Custom Big Single Turbo To Custom Twin (S55) Turbo upgrade
- Thread starter Dumaurier7
- Start date
I came across this photo or another one showing this set up where the turbo is located behind the engine mount and steering linkage closer to the fire wall. I went the other direction because I wanted to avoid having to fabricate a different mount as well as the complexities involved with the scavenging pump, I soon found out that no matter what you do there would be challenges. I believe I have now arrived at the best solution all around with the top mount intercooler which allowed me to retain much of the OEM components including the thermostat.
Her you can see how close the thermostat is to the 4” inlet pipe! I had to shorten the neck on the radiator placing the connector almost flush to the radiator tank surface! It’s all close but it works!
Her you can see how close the thermostat is to the 4” inlet pipe! I had to shorten the neck on the radiator placing the connector almost flush to the radiator tank surface! It’s all close but it works!
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So heres an update! after working through couple issues (oil leak, boost pipe adjustments etc.) it runs well until a 101F01 code for " air mass plausibility:calculated air volume in intake system implausible " is flagged, this basically says that the intake air volume is high in relation to the throttle position which suggests leaks downstream the mass air sensor. I expected this because I have a WI port to plug and all the clamps on the intake to tighten............these cars are extremly sensitive to vacuum leaks!....... more to come!!!
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Got ALL issues sorted motor runs strong with no fluid leaks....... however! NO Boost! 
and no codes! the hunt continues!
and no codes! the hunt continues!
Nice looking build! Question on that EFR - did you mount the factory diverter valve solenoid to the compressor housing? If so, were there any special parts you had to get/make to do that? I see those turbos come with the recirculation valve built in, but from pictures it wasn't clear to me if that cream colored cap can just be removed and bolt up the bmw oem diverter valve solenoid in its place and it would work.
Thanks, no the factory valve does not fit the EFR, I used a Turbo smart Compact BOV , you will need to get the one for the VW GTi model # TS-0223-1063.
Found it!!!
after doing a log I saw that I was actually getting boost up to 5psi but then it would immediately go back to 0.00 (I had a wrong boost sensor configuration in my P3 gauge so it just displayed 0.0psi 
). I traced the fall off to 0.00 to a leaking impulse line to the Tial BOV which had caused a lower pressure above the diaphragm allowing boost in the pipe to push the valve open as it (boost) increased.
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Nice to have an easy fix! Excited to hear how that EFR does once everything is dialed in! I've got my heart set on one of those things, I want to get the Speedtech 7670 EFR kit. Not as big as your 8474, but should still be a hoot on 93 oct.
So your're running the turbo smart diverter valve on the compressor AND a Tial blow off valve? What's the reason for running both vs. one or the other?
Gotcha. I looked up that turbosmart you mentioned and saw it was plumb-back and atmospheric vent combined. That plumb-back hole looked really small. Until then, it didn't occur to me that a diverter valve may not be able to keep up.
My AFRs' are going wayyy lean when the turbo begins to spool which suggests great boost response I am presently making arrangements with Mr. David Shoupe to begin the tuning process.
I am presently making arrangements with Mr. David Shoupe to begin the tuning process.
Update! found and fixed another boost leak at the jet pump hose ( I replaced this with silicone hose to allow for required flexibility) and also diagnosed and resolved a low fuel pressure/ LPFP issue ( if doing a custom harness inside the tank ensure the wire is compatible with fuel!), car is now boosting to 12 psi and making a DME calculated 450ft/lb of torque, however at this boost level the DME is reporting LOW Fuel Rail Pressure At Injection Event" and holding back the motor so I am now working to get the PI/Reflex online to take some load off the HP system. In the near future I will be upgrading the HPFP and introducing water meth then I'll resume tuning activities to get it all dialed in........... At 12 psi the car feels better than it did when I ran 20 on the OEM!!!!
This is great! You mentioned the dme reported torque, is that 450 n*m, or did you convert the reported n*m value into 450 ft*lb? Guessing ft*lb since you said it feels better than 20psi on the oem.
