I thought I would start a new thread to solicit input on an idea raised in Wastegate actuator swap for OM602.962?. As several of us have been trying to track down the right wastegate actuator to convert from vacuum-actuated to pressure-actuated (currently out of stock), I was discussing the matter with a Garrett distributor. He asked me whether I had considered installing a blowoff valve instead.

To the extent that I understand it, the idea is to install a valve somewhere along the intake tube to relieve pressure. So I'm assuming the idea is to leave the wastegate in place, eliminate the vacuum to the all the stuff on the passenger side of the engine, and rely on the newly-installed valve. I'm assuming this valve would simply empty into the exhaust??

Anyway, any thoughts? What's the feasibility of something like this?

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 178k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 75k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

You would be able to limit boost with a BOV, but your exhaust pressures could still get high and cause trouble, as the turbo would still see 100% of the exhaust flow.

My $.02

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

If you were under a load like pulling a Trailer up a Hill and the Blow Off Valve opened you could overspeed your Turbo Charger.

Where I worked we had Customers bring in 2 of the Turbochargers we Rebuilt. What had happend in both cases that the old Hose between the Turbo and the Intake Manifold had burst. That left zero resistance on the Copressor side and the Turbo oversped and the Copressor Wheels came apart.

After those 2 incidents We included a new Hose with each Turbo and never had the same issue again.

Now it could be that the Blow Off Valve is something different of small enough that it could prevent overspeeding. I don't know.

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84 300D, 82 Volvo 244Gl Diesel

Modern application of a BOV as I understand is to prevent slamming boost back into the compressor when you suddenly close the throttle body such as to shift a MT. It's that thing that goes PCHEW when ricers shift at high rpm... which is always. I think BOVs predate wastegates then wastegates became the primary means of boost control. Supposedly you've bypassed EDS control of the wastegate if you're running a BOV. Otherwise you have to plumb the BOV back to the compressor inlet - it's blows off clean air from the compressor, not exhaust - so as not to confound the airflow sensor. Hey, where'd all that air I just measured go? Face it, EDS is a bean counter.

There's an easier solution if all you want is the PCHEW sound - Akamoto – Fake Dump Valve – Dummy Blow Off Valve

Sixto
87 300D