M20 dyno results

[zaq123]

Post 170 here

AI can interpret dyno graphs no worse that it does X-rays

[MrBurgundy]

What size trumpets did you use?

[zaq123]

What size trumpets did you use?

40mm ones

[MrBurgundy]

40mm ones

I believe they say to use the 42mm for anything larger than the 2.5, so that might be hurting u a bit



Two Sizes available:

• 40mm Throttles used for standard 2.3-2.5L engines.
• 42mm throttles for larger stroker engines, raised compression, head porting, larger camshaft etc.

[zaq123]

I believe they say to use the 42mm for anything larger than the 2.5, so that might be hurting u a bit



Two Sizes available:

• 40mm Throttles used for standard 2.3-2.5L engines.
• 42mm throttles for larger stroker engines, raised compression, head porting, larger camshaft etc.

ITB size as recommended per RHD

• 40mm 265cfm 61Hp 350-500 cc/cyl
• 42mm 304cfm 70Hp 450-600 cc/cyl
• 45mm 362cfm 83Hp 550-700 cc/cyl
• 48mm 408cfm 94Hp 650-800 cc/cyl

so for 2.85L - 475cc/cyl

40mm is enough

[MrBurgundy]

gotcha! they make it seem like literally anything will warrant that lol

[AWDBOB]

haha, this is awesome. Karl was like "what is Alpina?" . Unfortunately my 885 head was machined, 3 angle valve job done all that but was never pressure tested by the shop before all that work. It had a small bubbling invisible crack in the usual spot. I sourced new (to me) 885 head ready to go but was itching to drive this car this summer hence AMC on it now. Pressure tested new 885 head myself and it's ready to go. Unfortunately machine shop lead times are months, KP dyno appointment took me a month from when I booked it as well. So I had it road tuned and had KP to fine tune it for me. Once this winter is here, thinking about swapping the head but for now, it's what it is I guess and there is definitely plenty of power to have fun with it.

ugh thats rough they didn't catch it before the machine work was done. I don't blame you for tossing the AMC head on and enjoying the car. Near 200whp is still a ton of fun in an E30.

I wish someone like Rabid Racing would offer a quantified, affordable cnc profile for an 885 like they do for 24v heads.

Do you plan on having any port work done to your spare head? Would be a neat opportunity for some a/b results

I wonder if some chamber work done by the right person could help with your knock issue

[zaq123]

gotcha! they make it seem like literally anything will warrant that lol

Sorry, I actually messed up in my calcs haha, just noticed.
Anyway, I edited my original post to keep confusion to the minimum for anyone's future reference but the results are the same, 40mm is plenty and definitely more than enough for this engine.

[zaq123]

ugh thats rough they didn't catch it before the machine work was done. I don't blame you for tossing the AMC head on and enjoying the car. Near 200whp is still a ton of fun in an E30.

I wish someone like Rabid Racing would offer a quantified, affordable cnc profile for an 885 like they do for 24v heads.

Do you plan on having any port work done to your spare head? Would be a neat opportunity for some a/b results

I wonder if some chamber work done by the right person could help with your knock issue

yeah. I'm not sure why it was knocking down low with my street tune, maybe shitty amc dome shape? It was very brief slight knock on the knock monitor once we got it on the dyno, nothin audible and my original base tune wasn't anything dramatic as far as timings go. At least midrange/top we got to MBT so I'll take it for now. You can see where it was knocking and were it wasn't, that base table shows it all. But right now this engine is knock free everywhere so I'll take it.

Not sure what I'm gonna do with the head yet. This car isn't exactly built for the track fun so I'm not chasing the power up top. I think I'll just do some basic rebuilt and 3/4 angle valve job over the winter and put 288 cam in it, the cam I had in cracked 885. Put it back on the dyno and see what it will do.

At the moment, it is a very fun car with nice pull, plenty in midrange and super responsive that pulls nicely to speeds that aren't exactly appropriate for most public roads. I don't need to constantly shift it to stay in the powerband, it's fun little car right now, nothing breathtaking but I did have to mount a radar detector in in, just in case .

I'm sure once roads will be salted and it will be parked for its winter rest, I'll be itching to do something with that head

[zaq123]

Here is stock 3L n52 dyno from 2011 128i.

I think for the good old M20 to be there ain't bad at all, considering e30 is 500lbs lighter. This M20 has 7 less hp that peaks 400rpm earlier than N52 but has 12lbs more torque that peaks 700 rpm later than N52. Not a screamer like N52 but definably pulls like a donkey everywhere.

[digger]

As a point of reference Here is a 2.9L (Mahle MS piston) with 40mm RHD kit and Schrick 272, RHD flywheel makes 231 whp / 213 wtq with SAE units



some videos

https://www.youtube.com/@xristodoulos88/videos

[zaq123]

As a point of reference Here is a 2.9L (Mahle MS piston) with 40mm RHD kit and Schrick 272, RHD flywheel - makes 231 whp / 213 wtq with SAE units



some videos

https://www.youtube.com/@xristodoulos88/videos

It says STD in that graph on the bottom, not SAE. Considering STD correction inflates numbers by about 4% from SAE, still good numbers, ~ 224 whp and ~204wtg on perfect 21C day they ran it. It didn't help that it was 32C on my dyno day. Although dyno corrects for ambient temp with STD or SAE etc, there is no correcting AIT heat soak but regardless of all that, it's obvious that the engine could use better breathing head.

My tuner said to expect about 10-20hp increase in high rpm with better breathing cyl. head. Which seems about right looking at this dyno graph

[digger]

The big takeaway is you don’t need a big cam to make good numbers.

duration just makes the engine want to rpm which can sometimes make more power if the rest of the engine can support it. The system needs to work together

[zaq123]

The big takeaway is you don’t need a big cam to make good numbers.

duration just makes the engine want to rpm which can sometimes make more power if the rest of the engine can support it. The system needs to work together

that makes sense. would be interesting to see what ign. timing and type of fuel he runs