M20 B3x Naturally Aspirated Stroker build past, present and future

[JinormusJ]

Finish this thing already

If 220bhp from your previous m20 wasn't satisfactory, I can't wait to see the figures you're getting on the new one!

[digger]

Finish this thing already

If 220bhp from your previous m20 wasn't satisfactory, I can't wait to see the figures you're getting on the new one!

My current 3.1L engine at one point made 164 rwkw / 295 rwNm (220 whp / 218 wtq) on a dyno dynamics shootout 6. It made 217 rwhp / 213 rwtq on a second dyno also dyno dynamics so not a fluke run and so a reasonable point of comparison.

i'm hoping for 210-220 rwkw (280-295 whp) of streetable power peaking at ~6700 rpm cutout at 7500 rpm on the same dyno dynamics machine.

Midrange torque should be huge hopefully around 250 wtq. EAPro and Pipemax both suggest this is realistic (flywheel 320-340 bhp / 270-290 tq).

Also the 25% more time-area from improved headflow and cam lift profile agree that the potential is there with intake and exhaust tuned accordingly of course.

164 rwkw x 1.25 = 218rwkw

For reference on same dyno I’ve seen

- 2 x stock M54B30 do ~130rwkw (170kw fly).
- E90 335i do ~175rwkw (220kw fly).

I’m not chasing peak numbers the cylinder heads don’t flow well enough to support a lot of hp with a very broad power band and nice low rpm manners the S54 is king there no question. I’ll leave that for guys that purely race competitively and can actually use the topend power regularly.

For those with that in mind more compression, more work on the head, 25 degrees more duration and E85 would easily add 30rwkw had i chosen that path.

[JinormusJ]

Can I hire you as my personal engine builder? Lol

290hp dailyable m20 is no joke
That's like overshooting my dream m20 by like 90hp lol

[digger]

Can I hire you as my personal engine builder? Lol

290hp dailyable m20 is no joke
That's like overshooting my dream m20 by like 90hp lol

honestly it is just correctly matching parts using techniques know for decades.

i am always happy to give an opinion. 200whp is easy

[JinormusJ]

Rest assured I will be watching sub'd and supporting like a hawk

[darvo]

honestly it is just correctly matching parts using techniques know for decades.

i am always happy to give an opinion. 200whp is easy

INDEED!!

Great to see you working with Rama!! ;D

[digger]

INDEED!!

Great to see you working with Rama!! ;D

indeed his universal TB and manifolds open the door for much easier power from the M20.

[digger]

couldn't get the main section how i want with clear finish so reverted back to plan A which is flat black and a bit more OEM looking which i prefer anyway. kept the CF finish for the lid.

will get proper photos when i can take pics during daylight hours and also with it installed and trumpets inside etc.

[2mAn]

one of the greatest M20 builds ive ever seen

:bow:

[325ix]

Wow, that is a fantastic looking intake!

[eb224]

Looks great, nice work. You are tempting me into replacing my dbilas intake with trumpets and then doing my own plenum chamber as well. Have to think about it more and work out the costs.

I love love to know what power you get when done.

[digger]

Looks great, nice work. You are tempting me into replacing my dbilas intake with trumpets and then doing my own plenum chamber as well. Have to think about it more and work out the costs.

I love love to know what power you get when done.

do it:) the difference is worth it IMO.

[digger]

curved adapters 3D printed in ABS plastic and clamps from 48mm trumpets (e21 JPS aka RHD) so that i can use a thicker wall without crushing them. they are to get everything inside the airbox and clear the hood without using a excessively short runner and provide additional clearance to the booster and not shroud the trumpet. you can rotate the whole trumpet to point them forwards slightly to but you need to rotate them all because the centre spacing is about 90-92mm and diameter is 80mm of the bell mouth



trial assembly, trumpet length is 30mm shortened to have same centreline runner length as previous. i chose 30mm so that i can shorten them a further 30mm if needed more fasts. the new engine will require about 25mm shorter length according to calculations and simulations. the dyno will decide so i favour the longer length in the interim



this is why they are needed. this is runner 2 (no curved adapter), runner 1 is worse and runners are angle downwards. runner 6 is angle upwards but less of an angle this is to clear the booster by additional amount



runner 1 & 2 are angle down to give about 30mm less height, runner 3 is about 20mm but is not 100% needed. this was done to centre the trumpet in the box height wise



a view inside from the inlet



did some conceptual CFD to deliberately look at shrouding (distance between the trumpet and wall opposite opening) and some basic distribution to convince my self it wont be a disaster. i modelled the trumpets longer so they get quite close to the opposite wall to exaggerated the issue



quite a bit of flow comes from around the sides rather than from straight above







alot of flow comes from bellow the bellmouth



open trumpet flowed 0.152kg/s by itself. when flowed with box it is 0.150kg/s runner 6 and 0.152kg/s runner 1 so not much difference to open trumpet provide the K&N isnt restrictive. i have room for larger filter so will search the K&N site for suitable one

[LJ851]

What do you think about mixture distribution equality in the cylinders with the different angles of entry ?

[digger]

ideally having more room opposite the bellmouth entry and a shallower entry would probably work best. an even bigger inlet helps to. its not really possible to get much different there was only really one area the filter will fit.

i should add that i only modeled air being drawn through 2 runners at a time as this is really what happens at any instant and 1 and 6 aren't occurring simultaneous from memory. its more complicated to do a full transient flow

typical turbo manifold



m50 style


i would say having the trumpets proud of the wall rather than having a flat plate with radius might be advantageous