Good thinking, I’m more used-to seeing the ball type one way valves.

Update?

Nothing yet unfortunately, work asked if I would stay longer in exchange for some favors so I took the offer. Looks like I’ll be home the beginning of March

I’ve had some time to work on the car, it’s nearing completion. Lots of little things, running vacuum lines, wiring, switches, making sure everything is prepared for heat if it is next to exhaust manifolds etc

in the process ive run into some ****ty welds/exhaust leaks from a previous welding job I had done by a muffler shop years ago. So I will have to take some extra time with the exhaust to get everything up to par

Speaking of which, I ordered a set of relays/fuse with a “box” to house them in. I also picked up a 4 switch rocker panel, with usb and voltmeter readings from amazon for a good price. These will be mounted in the center console for turning on the oil pump, the boost gauges, my amplifier for my subwoofers, and maybe some led lights for the trunk?

some would say to just wire these devices to an accessory 12v power source, but with the W215 being quite electronically laden, the less devices trying to start when the starter is cranking, the better. And I like having seperate control of things like the oil pump for changing turbo oil, or the amplifier for times I may not want the extra bass for example.

pics below of some of the amazon gadgetry. This thing feels like my own little SAM lol...
https://cimg1.ibsrv.net/gimg/www.mbw...27a4c8bb26.png

https://cimg5.ibsrv.net/gimg/www.mbw...244cc992d9.png

The sizing of the switch panel is great for the center console of the w215

i’ve test fittted the turbo, with all the oil lines etc and luckily everything fits. I’ll likely be able to retain my subwoofer placement (2x12”) and when finished I’ll even be able to get a spare tire in the trunk. However there is quite a bit of work to be done with the trunk now that I have cut out the entire flooring of the trunk. I’ve also removed the OEM mufflers to make more space for everything

ln the meantime I’ve ordered an aluminum rear diffuser and some of the classic, semi period-correct amg quad exhaust tips so the car will again have exhaust tips. However these tips will likely be entirely for show, I doubt I will have any real exhaust routed to these tips.

Instead I plan on exiting the turbo exhaust under the car, very near to the rear bumper and sort of built into the rear diffuser with a 3” or 4” exhaust. Having such a short exhaust , being a rear mounted turbo should make some awesome turbo noises.

im also in the process of quality testing some of the eBay components like the blowoff valve and wastegate. As you can find ad nauseum online, the eBay stuff isn’t bad if you plan on taking your time to thoroughly inspect and rebuild the parts with threadlocker, proper torque specs, and most of all cleaning the parts for any metal shavings/slag, etc

Monday I am leaving for Ohio, this time for my significant others new job training/orientation. I am getting quite sick of traveling. This will make about 10 weeks I’ve been away from home in the last 4 months or so. All the while dragging out this project from being completed. But soon enough it seems, soon enough

i think I underestimated my original figures, I think this setup should yield closer to 500-550hp but more importantly this thing should be a torque monster

ive considered in the future maybe trying e85 fuel to safely run more boost pressure for more horsepower. From what I understand the m113 n/a ecu (Bosch 2.8) will only get you going up to about 550hp. I am not terribly interested in doing a standalone or piggy back setup, so retaining the stock ecu for as long as possible is one of my goals

E85 should only be necessary after 800hp or so. If you do that, you've got to upgrade fuel lines, injectors, and most likely a new ECU for the power levels to make E85 worthwhile.

Today I was able to let the car idle with the turbo mounted and most of the exhaust finished. The oiling system is also in place with no leaks. I still have some spots to repair in the exhaust from previous exhaust work from a local shop, then I have my own welding around the turbo flange to touch up.

the fabrication side of this project is taking the most time I believe. Mostly because I am working with very basic tools, a cheap flux core welder and a $15 grinder. I’m also trying to re-use as much as I can from the old exhaust, if I had a large selection of flanges, pipe sizing, odds and ends, this would go faster. Plus the learning curve with proper weld penetration/strength, whilst using basic equipment is not ideal for time constraints. I am often running two or three passes to ensure strong welds, where a more experience welder may run one bead

and ultimately the car will see a new exhaust system someday, I am tired of the “bits and pieces” from old exhaust shop work, and my current work as well. The car deserves a proper system with ideal solutions for optimum exhaust velocity, etc. I’d like to make some headers some day as well, despite the fact headers are tested to not provide much benefit in turbocharged applications

