turbo from factory. only passing on the info about recirculate pre-compressor, post maf, that is simply the OEM method.
    ↕▬> Recirculate raises pressure pre-compressor and allow maximum steady state shaft rpm for engines at idle and cruise, which helps minimize turbo lag. Free increased energy with negligible temperature raise is welcome precompressor as kinetic energy is conserved within the system to provide air pressure boost both pre and post compressor when compressor flow is in excess of engine flow rate. typically an issue with smaller turbochargers which is why I am so aware of it happening. Often if you block one of these systems the compressor will alternatively speed and slow as it approaching surge over and over in a never ending rubber band as compressor flow rate exceeds engine flow rate and the compressor surges (stalls) which lowers wheel speed and the process repeats forever.

    Intercooling advice:
    To pass air through an intercooler costs energy. Intercoolers reduce engine power output for this reason. A compressor sets the flow rate, anything downstream merely subtracts from that, is "in the way". Imagine if the plumbing length is approaching infinity. With enough length, enough pump head is impossible to produce. An intercooler is just another length of pipe, except that it is designed to force the air turbulent in effort to heat exchange. All heat exchangers have some limit for heat extraction, it is unwise to unnecessarily load a heat exchanger because this will obviously reduce its efficiency and impact performance.

    A compressor pump working against an intercooler "turbulent pipe area/length" needs to provide enough kinetic energy (V^2/2g term) to air molecules that are scraping the insides of an intercooler which puts load on the intercooler's cooling capability &c as a heat exchanger, also puts load on the pump's drive or turbine, thereby raising exhaust gas pressure and temperature and reducing engine efficiency. By dumping this air after all the heat exchange and kinetic energy losses you are inducing, as Def would might say, "significant minor head losses" as the pump is now having to make up for additional friction head, which of course puts load on the pump's drive or turbine, thereby raising exhaust gas pressure and temperature and reducing engine efficiency, while at the same time you are also loading the intercooler capacity by sending hot air through to be cooled and then dumping it to the atmosphere afterwards in a complete waste. I know fluid mechanics is difficult to correlate sometimes with auto performance because of the compressibility of air as a fluid and exacting technology behind turbocharger manufacturing, but here is some more facts. There is a thread in this same section of this forum where somebody mentions these same ideas and I am surprised you missed it. The other fact is that in recognition of public problems with bypass use-placement some turbo manufacturers are now directly incorporating the bypass directly into the compressor cover to eliminate end user mistakes.
    Last edited by Kingtal0n; 07-25-2018 at 04:31 PM.

  18. #68
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    everything you just said is asinine


    86 325es, 2.8L m50, S472sxe, MS3pro Ultimate, e85, solid rear axle, 4 link, spool, TH400 trans, Protorque converter, 28x10.5w slicks, zip ties
    Best = 9.43 @ 149.15 mph, 1.30 60 foot 28 psi boost

  19. #69
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    I am lost for words due to the imensly pointless copypasta, so i decided to just post another picture. Its the nozzle of my DIY water-meth injection pre throttle body. Maybe gonna add another one pre comp just for fun, depending on temps.

    IMG_20180724_141706.jpg

  20. #70
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    No hate man, you may be right with some of your statements, but its not like I reinvented the wheel with the bov in front of the TB. There was a time when people all told you to put the bov as close to the TB as possible to not harm the turbo, now its the other way around or what. I think we got bigger problemd to adress, as bov placement never seemed to be an issue nor performance killer in the last 30 years. I like to learn new things, but this seems to be a bit overdone.

    so if i place the bov after the comp, whats wit the air that is already after the BOV in the charge pipe, ramming against the shut TB? It has now to pass backwards thru the intercooler to leave the charge pipe, went thru the IC twice to do that and had to switch directions of flow... seems even worse for me, as a non rocket scientist.
    Last edited by PowerKraut; 07-25-2018 at 05:07 PM.

  21. #71
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    I never even thought about my BOV this much...

    My head is spinning. I feel like need a better explanation. I've never seen a Bov flange welded near the compressor on our cars.

    (I'm no genius or anything
    King where are you copying and pasting from? I don't see why it would make a difference where the BOV is placed. Pressure should be the same from the outlet of the turbo to the intake manifold as long equal load is applied and the intercooler is preloaded (and yes there is lag with in an IC, anyone could figure that out). When the throttle is let off the TB closes and vacuum opens the valve... The air will then find the path of least resistance, no matter where its located. When throttle is let off and you are out of boost and the engine is basically a vacuum cleaner. You want the BOV as far away from the MAF as possible, that's it - been that way for awhile. As far recirc, some are setup like that too

    Power, I use meth as well and was think about a second nozzle at the comp intake

    Sent from my SM-G960U using Tapatalk
    Last edited by 328iFun; 07-25-2018 at 07:24 PM.

