M50 swap feels sluggish

[OrangeFiero]

I just completed my m50 swap and took it out for a spin when it had a couple heat cycles just to make sure everything was settled and working. It idles goodish, my old m20 had a vacuum leak and was slightly down on compression so i havent had a good idling car to compare. It wanders maybe a 100rpm or so and air fuel ratios wander from 13.8 to 16 when hot, not sure if they should. When i drove it, it felt almost the same as my 200k m20... felt really slow in lower rpm and picked up eventually, but not any harder than my m20 did.

I checked for vacuum leaks, intake booot was torn up so i temp fixed it with tape and there doesnt seem to be any large or even medium leaks, maybe small.
I checked for weak spark and it was not exactly strong, so i double grounded all my coils. Id say it improved slightly but not enough for me to stop thinking.
I did however notice that when i unplug the maf, idle doesnt really change that much, and it revs up exactly the same... this confused me. Although i didnt drive it with the maf unpluged, it didnt seem to do much.

Any suggestions on what to check?
M50nv, gearing stayed exactly the same, same tranny and diff, so no its not gearing. New plugs too.
Pic for people who cant contribute, just so im not wasting your time, people love pics...

[plmichal]

I hate to say it but a NV M50 isn't going to make a huge difference.

I know what you're feeling. I swapped a NV M50 into a previous E30 that had a strong 165k M20. I learned the hard way that it wasn't a great improvement over the M20. Maybe slightly better top end. kindasortamaybe.

My current E30 has a great running M20 and I swear it's just as quick as my M50 swapped car.

Atleast you don't have to do a timing belt anymore...
And it has a drop-in filter which is nice...

Maybe I just had a shit M50. After you fix all your issues, I hope it's not the same.

[OrangeFiero]

Yeah i was worried this was the case but im not going to be convinced quite yet. If i had a good running m20 and my m50 swap felt the same, then i prolly wouldnt think much, because 20 hp would barely be felt, but the fact that my m20 had 200k on it and dynoed at 135hp just months ago... and the m50 feels the same if not slower in some rpm ranges. My m50 only has 130k on it too.

Another point i will add, i am running an auto tranny dme and just though about that being the issue. I had a fiero v8 swapped and i had to fool the ecu to think it was in drive not park or else it would run a predetermined fuel map.

[plmichal]

I ran both the auto and manual NV ECU's I had to see if there was a difference.

No performance (butt dyno) differences but I do remember one of the ECU's back firing a lot more while downshifting. No idea why.

[RobertK]

NV M50 swaps are like 20hp over M20 but without VANOS its no different than if you had a DOHC M20.

My very first swap years ago was a NV M50. It was a lot of work for the disappointment that followed.

[OrangeFiero]

Well if it is running right and good, and its this slow, at least i did the swap for under 1200 and now i have a low mile engine rather than a 200k m20. Plus a better platform. Ill eventually get it dynoed to see how it compares.

[plmichal]

My very first swap years ago was a NV M50. It was a lot of work for the disappointment that followed.

My feel...

Atleast a 24v swap will be a breeze for you now!

[LowR3V'in]

Offtopic but why the choice in non-vanos?

Sometimes people exaggerate hugely online when doing upgrades.
Like when I got a 325i coming from a 325e. People where saying it's "peppy"
worlds faster then a 325e.

One of the slowest cars I've ever driven. :)

[Cyrix2k]

I own two M50B25 NV swapped e30s. One is megasquirted with a turbo while the other is NA. The turbo one is fast in and out of boost. Even when it was NA in an e36, it had balls. The NA one is a fresh build (fresh head/bottom end), all new seals, all new sensors, ebay headers, and is currently chipped although I also ran it on the aforementioned e36 dme. It feels sluggish, even with a 4.10 diff. What gives? Honestly, I think it's the headers - they KILL the bottom end.

That said, I wouldn't expect that much difference in performance from an M20. It's a more modern design with higher compression, but the same displacement - how much performance can you really expect to pick up?

[JinormusJ]

M50

There's your problem

[LowR3V'in]

cyrix: Even off-boost, the engine is getting feed more air then it
can suck in by itself n/a.

[OrangeFiero]

I do have ebay headers, so that may contribute a bit. Its my drift car and i somewhat daily it but im talking like 20 or 30 miles a week or so, so having the extra torque is... eh.

I did however check out my alignment as i swapped an e36 rack in at the same time... When i mocked it up, it was pretty bad toe out, now that its all settled, i have massive toe out issues. Traveling straight, my tires will squeal on dry pavement where there is crack filler, and you should hear concrete... Getting an alignment before i drive it anywhere and that should free up a good 10hp. Ive seen and been told that for every degree of toe in or out, you loose a little over 1% of your power. I definitely have a good 6 or 7 degrees of toe out. Plus supper grippy tires up front.

I also got a new maf that is not dirty and does not appear to have been pulled out of a junkyard with pliers, as my old one did.

As for m50 being slow, i agree, but i needed a new engine either way and i can go a little bit farther with boost later since i now have 24 valves. Plus it only took 18 days and 1200 bucks, so imma call it a success even if this is how its going to feel. Thanks for the input guys.

[Killacortes]

I learned the hard way aswell. A nice healthy m20 is a better choice than a non vanos m50. I still like 24v swaps but I dont think its worth it unless you go s5x swap

[Cyrix2k]

cyrix: Even off-boost, the engine is getting feed more air then it
can suck in by itself n/a.

no, that's not true as far as I know - and it feels significantly more powerful (it even did in the e36 bone stock). Anything under atmospheric pressure is the same NA & boosted - if anything, the turbo motor will show less power due to driving the turbo.

[justin_l_]

I liked my NV M50 :) It was definitely a big difference in power for me. I pulled out a low mile M20B27 when I did it. But as everybody knows it was a freak of nature. It pulled on M50B25tu all day. Were trying to get my room mates S52 done by the bavauto show, and hopefully down to New England Dragway to see how it compares to my old NV M50. Going to be a feat, currently we have a gutted rolling chassis :-/