One annoying hold up is despite using the Mb parts catalog to order a replacement exhaust flange gasket (graphite), somehow the gasket listed for my car does not actually fit. It’s too small so I ordered a new one based off of physical dimensions rather than trusting the parts catalog. Who knows maybe the cl500 sport models came with slightly larger exhaust??

another thing I am sorting is that the car idles lean. I unplugged the airflow meter and the car runs great around 14.7 afr again. This tells me I need to diagnose the airflow sensor or figure out why my voltage clamp system isn’t working as intended. One of the overall goals was to not have drivability too far affected if the car was driven off boost

nonetheless. The project is well underway,

Here’s a video of the car last week running off boost(no charge piping yet) with some turbo spool noises. In this video the car still had a few exhaust leaks as well as a missing exhaust gasket I will mention later


the “prototype” is nearly complete, right now I am just troubleshooting mostly.

I replaced the exhaust gasket that disintegrated, luckily we had one in stock at work while I had some free time. We are pretty slow right now with the Covid19 stuff going on so I’ve had a good amount of time to work on the car. The exhaust is now much more controlled and even quiet sounding, however with the exhaust all repaired there is a bit more “droning” noise inside the cabin, I like the noise but the typical Mercedes Benz enthusiast may find it disruptive. It’s about 5x quieter than the exhaust when I had straight pipes n/a, for reference

the car surprisingly has a lot of power even though the 5.5 liters is being forced through 2.35” exhaust piping after the oem x-pipe. It seems these really engines like the “back pressure”.

since this video I’ve installed the blow off valve. The charge piping. The fuel regulator, etc

I’m still chasing down a MAF issue, the car gives a p0100 code over and over again and doesn’t go away, ( i have not hooked it up to star diagnostic machine yet, I am only using my cheap obd2 scanner at home since it usually gets me in the right direction 95% of the time)

at first I believed this was a bad MaF sensor, so I tried another maf sensor I have. The old sensor also soon gave the same p0100 code. I checked and rechecked my wiring with my variable resistor I installed across the maf signal wire... however the p0100 remains. Today I am going to try a simple 330ohm resistor instead of the potentiometer setup. I have more resistors coming in the mail but right now I have some 330ohm ones lying around

overall the car seems to run better with the maf unplugged, luckily my maf was ordered through fcpeuro so hopefully the warranty exchange goes smoothly

Regarding the resistor, kleemann recommends a 550ohm resistor for their supercharger setup that runs around 7.5 or so psi, I read a mbworld thread about a kleemann g55 install where the resistor was missing from the package and kleemann suggested using a 550ohm resistor because the variable resistors are known to have problems

besides the p0100 code issue, I am seemingly having trouble building boost at this stage of the testing period. Today I accidentally realized my oil pressure is slowing my turbo spool, I had a partner rev the engine while in park so I could verify how much the turbo was spinning, and normally the turbo doesn’t spin much while the car is idling. However I accidentally forgot to turn on my oil pump for a minute and noticed the turbo was spinning nicely even while idling

this tells me I need to rethink my w20-50 synthetic oil, and consider an oil line restrictor. I’ve read restrictors are to prevent smoking issues with the oil seeping past the seals. I however have no smoking issues, so I didn’t think I needed a restrictor but my tests today, with seeing the turbo spin nicely with no oil pumping, says to me I need to reduce oil pressure to get the best spool

i believed that since this was a used turbo, thrown onto my doorstep with a broken vgt actuator arm, that some heavier weight oil would help fill any tolerance gaps that have developed with abuse/age. However the oil is too thick and ruining my spool to some degree

secondly this saddens me to realize my air flapper valve may be leaking, this will be very important to fix for me because I was only interested in the idea of the rear mount setup if I could somehow circumvent the initial throttle delay because of the throttle sucking through 10’ of charge pipe, but I’m not seeing why else I am seemingly failing to build boost. My boost gauge reads great vacuum but fails to build positive pressure. I will test my boost gauge today to verify it is reading correctly, but my wideband gauge seems to support the idea that I am not building positive pressure yet

