Need a definitive answer - M50 2.8 Stroker - 3.5 HFM worth it?

[dude8383]

I've been browsing around and these HFM's pop up from time to time on bfc...

Has me curious about whether or not there would be an improvement.

I have:

M52 rods, crank and pistons
S50 cams

I know that the 3.5" HFM requires a proper tune and 21.5# or 24# (thinking thats overkill)...I could send my TRM chip back for a flash so thats a no brainer.

Or should I stop looking at these bloody classifieds because I can make some power doing other things ...e.g. cams.

Don't say turbo or s/c because I'm a big fan of n/a power and would like to keep it that way.

[rpob5t]

I've got an ODB1 M52 (S52 cammed) with the 540 MAF (running a TRM tune); granted I have nothing to compare it to but is it may not be the torquey-ist thing under 3k but top end power is quite good; considering this is pretty much how I use the car (track/auto-x rat) I'm quite happy with it

[sharky]

I run a 3.5 540 maf w/ 21lb on a TRM tune. I believe Conforti/Turner used a 3.5 w/ 24lb, I doubt I am even getting close to maxing my injectors. I like the setup.

[dude8383]

Yeh I will likely pick up a set of 21# injectors also.

Does anyone have any dyno sheets by any chance?

[Adrian_Visser]

AFAIK it only adds a few HP like 2 maybe. I don't know think I have ever seen a direct before and after of dyno of a 3" and 3.5" MAF.

[dude8383]

AFAIK it only adds a few HP like 2 maybe. I don't know think I have ever seen a direct before and after of dyno of a 3" and 3.5" MAF.

I see, 2hp is negligible...Does the curve shift though? I mean S50/S52's get like 10-20hp from HFM and injectors (plus software of course.)

[Adrian_Visser]

I see, 2hp is negligible...Does the curve shift though? I mean S50/S52's get like 10-20hp from HFM and injectors (plus software of course.)

Where are you getting this 10-20whp number from? Like I said I personally have not seen a direct same day same dyno comparison of both MAF's. Take a look on bimmerforums at the e36m3 dyno thread if you like but in the end those are all different engines, different dynos on different days so the variables are way too great to make any accurate conclusion.

I do think however that 10-20whp from just a bigger MAF is bullshit, and s52 wise at least the stock 21lb injectors are more than enough until you upgrade your cams to get more air into the engine so there will be zero power added from 24lb injectors on an otherwise stock engine.

I would love to see a dyno comparison if anyone has one though... I am curious since I bucked up for a 540 MAF and tune with the 21lb injectors.

[dude8383]

Where are you getting this 10-20whp number from? Like I said I personally have not seen a direct same day same dyno comparison of both MAF's. Take a look on bimmerforums at the e36m3 dyno thread if you like but in the end those are all different engines, different dynos on different days so the variables are way too great to make any accurate conclusion.

I do think however that 10-20whp from just a bigger MAF is bullshit, and s52 wise at least the stock 21lb injectors are more than enough until you upgrade your cams to get more air into the engine so there will be zero power added from 24lb injectors on an otherwise stock engine.

I would love to see a dyno comparison if anyone has one though... I am curious since I bucked up for a 540 MAF and tune with the 21lb injectors.

Hang on, I saw a couple of dyno sheets on bimmerforums. Gimme a minute.

[dude8383]

Found one:

http://forums.bimmerforums.com/forum/showpost.php?p=19956760&postcount=3

That's 25hp right there...but again, these gains are S52 territory. I don't think I've seen any for the m50/m52 motors.

*EDIT*

Another in that thread:

http://forums.bimmerforums.com/forum/showpost.php?p=19963753&postcount=16

[Danny]

Well that is good news for me.

[dude8383]

Well that is good news for me.

Glad I could be of help...indirectly.

That being said, I'm going to try to find a place locally and finally fucking dyno my car to see what it makes. I'm hoping all my hard work will net me somewhere around 200hp (secretly hoping for more).

If I were to do this all over again though...which I will, I'd grab an S54 and call it a day!

[Adrian_Visser]

Interesting. I want to get my car dyno'd now.

[dude8383]

Few more:

http://forums.bimmerforums.com/forum/showpost.php?p=19071505&postcount=57

http://forums.bimmerforums.com/forum/showthread.php?t=1384192&highlight=3.5+HFM+dyno

God damn it...there's so much for the S50/S52's...

And damn both of you! LOL.

[Wh33lhop]

If I were to do this all over again though...which I will, I'd grab an S54 and call it a day!

It never works like that and you know it. Nobody "calls it a day" with a stock motor. ;)

[dude8383]

It never works like that and you know it. Nobody "calls it a day" with a stock motor. ;)

Shhhh, I'm trying to keep a positive attitude here!

Who am I kidding though...it'll be the same deal, "oh its on the engine stand...why don't I do this since its so easy to work on..."

On a side note I took the car to MaximumPSI today and had them dyno it.





Probe flew out on the 2nd pull thats why the dyno sheet shows a wacky A/F.



4th gear pulls.

205hp @ 6500 rpm
182tq @ 4650 rpm

Everything checks out really nicely, motor is strong and my a/f curve looks good. Mike, the shop owner, said that TRM could remap the curve slightly and grab some fuel from the 5300 rpm area and get some more fuel towards the end of the revving range to get some more power. Overall I'm happy to see that I've built a healthy motor!

$90 for 3 pulls.



Close up of curves: