The BMW M20 engine

[Erland Cox]

The flow in Pipemax is not the flow at maximum lift but the flow required at max piston speed which is around 73degrees.
Do you have a .55 valve lift measured on the engine with valve lash?
How much valve lift do you have at 73 degrees ATDC.
Here in Sweden dynos measure massively different.
All dynos can be used with different inertia correction etc. that will change how much power they show.
The only hp increase I have seen by using E85 is by the possibility to use more compression.
Same engine, same compression and ignition shows no difference.
Nevertheless your engine sounds very good.
My engines are required to have a long power band and have to be able to take WOT at under 3000 rpm.
The Rally cross 3 liter was built on a 330 engine and has a ported M3 manifold adapted, no flow zapping boosters in the way.
Some Pipemaxing raised power around 20 hp but I never got those dyno papers.
It only has around 12:1 compression but the difference there is less than 20hp.
That head flows 240 cfm at 12mm in, 236 with the manifold and exhaust flows 199cfm with a pipe.


Erland

[KnightEngines]

This one is circuit race, no "what's around this corner" to worry about, 3500rpm power band is plenty (2000rpm is enough with a good driver).

I've got an M3 head here, along with a set of big-un catcams, shimless buckets, ferrea +1mm valves etc etc - belongs to the guy holding the camera in that vid, will be finished shortly, I'll let you know how that one goes - we'll be revving it to 9k & it's injected, it should murder this M20.
Head flows a little over 300cfm through the TB's.

PS - From what I've seen E85 can be worth up to 5% power, or as little as nothing - very engine dependant, it would seem the faster the burn the better the gain.

[Erland Cox]

Being a 6 cylinder does of course help. I have a circuit Mercedes 2,5-16 customer that has done lots of testing.
He has at least 3 cars and the one that runs the best has one of my heads on it.
It has 39-33 valves and flows over 340 CFM. It has 350 hp at 8550 rpm with 2450cc.
This guy has tested more than 20 camshafts and more than 15 different heads.
He has tested lots of different exhausts and the intake and exhaust length and diameter has been modified on the dyno to the best power band length.
This is an ex DTM car with dry sump, 2 ring pistons etc. a real racing engine.
Still it does not dyno to more than 350 hp. An interesting thing is that he tested a 430 hp factory Mercedes ex DTM engine and it only had 285 hp on his bench.
It had a 2000 rpm power band and was dead below 8000 rpm. With a modified intake both power and power band is much better.
With the AMG head, Mercedes own factory head the best he has managed is 320 hp. My head had 5 degrees less lead, 33 instead of 38 degrees.
This is with a 97mm bore but a central plug. Not much squish but I build the heads for a lot of tumble.
So that makes a 2 valve BMW with Weber 45:s and 50 hp more very hard to believe.
Dyno comparisons should always be done on the same dyno at the same day.
We don't deduct acceleration losses and we don't use race dyno hp.

Erland

[KnightEngines]

Yeah, we're all just bogan redneck Aussies, no idea how to built a 'real racing engine' LOL.

Believe it or don't little care will be given.

You may be better asking how this was achieved rather than if this was achieved, you may learn something.

PS:

http://i5.photobucket.com/albums/y171/m ... a0dfa8.jpg

I'll let you know when we make 450HP from an M3 engine at 3L capacity.

[volodkovich]

TK, you're a legend! Hope to one day make similar power from my dinosaur Nissan L28.

What valve CL's are you running on this motor (If i remember you were asking for a 106/106/106 at cam?) If so, seems quite wide LSA for a motor running durations as large as this?

[KnightEngines]

105 LC from memory.

How do I know you - you with kelford?

I reckon around 350hp will be all she wrote on a no holds barred L28, intakes could do more but the exhausts will hobble it.

[volodkovich]

Cheers! Yeah, I am currently at Kelford, doing all the lobe designs and running the CNC grinder.

The Japanese claim 400hp from L series drag motors, running 55mm DCOEs. Must be spinning them to some decent rev's to get that out of them I'd think. You are right, that exhaust port is disappointing - typical Nissan. I'm tempted to mill off the side of the head and furnace braze in a billet piece with new ports.

How much after 8000rpm did this M20 hold on for? Impressed.