even with the slowed spool with my heavy oil, I still think the car should be able to generate a few psi of boost now with the exhaust leaks addressed and the charge piping installed

lastly it looks like I’ll want to consider some inter cooling, some people believe that with a rear mount setup, the extra length of charge pipe will help cool the charge before it gets to the engine. I felt the compressor housing after some test driving and the compressor housing gets hotter than I expected(keep in mind I don’t have many turbo builds to compare to, besides the oem turbo setups I see at work)

I have an air to air intercooler that came with the charge piping I ordered, however it’s a bit too large to reasonably install anywhere but under the car (there’s a cave/tunnel area over the rear axle, that does have some room between the dif and the wheels). HOWEVER , seeing how hot it gets here in Florida , an air to air intercooler a few inches off the pavement is not seeming like the best way to keep the charge air cooled. If anything I imagine it may actually add more heat.. so it looks like a fancy air to water setup may be in order.

ive read the weak point on boosting these engines is the top piston ring. It seems heat will overcome the ring eventually until it fails. Hence why I am developing a new focus on intercooling after seeing the compressor housing get that warm

here’s a photo of the engine bay with everything installed


edit: after reading a lot of arguing online about needing oil restrictors with holset turbos, it seems if I would have went with a smaller -3an size feed hose I could maybe avoid needing a restrictor on the oil feed. I went with -8an lines to be “more safe than sorry” in regards to oiling but even though -8an lines seem small to me, apparently they are not small enough

https://cimg8.ibsrv.net/gimg/www.mbw...a6309b62e.jpeg

I’ve figured out the problem with the lack of boost pressure. I removed the flapper valve and was able to finally build one or two psi of boost. This is the first time this car has officially seen boost so to a certain degree, this project has already been a success

Anyways the problem is the he531v turbo has a vgt system that is not ideal for the “spring backpressure” method of controlling the variable geometry turbine housing . Usually you can peg the vgt actuator arm closed with a spring, however the arm is “backwards” on these he531v compared to other vgt holsets I’ve seen

and there is no way to adjust the arm without complete disassembly which requires a turbo rebuild and balance.

ive since removed the turbo (removing a 50lb+ turbo is always fun by yourself) and am starting to fabricate a new system for the vgt actuator arm to actually be pegged closed in the opposite direction with a spring

knowing now that I had the vgt system backwards, I’m very confident this setup is going to perform very well once the new pieces are welded on to complete the vgt control

in other news I’ve ordered another maf sensor, I tried swapping the old ones, I’ve tried cleaning the maf sensors, I’ve tried removing my resistor device. All testing yields the same results, a p0100 code I did not have before this build. All signs point to a bad maf sensor

I am delighted to know the flapper valve was not the true source of the seemingly entire lack of boost. Instead I just had the vgt system wide open leaving my engine to spool this massive turbo, normally found on 10 liter semi truck engines, with no help from the vgt

now that I know this turbo does function well, and all shaft play has disappeared since I’ve applied an oiling system, at least this gives me a chance to clean the turbo and refinish it to give it the look it deserves. And to preserve the unit

pictured below is the backpressure spring vgt setup, which is actually backwards for this particular vgt holset
https://cimg4.ibsrv.net/gimg/www.mbw...d0a8d9aa5.jpeg

Hope you can get this going but you are probably starting to understand why this is so expensive to pay someone to do. On your turbo choice, in the past when looking to do this to another MB before they started putting forced induction of their gas engines, I researched utilizing a rear or center mount turbo. From my understanding, turbo size is of utmost importance when trying to get turbos to spool when away from the very fast moving hot exhaust. As exhaust travels down the exhaust pipe, it loses velocity and the velocity is what helps spool the turbo.

You may want to change turbos and or run dual turbos in the back. A 2 psi boost will be less than 50 hp total and dollar to hp ratio considering labor hours is just too low. I hope you are successful but that turbo may not give you what you want. Also, you may want to consider having your exhaust ceramic coated and wrapped to keep your exhaust velocities higher.

