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Turbo Boost vs MPG
Hello everyone,
I had a thought the other day. When I first drove my 300D 2.5 home from Columbus. It got 39MPG. This number is high from what I've heard for a 300D 2.5. As I worked on the car, I am now realizing the turbo is not actually doing anything. No boost. The car is still drive-able, just slow. 0-60 is 20 seconds. Even slower when the governor kicked out and I was stuck driving in second gear. A 240D would have beat me! This got me thinking. If my 300D can get HIGH 30s with no boost, and (presumably from everyone else's numbers LOW 30s with boost.. I only really need boost at certain times. Maybe I can get the best of both worlds.. I could employ some type of electronic wastegate controller... What do you guys think? Or is my reasoning here flawed? Was my 39MPG a fluke, now given that the turbo was NA?
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#2
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If the boost wasn't kicking in, then your ALDA was limiting fuel. By limiting fuel, no matter how hard you mashed that pedal your injection pump was being limited.
If you had an operational turbo and the fuel to match (POWAA!), would you take it easy on the pedal, limiting yourself to a 20second 0-60? On my 300D (different engine, I know, I know) I had it setup to relax the turbo on the highway at the flip of a switch. When cruising I ran 8psi, when flooring it I ran 18psi. A little extra boost can help your efficiency even if you're not completely matching the fuel quantity. You will have to monitor your intake pressure vs exhaust pressure to find the sweet spot.
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$60 OM617 Blank Exhaust Flanges $110 OM606 Blank Exhaust Flanges No merc at the moment |
#3
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I like this switch idea. What controller did you use? 90% of my driving is highway at speed, no real need for the turbo to be dumping boost. If i can switch it to a better mpg setting all the better.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#4
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I was running a VNT with a homebuilt regulator. http://www.peachparts.com/shopforum/2185307-post52.html
For the stock turbo you could splice in two boost controllers, and remote controlled valves(think electronic vacuum switches from the climate control or a gas car's EGR) to enable/disable each one. One at 12psi and one at #psi for cruising.
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$60 OM617 Blank Exhaust Flanges $110 OM606 Blank Exhaust Flanges No merc at the moment |
#5
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I'm not understanding the need to "relax the turbo" on the highway. The road load demand on the highway is only about 15 hp, so the boost would naturally be below 8 psi unless the turbo was exceptionally small and the vanes were closed. I don't believe this would be possible with the typical OE Garrett setup. |
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I'm just wondering what you'd label the switch on the dash for the active position, maybe "Suffer", and for the normal position, "Relief" ?!
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Cheers! Scott McPhee 1987 300D |
#7
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It might be different with the stock setup, I never messed with it. With the 2056V I noticed a drop in temps while cruising with the vanes open vs closed. I don't remember the actual amount.
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$60 OM617 Blank Exhaust Flanges $110 OM606 Blank Exhaust Flanges No merc at the moment |
#8
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I'd be curious if the variable vanes could be opened sufficiently to decrease the boost close to zero. At that point, you've got a naturally aspirated engine. The real question is how would it fare in fuel economy with no boost whatsoever? The answer might be valuable to those with stock setups if it offered some fuel economy benefits. |
#9
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Wow. How are you measuring 39 mpg? The current EPA figures for my 1985 300D is 19 mpg hwy, though I get ~22 mpg. I hope you aren't naively going by the markings on the fuel gage for consumption and the odometer for distance. Use the calibrated pump at fuel stations by measuring from fill-up to fill-up. For distance, use highway mileage posts or a GPS.
The turbocharger recovers exhaust energy, so disabling should make the engine less efficient. Diesels run WOT all the time, so a turbocharger is an ideal match. Some people who have added a turbo to 60's gasoline engines claim it improves mileage slightly. That is hard to believe since boosting the inlet pressure only to drop it across the throttle plate is a waste. Might be a very minor improvement from adding a little energy (heat) to the inlet air. |
#10
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Theoretically you can, but as I've been told the 2056V is on the small side. An external wastegate could always be added to bypass the turbo.
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$60 OM617 Blank Exhaust Flanges $110 OM606 Blank Exhaust Flanges No merc at the moment |
#11
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__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#12
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I'm thinking about reusing an old Megasquirt 1 controller to do a few things on my diesel. Not fuel injection obviously but if I can get RPM, throttle angle and manifold pressure signals to the MS box, it can easily control the waste gate any way I want to, PWM water meth injection proportional to engine load and RPM, turn on/off the electric cooling fans at any temp I want... etc. It can also take inputs from an EGT sensor, wide band O2 sensor (Bosch LSU 4.9 designed for diesel), coolant and intake temp sensors etc. Its on the back burner after I get the 5 spd swap and #17 head sorter. I spent too much time messing with EFI. Not having all sorts of multi color wires and zip ties all over the engine bay just doesn't feel right.
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CENSORED due to not family friendly words |
#13
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__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#14
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What do you want, modes? Ebeneezer Scrooge mode, only allow boost if there is a cement truck bearing down on us. Mosquito Season mode - AKA Super Speed (well, as super as a 617 gets) Peacetime mode - for when there is no war in the Middle East (cheap Diesel!) we can sort this one out last, I think we have the time.
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Remember, Safety Third! '99 E300 Turbodiesel, '82 300TD, 1996 12V Cummins Turbo, '94 Neoplan - Detroit 6V92TA |
#15
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I bought a cheap manual kit for the time being. Hell, it was cheap enough maybe I can rig up some kind of simple valve and run two kits! Time will tell.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
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