M52B28 dyno results

[Drew325is]

I got my car to the dyno this week...was good to spend some time dialling in the ignition timing. We came away with 10rwkw over what it had on the "home" tune. Was also interesting to play with the vanos...leaving the cam advanced cost about 10kw...and we're now retarding the cam at 4250rpm.

Anyway, car is noticeable better for the dyno time.

This is my old M20B25:


The final dyno result:



Specs:
M52B28 alloy block
M50 manifold
Megasquirt II
BMC CDA
Supersprint catback

Now I want some cams!

[hoveringuy]

It's too bad there's not an A/F line, 133Kw is about 180 HP which is good. I'm suprised a VANOS switch point at 4000 made the most power considering the factory did it at 5200. Looking at your torque curve there's no dip in torque before 4000, it's continously rising. How did you arrive at 4000?

[Drew325is]

Basically we just played around with it, and 4000 made more torque. Considering the manifold the factory put on this engine, I wouldn't be surprised if the factory vanos point had an element of economy about it...rather than outright power.

Try this link out (it's a dyno chart attached at another forum, so I'm not sure if it'll work for you)...but it shows an M52B28 with M50 manifold (blue line) on OEM injection. You can really see the torque dip at about 4000...so it's nice we've got rid of that:

http://forums.eurocca.net/attachment.php?attachmentid=5999&d=1110873581

If doesn't work for you, I'll re-host it.

The next thing to look into is the big drop in power after 6000rpm...the dyno operator reckons he heard a distinct change in exhaust note, and therefore thinks the exhaust might be becoming restrictive. Then again, maybe it's just the factory cams? I'm not sure what's the most likely TBH.

[nando]

I would have expected a bit more power than that (probably hot there?), but nice job on the tuning regardless. always a good feeling to get more power out of an engine with only software changes.

[Drew325is]

I would have expected a bit more power than that (probably hot there?), but nice job on the tuning regardless. always a good feeling to get more power out of an engine with only software changes.

Nah it's quite cool here at the moment...I haven't found much to compare to other than the dyno chart I just linked to (car belongs to our local BMW club pres), but I'm on par with it in terms of peak power...in our experience software changes have tended to add midrange, but geneally not much gains in peak (FI would be an exception I'm sure). Anyway, I'll be hanging out for the next club dyno day though...for comparisons between engines I don't think you can really beat the same dyno on the same day.

[hoveringuy]

This is what it looks like when torque dips before the switchover point. Ok, it's an extreme example. Yours doesn't even show the changeover. Nice!

The smaller dip is DISA switching.

[drifty340i]

Nice one dude, i bet shes got far more low down TQ than the m20

[EtaSport]

That last dyno graph show pretty much what mine does at ~4k. Mine peaked about the same point as your m52, but my HP curve stays flat all the way to redline and doesnt drop off. 225hp from 5500 to 7k with a 3.1liter. I think the cams make a large difference for the upper range.

[Drew325is]

Interesting to see that dip Steve!...Rick had a drive of the car at the track on the weekend before the dyno session, he mentioned how there was a definite change in torque after 5000rpm or so...so I think we now know why a change could be felt. Now it's just on the go all the way through the rev range.

BTW...my vanos switch point in actually 4250rpm...not 4000...switching at 4000 created a dip around 3500.

Nice one dude, i bet shes got far more low down TQ than the m20

Yeah for sure!...massive difference...but not quite a V8 difference I'm sure!

[hoveringuy]

BTW...my vanos switch point in actually 4250rpm...not 4000...switching at 4000 created a dip around 3500.

Huh? switching at 4000 created a dip before it even got to the switch point? You're running MS and I know it doesn't anticipate the switch, does it?

[Drew325is]

No, sorry, bad wording...basically, putting the switch point any lower than 4250 reduced torque...but the reduction was at the switch point rpm, not before it. 3500 was the lowest switch point tested, and the switch point was raised in increments until the best point was found.

[hoveringuy]

You're the perfect candidate for one of my VANOS controllers....

Maintain full advance until 3500 and then start tapering it off to zero by 5300. You'd gain some torque on both sides of your switchpoint.

12 1/2 degrees on-off is always a compromise, somewhere.

Variable VANOS on an M52? You betcha!

[daniel]

Variable VANOS on an M52? You betcha!

steve's vanos controllers now endorsed by sarah palin.

[Drew325is]

You're the perfect candidate for one of my VANOS controllers....

Maintain full advance until 3500 and then start tapering it off to zero by 5300. You'd gain some torque on both sides of your switchpoint.

12 1/2 degrees on-off is always a compromise, somewhere.

Variable VANOS on an M52? You betcha!

That's a pretty wild idea! So I take it the mechanical side of things are identical between the switched and variable vanos systems?...only the software changes?

[hoveringuy]

That's a pretty wild idea! So I take it the mechanical side of things are identical between the switched and variable vanos systems?...only the software changes?

Yep! Mechanically they are identical. Same soleniod, plunger, everything.

What changed is the software that generates the PWM signal. Any VANOS car can be back-fitted to be completely variable. MS would just make it easier.