Thank you for sharing and I loof forward to reading your posts and experiences.

Agreed, right now I want to get the turbo variable geometry system working properly but I hear they do not enjoy the high temperatures from gas engines over a long period of time, so sooner or later I think I’ll be looking into a more reliable turbo anyways

E85, injectors and a nice map is the only way to get big power out of these mid-size engines

Agreed, maybe someday. I hope to not ruin drivability in regards to power, I want a powerful Mercedes but if I want a quarter mile performer I would probably be looking into American muscle cars

update-
new turbo arrives Friday by 3pm, new maf came today so it looks like we will be in business by this weekend. Both compressor and exhaust housings will see some modifications, I’ll be cleaning and inspecting the turbo, and some quick welding to get the vgt levers working properly

in regards to any exhaust leaks involving the trunk mounted turbo, copper “spray a gasket” has been great for sealing up any leaks between warped(from welding) v band gaskets and such

You won't be able to extract enough power to ruin drivability. The CL chassis and driveline can take what you will be throwing at it with no issues.

I agree I just enjoy the plush ride of the w215/Mercedes platform

my future race car will likely have a jerky torque converter, an uneven idle from crazy cams, too loud of an exhaust, etc.

the turbo cl55 is not that car for me , it’s a part of the reason I wasn’t seriously interested in the supercharger retrofit and the turbo setup seemed more ideal for a “smooth car”.

Here are some photos of the existing center console, and my new “center control panel”

from here I will be able to control the following-

1. amp for subwoofers
2. Bluetooth/radar detector devices
3. turbo oil pump
4. ???


https://cimg7.ibsrv.net/gimg/www.mbw...ad0cd2733.jpeg
https://cimg8.ibsrv.net/gimg/www.mbw...bfb08e68e.jpeg
Still need to 3D print a cup holder for the empty space between the center console and shifter area....

edit: added picture of the control panel after the wiring is done
https://cimg3.ibsrv.net/gimg/www.mbw...30f7e368d.jpeg

I will have to change out the stainless screws for something black or darker colored...

Update, maf issues and new exhaust tips
Maf issues are sorted and today I installed an air to air intercooler in an unusual space, right below the rear bumper

I installed faux exhaust tips, as mentioned I went with the facelift w215 amg quad tips as aesthetically there are no better exhaust tip configurations for these models.. the turbo back 3” exhaust terminates under the car towards the rear, these quad tips are merely for looks to complete the look of the rear diffuser/intercooler etc

right now I also have the rear seats removed as I am running signal wiring from my oil temperature gauges, my control panel switches to the trunk/turbo area

the delivery of the replacement turbo was delayed until tomorrow

for the near future, I will likely upload photos sparingly until the project is more completed and I can work on getting the car to a more finished and cleaned up state

Update/troubleshooting -
I installed the new turbo, an intercooler, new maf etc etc but still the car isn’t building much over 2-3psi of boost!!

now that I have the vgt stuff figured out the turbo is spooling faster at least

i think I’ve found the issue, I think the wastegate is opening prematurely. I noticed evidence of exhaust gases getting past the wastegate piston! Which shouldn’t be happening at a mere 2psi of boost

ive ordered more wastegate springs and will update the thread afterwards

Here’s a video of some rear mount holset noises

Update
Today I was finally getting 4, maybe 5 psi if I worked hard at it. You can feel the car pulling noticeably harder. I know the new wastegate springs will help, but I’m starting to wonder maybe about an electronic boost controller to make sure I build boost more quickly

Developments/success
I installed the new wastegate springs, right now I have a “7 psi” and a “14psi” spring doubled up in the wastegate. I emphasize the parentheses around the pressure ratings as these are eBay springs and hardly entirely trustworthy... they are definitely holding a lot of pressure, getting the wastegate back together even with a large bench vise proved to be challenging...

but as of today I consider the project an overall success. I’m finally building 7psi in second gear. The car has not suffered in reliability at all. I’m a bit surprised, I really expected this to be a bit more difficult, to get everything running right. I had to chase down some exhaust leaks, experiment with some creative ways to vent crankcase pressure, and properly configure a Holset VGT control system. But overall the car has been very reliable.

