Valve spring upgrades for M104 - PeachParts Mercedes-Benz Forum

Mighty190 · #1 11-13-2019, 09:51 AM

I'm looking at trying to spin a 3.6 AMG M104 up to 7k with about 15lbs of boost. What are people's experiences with valve springs in these engines? I can't find much info on the stock ones and although I can "measure" them myself I don't trust the rate I'll find abd I don't know if I should be concerned about fatigue etc

Mighty190 · #2 11-13-2019, 10:01 AM

Looks like I have answered my own question. Turbo bandit sells springs intended for their turbo builds.

whipplem104 · #3 11-13-2019, 10:09 PM

You will be fine at 7k at 15lb of boost. Actually the only thing you really need to be concerned with is exh. back pressure on boost. The spring rate is pretty high on the m104. I do not remember the number but I checked a bunch out a few years ago when doing a diesel and they were about as high as we did with 40-50 psi of boost. But that was with a good a/r as well.
You will find you have a lot more trouble keeping the headgasket in place and the cylinder walls from cracking on the 3.6.

Mighty190 · #4 11-15-2019, 12:27 PM

Ok thank you. Do you know if the valve springs are the same or similar between the standard M104 and the AMG?

MAG58 · #5 11-16-2019, 08:59 PM

If you go by the EPC, Non AMG and AMG M104's have the same Part # for the valve springs, they just mill the head down a little on the intake side for the extra lift of the camshaft. Depending on which year M104 you have if you want heavier springs but are running stock cams just go to an earlier M104 setup. Before they had conical springs they were running dual valve springs in an early M104. If you get a CIS or LH head, they should all be dual valve springs and will live just fine well north of 7000.

Mighty190 · #6 11-19-2019, 04:21 PM

Ok thank you for the information!