Hello guys , Im new on here just wondering if anyone is using vems on either a M50 or M52 bemer engine...?
Theres a good number of BMW M50 and M52 engines running on VEMS in europe - most the the European guys dont come on here though.
IIRC GintsK has done one. I'll PM him to let him know that he's needed!
Rob
Not true. I had plan put VEMS on M50 as my first VEMS project. But at that time VEMS was no support for overlapping dwell for COPs(now it is). Engine is revy and we put on them another stand-alone.
But technically there is no problems until you do not have PWM controlled stepless VANOS. M52 comes with simple VANOS, right?
simple VANOS solenoid is easy to control with configurable output.
Theoretically needs two pairs of maps for both positions of VANOSed cam. For this is no official support as I understand, though this is in firmware probably. But there is easy way: tune engine on both positions of cam, find area where torque graphs cross each other and configure VANOS triggering at this rpms. Then manualy compile one pair of maps.
And look here: http://www.vems.co.uk/forum/index.php?topic=185.0
I know that Alligator in Sweden has a turboed E36 running VEMS.
You dont need to make the VANOS mapping system quite as complex, as with the 16x14 map you can set your breakpoints around the VANOS switching point which will help blend the two areas on the maps.
Rob, you do - otherwise how do you work out the optimal VANOS switching point?
Okay VANOS function is as follows:
"At idle, the cam timing is retarded. Just off idle, the DME energizes a solenoid which allows oil pressure to move that cup gear to advance the cam 12.5 degrees at midrange, and then at about 5000 rpm, it allows it to come back to the original position. The greater advance causes better cylinder fill at mid rpms for better torque."
So from the point of view of mapping you have your idle load sites, then load sites from idle to 5000, then from 5000 to redline.
I would divide the map up to have 2 rpm sites for idle, another 8 upto 4750-5000, then 6 from 5050-5500 up to redline.
The single VANOS stuff is no different to VTEC or VVT on the Toyota Corollas.
I've just been told that we have overlapping dwell working now.
But Rob I've mapped a couple of Hondas and found huge gains in the midrange by throwing away the quoted VTEC switch points and working it out from the point of view of raw performance rather than economy, emissions and all the other nasty things OEMs think about... ;)
Cool, theres no need to stick to the exact specs, I was using the stock figures to show how I'd set up the tables to cope with the cam change at a specific RPM. In order to get to there you must first start from here, and you might as well start from the standard timings and then play with the switching points.
As sidewaysbill has told me that he's going to use a different cam the whole VANOS timing will be completely different, but the way of setting up the map with Regions of Interest around the switch point will be the same wont it?
Rob
Yes, I'd use the concept of Regions of Interest around the switch point. It is, as you say, the best way of making a smooth transition.
I'd also come up with a rough cut map with VANOS off and one with VANOS on to analyse where the switch point would be. I'd then interpolate the 2 maps and make up a hybrid map with the VANOS switch at the point I deduced was best.
that all sounds very confusing...! thanks a mill for the info anyway more words of wisdom would be greatly appreciated. by the way what does PWM and COPs stand for....?
PWM = pulse width modulation
COP = Coil-on-plug (coils)
what would be the story with running it on e85 with vems...?
The Swedish boys have got a bunch of cars running on E85 with VEMS. ;D
How much bigger would you want the injectors or could you run them on a longer duty cycle?
I have plans for switching to E85 when it becomes more availble Up-north.,
regards Agriv8
its available about five miles from where i live at the mo and hopefully about a mile away in a couple of mounts so it would be rude not to use it....! Would i be right in saying with the right map its possible to get more power...?
Me too - I specified everything on the Griff with a view to E85.
There just isn't any available for the moment.
E85 as it stands will not give much more power. If you build your engine to run on it then you can get good gains.
By building it I mean increasing the engine's static compression ratio to make the most of the fuel's high octane rating, and using cams that will take advantage of the higher compression.
Turbocharged engines have the advantage that you can simply increase the boost pressure. There's one Irish lad on the SXOC who's running his SR20 engine on E85, having bought larger injectors, a walbro pump, and had a remap. He's very happy with it and reckons he's had good power gains without too much loss of MPG (as you have to inject almost twice as much E85 (Ethanol's calorific value is about 50% of petrol's) you have to expect lower MPG).
The fly in the ointment is the cold start issues that a lot of people have.
How high does the static compression need to be and what kind of cams are we talking about here to make the most of the higher compression?
