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Thread: S50 Individual throttle bodies on M54B30 (Help)

  1. #1
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    S50 Individual throttle bodies on M54B30 (Help)

    Hello and good day everyone.

    Long story short.. I'm swapping a low mileage M54B30 (drive by wire) in an E34 and converting it to OBD2. (The swap is doable and a mechanic that I know did the swap multiple times on E30s, E36s, and E34s will do the swap for me).. That aside..

    As the title suggests.. I've got my hands on a cheap S50 Individual throttle bodies -with an adapter- that I'm planning to replace the original M54B30 Intake manifold with.

    I looked online and didn't manage to find a definite guide or any sort of details on how that can be done.. the questions are below for your generous answers.

    1. Which TPS sensor can be used on the S50 Throttle bodies that would be compatible with the M54B30 MS43 ECU?
    2. Any idea on the vacuum lines?
    3. Is it possible to replace the M54B30 original MAF with a 3.5" MAF (or is it unnecessary)?

    Thanks in advance for your assistance.

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    I can answer number 3 real quickly. The M54B30 MAF is already a 3.5" MAF.
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    Quote Originally Posted by 328 Power 04 View Post
    I can answer number 3 real quickly. The M54B30 MAF is already a 3.5" MAF.
    Thanks a lot my friend. I'm sorry, I barely am able to get solid information online on the diameter.. I saw that M54B25 is a 3" and saw that the ZHP MAF for the 3.0L is a 3.5" but I thought that's only the ZHP, not any M54B30s.

    Hopefully someone in the forum is familiar with such installation. I would be grateful if you know someone that I can send a message to.

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    I'm not sure the juice is worth the squeeze... Only seen a handful of successful drive by cable ITB's on M54's, most run MS41 engine management and lose a lot of the advantages of the M54 like exhaust VANOS. The others I've seen are standalone engine management. None had significant power gains from just the ITB's. Frankly I think ITB's are more "cool factor" than anything else and just not worth the effort making them work

    Imo put headers on the M54 as it goes in and enjoy it as-is... It's gonna be a good engine in the E34 due to being lightweight but still making decent torque

  5. #5
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    Could you please shed more light on the lost advantages when adapting the ITBs?

    I would be grateful if you could point out the successful builds with me if there are build threads for them, maybe I could learn a thing or two.

    In terms of advantages, I’m seeking better throttle response and the induction noise.

    Thanks in advance for your generous response my friend.

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    Anyone?

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    The people I know who did such swaps don't have build threads for them, so to supply sources I would merely be Googling, same as what you can do

    The biggest complication with this swap is that, AFAIK, the MS43/MS42 do not support drive by cable. I know some people convert to MS41 to get around this issue, running the engine in essence as a 3.0L M52. This means you get all of the M52 tech, none of the M54 tech - most of that (like the DISA) won't matter as much if going ITB's, but you would lose the exhaust vanos as I mentioned previously. And if you were looking at an MS45 M54 you would also lose the faster responding wideband O2's and updated MAF. I am not sure the intricacies of running an M54 on MS41 either, as I haven't done it myself. I imagine it's mostly plug and play although not sure the complications regarding sensor compatibility or the DME tune/coding.

    The other option is standalone engine management, but that can get very expensive. There may also be ways to run an MS43 as drive by cable, possibly using the tps as pedal input but I have not seen this explored to any significant extent on that DME. It has been done on S54's but that is a completely different engine management system.


    This is not a very commonly done swap, so there are not easy or readily known answers to your questions. Frankly, the M54 manifold is very well designed, the DISA resonance system boosts low-end torque without compromising up top power. It also has turbulence runners which are secondary intake ports supplied by the ICV. These supply only one intake valve with a stream of high-velocity air, which greatly increases the mixing of fuel and air at low speeds. This improves low-rpm/low-load economy and torque characteristics. The high velocity air channel also increases throttle response greatly compared to previous generation intake manifolds.

