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Turbo time for the C250TD

13K views 13 replies 5 participants last post by  Richard112 
#1 ·
Holy crap, I didn't know it was going to turn out this way :cool: . It took a while to complete, but this little five-cylinder is packing some punch with the new Holset. In short, I ditched the stock Garrett GT25C for a Holset HE221W, together with some other goodies.

Some before photos:











Right, so where to start. Initially I thought I was very clever by designing a very compact flange adapter for the Holset to mount to my exhaust manifold. My eyeball measurements indicated that the Holset wasn't much wider than the stock Garrett, so I thought there would be enough clearance for the Holset to mount where the Garrett was. The Holset fitted, but it was jammed against the steering box and there was no free space for the waste gate actuator to move.









I had to resort to a similar solution to Charlie using 50 mm diameter short-radius buttweld fittings. Furthermore, I designed my own turbine cover by scanning the turbine housing to my PC and tracing it to scale in AutoCAD. I then had it laser cut and machined. After test fitting the turbo to the flange adapter, I trial fitted a downpipe to tie in with my existing exhaust's downpipe flange. I didn't have to cut any part of my stock exhaust system. I also used 50 mm diameter buttweld fittings for the downpipe. I realised only after having the turbine cover and downpipe fabricated that the downpipe may be too narrow. However, so far it doesn't appear to be too restrictive.








This is the scanned image of the turbine housing I used for the turbine cover :D . I'm not kidding when I say that my laser cut housing has less than a millimeter of deviation to the turbine housing.














I ported the manifold's standard 40 mm-odd opening to 50 mm using my (slightly overused) Dremel tool. I also had the EGR opening welded shut.









Exhaust manifold and flange adapter fitted:







Oil return drain pipe fitted:




Oil feed line fitted with P-clamps to hold it in place:





 
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#2 ·
I didn't my intercooler plumbing to be the oily mess that the stock system was. I almost bought a cheap Chinese oil catch can, but happened to come upon the Provent 200 oil catch can system (made by Mann Filters in Germany). A local guy imported one from Australia for his C250TD, but sold the car before fitting it. I wanted the setup to be as stealth as possible - and I think I succeeded :cool: .










Although fitting my intercooler was fairly straight-forward, getting the plumbing right was not. The stock radiator cradle was in the way of fitting the 2.5" intercooler piping. This required me to have a custom radiator cradle fabricated. However, this new cradle had to be fitted to my car's front cross-member. It seems my car had been in a small bumper bashing in its previous life, which had left the cross-member rather badly bent in the area where I wanted to mount the new radiator cradle. Not wanting to deal with misalignments, I had a moment of insanity and went about to carefully grind off all the spot-welds that hold the cross-member in place (it is not bolted on like more modern cars). I managed to source a brand new OEM cross-member for very cheap from Germany. Instead of welding the new cross-member in place, it is now bolted on with 24 Grade 8.8 bolts and nuts. It's not going anywhere :D .

After having removed the cross-member:




The new radiator cradle:






Brackets for the intercooler that I had cut and bent (I couldn't fit bottom brackets, but the intercooler is very well supported):










The one thing I'm not extremely proud of, is my labyrinth of intercooler piping - it is extremely complex, with endless bends :-/ . However, all bends are very smooth radius stainless steel (except for the ones going into and coming out of the intercooler). Hot side is 50 mm diameter 1.5 mm thick stainless steel, cold side 63 mm 1.5 mm thick stainless steel. I test fitted all the pipes by using an epoxy adhesive. I then marked each joining pipe, after which I broke everything apart and had them properly welded.













Another issue was engine cooling. I decided to remove my non-functioning viscous fan and in its place bought a 17" Tripac two-speed fan. This fan also replaces the two brushless auxiliary fans where the new intercooler is mounted. However, this brushed fan does not like the soft-start and variable voltage of the fan controller. So, I'm going to keep the fan controller plugged in, but have the fan connected to a W124 two-speed fan switch as well as a W124 a/c pressure switch. These I still need to connect with three normal SPDT relays. It's not very high-tech, but I reckon it'll do the job.






My Chinese boost controller, which I'm still to connect (currently running on the stock Holset waste gate pressure).




And the end-product, taken tonight after some driving in the rain:




I installed the Stage 2 map of Seanyt tonight, with about 1.2 bar boost at the intake manifold (I'm going to install a replica Defi Advance ZD gauge this weekend - it did indicate 1.2 bar intake manifold pressure after quickly hooking it up). I'm going to crank the boost up to about 1.6 bar and see how things turn out.

At this stage, however, all I can say is this: WOW!
 
#14 ·
I didn't my intercooler plumbing to be the oily mess that the stock system was. I almost bought a cheap Chinese oil catch can, but happened to come upon the Provent 200 oil catch can system (made by Mann Filters in Germany). A local guy imported one from Australia for his C250TD, but sold the car before fitting it. I wanted the setup to be as stealth as possible - and I think I succeeded :cool: .










