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Thread: BMW M5X ITB build.

  1. #1
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    BMW M5X ITB build.

    Ive posted a previous thread about my attempted ITB builds, but none of those ideas went anywhere. So i figured id make a new thread, where i can post my process, and discuss the various revisions i am going to make to this design.

    Anyway, lets start at the end. The following pic is of the complete V1. just to show that something did come of this.

    IMG_0025.jpg

    So. having seen it all on the engine, how did I do it. 2 (6) aluminium plates, and some bent flat bar. I made this as 3 pieces, 2 cylinders each, purely because i only have one vice for my mill, and couldn't hold something the entire length rigidly enough to machine accurately.

    Plate 1: M5X cylinder head. Easiest thing to do here is take the manifold off your engine and cut the runners off so you're left with just the plastic flange. then use a set of indexed centre punches to transfer the bolt pattern from the flange to your pieces of aluminium. I used 50x10mm (unsure of the grade). For those that don't know, indexed centre punches are just like normal hole punches, except you buy them in sets, and their diameter increased by 0.5mm. like drill bits. simply find the size that fits snugly (pretty sure it was 7.5mm) and mark your hole centres. Whilst you've got the manifold flange on the piece of alloy, also helps to scribe the ports onto it. This is where marking dye comes in handy. obviously if you;re using an M52 manifold the port sizes are gonna be smaller than on the actual cylinder head. (this is fine). When ll your marking is complete you should have 3 plates. i put these on my mill, used standard drill bits for the holes, and a slugger cutter/end mill for the ports. The head studs are an M7 thread, so the closest you can get the stud holes to 7mm, the better your fitment will be. Ideally i would suggest drilling the hole with a 6.5mm drill bit and hand reaming them to 7mm, or whatever size is needed for easy cylinder head fitment. (this will depend how accurately you marked and drilled the holes)

    Plate 2: ITB stud pattern. This plates are a little harder, as the ITB's (both S50 and S54) have locating dowels, which is good for alignment, but bad for marking out. Basically though, its the same process as the head side plates. Mark, drill etc. except, the holes for the locating dowels will need to be stepped. So the top of the hole accepts the dowel, but the bottom of the hole can still be tapped so you can affix the ITB's to the adaptor. Nut and bolt would work here, but it is a pain in the ass to get in and tighten it all up - tapped holes are much easier.

    Ultimately your plates should end up looking like this.

    IMG_0012.jpg

    runners: These are what probably had me stumped for the longest - until i was watching someone build a roll cage who showed me a trick for bending flat bar or sheet. what you need to do (and this may seem obvious to some) machine up a piece that is exactly the same radius as the curved side of the ports (25mm). then make up a deep box that is 25mm + the thickness of your flat bar (mine was 1.8mm). then using a press or a vice, press the 25mm round piece down into the box, on top of your flat bar. The more accurate your box is, the less work you will need to do afterwards to get it a perfect 180°. This is what i used: just some angle, and some flat bar. I then chucked these runners in the mill to square them off. (put a 25mm block inside them so the vice has something to clamp onto.

    This the the jig i used. Simply place the flat bar on top, put your round stock in the middle, and press.

    IMG_8451.jpg

    welding: depending on your skill set, this will either be the easiest or hardest step. Im more comfortable welding on DC, which made this a bit of a challenge for me seeing as I'm using aly. But i didn't exactly do myself any favours along the way. a few tips i found.
    1 - When welding the 2 halves of the runners together, stick a heatsink on the back side of the weld. 1.8mm is THIN, and will happily sag away. Also, be careful not to blow the corners off, as this can make welding it to the thicker stuff harder.
    2 - When tacking the runners to the flanges, light up away from the runner, start your puddle on the thick flange, and then coax it over to the thin runner. welding 10mm plate to 1.8mm flat is challenging at the best of times, so direct most of the heat into the plate.
    3 - stick a bolt through the drilled holes to prevent distortion.
    4 - to get in between the 2 runners use either a large gas lens cup with a long stick out, and the gas flow bumped up a bit, or a long thin cup with the gas flow right down. Either way this is a bit of a bitch. (another reason to do it in 3 parts).