  22. #72
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    In practice it doesn’t make any tangible difference that anyone can tell before or after the intercooler so put it wherever it fits best. There is like a cubic foot of air in the charge pipes that needs to be vented and after that it’s just whatever the compressor moves as it’s freewheeling. If you have a blow through maf put it at least a foot before the maf. If you have a draw through maf you probably have a 1.8L golf or some other boring POS so I don’t care what you do.


    86 325es, 2.8L m50, S472sxe, MS3pro Ultimate, e85, solid rear axle, 4 link, spool, TH400 trans, Protorque converter, 28x10.5w slicks, zip ties
    Best = 9.43 @ 149.15 mph, 1.30 60 foot 28 psi boost

  23. #73
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    Quote Originally Posted by PowerKraut View Post
    No hate man, you may be right with some of your statements, but its not like I reinvented the wheel with the bov in front of the TB. There was a time when people all told you to put the bov as close to the TB as possible to not harm the turbo, now its the other way around or what. I think we got bigger problemd to adress, as bov placement never seemed to be an issue nor performance killer in the last 30 years. I like to learn new things, but this seems to be a bit overdone.

    so if i place the bov after the comp, whats wit the air that is already after the BOV in the charge pipe, ramming against the shut TB? It has now to pass backwards thru the intercooler to leave the charge pipe, went thru the IC twice to do that and had to switch directions of flow... seems even worse for me, as a non rocket scientist.
    We need to keep in mind the fact that the engine is still running. Air doesn't just stop and turn around- it still goes into the engine at some rate. Lets say the engine decelerating from 6000rpm and the throttle blade closes, vacuum sky rockets but what is the engines air flow rate in cubic feet/second? Use a rough calculation of 150cubic inches, and lets say 15% VE:

    150x6000/3456 = 260cfm * .15 = 39cfm or .654 cubicfeet per second of air

    How much air is in a 3" pipe 5 feet long?
    5ft length times pie(.125ft)^2 = .2454 cubic feet of air

    so .2454/.654 = .37 seconds to remove all of the air in 5 foot section of 3" diameter tube by a 150 cubic inch engine at 15% VE and 6000rpm

    Just rough to see without any help from any bypass being open.
    Lets see if we can find some raw comparative data from someone on this forum though,

    From when throttle starts to close, to when the inlet manifold goes into vacuum, it takes 0.154 seconds.

    When the throttle arrived at 10%, to when the inlet manifold went into vacuum, it takes 0.077 seconds
    https://www.bimmerforums.com/forum/s...8#post29948278

    Also same guy
    https://www.bimmerforums.com/forum/s...6#post29767606
    Quote Originally Posted by PEI330Ci View Post
    It will be really interesting to compare the inlet/outlet temps before and after the heat shielding. Being that my inlet manifold temps are really good, it's not critical for engine life, but I'd rather not be putting that heat in there in the first place. Kind of like putting a BOV after the intercooler....where you're dumping air that's been cooled, and the intercooler is shedding that heat for no reason.



    The important part is to realize that the air doesn't all just "stop and turn around and go back through the intercooler". There may be a "water hammer" effect, a pressure wave undoubtedly travels away at the speed of sound from the closing throttle valve because that is how fluids behave when you slam shut a valve. But that wave is the same intensity regardless of where you position the bypass valve because the pressure wave amplitude is based on the speed of the shutting valve iirc, and the velocity of fluid will be the same initial condition because the bypass is never open during WOT.

    I don't copy and paste unless you see "quote" tags it will be clearly quoted. Furthermore try imagining a situation where the length of pipe approaches infinity and position a bypass valve on the end of it. What is the result as the pipe length increases? As you can see, at some point the valve's ability to provide relief for the compressor (its intended job) is diminished the father away the bypass gets, as the volume of air in the tubes increases to infinity with the length. It is therefore imperative to keep the bypass as close as possible to the compressor to minimize this volume.
    Last edited by Kingtal0n; 07-26-2018 at 01:59 AM.

  24. #74
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    I need a gif that shows a guy opening a box and inside the box is a brand new blow off valve.

    The animation as follows:

    1. opens box and see blow off
    2. Says to himself "This part protects my turbocharger from compressor surge"
    3. finally he installs it halfway around the car on the other side away from the turbocharger.


    -.-

  25. #75
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    Sometimes you have to make do with the room you have.

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