Has Anyone Experimented: Turbo Delete? - PeachParts Mercedes-Benz Forum

greazzer · #1 10-12-2017, 09:14 AM

OM617.95X engine application (and with manual trans).

Has anyone ever experimented by deleting a turbo from a turbo'd engine to see how the MPG suffered (or not)? I've read a bunch where a turbo actually hurts MPG in a gas engine and some pro's and con's relative to a diesel engine. I received an opinion from a learned source which I trust which says it will shave off some fraction of a MPGs.

The OM617.912 NA probably came originally with a Bosch (German Made) Nozzle 240

The OM617.95XX came with the Bosch (German Made) nozzle 240/

The 240/ sprays around 15% more fuel. Other than that, the MW pump is the same except having an ALDA vs. ADA from what I can tell.

If I swap in a NA pump for what's it worth (I am driving where altitude doesn't matter), with fuel sipping nozzles, will I be in the same boat as if I had a turbo?

I've ran a OM617.912 WITH #242 nozzles and #1930 nozzles. The #242 made the car incredibly peppy but then again, I am spraying 5x the fuel. The #1930s are fuel sippers and the car ran "regular" and got pretty good mileage, e.g., around 28-30 MPG.

So, anyone ever do any real experimenting to see how it affected MPGs? I am OK doing a turbo delete for pure simplicity since I really don't care about having a peppy fuel saver as once the car is up and running 70 MPH, it's doing just what I need it to do.

dude99 · #2 10-12-2017, 09:26 AM

I haven't deleted a turbo, but I can tell you that my 300SD got much better fuel economy than my 79 300D NA. Worth noting is that my SD had the 2.46 rear end in it. If your still planning to use the same rear end id keep the turbo. Otherwise you'll be mashing the pedal forever to get to speed and would probably burn more fuel doing so. With the turbo it was a very nice car to drive.

torsionbar · #3 10-12-2017, 09:55 AM

Generally speaking, a diesel engine with turbo will always get better MPG than the same engine without a turbo. We can see this in existing production models - the om606 turbo gets better fuel economy than the om606 non-turbo. The VW TDI (turbo) gets better fuel economy than the VW SDI (non turbo). More power + improved fuel economy = win-win.

About the only exception to this rule, is stationary industrial engines that run at a fixed rpm.

greazzer · #4 10-12-2017, 10:06 AM

In regards to the differential, I plan on using the 2:47 in a 300CD. From experience, I ran a 2:65 LSD in a W123 sedan with NA engine and it ran just fine. Then again, manual tranny.

A lot of folks said it would not work, it would be too sluggish, and the list went on. I sought actual experience and a few folks said it was great. I tried it. And the verdict was incredibly clear to me: winner. So, 2:65 LSD in a W123 with OM617.912 ran just fine with manual tranny.

So, is there a great deal of difference in a 2:47 vs. 2:65? Turbo or not ... My suspicions is that the answer is no.

So, I am guessing if I lost one (1) MPG with a turbo delete, that would be 20 miles per tank and I would be fine with that for the simplicity. My driving habits are long trips interstate, buzzing along 70+ MPH and a handful of miles off the interstate. So, getting up to speed is only an issue for a few minutes each way on each trip.

I guess the real chore for me is to try it with and without the turbo on a trip to see what the difference is. I am trying to exert my laziness now ... and avoid the swapping ... lol

CDTurbo001 · #5 10-12-2017, 10:53 AM

From what I've observed gas engines have different appetites than diesels. Gassers, the further into the throttle you push, the more gas they'll burn. Get aggressive with my '13 Cruze 1.4T and mileage will drop 3 MPG. My BIL's '03 TDI Beetle, loaded to the gills with luggage, actually got better mileage on a trip through Nebraska, SD, Montana, and Wyoming than he usually does commuting.

And consider that, if the turbo injectors in your example dump an additional 15% fuel, how much more power are they helping create because of the turbo? I think it's well more than 15%.

Diseasel300 · #6 10-12-2017, 10:54 AM

Keep in mind a power-weight ratio. The car is going to weigh the same with or without the turbo (for all intents and purposes). With the turbo attached, you will have more power and far more torque at cruising speed. With a tall differential gearing, that translates into LESS fuel for the Turbo to do its thing since it produces more torque and more power for a given RPM. The fuel quantity injected may or may not be greater for a given RPM at a given speed.

