BMW N73 Test Mule run on Stutska Dyno

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Einar1969
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BMW N73 Test Mule run on Stutska Dyno

Post by Einar1969 »

Good day everyone, I am Einar and I recently picked up an N73 test mule engine as a project - going to get it to run on my dyno and tune for installation in something interesting, possibly a boat. I essentially want to have an operating engine power source that will run standalone and available to install in any project.
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AndreyB
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by AndreyB »

You've got just an engine or the whole vehicle? A picture would be a worth a thousand words here.

Did you get any electronics with the engine?

Do you have roller dyno or hub dyno or else dyno?

Right now as is I am pretty sure that you would be able to run N73 as two GDI inline 6 engines with two Proteus units and two of https://rusefi.com/forum/viewtopic.php?f=4&t=1564

That would be annoying to tune two boxes separately, relatively easy to attempt software progress to have two Proteus units to communicate.

We've made zero progress on variable valve timing gear control - not the VVT, the fancy one.

See also https://github.com/rusefi/rusefi/wiki/BMW-N73
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Einar1969
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by Einar1969 »

I have just the engine - no intake manifolds, no exhaust manifolds, no fuel system and a bunch of damaged and missing sensors. It was a used take out that was stored for years and never used. I am looking into ITB setup and going through the wiring diagram to determine what I/Os would actually be needed to run it. I have to study up on the VVT and the Valvetronic variable lift functions. Has anyone looked at using a more powerful processor to avoid using mulitple Proteus'? Here is picture of palletized engine.

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Re: BMW N73 Test Mule run on Stutska Dyno

Post by AndreyB »

Einar1969 wrote:
Sun Mar 26, 2023 12:39 am
I have just the engine - no intake manifolds, no exhaust manifolds, no fuel system and a bunch of damaged and missing sensors
Would getting a complete full donor 760 be the cheapest way to get all the missing parts especially the fuel system?

Plan single computer would be a bespoke design since no one needs so much input/output on one ECU. Maaaaaaaaaaaaaaaaaaaaaybe the way to go single Proteus would with smaller port extension box but that requires software changes https://github.com/rusefi/rusefi/issues/4096

See also https://github.com/rusefi/rusefi/issues/3841

Which brings us to the time/cost/skills hexagon, you have my cell if that seems like the simplest way to understand each other.
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bill
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by bill »

Einar1969 wrote:
Sun Mar 26, 2023 12:39 am
I have just the engine - no intake manifolds, no exhaust manifolds, no fuel system and a bunch of damaged and missing sensors. It was a used take out that was stored for years and never used. I am looking into ITB setup
i currently own and attempt to drive one of those pieces of shit 760iL
worst car i have ever owned
the N73 seems like a good engine,
BUT
you are in for a world of pain for your wallet if you have to go out and buy 12 injectors ( 100 bucks each) , 2 fuel pumps ( a thousand bucks each), etc

there was a complete N73 in a junkyard in maryland a few months ago,
i did not pull it out

you do not need ITB's... the valvetronic will serve that function
exhaust manifolds are easily substituted with some tubular headers
same on the intake manifold-- it does not need to be anything other than tubes coming off the head, since no need for ETB, MAP sensor, etc
many parts are in common with the 6 cyl BMW engines... so are available and reasonably priced

if you can get proteus to control the 2 Valvetronic motors ( which i believe is not very advanced... just a 12V DC motor with sensors to read the position)
you can have a running engine, no problem

good luck!
you will need it
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by bill »

where are you located? Germany?
are you sure there are no injectors? its really hard to pull them out ... somebody would have to work hard to get them out
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by mk e »

bill wrote:
Sun Mar 26, 2023 1:06 am

you do not need ITB's... the valvetronic will serve that function
Nobody NEEDS ITBs and yet everyone needs ITBs :D They look cool and there's usually a 5ish % hp bump at higher RPM (so maybe irrelevant or even unhelpful on a boat). All sport bikes use them so they are availably pretty cheap on ebay...and have impedance injectors ss plug the GDI holes and move on.

On the valvetronic I'd be very temped to find a way to lock it out of service and be done with it, at least to get it up and running.

