M104 AMG CYL head porting. - PeachParts Mercedes-Benz Forum

JayRash · #1 06-06-2012, 01:30 PM

the head is out of the car yet again for another gasket job, this time the whole block is out too for a complete head and block resurfacing.

Pls advise would i gain from porting the intake runneres while leaving the valves at stock size?

my miller claims gains will be minimal and not worth the trouble. what whould u guys suggest?

JayRash · #2 06-06-2012, 02:26 PM

for the record in an attempt to reduce any further risk with blown head gaskets i have done the following.

i am making a custom copper headgasket thats laser cut of the same thickness as the oem gasket.

i had copper wire inserted into the water gap between the cyl bores. those familiar with the m104 design will know that between the bores we have a thin gap that the gasket covers. i closed off this gap while leaving the adjacent water holes open.

whipplem104 · #3 06-06-2012, 05:11 PM

I doubt you would see much gain on a n/a motor. The intake side is pretty good. Maybe a little clean up on it. The exhaust if the bowls are not worked from the standard m104 head has room for improvement. I know that AMG worked the exhaust side but what they did I do not know. Even the standard head would be minimal on a n/a engine. 7% gain is what I was told. Just the bowls though. The ports should be left alone for the most part except some cleaning.

JayRash · #4 06-06-2012, 06:37 PM

Thanks. Good to know. The exhaust side is worked half way thru by Amg. It's polished and it shows. Intake is not touched.

Pagz · #5 06-06-2012, 07:07 PM

Hi Jay,

Interested in how your gasket mods work out,please post pics of the now blocked water ways!
Does the difference in head gasket compression need to be factored in? any changes in head bolts needed?

Cheers!,Paul

Chlippo · #6 06-06-2012, 10:33 PM

Quote:

Originally Posted by Pagz

Hi Jay,

Interested in how your gasket mods work out,please post pics of the now blocked water ways!
Does the difference in head gasket compression need to be factored in? any changes in head bolts needed?

Cheers!,Paul

I think the head will be cleaned (milled) just a little bit (very little in fact) and the change is minimal so the compression wont change. Bolts would stay the same as well.

400Eric · #7 06-07-2012, 02:26 AM

According to David Vizard's "How To Build Horsepower" book, there is some gain to be had from sharpening the divider in the middle of the intake port, where the port divides into two parts heading to the two valves. Just sharpen the divider, don't reduce or shorten it. That and lightly clean up the bowls.

I would also switch those head bolts to studs too to improve clamping force.
Regards, Eric

MAG58 · #8 06-07-2012, 02:38 AM

Quote:

Originally Posted by 400Eric

I would also switch those head bolts to studs too to improve clamping force.
Regards, Eric

I'm always interested in these people obsessed with head studs. I've never actually seen one of the TTY bolts fail in any situation where forced induction isn't part of the deal. Seems largely like an engineering masturbatory exercise, but do what you want.

And you wont gain much porting the later style head. Like Eric said, light bowl work and a little more port matching on the exhaust is the best you can hope for. You're more hindered by teeny cams that poor flow. The CIS head on the other hand benefits more from porting, which is why the AMG 3.4's had both sides ported.

400Eric · #9 06-07-2012, 03:28 AM

I'm hardly "obsessed" with headstuds.

True, TTY bolts may not "fail" very often but they do sometimes slacken their hold over time. Studs would be an improvement. And not just from a consistently stronger point of view, but also in the way they load the block. True this may not be a forced induction application, but it is still a highly stressed one because of the massive overbore performed by AMG, leaving the block wafer thin. Clearly, the present headbolts have not been working out very well, why not go for that extra little bit of protection while the engine is apart? I'm one of the cheapest guys around here, and even I would perform this upgrade in this case.
Regards, Eric

MAG58 · #10 06-07-2012, 02:25 PM

I'm not saying you are head stud obsessed, but I feel between all the MB forums I frequent you cant make it 20 posts into a thread without some long diatribe on head studs. Though I was wrong, the fact that MB specs re-use up to a certain length means they're not true TTY, but instead just tightened to a certain amount of stretch. TIL...

TBH I do not think that studs will increase his rigidity where it counts, between the cylinder walls. Studs do not increase the individual rigidity of the cylinder wall, they just allow for more precise clamping to be provided. There are no off the counter designs for the M104 head stud (as bahaimus found out with the ARP rep), only M30 bolts which come close-ish-sortof. I have no idea where his HG keeps failing so I have no way to determine if it's head bolt related. But his current approach, to replace the composite HG (The actual faulty part) and sealing the steam cuts (the location of the block instability), seems like a very logical approach.

After geting my hands on a C36 engine of my own

, I can say that outside of the steam cuts, the block isn't as wafer thin as I've always been lead to believe (sheeple moment for myself). The issue at hand is being corrected. The only dilemma I could see would be the copper in the steam cuts having a different thermal expansion rate than the Steel (I have no idea if it does). If the expansion rate is enough greater, it could cause cylinder walls to deform which would smoke another HG.

JayRash · #11 06-07-2012, 03:48 PM

The oem head bolts can be torqued to abt 110nm while standard arp ones go up to 145 nm. I don't think head tension is the issue but rather the difference between the head material and block and their related heat expansion rates.

As for the copper inserts well if they r to expand and they will, they can expand downwards and left and right as they r not restricted in those directions. I doubt they will deform the cyl sides.

Unfortunately I will not be using a copper hg as it needs a min of one week to be made and I can't afford waiting that long.

I do believe the true problem with my Amg is that there might be knock going on in the engine although the pistons and side walls don't show any signs at all.
I always use the highest octane fuel on offer which is 98 in my money or 93 in ur money in the USA.

Any way I'll take pics of the final result before assembly.

JayRash · #12 06-07-2012, 03:49 PM

The own head bolts can be torqued to abt 110nm while standard arp ones go up to 145 nm. I don't think head tension is the issue but rather the difference between the head material and block and their related heat expansion rates.

As for the copper inserts well if they r to expand and they will, they can expand downwards and left and right as they r not restricted in those directions. I doubt they will deform the cyl sides.

Unfortunately I will not be using a copper hg as it needs a min of one week to be made and I can't afford waiting that long.

I do believe the true problem with my Amg is that there might be knock going on in the engine although the pistons and side walls don't show any signs at all.
I always use the highest octane fuel on offer which is 98 in my money or 93 in ur money in the USA.

Any way I'll take pics of the final result before assembly.

Pagz · #13 06-07-2012, 05:30 PM

Damn! was looking forward to seeing how the copper would turn out =)

I know of at least two others who have replaced there 36 HG twice each in there ownership,does this happen to all M104's or just the 36?

MAG58 · #14 06-07-2012, 05:55 PM

All 104's get leaky HG's at the right front corner where the block, head, and front covers meet. That's usually the reason for replacement. 36's like to actually blow them more so than your average 104.

JayRash · #15 06-07-2012, 07:02 PM

The 36 is known for blowing it's hg. Other m104s leak on the side when the hg rots out of age and different thermal expansion rates of head and block. But it lives long enough not to be a real issue. And at usd60 for a regular m104 hg the cost is not a big deal.
But the Amg one is usd 230 at a special rate for me. And that is an issue. The hg I removed off of my car looks brand new. It just decided to leak between cyl 2-3 and cyl 4-5.

I don't expect the new one to last more than a couple of years even with the resurfacing of both block and head and the copper inserts ( if they even manage to help at all).