Boost control solenoid on a 300SD? - PeachParts Mercedes-Benz Forum

turbozeke418 · #1 09-09-2012, 05:18 PM

I recently got a 1983 300SD and although my 3rd Benz and 2nd Diesel, it's my first turbo charged one. I had 2 1988 Ford Thunderbird Turbo Coupes and I installed a boost control solenoid on it to crank the boost up to 18psi and the cars were rockets. I've been trying to read up on something similar here and can't seem to find much. Maybe it's called something different here or just can't be done? The reason I ask is that I can't even hear the turbo spooling on my car. It's got only 131k on it and was owned by 1 owner. Can you just not hear it because its a loud diesel? I was thinking about hooking up a small boost gauge somewhere inside to see exactly what its cranking out. Any input on all these questions would be appreciated.
Thanks!!

This is what I used for the Tbirds...very basic and you just dial it up to the desired boost you want.

http://www.ebay.com/itm/Manual-Boost-Controller-Mustang-SVO-Turbocoupe-Ford-2-3L-turbo-Gillis-valve-/271055600232?pt=Motors_Car_Truck_Parts_Accessories&hash=item3f1c2c3a68&vxp=mtr

tyl604 · #2 09-09-2012, 09:48 PM

Check or replace your switchover valve - it is on the driver's side firewall and has (as I remember) three plastic hoses going to it. If it is clogged up or if it has been replaced and the hoses are not on the correct nipples, you will not have much power. My SD is an 81 and I just replaced the original switchover valve with the new style; got the plastic hoses mixed up and could not get over 30mph - changed the hoses and have great pep again (for a diesel). See pic.

turbozeke418 · #3 09-10-2012, 03:17 AM

OK that is what the Alda line is hooked up to? I cleaned removed the banjo bolts from the Alda and the back of the engine on the passenger side and both were free from any build up. They looked like new. I disconnected the switchover valve for the hell of it and it did nothing for the performance.

Secondaries · #4 09-10-2012, 10:54 AM

Quote:

Originally Posted by turbozeke418

I recently got a 1983 300SD and although my 3rd Benz and 2nd Diesel, it's my first turbo charged one. I had 2 1988 Ford Thunderbird Turbo Coupes and I installed a boost control solenoid on it to crank the boost up to 18psi and the cars were rockets.

What you are referring to is not a solenoid, it is a manual boost controller (MBC). It's a simple ball and spring valve, in which the spring is loaded by the thumbscrew until it stays closed until the boost pressure you desire is reached.

Quote:

I've been trying to read up on something similar here and can't seem to find much. Maybe it's called something different here or just can't be done? The reason I ask is that I can't even hear the turbo spooling on my car. It's got only 131k on it and was owned by 1 owner. Can you just not hear it because its a loud diesel?

You can't hear it because it's a Mercedes! Well, also because the air intake is enclosed and muffles the compressor whine. If you remove the filter housing and plastic u-tube, the compressor whine is pretty easy to hear. But that's not a very good idea. Everyone on here (and I am inclined to agree) that the stock filter setup is just about the best performance you can hope for. I hope you wouldn't cripple the stock system just to "hear the turbo".

Quote:

I was thinking about hooking up a small boost gauge somewhere inside to see exactly what its cranking out. Any input on all these questions would be appreciated.
Thanks!!

If you are actually interested in increasing the performance from your motor, this isn't a bad idea. Boost gauge and EGT are the two gauges that are best to have if you are increasing boost/fuel. Keep in mind, unless you're interested in dropping thousands of dollars on pump mods, you're going to be limited to about 15-25 more horsepower over stock. These cars aren't rockets. 12 psi is stock. If you turn up the pump, it can supply fuel for about 14psi. Any more is wasted energy.

Quote:

This is what I used for the Tbirds...very basic and you just dial it up to the desired boost you want.

http://www.ebay.com/itm/Manual-Boost-Controller-Mustang-SVO-Turbocoupe-Ford-2-3L-turbo-Gillis-valve-/271055600232?pt=Motors_Car_Truck_Parts_Accessories&hash=item3f1c2c3a68&vxp=mtr

That is a manual boost controller, and it is extremely overpriced. This one here will do the same exact thing as the one above for a quarter of the price.

1New Polished High Quality Manual Boost Controller for All Turbo Cars EVO STI | eBay

Keep in mind gassers and diesels are worlds apart when it comes to performance. Forget everything (most) of what you know about making more power with a gasser motor! But if you're still interested, you should check out the SuperTurbodiesel forum. They're more interested in hopping up these old cars than this forum is.

turbozeke418 · #5 09-10-2012, 04:12 PM

Thank you all for the input. I was just looking for a little more. Nothing drastic. This car is already twice as fast LITERALLY than my N/A 300TD.

turbozeke418 · #6 09-23-2012, 09:10 PM

I hooked up a boost gauge (mounted it under the ignition and doesn't look out of place or tacky either). It appears when at full throttle I'm running 10 lbs of boost. Does this sound about right for stock? She builds up through first gear and tops out at 10 lbs by 2nd and holds it all the way through until I let off the accelerator.

compu_85 · #7 09-23-2012, 09:16 PM

First I would be sure your gauge is working right. Then I'd consider adjusting the wastegate for 12 PSI.

-J

turbozeke418 · #8 09-23-2012, 11:04 PM

Quote:

Originally Posted by compu_85

First I would be sure your gauge is working right. Then I'd consider adjusting the wastegate for 12 PSI.

-J

I bought an external boost controller. Do I hook it up between the turbo inlet and the wastegate line? That seems to be the only line to link it to.

Secondaries · #9 09-28-2012, 10:38 AM

Quote:

Originally Posted by turbozeke418

I bought an external boost controller. Do I hook it up between the turbo inlet and the wastegate line? That seems to be the only line to link it to.

Bingo.