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  #16  
Old 01-17-2010, 06:00 PM
Knappy Drag Racer
 
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Here's that other thread.
M103 3.0 to 3.6 Build Discussion

On the early head the incoming charge is shooting across the valves while on the later head it's shooting down through the valves. Even if the shape isn't as good (I don't know if it is or isn't), the higher placement of said port is what does the trick. If you go back and look at that engineering paper, look at the cutaways of the older and newer M104s you'll see what I'm talking about.

Jay, aren't you routinely revving your C36 to 7,000 RPM?

Bob, could you please post a few shots of the main webbing of both blocks? Post over on that other thread if you want to keep this a head only thread.
Regards, Eric

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89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.

Last edited by 400Eric; 01-17-2010 at 06:07 PM.
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  #17  
Old 01-17-2010, 07:47 PM
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Nah, let's get all the M104 information in here that we can! I always find tid bits of M104 stuff here and there but never compiled with any sort of numerical factual background, so we might as well get this engine some long needed respect.

... Since of course it is, imho, my favorite I6 and one of the best made!.


Now, onto blocks, I'm actually at college right now so I cant snap pics quite yet but here are some notes I've made.

The .98 blocks do not have the mounting tabs for the lower intake that bolts to the block on the later models. The later models also have more ribbing on the exterior of the block. HOWEVER, this comes at a price as all the .94/99 blocks are windowed above all 6 forward main bearings, while on the .98 block it is not webbed on the front main. Also, the .98 block has much thicker webbing in the skirt than the .94/.99 block, which coincidentally also have holes in the webbing that runs between the main bearing saddles and the skirt.


Though on the head design, I think that the valves on the .98 look more shrowded because of how I took the picture. When looked at straight on, the port floor and short radius don't look as pathetic and there also seems to be much more meat to port into. I've done a bit of porting before so this is good. The .94/.99 head looks like a much more refined design, with smoother ports and less casting flashing, but the earlier head looks like it has much more potential on the intake with a little TLC. The exhausts do appear to be identical, though does anyone know how to delete the Air injection ports? I'd love to get rid of them and port out the little mouth/nozzle that is cast into each exhaust port as well.





Onto the topic of cranks, stroker cranks, etc. etc. Here are a few values for you...

Block Deck Height:
217.625mm (I know, it's spastic, but I measured about 20 times to confirm)

Rod/Stroke ratio:

2.8L: 2.02 (That's getting into F1 rod/stroke ratio)
3.0L: 1.80
3.2L: 1.73

350SDL Crank with 2.8 rod: 1.61
same crank with 3/3.2 rod: 1.57

For reference:
BMW 3.2L S54: BxS 87mm x 91mm, rod length 139mm, R/S: 1.52

On Rod/Stroke ratio: From what I've heard from engine builders, 1.75 is considered the ideal rod/stroke ratio for efficiency vs. packaging. Over that increases efficiency but over about 1.85 you're getting into the laws of diminishing returns. F1 cars regularly run over 2.0:1 but we're not spinning our motors at 18k. Anything below 1.5:1 is considered a very short rod and should be avoided if possible. The rods on big cube SBC strokers may dip below that, but you're risking serious rod angles and piston skirt side loading. Short rods also make the bore more prone to deformation at high boost/hp levels should that also be in your list of interests.

