Supercharge M104.980 - Page 3 - PeachParts Mercedes-Benz Forum

Rital24 · #31 04-11-2019, 05:39 PM

Last week The car was on Dyno for the first time in its 30 years of life!
Never say never...

The verdict is 340 hp, 40 Kg/m at 6000rpm

I'm very happy for the result.

The engine is the original M104980, no reducing in compression ratio, original CIS controlled by Frankencis System, Microsquirt for the management.
Original is also the exhaust system and 722.5 tranny.
With Dyno operator we have notice that the limit of Cis has been reached.
At full open throttle AFR don't go down 13.5.
Up to 0,5 bar AFR stay around 11,5/12 without problems.
Anyway I need some more fuel flow, at the moment I don't have fuel pressure sensor but I'm planning to mount it shortly in such a way as to understand what happens in the fuel plant.
On my Rotrex C30/94 is mounted a 90 mm pulley with wich I've 0,75 bar of boost, I've also a 95mm that I could use until I find a solution for fuel delivery.
The Frankencis guys told me to try with a V8 fuel distributor...

I use NGK BCPR6ES but I suppose that more colder sparkplugs would be better.

Rital24 · #32 05-31-2019, 05:45 PM

Hello guys!
Could please someone explain this:
For a few days now from my blowoff valve I see oil vapors coming out. That happens clearly at idle when the valve is open.
I'm sure it isn't coming from the supercharger because its oil is blue.
Besides I don't think it is a blowby situation for the reason that I've connected the breathe system pipes to the inlet of the compressor but with a canister in which I found only trace of oil.
My idea is to replace the valve stem seal but I'm not sure I can solve the problem this way.

sm. pelle · #33 06-13-2019, 03:16 AM

I use NGK BP7EFS, compeared with sock ones resolved some sputtering issues under load.
With hot engine some vapors at idle, i wouldnt worry.

Rital24 · #34 06-13-2019, 03:31 PM

Quote:

Originally Posted by sm. pelle

I use NGK BP7EFS, compeared with sock ones resolved some sputtering issues under load.
With hot engine some vapors at idle, i wouldnt worry.

Unfortunatly I have too many vapors coming out from the hood at idle and also some white smoke from exhaust.
The mistake is that there is no oil in the oil catch can and the air pipes and intercooler are almost dry.
This may be due to the fact that I made few miles since the problem arose.
The spark plugs are all black equally and I think it is oil burned inasmuch engine don't works rich and the carburetion was perfect.

Rital24 · #35 07-02-2019, 02:04 PM

At the end I removed the head and found this!

I believe this happened because of air bubble in the cooling system, I drived for a while at too high temperature...

But now I want to solve rapidly this misadventure!

I' ve a complete M104981 ready to be mounted.

I should mount the complete engine in my garage and don't have a hoist!

Considering this could please someone help me by telling me if Is better to leave the trasmission at its place or removing all together?

If don't removing the trasmission I need to drain the oil or it remain inside when decoupling it from the engine?

Thank You

97 SL320 · #36 07-02-2019, 08:00 PM

Quote:

Originally Posted by Rital24

At the end I removed the head and found this!

I believe this happened because of air bubble in the cooling system, I drived for a while at too high temperature...

Not air bubble , might be piston ring end gap too small.

Everything You Need to Know About Ring Gap!

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

Might also be a lean condition.

SpartanV · #37 07-04-2019, 03:44 PM

You can leave the transmission attached to the motor when pulling them both out.

Though I'm not sure how you can pull the motor out without the head attached and the front and rear lifting brackets bolted to the head...

Good luck with the repair and I will be following this thread!

Rital24 · #38 07-04-2019, 07:34 PM

Thank You 97 320SL !

Yes it's probably like You say.
The engine has over 300000 KM with original pistons and rings!

Thank You also SPARTANV!

I thought I would only remove the motor since I didn't have an hoist but it seems there are the 2 upper bolts very difficult to remove.
Therefore I'm going to remove also the trasmission..

ps I will sent to You the bracket design in these days, even better I would share on this forum the file.
(We are talking about my bracket for Rotrex C30 94 if someone else wanted to try their hand in supercharching M104980/1.)

SpartanV · #39 07-06-2019, 03:48 PM

Yes it is quite the pain to remove those upper bolts, you need a combination of very long extensions or wobble extensions and the motor has to be lifted or jacked up slightly with the motor mounts unbolted from the lower body holes. It can be done but putting the engine back into the car and aligning the transmission to the motor is the most difficult part and nearly impossible if doing it by yourself.
Pulling the motor with the transmission is much easier if you have an engine crane or cherry picker.

Good luck and awaiting that email 🙏

Rital24 · #40 07-24-2019, 08:30 AM

This is how I pulled out engine and trasmission without head.

Rital24 · #41 07-24-2019, 08:45 AM

...and here What I found.

The fifth piston is broken, the cylinders wear is max 0,1 mm, ovalization is 0,05mm to 0,1 mm.
Now I could polish the cylinders changing only one pistons and all the rings or rebore all the cylinders and buy new forged custom pistons with rings.
So I could also reduce compression ratio.
I'm searching where to buy a complete set of pistons at reasonable price in US.
Have any of you already done it?
I thought to CP pistons, some advice?

oldsinner111 · #42 07-24-2019, 09:52 AM

turbo bandit uses stock pistons to 600hp,then adds forged rods to over 1200hp.

Rital24 · #43 07-25-2019, 08:06 AM

Thank You oldsinner,
Yes I know what turbobandit does with those engine though I think his numbers are a little exaggerated..
If my engine wear is out of tolerance I need to buy 6 new pistons 1 size bigger, 89mm in my case.
With a little more I could buy custom pistons with the possibility to reduce compression ratio.
I'm emailing with some Carrillo distributers in California.
If someone here has done the same job is possible that they have in the database all the dimension they need to build a set of pistons for the m104980.

oldsinner111 · #44 07-25-2019, 10:25 AM

no they sell good kit for $30,000 usd. you have to ship car to them

oldsinner111 · #45 07-25-2019, 10:31 AM

I'm thinking w126, and m104 motors are malhe pistons.My son is a engineer there, at tennessee plant. They do offer custom sizes.some people use a compound head gasket to lower compression,plus they are better than stock ones.
Since most things will be electric soon,son willl move to Denso,in my area also.