Keep in mind if you delete the turbo you're going to want to delete the ALDA and re-tune the IP to reduce fueling and get rid of the ALDA function. Or switch over to an N/A injection pump.

Another thing worth thinking about: Are the cams different between the Turbo and N/A engines? The prechambers are different as are the pistons. Will that difference affect combustion negatively without the turbo installed?

Just out-loud thoughts without enough coffee in the system. Possibly a dangerous combination...

Simpler=Better · #7 10-12-2017, 11:26 AM

Did you end up porting that head? Pumping losses will getcha too.

If you want more efficiency, a turbo designed in the 2000s will do much better than the 70s lump from the factory.

ROLLGUY · #8 10-12-2017, 11:39 AM

Quote:

Originally Posted by Diseasel300

Keep in mind a power-weight ratio. The car is going to weigh the same with or without the turbo (for all intents and purposes). With the turbo attached, you will have more power and far more torque at cruising speed. With a tall differential gearing, that translates into LESS fuel for the Turbo to do its thing since it produces more torque and more power for a given RPM. The fuel quantity injected may or may not be greater for a given RPM at a given speed.

Keep in mind if you delete the turbo you're going to want to delete the ALDA and re-tune the IP to reduce fueling and get rid of the ALDA function. Or switch over to an N/A injection pump.

Another thing worth thinking about: Are the cams different between the Turbo and N/A engines? The prechambers are different as are the pistons. Will that difference affect combustion negatively without the turbo installed?

Just out-loud thoughts without enough coffee in the system. Possibly a dangerous combination...

I believe the cam is in fact ground different for the turbo vs N/A. What that means for the overall performance and fuel mileage, I wouldn't know (or even how to calculate). If it were me, I would try the turbo for a month or so, and then change everything out to N/A, carefully calculating the MPG. Yes it is an afternoon of work, but you would have real-world data that this community may be able to use.

OM616 · #9 10-12-2017, 11:59 AM

Quote:

Originally Posted by greazzer

OM617.95X engine application (and with manual trans).

Has anyone ever experimented by deleting a turbo from a turbo'd engine to see how the MPG suffered (or not)? I've read a bunch where a turbo actually hurts MPG in a gas engine and some pro's and con's relative to a diesel engine. I received an opinion from a learned source which I trust which says it will shave off some fraction of a MPGs.

The OM617.912 NA probably came originally with a Bosch (German Made) Nozzle 240

The OM617.95XX came with the Bosch (German Made) nozzle 240/

The 240/ sprays around 15% more fuel. Other than that, the MW pump is the same except having an ALDA vs. ADA from what I can tell.

If I swap in a NA pump for what's it worth (I am driving where altitude doesn't matter), with fuel sipping nozzles, will I be in the same boat as if I had a turbo?

I've ran a OM617.912 WITH #242 nozzles and #1930 nozzles. The #242 made the car incredibly peppy but then again, I am spraying 5x the fuel. The #1930s are fuel sippers and the car ran "regular" and got pretty good mileage, e.g., around 28-30 MPG.

So, anyone ever do any real experimenting to see how it affected MPGs? I am OK doing a turbo delete for pure simplicity since I really don't care about having a peppy fuel saver as once the car is up and running 70 MPH, it's doing just what I need it to do.

When it is said that a nozzle flows XX% more fuel, it does not mean that if you change to that nozzle you will be injecting more fuel at the same rack position. What it means is that at the same pintle lift height, one injector will flow more than the other at the same pressure, and it is the volume / delivery rate, flow/lift rate, and pop pressure, that affects the pintle lift throughout the injection.

At a given rack position, the element will displace the same about of fuel regardless of the nozzle on the other end, however, the quality of the injection is directly related to the flow rate and pattern of a nozzle.

A nozzle is sized to flow a range of fuel at such a rate that the pintle lift does not exceed a certain point. One reason why you see superpumped engines smoking so much is they are pusing way more fuel and at a faster rate, then the nozzle was designed for and the pintle is getting pushed out of the throttling area, turning the injection from a fine mist delivery into a fire hose stream.

