Improving low end power of 617
 

So my dad's had a 240D for years and now we're making the car he always wanted, a 300D Turbo with a manual transmission. Engine is now in the car but we are having to sort out the turbo as none of the multiple spares I have are rebuildable. One thing my dad is worried about is low end power. He didn't like the turbo lag in his friend's 87 300TD and wants to figure out if we can do something about that for this car.

What options do we have?

We've thought about putting in a Sprinter turbo but don't really know how exactly that would be accomplished. Are there simpler solutions?

We're not trying to make the engine significantly more powerful, just want better low end.

The flanges are different between the turbo of a sprinter and a om617. That's easy enough to make and fabricate with some welding and cutting to fit.

To decrease turbo lag, you would want a small turbo housing. Larger housing increases lag.

If you want more power, intercool it, larger turbo, exhaust and tune the pump.

The om603 does not have a lot of turbo lag. Something had to be wrong with that car. Mine hauls a$$ for what it is.

He just remembers that the first turbodiesel he drove, a W124 300TD, had problems with starting from a hill because of little low-end torque. He also had the same complaint driving my brother's W116 300SD.

There's a person on eBay selling a flange adaptor for a T3 to Sprinter turbo so that bit isn't hard to figure out, it's the intercooler piping and air filter housing.

You can always delete the ALDA and not have to worry about the reduced fueling at low RPM/boost.

A turbocharged diesel is one application where an automatic transmission is superior to a manual - it allows the turbo to stay spooled between gear changes.

If I had a straight drive and wanted a hole shot I'd spool it up before I dumped the clutch. Not really, I rev it then let the clutch our easy to get it rolling properly.

It seems like a 617 would launching a 123 body.

It's probably better to adjust the ALDA or change rear end ratios, but a great opportunity to get a more modern turbo in there. Let's face it, the old T3-45s are crap...

Something with a smaller turbine housing will spool faster but you don't want to choke your top end. Something like a Holset HE200WG (only bring that up because I have one) would be alright since you're not going for more pwoer really (although it's compressor will flow more). Need a T3 to T25 adaptor for one of those though. Still many other options out there as well.

Just remember intercoolers etc will add to the lag slightly...

A friend that drives Datsun Z turbos complains that no one has problems with NA lag. He swears that people drive and don't rev the motor to the proper level.

Twin scrwoll but that's expensive.

How about a tune up and properly rebuilt turbo? No one would have paid what these things cost new if there was turbo lag.

Sixto
98 E320s sedan and wagon

We're putting in the 240D rear end. Engine is a factory rebuilt unit we pulled out of a wagon in the yard, tested nearly 400psi on all cylinders. We put in rebuilt injectors that we tested for consistent spray pattern. Fresh valve adjustment. I might just reseal this K26 we've got laying around then my dad can decide whether or not he wants us to upgrade the turbo.

Are you saying the 617 with laggy turbo doesn't pull better from a stop than the 616? I'm surprised you feel turbo lag with 3.88 gears. The best part of such a swap might be longer legs like a 3.07 unless you don't do much long distance cruising.

Sixto
98 E320s sedan and wagon

I had no problem with mine,I turned up boost by using a gas valve between the little hose on the turbo, then removed ALDA.

I'd say keep all stock but make darn sure the turbo is healthy (building 14 psi at WOT at 2400 RPM) and the ALDA is not leaking pressure (new o-rings). You'll probably be happier if you get a rebuilt IP with new ALDA, much simpler than trying to source / engineer a different turbo that will fix the low end.

Also note that these engines are much higher revving than what most 'Mericuns are used to, one must keep the engine at a higher speed to get all the torque and power. A manual trans will facilitate that.

I vote against the "ALDA delete" recommendation, that may be effective as a trouble shooting method but in the long run I would think it bad for the engine (excessive carbon buildup from excessive fuel that doesn't burn completely). I would also expect that fuel consumption would increase.

This is a very valid point. When I first started driving my swap, I was pretty disappointed with how little power it had. Having only driven Cummins and Powerstroke diesels before then, both with huge torque just off idle and a redline under 3k RPMs, I simply wasn't spinning my short-stroke 617 fast enough. Poor engine was barely getting on stride before I shifted. Yes, it struggled to drag a 3500lb truck up a hill at 2000 RPMs. After I got used to driving it properly and took my dad(old school long haul semi driver) for a ride, he actually yelled at me for revving a diesel like that.

Let 'er spin.

If you really want boost get a variable vane from a sprinter or jeep.

With a 2056v I could build boost revving in neutral. When driving I could get pretty much instant boost, it made a huge difference.