Thats going to be a tricky thing to quantify, if theres not already someone running a high compression M50 motor to lead the way then its down to you to do the development work. I'm sure theres a few of us here that would help your research.
I have 11:1 (up from 10:1) on my Griffith. It's a compromise really, if I could switch to E85 full time I would go for 12:1 or maybe even 12.5:1
As for cam, I went for the wildest road cam on the market, but that's just me... ;)
If it were my experiment, I'd start at a 5 to 10% increase in compression and see what happened. Remember that it's easy to increase the compression, but as yet there isn't a "putting-back-on machine" for decreasing it again... ;)
On my engine I'd expect more gains than most because the ports and valves are really too small for making big power from petrol, but it all seems to work out better for ethanol. (One of the snags of a 40 year old design of engine ;) )
I was hopeing to run it at about 11:1 or 11.5:1 if needs be with a set of 272/264degree cams , yea or nea...?
Is there barometric compinsation built into the vems units ...?
you can see gains with E85 not changing anything on the engine as you can run some pretty angry timing. on a stock S50 gains could be as much as 30-40HP according to PPF (swedish bmw tuner)
as for injectors, calculate 30% bigger to use E85 on aprox same duty cycle.
E85 does make your car smell like your college buddies. ;)
Quote from: andersn on July 25, 2007, 10:51:21 AM
you can see gains with E85 not changing anything on the engine as you can run some pretty angry timing. on a stock S50 gains could be as much as 30-40HP according to PPF (swedish bmw tuner)
as for injectors, calculate 30% bigger to use E85 on aprox same duty cycle.
E85 does make your car smell like your college buddies. ;)
I had heard this but usure if it was 'true fact' or 'WWW fiction'.
Hope to get arround to finding out one day ;) timming and fueling will need to be fiddled with ???
Regards
Agriv8
Increase req_fuel by 30% on the same injectors and you should be reasonably close for fuel.
Timing is another matter... ;)
with the vems in place would be possible to get away with just using standerd injectors or lets say ones out of a e36 m3 or something as you can leave them open for a much longer duration than a standerd ecu can...?
You're only going to be able to flow so much fuel through the standard injectors. If you need 85% duty to run WOT up at MAX rpm then you're nearly out of headroom.
Rob
Rob whats the chances of the m3 injectors being bigger than the standerd 2.5 ones...?
The stock ones from m50b25 are 192cc...i think for the m52 is the same....but never checked...
Read the bosch number on the injectors and use this info to find biger ones...
http://users.erols.com/srweiss/tableifc.htm
nice one for that i will check it out in the morning...!
the super duper fancy camshafts finally landed today , next thing get the finger out build it , fit VEMS and map the S**T out of it.....! ;D
I installed VEMS on M50B25 equipped E30 carbio last summer and it worked like a charm even without overlapping dwell. It's a non-VANOS engine though I recently installed VEMS on Mercedes 190E with 3.2liter 24valve engine from 1996 S-class that has some sort of "variocam". It's a simple on/off type and retards intake cam below 2000 rpm, then goes normal position and retards again after 5000 rpm.
We dyno-tuned the car without it (255 hp/380 Nm) and next session we're going to play with the cam timing as past 5000 rpm torque and power fell off like a rock without the cam retard.
has anybody a safe spark map for m50b25?
I found an oe. map, but it is load/rpm not map/rpm.
(http://www.cosworth.hu/misc/bmw_e36_oe_spark_map.jpg)
Do you think is it usable for start?
You should be able to estimate a 100kpa from the load and use those ignition values.
Obviously 100kpa is not the same load in kg´s/s as used by motronic.
Maybe 3.2 is 100kpa@800rpm and 8.2 is 100kpa@6400rpm?
is this a boosted motor? or NA
if boosted i wouldn't run that high of timing values.
I think my max timing in full boost is around 15.
I was kinda under the impression the spark maps were a modifier on a base timing number. The top row values seem too low
They are based on actual load which is mass of air per second. You can reverse calculate your MAP based setup to reflect that if you must know the exact VE of your engine and how much air mass it´s inhaling.
Not TPS and not MAP.
The 6.6 number might be 3bar boost if your getting that at 1000rpm . So that ign value reflects that.
But at 5k it´s only 80kpa on that engine.
That also might be the full MAF scale on the M50 80mm maf. So that doesn´t mean that a WOT standard M50 even reaches the 6.6 load at highest rpm.
it is a full oe. NA engine. So rpm midrange and up about 24 deg usable at wot?