BMW M20 Head Flow Data

[digger]

This thread is for people to show the data for cylinder head flow and related aspects and hopefully be stickied.
Those putting data here should mention as much of the following where possible.

- Casting P/N i.e. 885, 731, 200 etc
- Brand: BMW, AMC, etc
- Valve Sizes if not stock: Stock 885 42mm/36mm; Stock 731 40mm/34mm; Stock 200 40mm/34mm
- Valve Brand if non OEM: E.g Schrick, Supertech, Manley, IE, etc
- Test Pressure: i.e. 10” H2O, 25”H2 O, 28”H2O
- Configuration: Bare cylinder head, cylinder head with manifold, etc
- Shop that did work.

Some data I have
Stock 885 vs Alpina 885 vs Metric Mechanic Rally 885 ST valves 42/36
Bare Cylinder Heads, BMW castings; Test pressure 10” H2O Racetec

http://www.racetechautomotives.com.au/services.php

Stock 885 BMW vs Knight engines (TK) Ported 885 AMC casting 45/36 Manley valves
Bare Cylinder Head; 28" test pressure

https://www.facebook.com/pages/Knight-Engines/126965897370701

Inlet


Exhaust



Stock 885 BMW vs Stock 731 BMW vs Racetec ported BMW 885 standard OEM valves
BMW castings, Bare Cylinder Head Test pressure 28” H2O

[digger]

link to Marquis Rexs data

http://speedtalk.com/forum/viewtopic.php?f=1&t=8652

[e21jps]

heres my ones @28" bare head with 10mm radius entry plate
I also tested it with ITB intake manifold on, also with 10mm radius entry plate

oem 731 casting, custom stainless valves 36ex 44in, porting done by RHD

gone for a slightly different approach to TK i tried to concentrate on low and mid lift flow more than top end flow but not sure if its actually better or not.

This is the actual head fitted to my 293wHp race engine


Intake bare head
Intake with inlet manifold
and exhaust

[e21jps]

some plotted overlays, would be interesting,
that would give us some nice comparisons of two porting styles and will be interesting to analyze with dyno results later too

anyone with a printer??.....

[digger]

lets keep this as a database for DATA only

[LJ851]

lets keep this as a database for DATA only

Great idea, where did those theories go? ;)



I have high hopes for this thread, wish i could contribute some DATAS.

[bmwmaster81]

Here some data which i got today.
Its an 731 Head with 42mm / 36mm Valves and 3 angled seats. I think Intake flow is better than stock 885 Head.

By the way does someone know .050 inch duration of stock 325i cam?
Need to do some calculations.

[digger]

Valve lift at 0.050" absolute is approx 209*

i had a test done on old 885 head in 2008, it was an old superflow tested at 10"

0.200 = 64
0.300 = 91
0.400 = 105
0.500 = 114

[jeffnhiscars]

Here some data which i got today.
Its an 731 Head with 42mm / 36mm Valves and 3 angled seats. I think Intake flow is better than stock 885 Head.

By the way does someone know .050 inch duration of stock 325i cam?
Need to do some calculations.

That's the exact built head I have sitting here w a 272 so it sounds encouraging. I just wish I knew what any of this meant

[bmwmaster81]

That's the exact built head I have sitting here w a 272 so it sounds encouraging. I just wish I knew what any of this meant

In the diagramms you can see how much flow goes through a port at a given pressure and valve lift.

More flow = more performance.


@digger

Your stock 325i head numbers are everywhere higher than my optimized 320i head. I hope this is caused by different methods and benches.

especially that it flows everywhere better makes me little surprised.

Shouldn't my head have some advantages ? eaven at some lifts?



It has:

-The same valve size like 325i
-its ported with really round and good short radious transition
-seats have 3 angle cut
- valves have back cut
-better port angle entering the chamber

Maybe flowbench doesn't benefit from this advantages like hopefully real world flow does ;D
Smaller ports at some point should cause more velocity at some points and also fill cylinder better ?

We will see.....

[digger]

why not just flow a stock 885 head on same bench if you want the real answer?

[bmwmaster81]

its not possible....sadly
it is done at a bench 1500km away where i sent the head for machining the seats etc....