    The head is also port matched to the intake runners, so the head will be a restriction to airflow with the larger ITB's and there is no easy way to address this given that the secondary ports described above also go into the head. ITB's have two big performance advantages, throttle response and total airflow volume, the latter of which is neutered by the restriction at the head, the former of which the M54 manifold works to resolve with the turbulence runners. The thing is too, with ITB's you want the throttle as close to the cylinder as possible. Spacing it away with an adapter is decreasing the throttle response. Maybe not be a significant amount, but it won't feel or perform like an S50 or S54 and it makes the difference compared to a stock M54 less significant. As such, the main advantage you'd realize with ITB's on an M54 is the sound. So most people choose not to spend big $$$ on this mod, as there are much better modifications to be made elsewhere, and ITB's also inherently compromise some features of the M54 tech as they eliminate those secondary runners (and in most applications also eliminate the exhaust VANOS)

    So as I said before, it's a lot of squeeze for very little juice

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    Quote Originally Posted by BimmerBreaker View Post
    The people I know who did such swaps don't have build threads for them, so to supply sources I would merely be Googling, same as what you can do
    Oh, that's unfortunate.. Trust me my friend, I've been Googling this for more than a week now which is why I created this thread..

    Quote Originally Posted by BimmerBreaker View Post
    The biggest complication with this swap is that, AFAIK, the MS43/MS42 do not support drive by cable. I know some people convert to MS41 to get around this issue, running the engine in essence as a 3.0L M52. This means you get all of the M52 tech, none of the M54 tech - most of that (like the DISA) won't matter as much if going ITB's, but you would lose the exhaust vanos as I mentioned previously. And if you were looking at an MS45 M54 you would also lose the faster responding wideband O2's and updated MAF. I am not sure the intricacies of running an M54 on MS41 either, as I haven't done it myself. I imagine it's mostly plug and play although not sure the complications regarding sensor compatibility or the DME tune/coding.
    I'm going for the MS43 (due to its tuning capabilities). I read online about converting to drive by cable, and Indeed it's not a walk in the park.

    Quote Originally Posted by BimmerBreaker View Post
    The other option is standalone engine management, but that can get very expensive. There may also be ways to run an MS43 as drive by cable, possibly using the tps as pedal input but I have not seen this explored to any significant extent on that DME. It has been done on S54's but that is a completely different engine management system.
    Yep, Indeed, I saw the S54 conversions and they're almost too common.. I also managed to see the installation of the S54 ITBs into M54, but not the S50...

    Quote Originally Posted by BimmerBreaker View Post
    This is not a very commonly done swap, so there are not easy or readily known answers to your questions. Frankly, the M54 manifold is very well designed, the DISA resonance system boosts low-end torque without compromising up top power. It also has turbulence runners which are secondary intake ports supplied by the ICV. These supply only one intake valve with a stream of high-velocity air, which greatly increases the mixing of fuel and air at low speeds. This improves low-rpm/low-load economy and torque characteristics. The high velocity air channel also increases throttle response greatly compared to previous generation intake manifolds.


    The head is also port matched to the intake runners, so the head will be a restriction to airflow with the larger ITB's and there is no easy way to address this given that the secondary ports described above also go into the head. ITB's have two big performance advantages, throttle response and total airflow volume, the latter of which is neutered by the restriction at the head, the former of which the M54 manifold works to resolve with the turbulence runners. The thing is too, with ITB's you want the throttle as close to the cylinder as possible. Spacing it away with an adapter is decreasing the throttle response. Maybe not be a significant amount, but it won't feel or perform like an S50 or S54 and it makes the difference compared to a stock M54 less significant. As such, the main advantage you'd realize with ITB's on an M54 is the sound. So most people choose not to spend big $$$ on this mod, as there are much better modifications to be made elsewhere, and ITB's also inherently compromise some features of the M54 tech as they eliminate those secondary runners (and in most applications also eliminate the exhaust VANOS)
    Can never thank you enough for the information.

    However, and please hear me out.. I already plan on porting and polishing the head, so I believe that solves the part related to matching the head and the manifold port.

    And I also came up with an "idea" that looks slightly good on paper, didn't try to implement it yet... The idea is to modify the M54 throttle body in a way and attach it to the S50 ITBs by the TPS sensor and have it as a drive by wire ITB. Therefore not losing on the exhaust Vanos system, but will indeed lose the DISA functionality.


    IE: cut the portion of the throttle body in red seen below





    Create a custom bracket on the TPS sensor location with correct orientation.





    Eventually connecting the M54 throttle body to the rod that rotates the ITBs.


    Note: I know that the ITBs are spring loaded, and I removed these springs and managed to twist the rod with my fingers.

    The difficulties that I'm expecting are below.

    1. The rotation of the M54 throttle body seems to be counter clock wise. And the rotation of the S50 ITBs is clock wise. In theory, I believe can be solved by switching the ground and positive cables on the stepper motor and the TPS sensor (must be studied further, I'm not sure switching the polarity on a stepper motor reverses the actuation)
    2. Does the stepper motor have enough torque to rotate the throttle bodies.. I searched online to find the part number of the stepper motor in order to see how much torque it produces, but didn't manage to find any details on it.
    3. Assuming that the stepper motor can rotate the throttle bodies, will it respond fast enough to throttle input (due to having more mass to rotate) -- I will need to disassemble the whole throttle bodies, clean them thoroughly, and lubricate them in order to assure they move without needing too much torque.