    I did most of this with a number 20 water cooled torch flexloc, and a number 8 pyrex cup with gas lens. But whatever works best for you.

    IMG_8452.jpg

    Final machining: first and foremost, welding WILL have distorted the flanges. this means they will need to be surfaced to make a good seal. I elected to use a fly cutters as I've had good results with them before. (i also had to make a fly cutter, but that wasn't really a big deal). Each plate will probably have distorted differently and will require a different amount of surfacing. doesn't really matter how much you take off where, as long as in the end each set of 2 is the same height. id say around 1-2mm is about the max difference you could have before you get binding in the shaft in the ITB's. Also notice, that the flanges on the M50 head side have been interlocked. you can either do it this way, or just have half a hole on either plate. Doesn't really matter. It should also be noted that both the S50 and S54 ITB's are different shapes to the M50 cylinder head. address this by simply porting them with a die grinder. If you go to far, just add some weld metal, keep porting, and resurface.

    This is hopefully what you should wind up with after surfacing.
    IMG_0017.jpg

    Gaskets: The ITB's should have rubber seals with them, so that side isn't an issue. To seal on the head side, get either cork or paper gasket material and just cut out your gaskets. or use the dreaded gasket maker.

    This isn't exactly an easy project, and in the grand scheme probably wont gain you a whole heap of HP. But its definitely something very rewarding, and very unique. Patience and precision goes A LONG way. this entire project could probably be completed with very simple workshop tools, and a lot more patience. But having the right tools will result in a better job.
    Last edited by Kurtisja; 07-19-2017 at 02:05 AM.

  2. #2
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    As for measurements, the studs protrude about 40mm from the head. So if you make your runners around 30mm long, along with the 10mm baseplate, you should have enough clearance. If the possible, another option is trimming the studs. This being said, I believe there are benefits to longer runners. however i cant confirm without testing. In the case of this manifold, you're playing a balancing game between long runners, having enough room under the bonnet, and keeping the injectors close enough that you have accurate control.

    Ill try and remember to update this thread as i make improvements. But firstly i need to get this tuned, and make sure the injectors are still functional in that location. Im hoping V2 can be a full billet piece. But for now, here are some more pics.

    Attachment 605318Attachment 605319Attachment 605320

  3. #3
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    Excellent work!

    Hats off to you sir - love the innovation of the runners.
    Eat, drink, and be merry - for tomorrow we drive.

  4. #4
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    Finally Kurtis, we meet again, very well done

    - Hyde
    "So we've come to the conclusion that BMW just has parts laying around they decide to throw on cars for no reason."

    Interest on a Very Budget Supercharger Build??



  5. #5
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    Haha Hyde. Yes we do. I apologize for dropping off the face of the earth. I have been rather busy. But hopefully I can hang around and be a bit more active.

  6. #6
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    Very cool, what throttle bodies did you use?

    Always wanted to do a project like this. Would you ever remake and sell those spacer/adapters? I would be very interested if you did

  7. #7
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    Chronivrous, Ive sent you a private message. But yes, i am looking into producing and selling these (for anyone else interested). For now I'm keeping the idea under wraps, until I have a final product.

    If anyone else is interested in purchasing a set. feel free to send me a message.
    Yes I can buy it. But I can probably build it cheaper. And better.

    ​-E36 calypsorot track rat.
    -KW Coilers
    -ZF 5 speed with M5 puck clutch
    -M52B28 w Euro S50 Headers, Euro S50 ITB's, S52 cams, EMU standalone.
    -3 clutch LSD
    -330i brakes front and rear

    -E36 Violetrot V8 daily (still being built)
    -M60B40 V8
    -G420 6 speed
    -Brembo fronts/porsche rear brakes
    -BC coilers
    -3 clutch LSD
    -Vaders.