I drive it just about everyday to work and back, as well as running errands and whatnot. The car gets a lot of attention in the Mb shop, only a few people have ever really seen a rear mount turbo setup, nor a turbo this big in a Mercedes passenger car.

air/fuel ratios seem to be staying safe. I have not implemented the fuel pump voltage booster system yet, as I have been having no problems with the fuel delivery from a simple rising rate fuel regulator. as the boost pressure increases, the aftermarket regulator bypasses the OEM regulator and allows more fuel pressure to happen during boost

future plans/intercooling and trunk rebuild
now I am onto focusing on system optimizations, I want to reinstall the Volvo air flapper valve, to get some of the punchy n/a throttle response back, and to encourage the turbo the spool sooner. I also want to install some smaller diameter charge piping (2.25” instead of 2.5” aluminum pipe) to help the charge air have a faster velocity through the long run of pipe from the trunk to the throttle body

lastly I am onto developing a performance oriented trunk floor. I cut away the trunk floor to make all of the exhaust and intercooler piping setup easier. Right now I have a cheap eBay air to air intercooler mounted horizontally under the rear bumper. It’s not an ideal position at all, it was really just a quick setup to see if the intercooler would provide any intake air temp reductions

sure enough even in a non ideal position, the intercooler has 20 degree Fahrenheit cooler piping after the intercooler.

today I got to work on a c7 corvette z06, and I got to see how exactly the front and rear air duct/vents are setup to aide braking performance. So I would like to design a unique trunk setup with air ducts directed to cool an intercooler. I think the cooler intake air temperatures will be paramount to the longevity and reliability of turbocharging an n/a engine, as well as maximum power


video proof/throttle response optimization
linked below is a video of the throttle response/ turbo spool at city cruising speeds. As I mentioned, I’d like to reduce spool times and improve throttle response to be more like it was from the factory. An electronic boost controller and the air flapper valve should help a lot. I also have an unrestricted oil feed going to the turbo, which I’ve learned is not the best for quick spool times. This weekend I am implementing the smaller diameter charge piping and an oil pressure bypass system where you can divert excess oil pressure back into the reservoir, soon I will have this oil pressure relief line plumbed into an oil cooler to further enhance the longevity of this design


edit
just remembered I also still need to de program the egr valve. For now to prevent a check engine light from the egr valve, I have the egr valve left plugged in, but the egr valve is simply dangling from the fuel rail with a zip tie, it is NOT plumbed into the system. The egr ports are otherwise blocked off or re purposed for the engine breather system. This has yeilded no check engine lights for anybody wondering about an egr delete. However the “proper” method is to have the egr system disabled in the cars software

Vgt arm/spring control example


heres a crude video for testing purposes mainly, taken with an endoscope while driving. but this shows how the vgt control lever reacts to exhaust backpressure while doing a 1st/2nd gear pull with moderate to heavy throttle

An electronic waste gate may do you some good and would give you greater control.

Just picked up an eboost2 controller, so add $300 to the shopping list! I really like how the controller can prevent boost spikes, but mostly the level of control over the wastegate, this means instead of solely relying on spring pressure to control the boost, the boost will be controlled electronically via solenoid

In other news, the car has been parked this week...last weekend I was making modifications to the oiling system, I added a 3 way Wye fitting to my oil feed line, since I am not running a resistor on my oil line, this is an old trick to divert excess pressure back into the reservoir (much like the fueling systems on our cars). It can even help keeping oil temps cool, especially if the diverted oil flow is sent through an oil cooler before it reaches the reservoir

In the process I’ve learned/decided that I need to install a proper weld-on fitting to the oil reservoir for my turbo drain line. Before, I just slipped the drain line into the oil reservoir through a hole. Because there is not a dramatic decline of pitch from the turbo to the reservoir, the oil has been slowly wicking BACK up the drain line and outside of the reservoir. This was made worse when I installed the new Wye fitting and had to re-orient the reservoir slightly. Now I am waiting on parts to arrive because I do not like how much oil it seems could leak. My stainless braided 16an hose seems too large to fit into my 16an straight fitting... so I am going to try some non stainless braided hose

i have not really seen any temps over 184 degrees Fahrenheit along my oil lines, or my oil tank itself (measuring with an infrared gun) but I have not needed to drive the car( with the turbo installed) more than an hour or so . I don’t think adding an oil cooler will be a bad idea at all...