If you install higher flowing nozzles in an engine where the pump has not been turned up or modified in any way, what will happen is the gap that the fuel passes through between the pintle and the nozzle will be tighter than the OEM nozzle, which "generally" creates a finer mist / better injection. But that is not always the case. Depending on the throttling area and Pintle design, if too little fuel is delivered, then the pintle could never get out of the primary injection phase, and the pattern could be crap, not disperse well..

The nozzle is more than just a valve where flow volume is a concern. The geometry of the nozzle and pintle create the spray pattern and density that affects dispersion and how well it will ignite as injected.. Nailing happens when a percentage of the injected fuel is not burnable as injected, and it needs the heat and swirl created by the fuel that did ignite to brake down the fuel density and when it does, bang!!

The key to making the .95 run like the .91 is in the pump. The easiest way to do it is to put a .91 pump on it. Other wise you will have get rid of the ALDA and detune the .95 pump.

moon161 · #10 10-12-2017, 12:06 PM

The NA cam has some valve overlap for scavenging that the turbo does not, I think. The engine shop manual should show it.

DeliveryValve · #11 10-12-2017, 12:31 PM

Quote:

Originally Posted by moon161

The NA cam has some valve overlap for scavenging that the turbo does not, I think. ...

Yes that is true..

DeliveryValve · #12 10-12-2017, 12:35 PM

I think the key here in which a turbo has adverse effect in mileage is how much back pressure is it causing? I believe the ratio is close to 2 to 1. So if your cruising and making 5-6 psi of boost, your back pressure is around 10-12 psi. The engine has to overcome that backpressure with more mechanical work. The turbine is not as efficient and boost is come out lower. Has an effect on chamber savaging and combustion is effected. Thus more fuel has to be used to overcome all this.

Perhaps besides a turbo delete, install a huge turbo. i.e. Holset hx35 or even hx40. Those turbos will not be making any boost until past 3000 rpm's and back pressure would be minimal at my assume RPM range your are cruising at. 1500-2000 rpms.

.

moon161 · #13 10-12-2017, 02:25 PM

User Graminal95 Turboed and intercooled a 616 and used a 5 spd and monitored his mileage. If you look up the posts you should see results as far as power, egt and mileage.

BillGrissom · #14 10-12-2017, 02:47 PM

Turbo in a gas engine is totally different energy accounting than in a diesel because gas engines have an intake throttle and diesels run wide-open throttle (WOT) (some newer diesels do have a throttle used near idle for nefarious reasons). In a gas engine the turbo is only useful at WOT because otherwise, any boost pressure made by the turbo is just dropped across the throttle to get the desired intake manifold pressure (and thus desired torque). In a diesel, the turbo boost is fully used all the time, and thus kind of "free recovered energy" though there is a slight downside in the back-pressure acting on the piston (post 12).

My guess is you wouldn't see a measurable mileage improvement from eliminating the turbo and perhaps even a slight decrease. You might do better by advancing the injection timing (start of injection at 27 deg BTDC vs factory 24 deg) and/or lower flow injection nozzles (finer spray).

jay_bob · #15 10-12-2017, 03:29 PM

Quote:

Originally Posted by torsionbar

Generally speaking, a diesel engine with turbo will always get better MPG than the same engine without a turbo. We can see this in existing production models - the om606 turbo gets better fuel economy than the om606 non-turbo. The VW TDI (turbo) gets better fuel economy than the VW SDI (non turbo). More power + improved fuel economy = win-win.

About the only exception to this rule, is stationary industrial engines that run at a fixed rpm.

Well I mess with big generators at work. Typically 2 to 3 MW machines with 16 to 20 cylinder diesel engines. I can tell you these engines all have turbos, in fact there are usually 4 of them, the engine is divided in fourths.

The engine runs at a carefully governed 1800/min so that the alternator produces exactly 60 Hz.

If there was a benefit to not having a turbo they would certainly do it. However the reason they do have a turbo is the same reason you want it in your car, namely a power boost. In a car the boost is needed when leaving a red light or passing. In a generator you need the boost when you are at zero load and you instantaneously go to 100%.

This is one of the more fun tests to watch, the engine goes from chugga chugga chugga to WAAAAAAAH in about a half a second, the turbos are screaming, huge puff of black smoke out the stack that would make Dieselmeken jealous. Would not be possible without the turbos.