M20 B3x Naturally Aspirated Stroker build past, present and future

[evandael]

damn. that's a nice powerband and excellent results for 80's engine architecture.

nearly 100 more bhp than a stock m20!

[LJ851]

Definitely needs more brakes, the pedal travel versus braking torque should be more linear and less effort to bite. tyres will limit peak braking torque but at the moment its hard to access it all the braking performance

What kind of pads are you running ? A decent pad makes a huge difference if you are not already running them.


Also, we are going to need some videos up in here.

[digger]

spring tension has been increased and it drives like a dream.

Definitely needs more brakes, the pedal travel versus braking torque should be more linear and less effort to bite. tyres will limit peak braking torque but at the moment its hard to access it all the braking performance

a 5mm spacer with 16" Alpinas allows UUC 11.75" kit and massive 11" perhaps even the 11.75".

[digger]

Nice !

This is still with your old exhaust, correct?

How high are you revving it to on those graphs ?

yeah not redone exhaust yet....currently planning that doubt that will be done before end of june. should be some pretty decent gains in midrange i think.

3400rpm is 100km/h IIRC so 6700rpm or so. limiter is 7100rpm and pulls easy to there but wasnt hitting in in these runs

[LJ851]

Nice !

This is still with your old exhaust, correct?

How high are you revving it to on those graphs ?

[digger]

final results are in now that everything is tuned.

It just goes to show that ITB and new induction system can make more power everywhere and there are no downsides once you use the right diameter runners, right runner length and feed it cold air.

Made 160rwkw (215rwhp) on one run but this is the best overall powerband.

best part of 30whp gain peak to peak which is a difficult task on the m20

first graph is 42mm ITB, 12" runner length and custom GRP/CFRP airbox and K&N filter Vs a BMW OEM casting with some massaging done to it



the setup with the airbox trumped the open trumpets, which was good, though some no doubt due to the tune.

graph is as above but with open trumpets also added into the mix




had a few issues, the throttle got jammed WOT on the dyno (better there than on the street). Already had a spare at home because it started to look a bit frayed. the internal sheath deteriorated due to long term heat exposure from the exhaust is my guess and added too much friction. had to baby it home but all sorted now. i now realize it had been on its way out for a long time as the pedal is so touchy and responsive now with a brand new cable. i will adding a bit more spring tension to make it a little easier to drive otherwise it will be a handful in the wet.

[bmwandhonda]

that 12 kw doesn't include the probably 10 kw from sucking in 60C air instead of 30C so its worse than that.....when the hood is open on the dyno you get cooler air.

im enjoying the added performance more than im missing the sound TBH

This is true.

[digger]

I am currently getting an ITB'd m20 tuned atm (still at the shop) and will be running individual dry filter socks. Surprising that there is a 12kw difference between the open trumpet, no filter setup :/

That is a big power difference when it comes to an NA engine.

As much as power/efficiency is more important, the sound is something i just don't want to lose by boxing them up.

Anyway, will keep checking your thread for more updates.

that 12 kw doesn't include the probably 10 kw from sucking in 60C air instead of 30C so its worse than that.....when the hood is open on the dyno you get cooler air.

im enjoying the added performance more than im missing the sound TBH

[bmwandhonda]

thought people might be interested in a test i did last year with the socks and older ITB setup. i oiled the socks using the stuff you get for dirtbikes. they restrict flow a little ;)



cleaning them with kero and running them dry improved alot and it made 130kw ish which was still down about 12 kw from the equivalent unfiltered setup so individual socks are not great.

ideally you want a common large filter that all runners use not individual socks

I am currently getting an ITB'd m20 tuned atm (still at the shop) and will be running individual dry filter socks. Surprising that there is a 12kw difference between the open trumpet, no filter setup :/

That is a big power difference when it comes to an NA engine.

As much as power/efficiency is more important, the sound is something i just don't want to lose by boxing them up.

Anyway, will keep checking your thread for more updates.

[digger]

great summary thanks digger. very consistent with your prior comments

this is that setup (dbilas adapter 42 ITB) skinny longer runners. BLACK curve, vs regular dbilas and vs baseline

[bradnic]

you can get the midrange back by using smaller longer runners if you ditch the plenum, it will still be down on peak hp though since the alignment of the adapter is inferior and heads flow potential gets hurt by creating more turbulence. the dbailas has good drive ability and response but is just pretty flat

great summary thanks digger. very consistent with your prior comments

[digger]

So 143kw = 193hp is that right? this is at the rear wheels correct?

you can get the midrange back by using smaller longer runners if you ditch the plenum, it will still be down on peak hp though since the alignment of the adapter is inferior and heads flow potential gets hurt by creating more turbulence. the dbailas has good drive ability and response but is just pretty flat

dbilas made 143rwkw so 193 rwhp with 42ITB
RHD made 205rwhp with same 42mm ITB alot more mid range.

after driving on the new airbox it is so much better its not funny. i don't remember it pulling this hard even back when it made 220rwhp several years ago but perhaps my memory has diminished and the butt dyno is not reliable. 65C hot air through restricted socks on the street hurts alot perhaps i have been driving this too long and got used to the crappiness.

im still using the tune from the dbilas so it runs a little lean especially at part throttle i seriously need to upgrade the brakes

if i had of done the ITB swap a few years ago i think it would have been pushing 240whp. the goal is to get back to 220whp after new exhaust before i drop the new engine.

[bradnic]

So 143kw = 193hp is that right? this is at the rear wheels correct?

[bradnic]

yeah me too. digger knows what he's talking about. not ready to give up on it yet though - SC + ITB at some point.

[ForcedFirebird]

please sell it and use something better in that case.

I actually LOL'd