    Only in theory that seems possible, but I never know what I might come across.


    And of course, if the above is implemented successfully, I'll need to get a tune due to the changes in the intake and the exhaust manifolds.

    Thanks for bearing up with me, my friend.
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  9. #9
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    Porting the head won't help a ton if the adapter between ITB's and the head is matched to the stock M54 port size

    Customizing the S50 ITB rail to be dbw actuated seems like a rather pointless endeavour since you may as well just use S54 ITB's at that point and then there isn't any question about whether or not they work

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    Would the OP be willing to move away from the better response of ITBs if his goal is more power and sound and do a mild turbo instead?

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    Thanks chief.

    I had a call with a local mechanic and tuner who said that it’s possible to do the adaptation; however, he came across numerous issues and instabilities when adapting the S50 ITB’s to M54.

    Regarding the S54 ITB’s, they’re very scarce around here and would cost a fortune if found. I found the S50 ITB’s for cheap tho.

    The tuner and mechanic suggested a big bore throttle body instead; saying it’s much more stable and will give good enough throttle response with a tune.

    I don’t totally trust him though since I already read about big bore throttle bodies on M54 are not necessarily a useful mod, so, I’m taking what he said with a pinch of salt.

    I decided to sell the ITB’s, and seek more info on the big bore throttle body.

    I’m grateful for your responses. Thanks a million.

    - - - Updated - - -

    Quote Originally Posted by pbonsalb View Post
    Would the OP be willing to move away from the better response of ITBs if his goal is more power and sound and do a mild turbo instead?
    Thanks a lot for the suggestion, but unfortunately I’m not planning on going FI route due to the issues that comes along.

    I’d rather have a reliable car with a little bit of more power than average on a tight budget.

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    Maybe look into aftermarket camshafts. You would need to tune for them.

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    I think it is right to not bother with the S50 ITB's and also to dismiss the mechanic's suggestion of a big bore TB. There is a general mindset of "bigger = better" but TB diameter should be matched to airflow requirements and too large will decrease performance by slowing the intake velocity. For F/I or heavily modified applications, BBTB's make sense because you need to flow more air, but for an otherwise stock engine they rarely offer any advantages.

    Cams would be a good idea, if you can source ZHP cams from a US car perhaps, or use the money from the ITB's to buy some Schricks. I think that will give you plenty of what you want. Just make sure you can find a good tuner.

    Also, headers... the M54 responds very well to headers since the stock setup has the catalytic converters integrated into the header and a merge very close to the head

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    Quote Originally Posted by pbonsalb View Post
    Maybe look into aftermarket camshafts. You would need to tune for them.

    I'm going to get a tune anyway since I'm installing a CAI and free flowing exhaust and headers.

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    Quote Originally Posted by BimmerBreaker View Post
    I think it is right to not bother with the S50 ITB's and also to dismiss the mechanic's suggestion of a big bore TB. There is a general mindset of "bigger = better" but TB diameter should be matched to airflow requirements and too large will decrease performance by slowing the intake velocity. For F/I or heavily modified applications, BBTB's make sense because you need to flow more air, but for an otherwise stock engine they rarely offer any advantages.

    Cams would be a good idea, if you can source ZHP cams from a US car perhaps, or use the money from the ITB's to buy some Schricks. I think that will give you plenty of what you want. Just make sure you can find a good tuner.

    Also, headers... the M54 responds very well to headers since the stock setup has the catalytic converters integrated into the header and a merge very close to the head
    Yep, the ITB's idea was discarded thanks to you of course.

    Regarding the BBTB, I had a discussion with the tuner, and he seriously believes that it works and even went to the extent of showing me some dyno charts with a different of 7 to 10 horses before and after the BBTB upgrade and an increase in torque but later in the rev range. Now, I don't know whom to believe really...... :/

    I searched locally for the ZHP cams, but they simply don't exist in my country. I searched online their price is around 400-450 USD, but after shipping, taxes, and customs, they're going to end up costing up-to 1100 USD, thanks to my lovely country of course.

    Schricks costs over 1700 USD here, which simply makes their added value not worth it at all....

    In conclusion, ordering anything from outside of here will cost a fortune. And I'm not planning on breaking the bank lol.