On 2 ECUs, motec had a setup for pairing 2 M800s. They connected both to the crank and cam triggers then CAN shared the MAP, TPS, CLT, IAT and the main tuning table primary to slave ecu. Cylinder trims were still in the separate ECUs but main tuning was much easier to do. I might have still have the pdf explaining the setup somewhere but that was more what setting to make in each ECU to getting working so mostly not applicable to rusEFI but I can search it it would help. I did a 2 haltech install years ago and know a couple guys that have as well....its not HORRIBLE but it sure slows things down. I used 2 laptops because I couldn't connect 2 ECU to a single which helped but no idea if 2 is possible with rusEFI.
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by bill »

mk e wrote:
Mon Mar 27, 2023 2:47 pm
bill wrote:
Sun Mar 26, 2023 1:06 am

you do not need ITB's... the valvetronic will serve that function
Nobody NEEDS ITBs and yet everyone needs ITBs :D They look cool
.and have impedance injectors ss plug the GDI holes and move on.

On the valvetronic I'd be very temped to find a way to lock it out of service and be done with it, at least to get it up and running.

On 2 ECUs, motec had a setup for pairing 2 M800s.
i think you missed the point-- the engine does NOT need ITB or ETB or anything if valvetronic is present.

and GDI gives more power and fuel efficency --usually 15% more
so disable that and lose power (15% of 440HP is 60HP, a substantial amount of power)

if you lock out valvetronic, then you then NEED a ETB or ITB
and again, lose the efficiency that valvetronic provides

i have run a V12 on a single proteus, no problemo ... no need to Two ECU's

the main problem preventing running the N73 as is ....
would be the valvetronic setup
and nobody at rusefi wants to make the valvetronic work with rusefi / proteus

sooo.. its ditch the valvetronic and run ETB's if you want to run Rusefi
I would leave the GDI, since its a substantial loss of power to get rid of it
and Rusefi / proteus can run the GDI on the N73
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by mk e »

bill wrote:
Mon Mar 27, 2023 6:27 pm

i think you missed the point-- the engine does NOT need ITB or ETB or anything if valvetronic is present.
No I got it but I thought I read the ecu doesn't support vavletronic and therefore the build needs to have TBs added? Either way it needs an intake manifold which I think I read it doesn't currently have? So ITBs or I guess with valvetronic it could just be individual velocity stacks but either way smooth, straight runners flow a bit better than anything with bent ones or 90 degree turns in the plenum so there is normally a slight hp gain.

The rest, not sure. Most of the GDI stuff is emissions related with the hp gain coming from a lot of little things like more aggressive cam timing you can run when you aren't worried about losing charge out the exhaust. I've seen GDI pulled from a couple engines and they gained hp, but there were other things done at the same time (ITBs on 1 of them) so I truly no idea what just removing GDI would do hp wise. I know for sure on applications that are not strictly emissions restricted like sport bikes they still run port injection and make 240hp/l naturally aspirated but again certainly not an apples to apples comparison.
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by Einar1969 »

I am located in Wisconsin, will check to see if injectors are still installed, both HP fuel pumps and lines are gone as well as VVT solenoids and camshaft position sensors. This was a motor pillaged for parts so the options are going to be interesting. My new approach will be to evaluate conversion options. Looking at S54 ITB conversion to a port fuel injection arrangement. Since I have access to machine shop if I need to make any conversion parts that won't be a problem. I will strip harness and clean up engine to get an inventory of what is missing.
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Re: BMW N73 Test Mule run on Stutska Dyno

Post by mk e »

Einar1969 wrote:
Wed Mar 29, 2023 3:10 pm
Looking at S54 ITB conversion to a port fuel injection arrangement.
Can you get that stuff at a decent price?

Early Hyabusa TB are usually around $150/set of 4 but you'd probably need 4 sets plus some rework to get all the right bits so maybe not worth the bother. I use ducati 999 TBs because they are pretty big at 54mm, but they are like $100/pair and a big pain in the butt to install since that are not meant to be rows so not sure I'd recommend that path.
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