  8. #8
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    Another ITB Update. Between work its been a mad effort to get this car done and dusted (problem with your daily also being your project car). I reckon these have been off and back on about 6-7 times now, trying to fix vacuum leaks. firstly, gasket paper was a bad idea, especially if the surface finish isn't perfect, and the surfaces aren't perfectly clean. RTV goop between the head and the adaptors ended up working a treat. Next issue was the ITB O-ring seals. They seal fine, but i had to get all 3 adaptors perfectly flat. An issue given that I surfaced all 3 separately, due to the size of my mill. I had about a mm difference in height. After a bit more head scratching I got all 3 fixed to the mill, and using my rather large fly cutter, got them all flat.
    IMG_8726.jpg
    And here they are bolted to the engine.
    IMG_8732.jpg
    As with everything, Preparation is everything. Had I done this the first time, I wouldn't have needed to remove and refit so many times. Biggest thing I can say is, you will never get an ITB with a MAP sensor running right if you have vac leaks.

    All that done, and a few hours spent adjusting the throttles so they actually closed fully (again really important), we finally got it to idle at around 1000RPM.

    IMG_8743.jpg
    This is by no means a final product, but it is definitely getting closer. Next job is to synchronise all 6. The make a plenum that fits.
    Yes I can buy it. But I can probably build it cheaper. And better.

    ​-E36 calypsorot track rat.
    -KW Coilers
    -ZF 5 speed with M5 puck clutch
    -M52B28 w Euro S50 Headers, Euro S50 ITB's, S52 cams, EMU standalone.
    -3 clutch LSD
    -330i brakes front and rear

    -E36 Violetrot V8 daily (still being built)
    -M60B40 V8
    -G420 6 speed
    -Brembo fronts/porsche rear brakes
    -BC coilers
    -3 clutch LSD
    -Vaders.



  9. #9
    Join Date
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    monterey park , california
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    1993 325is s52 6 spd
    sweet will there be an adapter for the s54 throttle bodies as well?
    could you pm me the dimensions of the s54 adapter plate you had before?
    Last edited by coolx7; 09-07-2017 at 04:11 AM.

  10. #10
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    another update (i know I'm terrible, but patience is a virtue). Everything is finally coming to an end. We have a pretty rough tune in it, and i am driving it on the street. I ended up going with en ECUmasters EMU ecu, purely for ease of tuning. Its a very easy ecu to use, comes with good instructions and is easy to use.

    Im still facing a few drivability issues, as the throttles simply flow so much air. Im seeing atmospheric pressure at around 15% throttle. throughout the rev range. S50's combat this by A being a larger capacity engine, B having a better flowing head, and C through vanos allowing a more efficient intake at lower revs. However i am confident i can sort this with a different throttle actuation system, and more precise tuning. (we went form no fuel/ignition map, to drivable in about an hour).

    IMG_9250.jpg
    this is the engine bay almost complete. Lots of little things needed tidying up, and lots of things have just been removed for ease, to be added when/if i can be bothered.

    car made 183HP at the treads, and we are thinking there is more in it. which is up from 167with the M50 manifold. So its hard to say how much is the throttles, and how much is just good tuning. But this is where I'm at. It is definitely a viable mod, if you have the ability and patience to pull it off.
    Yes I can buy it. But I can probably build it cheaper. And better.

    ​-E36 calypsorot track rat.
    -KW Coilers
    -ZF 5 speed with M5 puck clutch
    -M52B28 w Euro S50 Headers, Euro S50 ITB's, S52 cams, EMU standalone.
    -3 clutch LSD
    -330i brakes front and rear

    -E36 Violetrot V8 daily (still being built)
    -M60B40 V8
    -G420 6 speed
    -Brembo fronts/porsche rear brakes
    -BC coilers
    -3 clutch LSD
    -Vaders.



  11. #11
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    Sounds good! Keep us posted.

    Why not post a video so we can hear how it sounds.
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
    Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".

