Built M20, M20 Turbo, or S52 Swap?

[Sail Boat]

Hi everyone

This has been asked before but I'm hoping to get some personal experiences on the best engine modifications for a reliable setup that doesn't require constant tinkering. I want a powertrain that just works - a one and done deal that can follow normal maintenance post install. Power isn't really my greatest concern, but if it can be had reliably, that's great!

Despite what I've read in older threads, a built M20, M20 turbo, and S52 swap all cost about the same - around $6,000 complete. This is not including labor or time since I'll do the work myself and have a CPO M235i daily driver (CPO important in that IF it does break down, I am able to take advantage of BMW's lovely complementary car service).

To be honest, I'm leaning towards a built M20... seems to be the best bang for the buck considering reliability and ease of completion. Not to mention, I'f I look for more power in the future, the engine is good to go for forced induction. AC is a must, since I will take this car on long road trips. Let me know what your experiences have been and what you think is my best move!

Built M20
200 WHP (+50)
This is an attractive option since it is very much a plug and play solution and a comfortable one for me since I have previous experience with the M20. Complete 2.9L stroker kits are only $1,900 and the Bimmerheads 885 Race head with upgraded cam around $2,200... Add in a fancy new clutch, injectors, chip, head gasket/studs, and larger radiator, the total comes to $6,000. Plus, AC is bolt on - nice - and about 500 more RPMs to play with over stock. As I understand it, these motors are extremely reliable and appear to produce great power for a N/A 12V engine.

M20 Turbo
250 - 300 WHP (+100/150)
According to dyno sheets, M20's with wither the KAMotors or TCD Stage 2 kits are producing great numbers at very good prices. I'm inclined to select the KAMotors kit as I prefer the plumbing and intercooler placement to the TCD kit, not to mention its about $1,000 cheaper with megasquirt coming in around $4,000. Add in the fancy clutch, fabrication work for oil lines/making the AC fit, head studs and gasket, I'm right around $6,000. This probably isn't the end of the bill though, I'd likely have the stock head rebuilt. Let's say $7,000. Unfortunately, reliability isn't great... but some of the well built M20T's appear to be holding up. On the other hand, we are talking 100 HP over a built M20.

S52
220 WHP (+75)
Discussed and executed in depth, the pros of this swap need little explanation from me. In terms of cost, These engines can be had all day for around $3,000 in good condition. Factoring in a rebuilt head, AIR CONDITIONING, ECU, clutch, and other required bits, the total appears to hover right around $6,000. Reliabiltiy is great, as expected, but the swap is a bit more involved than the Built M20 and would require more time. Yes, I know this swap can be done for less than $6,000, but I would want to rebuild the head and have AC fitted. On a less positive note, the M20 is gone and I find the engine bay to look a bit funny with a modern motor - doesn't bother me much though.

[Jamie325]

I'm subbed. Im in the beginning of all of this,so I have a blank slate to start with.

Sent from my SM-N920P using Tapatalk

[White325is]

LS swap. 350+ more reliable.

[frshmaestro]

I've had this same question in my head for the last two years. I think the built M20 is the way to go. Especially if you go with ITB's, the induction noise alone would do it for me.

[SkiFree]

This has been rehashed ad-nauseum, as you have seen. There is no "right answer" per say, but you have done a decent job of laying out the basics. In terms of longevity (and ease-of-maintenence) sticking with a built M20 makes the most practical sense. As you note, a properly built stroker is a LOT of fun and can run forever.

This is my distilled list that is EASILY REPLICABLE, long lasting, and not reliant on any not-easily-obtainable parts. Obviously, it can be tweaked as needed, but for best results the cam/specific-pistons/stroke/intake system were all formulated to match up well.

https://adamsautosport.com/information/tutorials/bmw-m20-ultimate-street-stroker-engine-checklist/

----As a fun data point....
Just this last week I finished rough tuning on a client's car that utilized the above checklist. I handed it over to Church for better tuning. He got 243whp out of it, with room for a bit more with larger injectors. The car is an absolute blast to drive.

[MrBurgundy]

243whp na m20?


ummmmmmmmmmmmmmmmm do that one

[SkiFree]

To be fair, that is with a lot of dyno time and an excellent tuner. It was 15-20hp more than I was expecting.

[SOneThreeCoupe]

243whp.

M20.

Reliable.

Hello, reason to keep my scored block.

[Supadave]

LS swap. 350+ more reliable.

This

[Sail Boat]

This

I thought about this, but that 350 + HP comes in at $10,000+ using Sikky parts and an LS in good shape... not to mention the AC problem. For that kind of money and sacrifice, would rather snail the built M20.

[DesertBMW]

I've had all 3 options in my car. I would say S52 is the best option.

Don't look at the peak power but how the power is delivered throughout the rpm range. How much time will you spend on 6000rpm + ? Built M20 never idles smooth, there is always some annoying stumble, gas mileage is bad, you have to rev the crap out of it to have any fun. M20 turbo will always have a lag, most of your driving will be in that 'lag' area and it gets old after while.
Now I got M52B28 and I love it.

[SkiFree]

Well, what you describe doesn’t sound a decently built m20 imo. Was just driving an s52 swapped e30 today and found it not nearly as much fun.

[Metallated]

Well, what you describe doesn’t sound a decently built m20 imo. Was just driving an s52 swapped e30 today and found it not nearly as much fun.

I feel like a lot depends on how the swap was done.

[digger]

I would do whatever you want to do.
Note that modifying a NA m20 for performance is never going to be good BFYB but that doesn't means it's not the right answer.
On the other hand think about the long game when you've got your 200whp m20 are you going to want more ?

[zaq123]

Note that modifying a NA m20 for performance is never going to be good BFYB but that doesn't means it's not the right answer.

I would disagree due to the fact that M20 e30s have better resell potential for "originality" stand point. IMHO, if the body is in good shape, I would keep m20, if the body already patched up etc, swap away.