M20 vs M50

[wworm]

"timing chain" is a weak ass argument. Chains still wear out, and a 25 year old M52 is going to need some work.

If you want a very slightly more powerful engine, great. If you just like the 24v engines, vanos, etc - awesome! But the argument over chains vs belts is retarded. In 20 years you would only have to replace a belt 4 times, it's cheap as dirt and easy to do. Also, belts are actually more efficient.

But replace all the timing chain bits, sprockets, guides, tensioners? That's going to set you back a few bucks an it's not going to be fun unless the engine happens to be on a stand..

totally correct here, just trying to flesh out why someone on the internet would want an m50 over an m20, not necessarily trying to present facts by any means.

[e30RS]

I have driven both non-modified and did not notice a discernible power gain with the m50. Has anyone had a different driving experience? Just posing the question since the technical aspects have been adressed by agent and others.

[digger]

stock for stock the m50 is an improvement but its about 10%

[nando]

totally correct here, just trying to flesh out why someone on the internet would want an m50 over an m20, not necessarily trying to present facts by any means.

Yeah, it's just funny because after 20 years of this BS, IMO interest in original M20 builds has increased while M50 swaps have waned.

[wworm]

I think overall people have started investing in cars a lot more and theres significant value in keeping things closer to original. Not to say a custom engine is original by any means but "sprucing it up" rather than swapping it out is probably going to maintain more value and it's also a period correct modification (lol again-sort of. m5x crankshafts arent exactly of the era)

[ForcedFirebird]

Granted I came from a m20b27 e30, but have driven plenty of m20b25(s), and I will have to say my m50b25tu swap seems night and day from the m20(s). My m50 is lightly modded though.







Also, from my understanding, to get a m20b25 over the 200bhp(n/a) will cost you a lot of time and money. Or just money.

I build m20's every day that will eat m50's for breakfast, and have done many on the cheap. Recently we took a couple of high mile m20's, put fresh rings/bearings on eta cranks/rods and high mile b25 pistons. Aside from decking the blocks .080" ($100/ea), $0 spent on machining. We balanced them out and they crank out 180whp/180wtq. A local just gave away 2 eta engines for free (we missed out on them), but you can find them for less than $200 pretty regularly. If you do the work yourself, you can have a good m20 for about $1k. Albeit not "on the cheap" I have successfully broken 200whp many times with NA m20's.

Whereas the m50tu will simply need a tune to achieve that. Then you can go even farther for a n/a application with s50 cams, 3.5" Euro/540i MAF, and a proper tune. AKA 200+ WHP.

Dyno proof of this? s50 cams in a 2.5l makes about 180-190whp. Stock s25's in good shape barely break 200 on a stock tune. 3.5" MAF doesn't do squat as the TB is smaller than the MAF diameter. Chevy LSx engines have a 75mm (2.9") MAF and easily pump out 400whp.

If I had more disposable income I would have gone with an s50/2 swap, but you live and you learn.



Just my 2 cents.

Everyone is entitled to an opinion, mine just happens to be "single cam for life!" lol. ***meanwhile, replacing lifters in the 250whp stock cam s50 we built a few months ago*** heh

[IRON-E]

This debate can get out of hand in no time, if you're going to do the M20 swap to 24V, go S5x. Not worth the time or money for 20hp max gains.
My personal reasoning was that parts are more readily available for the 24v platform, I wanted full NA power without tampering internals and if I do add, it'llonly be bolt ons.

[ForcedFirebird]

This debate can get out of hand in no time, if you're going to do the M20 swap to 24V, go S5x. Not worth the time or money for 20hp max gains.

Well said.

[Andrew325is]

If you're considering the M50 vs. the M20 I don't think there's a super compelling reason to do that swap anymore as others in this thread have pointed out. Most people want bigger gains if they're going to put the effort into a swap. From my experience, the most popular swap is the S54, by like a 10 to 1 margin. I've made hundreds of S54 harnesses. After that it is M54, then the S52 & M52 and M50. But considering M20 vs. M5x there are pros and cons. The 24V engines feel and sound more refined (especially M54 & S54), but the M20 is a pretty simple engine that's easy to work on. One downside for the M20 is that some of the parts like the ICV and AFM are no longer in production so eventually you won't be able to keep one running well without converting to megasquirt or something.

[CMBusch]

For me, the 24V M50 swap made sense. The car originally had a blown M10 and was an auto(among many other issues). The S50, S52, and S54 options were way too expensive so I decided to just rebuild a M50 and swap it in with a manual. Someone gave me a bare, blown long block for free and I collected other M50/M52 parts along the way. I tired to do the rebuild the right way, while also trying to save money(resurfacing the block myself/minimal machine shop work). The engine ended up being a 2.8L M50 "stroker" with higher compression than factory and S52 cams. Doing the upgrades while I had the engine apart made sense because they were cheap enough to be worth it. If it makes 230 at the crank I'll be ecstatic, but my main concern is for the engine to hold together. So far so good at least. I'm a college student who's usually broke so the M50 is perfect. If it blows up, it's cheap to get another.

[ForcedFirebird]

For me, the 24V M50 swap made sense. The car originally had a blown M10....

Yeah, but you didn't go from m20 to m50, little bit different for cars that started life with a 4 cylinder. In your budget, don't forget to include transmission and diff swap as well, the m20 drive train parts hold a 24v engine just fine.

[CMBusch]

You're right, I somehow thought the question was whether or not a 24V swap is worth it. If you have a healthy M20, I see no reason to do a 24V swap. S50s and S52s are cool but even those might not be worth it.

[e30RS]

Interesting that the m20 is dirt cheap and can be blown up to eclipse the m50.

[ForcedFirebird]

Interesting that the m20 is dirt cheap and can be blown up to eclipse the m50.

Using only stock m20 parts, we have eclipsed the m50 at my shop. Used b27 crank, used/recon 130mm b27 rods, used b25 pistons, recon 885 head with stock cam, block decked shaved 2mm, fresh rings/bearings and we saw 180whp/180wtq - of course we balanced it, and did some light head work (valve and seat shapes only, no porting).