Dyno day

[nando]

that's interesting. my engine does the opposite, the torque is flat from 4000-5000 and then it surges at ~5200rpm. it actually looks to me like an exhaust effect. you guys have to use the stock manifolds, right?

I'd like to find a Pro3 chart to compare, they have to use stock internals but they can do 1" of port work (yay), exhaust is open and so is the ECU. I bet some headers with good collectors would smooth out that dip.

[JGood]

Here is a Pro3 dyno chart:

http://www.unofficialbmw.com/e30/images/dyno_may18_2006_dale_hp_tq.jpg

Mods are:
- Ireland shorty headers
- custom exhaust, 3" flowmaster muffler
- Mark D'Sylva street chip, EAT Chips, 6700 rpm redline
- Unichip to tweak tuning
- head intake/exhaust ported to 1" from gasket, intake and exhaust gasket matched
- head milled raising compression approx 0.5 points
- no fan
- no power steering
- no A/C
- Redline MTL in trans
- Redline in diff

From:

http://www.unofficialbmw.com/phpBB/viewtopic.php?p=160029&sid=d067eea31514111008019b5155117995

[nando]

IE shorty headers.. ugh.. :p

but you can see, no torque dip. is SpecE30 forced to run a single 2.25"? I guess you guys *are* making the power, so who am I to say, but I think that's small. overall flow area is less than the stock dual pipes, except of course you don't have a cat.

Funny though with all those mods and they still aren't making more peak. I bet that 1" of porting hurts more than it helps, there's really nothing to gain by making the 885 ports larger. and IE shorty headers may as well be stock manifolds..

[jlevie]

Yep, no torque dip on that Pro 3 engine... It would be interesting to try a different exhaust and/or headers. But since I can't run any other configuration I'm not motivated to play around. Though I do suspect that the headers and exhaust is at least partially responsible. Metric Mechanic has done a lot of work looking for better flow through a head. There is more to that than simply opening up passages and you really need to have a flow bench to be able to tell what is going on.

I guess I'm not surprised that the peak numbers above are so similar. It is the torque curve that I'm impressed with. I'd love to have a torque curve that had no dip in it.

[nando]

in any case it really makes you wonder about the "mods" people do to their m20s. Specifically the budget strokers that don't make as much power as a stock blueprinted B25 with no chip..

[jlevie]

I don't think a lot of folks appreciate how well designed/tuned a BMW engine is. When it is operating properly you aren't going to achieve substantial improvments by simple mods. I've seen results from BMW crate motors that are almost as good as from a blue printed engine. I suspect that in more cases than not just making the engine run right is going to produce more power than any simple mods you can do.

[Sagaris]

I have yet to drive and M50 swapped e30 but I would like to think that a lot of people that do an M50 swap to improve performance dont give the M20 a fair chance. When I first bought my car, the engine had a lot of maintenance that needed to be done. I never imagined that the maintenance that I have performed would make the engine run as strong as it does right now.

[jlevie]

In my experience there isn't a lot of difference between an M50 and an M20B25 that is running correctly. There is a big difference between an M20B25 and a dual vanos engine.

[JGood]

I'll apologize in advance for going off topic...

I have yet to drive and M50 swapped e30 but I would like to think that a lot of people that do an M50 swap to improve performance dont give the M20 a fair chance. When I first bought my car, the engine had a lot of maintenance that needed to be done. I never imagined that the maintenance that I have performed would make the engine run as strong as it does right now.

I have an m50b25tu e30 and an m20b25 e30, and have a lot of experience/miles on both, and both have went from stock to modded.

Stock vs. stock, if both are in good shape, there isn't much of a difference. But the m50 responds to cams very well. An m50 w/ s50 cams will put down 180-200 whp from 5k-7k, which an m20 can't touch unless it's fully built. On the track, this would make a huge difference, but it's harder to stay above 5k on the street, which is where a cammed m50 really shines. If you like keeping the revs up, you will love a cammed m50 in comparison to an m20. It pulls harder and harder until you hit the 7k limiter.

The non-vanos m50 has hotter cams, but doesn't have the vanos to help with low end torque. The power rating from the factory is the same, but I've seen first hand a non-vanos engine outperform a vanos engine on the highway.


FWIW, I ran both my cars on the same track, on the same night, running the same tires (205 v710's). m20 car is 2400 lbs, m50 car is 2700 lbs (weighed on the same scale). Both cars were modded identically (Dinan chip, g260, 3.73LSD, long tube headers, single 2.5" exhaust, Maganflow cat, Borla muffler)

m20: 14.6@91
m50: 14.4@95

If the m20 car was 2700 lbs, like the m50 car, I think it would be closer to 15.0@90. I didn't run the m50 car with the cams yet, but I'm expecting a 14.2@97 or so.

I'd say if you're going to do an m50 swap and keep it stock, save your money. If you don't mind swapping cams, then it's worth every penny. Doing the engine swap is relatively expensive. Doing the cams is only a little more money, and it nearly doubles the gain over an m20 that the swap did in the first place. A cammed m52 is even an even better value, as they usually make 10-20whp more across the entire RPM range then a cammed m50.

[Sagaris]

That's some solid information :up: thanks for that!

[JRKOUPE]

numbers

JL....

just saw this thread...Ive never heard of such numbers, just fantastic.


great thread....great info...eye opening.

That being said my s50 swap is 20 hrs old.

Ive put on 150 miles so far......geez if feels fast.


I know we all get used to power very fast so we shall see

...but Ill be at track next week......my BBK is not on yet...Ill take it ez...but Im very stoked.

I am using the stock g260 and a 3 73 w/ a euro 323 fw and m20 clutch.....very light...revs well...same 2.5 inch single exhaust cat and muffler... Big change over a 124k m20... that I loved BTW.

[JGood]

JL....

just saw this thread...Ive never heard of such numbers, just fantastic.


great thread....great info...eye opening.

That being said my s50 swap is 20 hrs old.

Ive put on 150 miles so far......geez if feels fast.


I know we all get used to power very fast so we shall see

...but Ill be at track next week......my BBK is not on yet...Ill take it ez...but Im very stoked.

I am using the stock g260 and a 3 73 w/ a euro 323 fw and m20 clutch.....very light...revs well...same 2.5 inch single exhaust cat and muffler... Big change over a 124k m20... that I loved BTW.

Glad to hear you got it running. Were you getting timed laps prior to the swap? I'm curious how much faster an s50 car is around the track then an m20 car, given everything else staying the same (tires, brakes, etc... which people usually upgrade at the same time).