Built M20, M20 Turbo, or S52 Swap?

[Blake B]

---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.

Is there a Dyno sheet for this build? Really want to stay NA I have a m30 and a m20 that needs needs to be rebuilt. I could really go either way at this point. Turbo is always an option but consistency and reliability are what I'm really shooting for. Building m20s are not cheap and I only want to do it once.

[DTedeschi]

I find this thread very interesting in that I need a better performing engine in my Spec E30 racer. The car has dents, faded paint, no interior, no power steering, no heat and A/C. The car is going into another race venue, World Racing League. The rules are different than Spec E30 when it comes to an engine. In Spec E30 you ran a stock motor and were limited to a certain HP. In WRL rules the Engine HP is not that restrictive. Rather than Sprint races that car will be running 9 or more hours per race. So I am looking at longevity and to be honest HP is not that important.


I would like to hear more about the M20 build.

[White325is]

Transmission… T56 never seem to be cheap.

Once again, Do you REALLY need a T56? The LS uses the same bolt pattern as 305/350/454 and Im sure some others. Any 5 speed will work just fine. The only difference would be shifter config which is a simple solution in the end since there are so many aftermarket options.

[redsubdivisions]

You can build an M20 turbo for much cheaper than $4k. I did it with mine for nearly half that and that includes the plug and play MS I purchased from whodwho and I'm making well over 300whp.

[iitsMikE30]

Who ever said you needed to buy the sikky kit?

You can purchase a truck LS for around 300.00 at any local pick n pull.
Canton oil pan. 150.00
drive shaft 300-400
Mount kit is 500 from Garagistic
Headers are 250-300
Have the ECU tuned is 200.00
As for the A/C all it takes is two splicers from amazon for 7.00 each. Most hose/line companies stock them and will crimp the lines together for around 50.00 with fittings included.

Everything else is nuts and bolts and hoses.. 10k for a LS swap is just stupid.

Transmission… T56 never seem to be cheap.

[Sail Boat]

Who ever said you needed to buy the sikky kit?

You can purchase a truck LS for around 300.00 at any local pick n pull.
Canton oil pan. 150.00
drive shaft 300-400
Mount kit is 500 from Garagistic
Headers are 250-300
Have the ECU tuned is 200.00
As for the A/C all it takes is two splicers from amazon for 7.00 each. Most hose/line companies stock them and will crimp the lines together for around 50.00 with fittings included.

Everything else is nuts and bolts and hoses.. 10k for a LS swap is just stupid.

ooo this is interesting. I'll budget it out and see how it goes - I'd be tempted to find a used LS3, wouldn't be opposed to spending a bit more cheddar for it

[White325is]

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.

Who ever said you needed to buy the sikky kit?

You can purchase a truck LS for around 300.00 at any local pick n pull.
Canton oil pan. 150.00
drive shaft 300-400
Mount kit is 500 from Garagistic
Headers are 250-300
Have the ECU tuned is 200.00
As for the A/C all it takes is two splicers from amazon for 7.00 each. Most hose/line companies stock them and will crimp the lines together for around 50.00 with fittings included.

Everything else is nuts and bolts and hoses.. 10k for a LS swap is just stupid.

[sert57]

I'm gonna echo downforce's sentiment:

The learning experience was great and now I have a unique engine which is what I wanted (not something everybody does/has) so that was important to me.

After I went standalone and ironed out a few kinks my NA M20 seems just as reliable as it was as a 2.5 on motronic, and all the realoem diagrams, part numbers, and other DIY tutorials still apply.

I wanted the experience of building an engine and seeing what all goes into it, and at the end of the day I have something thats unique and mine. I enjoyed putting it all together, selecting parts, and figuring out how to tune it.

With a stroker you always have to explain it, car people see a turbo or s52 and instantly know whats going on under the hood, not so much with a stroker. Just a thing to consider that could be a positive or negative depending on your view.

I'm definitely biased, but only one of these options gives you a completely new engine.

[downforce22]

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 ?

I haven't driven an s52 swap car and the only stroker I drove was my 3.2 L m20 before I went turbo. But i echo digger's statement. You already know the pros and cons of the three options. What type of car do you want? This can go back and forth all day since every person has different things they need out of a car and live in a different climate.

It sounds like AC is almost a requirement for you to enjoy the car. With that said, my turbo m20b32 doesn't have AC and, yes, it can get toasty, but I'd rather have the intercooler and turbo than the AC. Some people have done both before. My brother's e36 m3 is a fun car and I like the powerband of the NA engine since it is fun to keep pulling toward redline. But to me, I wanted to learn how to tune and do my own install of a turbo so that is the route I went. I also wanted a unique car and stuffed it in an iX and went big with an overbore and s52/m54b30 crank. I promise you, with the extra torque/ dispalcement, a stock 885, and a billet turbo there is not much lag unless you are in the wrong gear.

If I were to do it again, I would probably not spend as much on the built m20 with the custom pistons, rods, overbore and stroker crank. It was expensive and I could have gotten more power easier/cheaper with S52. I didn't even upgrade the head or camshaft at all on my stroker turbo. The learning experience was great and now I have a unique engine which is what I wanted (not something everybody does/has) so that was important to me. And i've got my base tune figured out on my car pretty well. Sometimes there is a slight hunt to the idle and I have to dial in the startup so it fires up faster, but besides that, my tune is as reliable as any other m20 I have driven and is way faster.I wouldn't be worried about reliability and driveability with an MS unit.

If I were to do it again on a non iX e30, I would probably do an m20 turbo. It makes all the right sounds and if you do it correctly with a nice correctly sized turbo (not an ancient holset or garrett) then you won't have the dreaded 'lag'

[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.

[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 ?

[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.

[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.

[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.

[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.