What's the best way to launch a diesel off the line? - Mercedes-Benz Forum

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post #1 of 11 (permalink) Old 09-21-2013, 08:32 AM Thread Starter
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What's the best way to launch a diesel off the line?

I've got a W204 C320CDI with the V6 3.0 litre turbo diesel. I have a DTUK tuning box and I'm now at approximately 190kw and 590Nm.

My best 0-60mph time is 6.28 secs as measured by my GPXPro I use on my track bike. I let the rear tyres down to 15 psi cold and had about a quarter of tank of diesel.

It seems to accelerate faster if I slowly depress the pedal rather than floor it. It's not a natural thing so you tend to push the pedal past the pressure point too quickly and I'm sure it slows down. This is my first high performance diesel so I don't know all the nuances yet. I know it has a fixed opening air intake and the throttle adjusts the amount of fuel injected rather than adjusting the amount of air as in a petrol engine. That's why I think you need a different technique to accelerate quickly.

Its the first 20m or so that seems to be the main problem. An LSD would help for sure.

I tried loading it up on the TC as well but I'm not sure if that helps. I'd love to crack a sub 6.00 second time.

Any suggestions or hints are welcome.

I'm riding for you #52, my dear son Cameron 1985-2009

2009 W204 C320CDI C Class sedan with Quaife LSD
2006 W639 115CDI Vito LWB Van for hauling motorcycles
2008 W164 ML320CDI Edition 10 (daughter's but I look after it)
2011 VW Polo 6R Hatch
2008 Honda CBR600RR race/track motorcycle
2010 Suzuki GSXR750 race/track motorcycle
2011 KTM 530 EXC Enduro motorcycle
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post #2 of 11 (permalink) Old 09-21-2013, 11:15 AM
st4
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Left foot on the brake, rev the engine, release brake and let the car shoot forward

Current Merc: 2009 C220cdi sport estate
Prev Merc: 2005 E320cdi sport
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post #3 of 11 (permalink) Old 09-21-2013, 01:56 PM
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for my OM617

the best performance is attained by:

1. Depress the accelerator to the floor
2. Open a beer and light a cigar
3. Wait
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post #4 of 11 (permalink) Old 09-21-2013, 06:21 PM Thread Starter
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Originally Posted by rocky raccoon View Post
the best performance is attained by:

1. Depress the accelerator to the floor
2. Open a beer and light a cigar
3. Wait
Ha .. Ha... It's not that slow!. The old diesels were like that but 6.28 secs 0-60mph is not a bad time.

I know I could get below 6 secs but it's the right foot technique that needs the tuning not the engine.

I'm riding for you #52, my dear son Cameron 1985-2009

2009 W204 C320CDI C Class sedan with Quaife LSD
2006 W639 115CDI Vito LWB Van for hauling motorcycles
2008 W164 ML320CDI Edition 10 (daughter's but I look after it)
2011 VW Polo 6R Hatch
2008 Honda CBR600RR race/track motorcycle
2010 Suzuki GSXR750 race/track motorcycle
2011 KTM 530 EXC Enduro motorcycle
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post #5 of 11 (permalink) Old 09-29-2013, 03:44 AM
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right foot on fuel left hard on brake.rev engine so that rear tire will not be spinning.I hold mine at 3000 rpms.release brake and mash fuel into the floor

1999 s320. and 83 300sd quit driving,people make me nervous
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post #6 of 11 (permalink) Old 09-29-2013, 10:09 AM
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Are computers on new cars allowing reving high with foot on the brake and gear engaged?
Our 98 300DT is electronically controlled, but still mostly mechanical engine.
It does have noticeable turbo lag and when I step on it, the first 2 seconds are a bit annoying as engine takes time to spool, but then it gives nice push.
I drove cdi with variable turbo and the turbo lag was almost non-existent.
That said, tunning and taking diesels to race track is not something owners of those cars do very often, so I will be curious to follow this topic.
What I love about my diesels is high speed acceleration. When I step on it at 50 mph, that thing moves instantly for passing, while still remember wet back when gasser took it time to downshift before accelerating and the truck in rear view mirror was growing really, really fast.
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post #7 of 11 (permalink) Old 09-29-2013, 06:31 PM
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Not sure which topic is more pointless - the MB vs BMW threads or this one.

If you want to get off the line quicker, trade in the diesel for a gasoline engine.
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post #8 of 11 (permalink) Old 09-29-2013, 06:40 PM
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And how many gasoline engines will give you 6.28 second?
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post #9 of 11 (permalink) Old 09-29-2013, 07:41 PM
DrX
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If you want to compare apples with oranges, a 2008 W204 C350 can do 0-60 in 6.0 sec.
http://media.caranddriver.com/files/...0-sport-ts.pdf
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post #10 of 11 (permalink) Old 09-29-2013, 07:45 PM Thread Starter
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Quote:
Originally Posted by DrX View Post
Not sure which topic is more pointless - the MB vs BMW threads or this one.

If you want to get off the line quicker, trade in the diesel for a gasoline engine.
DrX ... the diesel should be far quicker off the line than a petrol because of the huge torque at low revs. If you haven't driven a modern CDI then see if you can try one out because I'm now a converted "Diesel Head".

My frustration was the electronic throttle pedal seemed to be the issue. I couldn't find the right way to accelerate quickly from a standstill. The throttle felt slushy and seemed to have a lag built in. Exiting a corner was painful as it would coast for a while even though I was pushing the pedal then it would take off.

I spoke to the dealer and said I didn't like it and was there a software fix. As usual totally unhelpful and he just said that's the way they are and they are deliberately set up "soft". So I did my own investigations and fixed the problem by fitting a DTE Systems pedal box. It's transformed the car and it now has a direct, crisp and seamless power delivery. No lag at all. I push the pedal and it responds.

Details here:

http://www.benzworld.org/forums/w204...pedal-box.html

I will do another test when the weather is dry and put the results here.

The only modifications to the car are electronic ... the pedal box and a DTUK tuning box. The car is now about 190kw and 590-600Nm compared to the standard 165kw and 510Nm.

I plan to fit the Quaife LSD as soon as it's available for the C320/350CDI. These cars need them so due to popular demand Quaife in the UK have responded and are about to release a version for these cars.

I'm riding for you #52, my dear son Cameron 1985-2009

2009 W204 C320CDI C Class sedan with Quaife LSD
2006 W639 115CDI Vito LWB Van for hauling motorcycles
2008 W164 ML320CDI Edition 10 (daughter's but I look after it)
2011 VW Polo 6R Hatch
2008 Honda CBR600RR race/track motorcycle
2010 Suzuki GSXR750 race/track motorcycle
2011 KTM 530 EXC Enduro motorcycle

Last edited by Scott52; 09-29-2013 at 07:54 PM.
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