M20 B3x Naturally Aspirated Stroker build past, present and future

[mikey.antonakakis]

Thanks for this thread, really got the gears turning for me on my VGT build. Pretty dead set on 84mm stroker. Love that you’re using EngMod4T, I’ve spent a lot of time in the 2-stroke version.

[moatilliatta]

It seems like a handful of those 60-2s come flying apart.

[hasa]

I've also tried to figure out if E21 lower timing gear and M50 harmonic balancer could somehow work together in M20. Running electric water pump could perhaps simplify things in that concept.

[ForcedFirebird]

I have yet to get pics from my client that is using one. He modified an ATI to fit the m20 crank snout and put a vee belt pulley on it. He blew apart the stock damper at 8500rpm - took out the water pump, radiator, and even the CPS bracket was shattered. You can purchase 60-2 laser/water cut reluctor rings for short money.

[digger]

Something like this could perhaps be utilised for M20 ? https://www.summitracing.com/parts/ati-918040

Probably, if you are ok modifying timing covers and pulley setups you could get an existing product to work I did see something from user whodo iirc . If you went to electric water pump it would simplify things

[hasa]

OK I understand. M20 is legacy engine nowadays so there is not much demand for this kind of products.

Something like this could perhaps be utilised for M20 ? https://www.summitracing.com/parts/ati-918040

[digger]

Any news about this?

they have been backlogged so focussing on filling orders and supply of non custom / regular off the shelf stuff due supply chain /covid issues etc to so not anytime soon. i will be contacting them again to see if they have capacity to do progress this.

[hasa]

Been working on a side project for an ATI vibration damper for the M20 that's essentially plug and play, it is fairly well developed from a design point.

Any news about this?

[digger]

sounds about right for a stock 325i

[bmwmaster81]

Just because a a Lot of discussion hapened already regarding exhaaust an so on. I switched from stock 325i exhaust to custom built, with headers.....xpipe....Sport Cat.....with 2x 2inch Pipes Front to end.

It now Runs 16 sec 100 to 200 km/h and that ist 1.5 sec faster than before.

https://youtu.be/GCX0iUCoNF4

I think It must be an 15hp gain.

And I think a Stock m20b25 surely needs 25sec.

[nando]

Huh, I missed that whole post about your exhaust. Mine almost exactly matches your diagram for the 4th harmonic. I'll almost certainly move that further down next time I redo it, although I have a single exhaust and fitting the cat and 2 mufflers won't be easy that far down the line (maybe I'll just ditch the cat).

[Mr Mpower]

when i had my first exhaust done the BTB2 6-2 headers were 1-5/8" into 1-7/8" collectors and the shop just made the rear 2.25" from where the BTB collectors ended. 2.25" is more common for cats, resonators, mufflers etc so that's really the only reason it is 2.25" this was not by engineering or calculations but i didnt want to change the entire setup so left it.

really nice advise then!, thanks again!

[digger]

thats what i thought at first! thanks! is interesting how usually i see exhaust builds (with close to 0 science or investigation application) more restrictives in the final pipes but you develop the opposite (what i trust definitely), thanks for your help, this friday im going to apply this on my setup!

when i had my first exhaust done the BTB2 6-2 headers were 1-5/8" into 1-7/8" collectors and the shop just made the rear 2.25" from where the BTB collectors ended. 2.25" is more common for cats, resonators, mufflers etc so that's really the only reason it is 2.25" this was not by engineering or calculations but i didnt want to change the entire setup so left it.

[Mr Mpower]

2x2.25”

thats what i thought at first! thanks! is interesting how usually i see exhaust builds (with close to 0 science or investigation application) more restrictives in the final pipes but you develop the opposite (what i trust definitely), thanks for your help, this friday im going to apply this on my setup!

[digger]

2x2.25”