Also, after talking to JE, since the rod is piston guided, the width would not necessarily be important on the Big end, provided that the width is less than 28mm, the width of the M103/4/OM60x cranks and the diameter is the same at 48mm (1.998). The rods would have to be machined to a prescribed width at the top and then the piston/rod side to side clearance could be shimmed with steel shims of the correct width. This should be good news as 1st over on the .98 is 89mm which means tons of aftermarket pistons are available from other engines and the rod BE diameter is standard honda B series which means affordable forged rods are also extremely available. And let's be honest, Saving Japanese/Rice parts to be used in these wonderful motors is the most dignified use they could hope for.
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  #18  
Old 01-17-2010, 09:23 PM
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I wanted to say I do not have any pictures of the c36 head. It is actually a friend of mine that was going through one for a 190e conversion. There is actually a lot of room to port out the intake side though. I did when I built my intake and port matched. I opened up the intake side quite a bit. I plan on doing the exhaust next time the head is off. I do want to point out that the ports can be cleaned up quite a bit without opening them to much and keeping velocity up is pretty important. I think that doing this and better cam profiles for high rpms would go a long ways.
I agree that the early blocks are stronger due to the bore size and the blocks have a little less material. But I have not seen anyone find the limits of the block without being reckless. I know of some individuals making in excess of 500whp on turbo 3.4l motors that have very little in modifications to the block.
Also the c36 motor has the pins moved into the oil ring lands for piston height.
This and the cyl. wall thickness are the key failures when boosting the 3.6l.
I wanted to also say that not all m104s are 10:1 compression. Many of the later motors are not. They are 9.2:1. I thought the same for many years. I was looking at my pistons last time my head was off and noticed they were dished. The 2.8l motor I have has flat top pistons as did the .98 3.0l m104.
I went to work and looked up the compression on WIS and found out that most of the later motors were not 10:1 as I thought.
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  #19  
Old 01-17-2010, 09:35 PM
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Very interesting topic!
My M111 runs the 104's 149mm rods with an 88.4 stroke,so has a ratio of 1.68.

Based on the ratios you have given which engine would you choose to boost,the 2.8 for better high rpm or the larger 3.2?

Cheers,
Paul
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  #20  
Old 01-18-2010, 12:14 AM
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Pagz, what's your piston Diameter, do you know? Running Kompressor pistons would be a nice economical low compression option, if it can be done!

Either way, with everything together, in a 2.8 I do not think you could rev it high enough to see the bottom end becoming a factor, given it's built right. The ability of the head to breathe as well as the ability to keep the valves from floating would definitely be the determining factors. That said I'd still go with a 3.2. You still have the numbers on paper to rev them far past anything that a street car would ever see. You will also notice much faster spool and a whole bunch more bottom end to haul you around on the street.

Remember, the big number on the end of the dyno is cool, and I guess if you're street racing it's important, but in any real racing application the area under the curve as well as total torque output are worlds more important!

I was pretty sure that not all M104's were 10:1, though I don't think Mercedes did any numbering designations on the block to denote changes in compression ratio? Anyone care to weigh in on this?

Either way, I've got more .98 parts right now than I do for the other motors, So I'm pretty sure it's that head that I'll be going with for now. I know that both of these heads should flow very well, especially as noted by how relatively mild the cams are for their ability to rev.


Also, I'm not sure that having the oil ring and the piston pin occupying the same space is that bad, SBC guys run boost though this setup in big stroker motors quite a bit and they seem to tolerate it alright, but that side loading with that bore would lead to ovailing quite easily I would imagine which could quickly kill even the strongest blocks.
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  #21  
Old 01-18-2010, 01:37 AM
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Hey,
Original piston diameter is 90.9,but it now runs oe replacement oversized 91.4(mahle)

Hmmm i think 3.2 as well,and yes definitly whats under the curve,i run a smallish turbo for that reason

Interesting about the possible lower compression on 104,what was changed on the M111 to get the 8.8 compression?...if it was the pistons then would they be compatible with the 104?(the engines do look nearly identical apart from the obvious)
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  #22  
Old 01-18-2010, 02:17 AM
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91 are pretty damn big for a 104. That's the same size as the AMG motor. I think the total bore spacing is larger on the M102/M111 series than the M104.

I know pumpish makes a thick HG either 3.0 or 3.5mm to drop the M104 ratio down to solid levels.
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  #23  
Old 01-18-2010, 02:20 AM
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Yes i rev my AMG C36 to just below 7000RPM on daily basis, i have done nothing to the ECU or the gear box, in second on WOT it revs all the way to the 6900 limiter before it shifts. In third its slightly less as it shifts at 6600 if left to its own.

Here are a few pics of the AMG Head. as far as i know this is stock one.











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Jay,
-----------------
-1995 Blue W202 C36 AMG (M) SOLD ;(
-1995 Black W140 S500 (Lady)
-1992 Black W124 E300 (Dima) (Ex-Mosselman
Twin turbo Kit).
-1988 Black W124 300 E 4-Matic.(Nadeen)
-1983 Brown W126 500SEL.(Old Lady)(Sold)
-1981 Gold W123 280CE.(Dareen)(Sold)
http://www.youtube.com/user/jayrasheed
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  #24  
Old 01-18-2010, 02:44 AM
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Quote:
Originally Posted by MAG58 View Post
91 are pretty damn big for a 104. That's the same size as the AMG motor. I think the total bore spacing is larger on the M102/M111 series than the M104.

