M104 Cylinder Head differences... - Page 10 - PeachParts Mercedes-Benz Forum

Joreto · #**136** 02-26-2010, 03:38 PM

This might be a little off topic, but anyone know how much the stock m103 head flows ?

MAG58 · #**137** 02-26-2010, 04:08 PM

It's about 240@28'' iirc on the intake. I have no idea about the exhaust.

Joreto · #**138** 02-26-2010, 04:20 PM

Quote:

Originally Posted by MAG58

It's about 240@28'' iirc on the intake. I have no idea about the exhaust.

Thanks

kynsi · #**139** 02-27-2010, 04:31 AM

Quote:

Originally Posted by MAG58

It's about 240@28'' iirc on the intake. I have no idea about the exhaust.

and my M104 only 218cfm 28"

Is M103 better?

Joreto · #**140** 02-27-2010, 05:25 AM

Interesting, personally I find it hard to believe that the 12v head flows more than the 24v head, are you sure those flow figures are correct ?

400Eric · #**141** 02-27-2010, 05:34 AM

To really do this right all the heads in question need to be flowed by the same operator on the same flow bench.
Regards, Eric

MAG58 · #**142** 02-27-2010, 11:50 AM

As of right now, yes, the 103 flows the same. But Eric's right, they need to be tested on the same bench. But that said, I have a really hard time believing that at 500 thou the 104 head is only flowing 218. I actually cant think of many 4 valve heads that flow that poorly.

JayRash · #**143** 02-27-2010, 12:16 PM

Bob
I know the M103 has a fine head but i really doubt the 24v head flows just the same. I mean the M104 3.0 makes 230 hp with efi in the W140 so it must be down to the head flowing better.
For sure the oil pan design and the less friction internals help and the cams, but a jump from 188hp tp 230 hp is no easy work.

MAG58 · #**144** 02-27-2010, 12:27 PM

Agreed. Taking friction reducing measures in the bottom end may be good for 5ish hp tops, but that is negated with the drag of an extra cam and 12 more valves. I don't think the lift profiles on the M103 are bigger, actually the rocker arms will most likely give more gross lift on the 103, but I know for a fact the net curtain area on the 104 is much greater than the 103...

Hmm...

Edit: A stock S14 (E30M3) head I just read to flow under 200 @25''. We al know that the S14/S38 head design is fantastic to say the least. I just don't get it though, I know flow isn't everything, but gross flow numbers can out do good engineering when the flow is 150% greater...

I'm bewildered. And still cant find a good head guy around here.

JayRash · #**145** 02-27-2010, 12:40 PM

IIRC the M103 lift is abt 9.8mm max, this is what i can recall and i can be wrong here.
Anyway i am sure the M104 heads should have more flow, go back to the german PDF and ull find that the M104 3.0 makes just abt the same low down torque as the M103 3.0 despite the cam advance, which usually should increase low pull. The head shows better power above 4500rpm which is where the the M103 drops, so we can see here that the 24v head must be causing lower air speeds at low rpms and good speed at high rpms, this is usually the case that happens when a head has better flow capacity.

And again its safe to say that the new 24v head must be better than the old, atleast as that flow test shows.

400Eric · #**146** 02-28-2010, 06:52 AM

I'm sure both of the 24 valve heads out flow the 12 valve head.

But by the same token, we shouldn't discount the benefits of the other improvements made to the M104. For example, on the 340 V-8 Dart in 1968 a windage tray was proven to be worth 15 horsepower on said engine at 5,000 RPM. How much more would it be worth on a longer 6 cylinder crankshaft at 6,000 RPM? I'm sure it was more than 15 horsepower but for this discussion, we'll be conservative and stay with 15. So there's 15 horses just from the windage tray that the M104 had and the M103 didn't have.

Also the 1 point rise in compression ratio is worth a 4% gain (an accepted rule of thumb) in power. We'll only allow 3% to be extra fair which equals another 5 horses for a very conservative total of 20. That's 20 of the 50 that the M104 had over the M103. Food for thought.

Guy's, here's a site to make your heads explode: http://users.erols.com/srweiss/tablehdc.htm
Regards, Eric

JayRash · #**147** 02-28-2010, 07:36 AM

true Eric,
i have a rule of thumb of my own, a good multi valve head is usually abt 40HP over same setup with a 2 valve head.

Its true for the M102 2.3 8v VS 2.3 16V
M103 3.0 Vs M104 3.0
M117 5.6 Vs M117 5.6 32V AMG

kynsi · #**148** 02-28-2010, 09:10 AM

Slow down people...

CFM at full lift, and horsepower from complete engine is different things.

I was only wondering M103 flow capacity at full lift compare M104 at full lift.

2 and 4 valve systems total flow is very different (even thou full lift was same) , because 4 valve flows so much better in part lift. And that is were most of power comes.

Bu the way, M104 head seem very close to toyota 2jzgte supra head flow figures.