    Seems like I'm only going with free flowing headers and exhaust, and a CAI on a BBTB (since the tuner knows for sure that it works) -- He also said that It'd be possible on these little mods to get around 230-240 HP and around 350 NM of torque at around 4500RPM on the wheels..

    He never came to mention anything about upgrading fuel injectors and fuel pump, which makes me believe the stock ones are sufficient.

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    My only qualm about the BBTB is that comparisons are usually apples to oranges. People install a BBTB, then flash a fully optimized tune, then compare to a stock tune with the stock TB. If you run a fully optimized tune for the stock TB size, then compare to a BBTB with a tune, it would be a fair comparison.

    I think 350n-m (a 50n-m gain) from just headers/BBTB/tune, plus only a 5-15hp gain, doesn't seem to quite compute to me. But if your mechanic wants to do it, I would just let him as long as the price is fair. Worst case you don't like it, the TB itself is easy to swap with the engine installed.

    Headers will be the biggest power gain on the M54 so make sure to get those done.

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    Quote Originally Posted by BimmerBreaker View Post
    My only qualm about the BBTB is that comparisons are usually apples to oranges. People install a BBTB, then flash a fully optimized tune, then compare to a stock tune with the stock TB. If you run a fully optimized tune for the stock TB size, then compare to a BBTB with a tune, it would be a fair comparison.

    I think 350n-m (a 50n-m gain) from just headers/BBTB/tune, plus only a 5-15hp gain, doesn't seem to quite compute to me. But if your mechanic wants to do it, I would just let him as long as the price is fair. Worst case you don't like it, the TB itself is easy to swap with the engine installed.

    Headers will be the biggest power gain on the M54 so make sure to get those done.
    It slipped my mind to ask whether the before dyno runs were previously tuned, or from factory ecu.

    I’m sorry, but I meant 230-240 wheel hp, but it was at the end of sentence (could possibly be grammatically incorrect. English isn’t my native)

    230-240 whp and 350 nm torque on the wheels too.

    Headers will definitely be part of the build, but I’m still on the lookout to find a decent one around here….. again, can’t source one from outside boarders, although, Schmiedmann M54 headers caught my eyes for only 270 euros, but after everything they’re gonna be very pricey. And custom made headers are also over the limit.

    I will probably be updating this thread as I go through. I’m going to start with the build on December 24th as my 10 day vacation starts.

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    If you have cats built into the headers, there should be good gains from going catless if you get away with that in your country. The BBTB is not going to do as much but every little bit counts (I have a Dinan BBTB on my turbo E36 3.2L). Could you have cams reground or would that require shipping to Europe and paying taxes?

    One way to improve acceleration (but reduce fuel economy) is a shorter differential if you can find one or build one. I don’t like the big jump some do from 3.15 to 3.91, but I have used 3.15, 3.23, 3.38 and 3.64 and the 3.64 was a lot of fun with cams to extend the power band. I liked it around town, but not on trips of more than an hour if going 80+ mph steadily. It still did 143 mph at 7000 rpm in 5th gear.

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    Quote Originally Posted by pbonsalb View Post
    If you have cats built into the headers, there should be good gains from going catless if you get away with that in your country. The BBTB is not going to do as much but every little bit counts (I have a Dinan BBTB on my turbo E36 3.2L). Could you have cams reground or would that require shipping to Europe and paying taxes?

    One way to improve acceleration (but reduce fuel economy) is a shorter differential if you can find one or build one. I don’t like the big jump some do from 3.15 to 3.91, but I have used 3.15, 3.23, 3.38 and 3.64 and the 3.64 was a lot of fun with cams to extend the power band. I liked it around town, but not on trips of more than an hour if going 80+ mph steadily. It still did 143 mph at 7000 rpm in 5th gear.
    This is the first time I ever hear about cams reground. I took a look at what that actually is and what I understood so far is that it’s a process of material removal from lowest point on the cams and then replace the shims/buckets with a higher one (please correct me if I’m wrong). there seems that there’s also the option of adding material to the cams and then grind it? I wonder how reliable that could be… I’m gonna check and see if such thing is being done locally.

    I’m planning on installing an LSD with 3.45 ratio and I’m going to pair the engine with GS6-37BZ 6 speed trans from a 330ci e46. I’m not planning on compromising daily drivability. I did some calculations using an online website where you enter the trans and diff ratios to see the rpm for each speed and it turned out to be the optimal diff ratio for me. I think using 3.45 will be a lot of fun with no compromises.

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