I know pumpish makes a thick HG either 3.0 or 3.5mm to drop the M104 ratio down to solid levels.
There are also some 2.0L pistons from european models closer in size from the m102 and m111 engines at 9.1 and 9.5 compression.
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  #25  
Old 01-18-2010, 03:53 AM
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I am some what sure that all M104s have CR of 10 bar the M104 AMG36 at 10.5
I have official merc brochures at home covering the 300-24 onwards. Ill check and confirm.
I am also sure that M103 came in 2 CRs, regular 9,2 (9.1) and the one that came on early 4matics and W126s with Cr 10.0 ( the CR was stamped on the Block of the M103.)
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Jay,
-----------------
-1995 Blue W202 C36 AMG (M) SOLD ;(
-1995 Black W140 S500 (Lady)
-1992 Black W124 E300 (Dima) (Ex-Mosselman
Twin turbo Kit).
-1988 Black W124 300 E 4-Matic.(Nadeen)
-1983 Brown W126 500SEL.(Old Lady)(Sold)
-1981 Gold W123 280CE.(Dareen)(Sold)
http://www.youtube.com/user/jayrasheed
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  #26  
Old 01-18-2010, 07:28 AM
Knappy Drag Racer
 
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Nice pictures Jay. Thanks for posting.
Jay, how come the dish on the next piston looks different? Not much of that piston shows in the picture but what does show is clearly different.

Those chambers look unmodified to me which tells me that AMG kept the C.R. in check with that piston dish alone.

There probably isn't anybody here who beats the long rod ratio drum louder than I do. (You can ask GSXR!) Same goes for bore to stroke ratios. But the available room (deck height) in any given block is put to better use by using it for more displacement rather than using it for a better rod ratio. That's why AMG built a C36 instead of a C28. In other words, the ideal bore to stroke ratio and rod length to stroke ratio that the 2.8 has still doesn't enable it to spank a 3.6 which has a fairly poor bore to stroke ratio and rod length to stroke ratio. Even when you throw in the fact that the bigger engine isn't as well "fed", (i.e. the bigger engine doesn't have increased breathing equal to the increased demand created by it's increased displacement), The bigger engine still prevails. Whether we are talking about a 302 Chevy vs. the truly awful 400 Chevy, or a 427 vs. 454 Chevy, or 400 vs. 455 Pontiac, or 360 vs. 401 AMC, or etc., etc. The list is endless, the bigger engine will win the race despite making less power per cubic inch, despite having poorer bore to stroke ratios and poorer rod length to stroke ratios and despite not being as well fed as the smaller engines. Food for thought. (Pun intended.) Also, if you chose to build the smaller engine, to get the same performance out of that engine you have to build it to make it's power in a higher RPM band which leaves you with a "peaky" engine with no low end torque or throttle response which is not a good formula for good fuel economy or good emissions or long engine life since you are always winding the pee out of it to do the same job as the bigger engine with the rotten rod and bore to stroke ratios.

I still say the approach to the valves is much better on the later head. Look at those cross sectional views in that engineering paper. Look at Jay's pictures. Those early heads were compromised by M.B.'s strange desire to mount the CIS fuel distributor above the manifold which caused the manifold to wind up mounted low and the intake ports in the head as well. They wouldn't have spent a ton of money to redesign and retool the head if those retooled heads didn't accomplish a pretty decent gain. They certainly didn't need to raise those ports to improve emissions! They probably did other compromises to meet more stringent emissions and fuel economy requirements and then got most of the power back with the improved head.

Don't be so quick to condemn those windows in the main webs. This is to manage air pumped by the pistons as they fly up and down their bores. This "bay to bay" breathing reduces those pulses by spreading them throughout the crankcase and is beneficial to ring seal and power production. (Remember, there is a windage tray at the bottom of those bores.) Ribs are ribs and are beneficial whether they are outside and/or inside the block.

I don't know my BMWs very well. What years and models are that awful 3.2 in? That's a truly abysmal rod length to stroke ratio. I'm surprised that even BMW would release an engine with that awful of a ratio.
Regards, Eric
__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.