  12. #12
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    Quote Originally Posted by Kurtisja View Post
    another update (i know I'm terrible, but patience is a virtue). Everything is finally coming to an end. We have a pretty rough tune in it, and i am driving it on the street. I ended up going with en ECUmasters EMU ecu, purely for ease of tuning. Its a very easy ecu to use, comes with good instructions and is easy to use.

    Im still facing a few drivability issues, as the throttles simply flow so much air. Im seeing atmospheric pressure at around 15% throttle. throughout the rev range. S50's combat this by A being a larger capacity engine, B having a better flowing head, and C through vanos allowing a more efficient intake at lower revs. However i am confident i can sort this with a different throttle actuation system, and more precise tuning. (we went form no fuel/ignition map, to drivable in about an hour).

    IMG_9250.jpg
    this is the engine bay almost complete. Lots of little things needed tidying up, and lots of things have just been removed for ease, to be added when/if i can be bothered.

    car made 183HP at the treads, and we are thinking there is more in it. which is up from 167with the M50 manifold. So its hard to say how much is the throttles, and how much is just good tuning. But this is where I'm at. It is definitely a viable mod, if you have the ability and patience to pull it off.
    I want to do the same with mine, is it that hard to do it? Or should I just buy off the shelf itb's to make it simpler? Any performance difference between the euro itbs and aftermarket? Cheers.

  13. #13
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    I want to do the same with mine, is it that hard to do it? Or should I just buy off the shelf itb's to make it simpler? Any performance difference between the euro itbs and aftermarket? Cheers.
    There is no performance gains with the euro ITB's, and quite honestly you will probably lose down low torque as they are too big for the standard engine and head. If you have the fab skills and the patience this isn't difficult, just time consuming. And challenges such as PCV, ICV and engine management will exist whichever route you take. I just went with the euro it's cuz its what i had, and the fab work was cheaper than buying a kit.
    Yes I can buy it. But I can probably build it cheaper. And better.

    ​-E36 calypsorot track rat.
    -KW Coilers
    -ZF 5 speed with M5 puck clutch
    -M52B28 w Euro S50 Headers, Euro S50 ITB's, S52 cams, EMU standalone.
    -3 clutch LSD
    -330i brakes front and rear

    -E36 Violetrot V8 daily (still being built)
    -M60B40 V8
    -G420 6 speed
    -Brembo fronts/porsche rear brakes
    -BC coilers
    -3 clutch LSD
    -Vaders.



  14. #14
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    monterey park , california
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    1993 325is s52 6 spd
    would you ever plan on making adapters for s54 itbs to m5x engines and selling?

  15. #15
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    This is a very nice build and I fully appreciate the effort in it. It takes a lot of patience and skill to do custom engine parts. Keep at it, I'm looking forward to seeing a video of it in action. I hope you can tune it to be nice and streetable.

    I considered ITB's for my rotary valve build but decided I didn't want to add more variables into the equation at once so went with a custom single throttle plenum. Heck at one point I considered 6 parallel Mikuni carburetors, but then decided I wouldn't give in to the ease of using a carb and buckled down and started modifying the tune on the ecu.

  16. #16
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    would you ever plan on making adapters for s54 itbs to m5x engines and selling?
    Yes I do. The only issue with the S54 throttles is to account for their size they need to be about 100mm away from the head, which means a custom made plenum is also required as the stock one wont work. Shoot me a message if you want to discuss further.
    Yes I can buy it. But I can probably build it cheaper. And better.

    ​-E36 calypsorot track rat.
    -KW Coilers
    -ZF 5 speed with M5 puck clutch
    -M52B28 w Euro S50 Headers, Euro S50 ITB's, S52 cams, EMU standalone.
    -3 clutch LSD
    -330i brakes front and rear

    -E36 Violetrot V8 daily (still being built)
    -M60B40 V8
    -G420 6 speed
    -Brembo fronts/porsche rear brakes
    -BC coilers
    -3 clutch LSD
    -Vaders.



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