M20 B3x Naturally Aspirated Stroker build past, present and future

[digger]

Crazy ass linkage across the back of the firewall.

not good for pedal feel.

not only are the headers compromised due to steering linkage the intake is compromised due to booster. double whammy

the hood latch is also still on the same side. cheap German engineering....

[TrentW]

thanks guys, i like the m20 due to its simplicity and rawness

Indeed.

[LJ851]

Never dealt with a RHD e30. Had no idea the brake booster and reservoir was still on the LH side of the car.

Crazy ass linkage across the back of the firewall.

[ForcedFirebird]

LHD? the car is RHD

Never dealt with a RHD e30. Had no idea the brake booster and reservoir was still on the LH side of the car.

[digger]

Looks fantastic, the finish you have got on the plenum looks like a factory build. I can't wait to see what it produces on a dyno.

Can I ask what brake booster you are using?

Cheers
Leigh

thanks, this is the stock booster and MC, im not expecting any gains with this over the open trumpet run ill be happy if its the same.

i plan to get it retuned only a quick and dirty tune about 30min worth tops, i will make a simple bellmouth to be able to test without a filter (bellmouth is needed to ensure the flow doesnt go over a sharp edge and hurt airflow thats is why sometimes removing the filter makes less power as the test is flawed) and one without the lid to see if there is a difference.

im waiting for my new K&N still so i imagine this might happen 2 weeks from now.

moving to fix the exhaust now

[eb224]

Looks fantastic, the finish you have got on the plenum looks like a factory build. I can't wait to see what it produces on a dyno.

Can I ask what brake booster you are using?

Cheers
Leigh

[digger]

Loving the skills digger. Normally don't say much on this site, but why are you LHD in up-side-down land?

LHD? the car is RHD

[ForcedFirebird]

Loving the skills digger. Normally don't say much on this site, but why are you LHD in up-side-down land?

[digger]

thanks guys

did the install today and everything fits and runs well.

unfortunately it is a fair bit quieter than open trumpets but still better then stock and dbilas which are too quiet.

definitely alot more power than the socks which lose about 15-20whp but i never drove this setup without socks so i dont know whether it will match the dyno run of 152kw with open trumpets no socks.

still got to find a better sized K&N filter and make a heat shield.....

[digger]

thanks guys, i like the m20 due to its simplicity and rawness

[tinkerputzer]

That's cause the guys from down under never gave up on M20's. Been following since the start, keep up the good work digger :up:

[nando]

nice, glad I saw this. it's amazing how much more information there is on M20 builds these days. Part of the reason I just decided to stop on M20s was because I knew I'd have to totally redo my entire motor from the bottom end up. If I knew back then what I knew now I wouldn't have done anything like what I have now in my 2.8.

[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

[LJ851]

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

[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