Last edited by 400Eric; 01-18-2010 at 07:57 AM.
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  #27  
Old 01-18-2010, 08:15 AM
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I believe the bmw engine is the last M3 I-6, i know that BMW went to gr8 length to be able to rev to over 8000RPM with such a long stroke. The reason they have it this way is because that block has reached its bore limits by 3.0L and going to 3.2 needed a really long stroke. it seems to them it would be cheaper to use light material pistons and rods than develop a new block (makes sense) cool thing abt this engine is that the long stroke give is good torque band.
but life span of such an engine will always be in doubt.

As for the pic of the engine, its not my engine, a fellow member on another forum and i believe the pistons are the same but only tricked in the pic by shadow and the fact its not on full throw like the first piston.

as for capacity, well u know there is no replacement for displacement , so you agree with me that the 3.6 AMG is a strangled for air engine, I really have no idea why AMG didn’t put better effort in making more power out of this engine. For this u have to respect BMW for their stroke compromised engine of 3.2l makes 343BHP at 7900RPM, and 274LBFT at 4800 I think.
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-1995 Blue W202 C36 AMG (M) SOLD ;(
-1995 Black W140 S500 (Lady)
-1992 Black W124 E300 (Dima) (Ex-Mosselman
Twin turbo Kit).
-1988 Black W124 300 E 4-Matic.(Nadeen)
-1983 Brown W126 500SEL.(Old Lady)(Sold)
-1981 Gold W123 280CE.(Dareen)(Sold)
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  #28  
Old 01-18-2010, 02:18 PM
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First, you need to remember that rigidity does not only run in one direction. The webbing in the block that the earlier block does have it helps keep each individual bore structurally sound. Ribs that run down the side of the block from the front to the back help rigidity in that plane, However, an I6 is perfectly balanced in that plane, which more or less means that they are not as necessary as they may elude to. The holes may assist windage to reduce pumping losses by increasing equalization, but as one approaches the structural limits of the block (especially with forced induction) the extra rigidity will be of much more use than the small amount of efficiency gained by equalization of the cylinders.

Also, the fact that the 3.6L makes more torque at lower RPM but less hp means that the AMG motor is running out of cam on the top end. I think these engines could hugely benefit from a good set of cams.

Has anyone heard about the 3.4L AMG engines based on the .980 engines? It appears that they only made 4 less hp than the 3.6L though at more rpm.
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  #29  
Old 01-18-2010, 04:27 PM
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yes the early 3.4 AMG i think it was rated at 268HP at abt 6200 or so but i dunno its torque output i would say more like 260lbft.
I have driven a W124 with this engine, but it was so long ago so i cant recal what diff it had but it sure was shorter than the 2.87 the 36AMG has.
Its a nice engine but i wish i can remember if it had CIS or EFI.

But guys the 3.6 AMG engine is a sweet one, it really feels like a V8 low down with almost 220lbft at 1500 rpm.
And i bet mine has over 280hp with cats removed and once i have time ill do a dyno run at Bosch.
I know it can make more power top end with better cams, but it still has enough pull all the way to 6500.
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-1995 Blue W202 C36 AMG (M) SOLD ;(
-1995 Black W140 S500 (Lady)
-1992 Black W124 E300 (Dima) (Ex-Mosselman
Twin turbo Kit).
-1988 Black W124 300 E 4-Matic.(Nadeen)
-1983 Brown W126 500SEL.(Old Lady)(Sold)
-1981 Gold W123 280CE.(Dareen)(Sold)
http://www.youtube.com/user/jayrasheed
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  #30  
Old 01-18-2010, 04:45 PM
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Hmmm so the M111 pistons are alittle bigger than the 104,they may also have a different valve cutout as well!.

The B series rods you mentioned earlier with the same BE dimentions,are they also available in a 149mm length?

I have two spare sets of custom JE pistons made for the M111 kompressor sitting on my desk they just need machining with spacers to suit the rods used.(but would need a new block if i wanted to use them).

Back on track with the breath topic,based on what BMW has achieved the C36 should make much more power and the head looks to be where its at,and if i ever swap out my 4 i think the 3.6 with headers,intake plenum,cams,manual trans and new ECU would be where i'd take it...no turbo!!

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