ive also swapped out the 2.5” charge piping under the car for 2.25”... I believe this will improve the velocity of the air as it travels from the rear to the front of the car. I made the decision after finding through research that 2.25” piping should handle 600hp without any problems. Basic fluid dynamics suggests air pressure travels faster through a smaller pipe. The same reasons you can’t always expect power gains when adding oversized exhaust pipes


i also reinstalled the Volvo penta air flapper valve, as lately I’ve been driving without it for troubleshooting purposes. The short and big 3”+ air intake straight into the engine gives the turbo exhaust a really throaty sound, and restores the great N/a throttle response this cars original engine had. And then as the rpms build and the car gets into boost, the valve switches and the boost officially takes over the air intake path and the boost level increases

I also think I will remove my blowoff valve to reduce the possibility of boost leaks.

Update
removed the blowoff valve, replaced a malfunctioning maf sensor under warranty from fcp euro, and fixed the oiling system flaws I mentioned in my last post

The car is running great and pulling very hard once into boost, I still have to give it a lot of throttle to build good boost, but once it’s into boost the car pulls hard. It seems my blowoff valve was leaking some boost because it’s never pulled this hard, id like to get the car on a dyno soon, if I had to guess the car is peaking well over 500hp now at peak boost

I’m gonna try heat wrapping the exhaust, a lot of rear mount turbo guys mention that without wrapping the exhaust it was harder to get a lot of boost pressure

ultimately the turbo may just be too big for this application! But I’m glad to have everything to a point where I can consider a more expensive/suitably sized turbo etc

besides the exhaust optimization, lately I have been experimenting with different resistors on the maf circuit, the 550ohm resistor Kleeman recommends in their kit seems to be too much resistance and throws p0100 obd codes... I tried 470ohm and I believe I got the same results. It will allow the car to reach full boost, but I’d like to avoid the error codes. Last night I tried a much smaller 20ohm resistor, the car pulled hard to about 4-5 psi and then cut throttle off, so I think I am on the right track with much smaller resistors than the 450-550ohm range

edit: I believe I’ve found the solution to my maf/volt clamp troubleshooting...

I found out instead of using resistors to trick MAP readings in some of the newer (2015+) Mercedes, people insist on using voltage clamps. The purpose of the clamp is to prevent altering the voltage normally, and ONLY when the boost kicks in does the voltage clamp cut down the signal

the problem with using a simple resistor, is you are ALWAYS modifying the maf voltage signal, even at idle and low throttle situations... this will obviously skew fuel trims and air readings...

I did some research and found out instead of buying an expensive voltage clamp for $100+ , that doesn’t do much more than dumb down a voltage signal, people have used zener diodes instead to clamp down voltage

the trend I’ve noticed is the ecu will close the throttle/cut fuel once it sees over 4.85 volts, so I have ordered a 4.7 volt zener diode , which will leave the signal unaffected UNTIL it reaches 4.7 volts where it will prevent the signal from going any higher of voltage

for anyone else trying this method, keep in mind you do not want to attach the zener diode directly to the chassis ground as this will apparently destroy your maf. Instead you will want to use a resistor between the diode and the chassis ground to prevent damage to the fragile maf sensor

ultimately this is where being able to use critical thinking and diagnostic skills will set you apart from the average guy simply following what others have done. Apparently Kleeman has told customers to simply strap a 550ohm resistor on the maf signal, but even from the start I was skeptical how this would affect low airflow situations, as the resistor would always be manipulating the signal, not just at high airflow. Maybe this is why lately I’ve been hearing stories of people blowing engines from the Kleeman setups? I’m not sure

Yes, wrap and ceramic coat the exhaust as stated earlier in the thread. That along with a smaller turbo would yield much better driveability and usable hp.

Research STS turbo systems and see what sizes they use for the Corvette. Let them share their R&D. Would save you time, money, and you would have a better overall driving experience.