Although fitting my intercooler was fairly straight-forward, getting the plumbing right was not. The stock radiator cradle was in the way of fitting the 2.5" intercooler piping. This required me to have a custom radiator cradle fabricated. However, this new cradle had to be fitted to my car's front cross-member. It seems my car had been in a small bumper bashing in its previous life, which had left the cross-member rather badly bent in the area where I wanted to mount the new radiator cradle. Not wanting to deal with misalignments, I had a moment of insanity and went about to carefully grind off all the spot-welds that hold the cross-member in place (it is not bolted on like more modern cars). I managed to source a brand new OEM cross-member for very cheap from Germany. Instead of welding the new cross-member in place, it is now bolted on with 24 Grade 8.8 bolts and nuts. It's not going anywhere :D .

After having removed the cross-member:




The new radiator cradle:






Brackets for the intercooler that I had cut and bent (I couldn't fit bottom brackets, but the intercooler is very well supported):










The one thing I'm not extremely proud of, is my labyrinth of intercooler piping - it is extremely complex, with endless bends :-/ . However, all bends are very smooth radius stainless steel (except for the ones going into and coming out of the intercooler). Hot side is 50 mm diameter 1.5 mm thick stainless steel, cold side 63 mm 1.5 mm thick stainless steel. I test fitted all the pipes by using an epoxy adhesive. I then marked each joining pipe, after which I broke everything apart and had them properly welded.













Another issue was engine cooling. I decided to remove my non-functioning viscous fan and in its place bought a 17" Tripac two-speed fan. This fan also replaces the two brushless auxiliary fans where the new intercooler is mounted. However, this brushed fan does not like the soft-start and variable voltage of the fan controller. So, I'm going to keep the fan controller plugged in, but have the fan connected to a W124 two-speed fan switch as well as a W124 a/c pressure switch. These I still need to connect with three normal SPDT relays. It's not very high-tech, but I reckon it'll do the job.






My Chinese boost controller, which I'm still to connect (currently running on the stock Holset waste gate pressure).




And the end-product, taken tonight after some driving in the rain:




I installed the Stage 2 map of Seanyt tonight, with about 1.2 bar boost at the intake manifold (I'm going to install a replica Defi Advance ZD gauge this weekend - it did indicate 1.2 bar intake manifold pressure after quickly hooking it up). I'm going to crank the boost up to about 1.6 bar and see how things turn out.

At this stage, however, all I can say is this: WOW!
Hi, I put the same turbo on my OM602 and I am getting oil in the intake. The oil pressure is too high but flow rate is below holset guidelines. Did you use a restrictor in the oil feed and what size of oil return line?
 
#5 ·
That looks fantastic! Can I just say one thing: you should fabricate an airbox for the air intake filter (or modify the stock one), and pipe in the air directly from outside. When the engine bay will get hot, you will be sucking in hot air, which is not good for power. I see this often on custom made intakes, where the air filter sucks in all that nasty hot air, you need cool air for max performance, and the coolest air will be from outside the engine bay!

If you'd want to fabricate such an airbox, there does seem to be enough room there to fit one (you could always cut the pipe a little bit shorter so the filter doesn't rest so close to the fender), you could use the factory intake piping (the part that's right beside the radiator) and feed it into your airbox, just make sure it doesn't have the air restrictor in place (my C220 had this, removed it, it didn't increase intake noise, and the engine seems happier in the top most RPM range).
 
#7 ·
Don't get me wrong, I'm not criticizing your work, I'm actually very impressed :D You've put a great deal of effort into this, and it's awesome to see a powerful diesel W202 (The stock diesels were pretty slow). However, I see free power and a happy engine if you make an airbox for that filter :D

It just see these open filters often in tuner cars, and people try to convince me that it's a cold air intake, and when I ask them why is it sucking in all the hot air around the engine bay, they give me the blank stare as if I just proved that their god doesn't exist or something.

Anyway, I just noticed, you put in a new front bumper support, I see the new mercedes sticker on it :D How much did it cost?
 
#8 ·
Thanks, Patman. Believe me, the K&N filter wasn't part of my initial plans. I wanted to mount the Holset where the original turbo was and use my stock airbox (I even bought a new air filter in December, which is now just laying inside its box) and only slightly modify the plumbing from the airbox to the turbo inlet. Unfortunately that plan had to be thrown out when I couldn't get the Holset to fit.

Space is rather limited at the moment. The pipes coming out of the turbo going to the intercooler occupy a lot of space. I did reinstall the original air-duct going to the stock air-box. Although it doesn't feed air directly to the air filter, I think it does help to get some cool air into the engine compartment. Obviously it's of no use when crawling along, but I do think it helps slightly. I must admit that the metal piping (previously plastic) is very hot to the touch after some extensive driving.

I see I have a slight oil leak coming from the turbo's oil return :rolleyes: .

Here's a quick test run I did (I still want to slightly up the boost; transmission was kept in Drive for the run). I know, I have a rear bulb that's out and I still need to have my airbags reset :) .

 
#10 ·
Also, am I seeing that right? -38 degrees outside? Sure your sensor isn't a little broken there? :D
It's summer in South Africa.

I guess he's never getting that fixed. But it doesn't really matter, since the weather here is quite simple: If it's not raining, it's hot...
 
#12 ·
As am I. But there is an endless conflict between my desire to fix what's broken, and my ability (and desire) to pay for it...
 
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