[KnightEngines]

If the cam ever comes out of this engine for any length of time I'll get the boys to lob it in your direction to see if you can copy it well enough.
It took CatCams 4 months to get this cam here, motor would have been running before Xmas otherwise!

Tis a pity you guys don't have beamer stuff, got a lot of it going on ATM & I've always been impressed with your subi/toyo grinds.

Have you got some good grinds for the L28? - Wade cams over here have some monster lobes that aren't in their listings & can't be ordered by the general public.
Mind you you can prolly just design your own LOL - forgot who I was talking too.

Have you seen how Mark Banyard does the exhaust ports on the 4 bangers? - he mills the floor out & welds in tounges to raise the short turn, seems to work ok.

Dunno how far past peak the M20 held for - something about an overspeed limiter on the dyno cutting in just after 8Krpm (they were running it in 4th, maybe it was overspeeding the rollers or something).

[volodkovich]

Maybe I should start designing some BMW lobes. Need some heads to measure up geometries first though. They are getting fairly popular to play with over here too.

We have some old grinds for the L series that work decently - none have enough lift for my liking though. I've just recently designed a few mild lobes with decent lift to test in my 240Z so that should be a good start.

I've heard of Mark Banyards work, never seen any of his ports though. Sounds like he does similar to a Datsun A series head I have here. Raised floor exhaust really helped, it flowed 158cfm on intake and 128cfm on ex at 0.500". Most struggle to get 70% E/I ratio.

Cheers
Robbie

[morerevsm3]

I was the one wobbling the camera, and it is my 3 litre M3 TK is talking about, this photo is straight off the screen from same dyno run as the video, so no funny heated up intake temps etc, which is the only thing that can be fudged on a DD dyno in shootout mode, as you can see on the pic, it is in shoot_6 mode



some more pics

[Hairyscreech]

Well, many questions here and quite a bit of surprise, i think this must be the most powerful na m20 around at the moment.

I think the first thing i want to pick up on is the piston.
Now from the look of it they are concentric and I assume the angled part is around the 21* of the squishband angle on the head.
How do thay fair with the rest of the chamber? for a while the thinking has been to stick with an offset bowl on the 885 head but this brings me back to wondering if the offset bowls actually end up directing the squish in undesirable directions.
One of the very early questions in this thread was about using a piston geometry very similar to that but with a bowl in the top.

[Erland Cox]

You never answered these questions:
The flow in Pipemax is not the flow at maximum lift but the flow required at max piston speed which is around 73degrees.
Do you have a .55 valve lift measured on the engine with valve lash?
How much valve lift do you have at 73 degrees ATDC.

Erland

[morerevsm3]

can only answer one of those, it has .550 lift at the valve with lash

[KnightEngines]

We have over 205cfm at the lift achieved at peak piston demand.

& we have a chamber that with some work produces very nice pressure recovery, have a look at the pic of the chambers I linked too.

[KnightEngines]

Well, many questions here and quite a bit of surprise, i think this must be the most powerful na m20 around at the moment.

I think the first thing i want to pick up on is the piston.
Now from the look of it they are concentric and I assume the angled part is around the 21* of the squishband angle on the head.
How do thay fair with the rest of the chamber? for a while the thinking has been to stick with an offset bowl on the 885 head but this brings me back to wondering if the offset bowls actually end up directing the squish in undesirable directions.
One of the very early questions in this thread was about using a piston geometry very similar to that but with a bowl in the top.

Don't spend too much time thinking about quench, get it under .050" & above .035" at the squish band & call it good, the answer to why it makes so much power is not in the quench.

Its in the effective use of the valve circumferecne & maintaining velocity into the chamber - something a 4V head will never achieve as well as nicely set up 2V.

We have a canted valve, high port head with fairly straight intake runners & a chamber that lends itself to good pressure recovery, we have a casting capable of accepting a valve large enough to support the engine at 120% VE & 8000rpm - sounds like a big $$ aftermarket race head to me, just BMW was kind enough to give these heads this potential from the factory.
The high/straight runners work well with higher velocity than a low port could use, which enables better inertia ram filling ABDC, combined with a very nice pressure wave signal & a clear path into the cylinder with the velocity into the chamber clearing the path for more charge & keeping as much charge as possible as close t the piston as possible.

Why hasn't it been done before? - I dunno, maybe because these are not considered a performance engine & no-one has bothered to spend the time & $$ to develop one to it's full potential.