Thread: Disco 300TDi dyno'd and ? overfuelling

When you backed off the pedal "a little" did you maintain your speed, if you did the reason it was blowing black smoke is because you had the pedal to the metal when you didn't need to. Use the torque of your engine, max. revs is rarely the optimal rev range. If your vehicle is pulling 100klm/hr up a steep hill with, say, 7/8ths throttle, putting the pedal down another 1/8th is only going to increase fuel use without any benefit, Regards Frank.

Yes I think you're right Tank. I don't think there was any discernible benefit in having the pedal that bit more depressed. Having said that I was a bit distracted by the engine watchdog temperature alarm sounding off (got up to 108 degrees before cresting the hill) so I'm a bit sketchy on the detail.

Also shortly after seeing the very thick black smoke that was virtually blanketting any view of cars behind I backed right off, not just to let other drivers see where they were going but also to ease up on the load put on the engine.

Without an EGT gauge you are playing with fire. The degree of smoke you are talking about will equate IMHO to some pretty excessive EGT's!!(Possibly over 800deg if driven like that up long hills.) The fact that the engine alarm went off also means that the heat generated under these circumstances couldn't be lost through the cooling system effectively. As Tank just said, until an EGT gauge is fitted, don't push it that hard or you will risk overheating pistons, damaging exhaust turbines etc etc. One would hope it was set up on the dyno with a Pyrometer, It probably was If TRS did it, they are pretty used to tuning performance vehicles and know about these sort of issues.

JC

Originally Posted by omvanders

Yes I think you're right Tank. I don't think there was any discernible benefit in having the pedal that bit more depressed. Having said that I was a bit distracted by the engine watchdog temperature alarm sounding off (got up to 108 degrees before cresting the hill) so I'm a bit sketchy on the detail.

Also shortly after seeing the very thick black smoke that was virtually blanketting any view of cars behind I backed right off, not just to let other drivers see where they were going but also to ease up on the load put on the engine.

Originally Posted by justinc

Without an EGT gauge you are playing with fire. The degree of smoke you are talking about will equate IMHO to some pretty excessive EGT's!!(Possibly over 800deg if driven like that up long hills.) The fact that the engine alarm went off also means that the heat generated under these circumstances couldn't be lost through the cooling system effectively. As Tank just said, until an EGT gauge is fitted, don't push it that hard or you will risk overheating pistons, damaging exhaust turbines etc etc. One would hope it was set up on the dyno with a Pyrometer, It probably was If TRS did it, they are pretty used to tuning performance vehicles and know about these sort of issues.

JC

What is going on here?

On max acceleration and load it will pump out the smoke as the engine revs are not matching the fuel the injector pump is putting in as you have your foot down saying you want to go faster but gravity/load wont allow you to go faster thus enginf revs wont increase.

Your comment on 108Deg? is that Farenheight? JC should be able to say weather that is ok or not, I have no idea, apparently higu 600's c and early 700's is ok but not much higher.

I take it the 108 was Degrees C and the water temperature..

Originally Posted by Psimpson7

I take it the 108 was Degrees C and the water temperature..

Ok that would make more sense.

The thing is that if you have the money to Dyno it and you have the money to put a bling IC into it then why didnt you fit the EGT guage first and then tweak the pump and then go through fitting a new IC etc.

There are a lot of go faster tweaks that can be done before spending big money and if you just go to the biggest most expensive first then you are limiting what you may get out of it and how much you can spend on other things.

Originally Posted by omvanders

I've just spent an hour or so reading some great info - especially to my less than informed mind re things mechanical - on the Thermoguard.com.au site about egt's, diesels in general, the effects of turbocharging, intercoolers, etc.

Given that I don't have an egt gauge and probably won't be getting one soon because of budget priorities I'm still keen to know what could be happening with my '99 300 TDi under full load.

Last week I had it dynotuned (following the fitting of an upgraged intercooler by TRS, resulting in an increase from 50 to 70kW at the wheels. Needless to say I'm pretty happy with the improved result at the touch of the pedal.

However I need to check out one thing... when ascending a long steep incline (Willunga Hill, SA) I noticed that if I kept the pedal flat to the floor in order to maintain 100km/hr (prior to dyno 80km/hr was the max possible) it was billowing out copious amounts of black smoke, indicating overfuelling if I'm not mistaken and corresponding high egt temps.

I noticed that the black smoke disappeared from the rear view mirror if I backed off just a little on the pedal. Is this normal. Should I be taking it back to be retuned at a slightly leaner setting, or can I safely leave it as is, knowing that overfuelling can simply be corrected by easing off out of the 'kickback' zone of the pedal.

Comments from the mechanically minded and very helpful people of this forum would be much appreciated. Thanks in advance.

Would you be able to scan the Dyno read out or post it up as this sounds like a GREAT mod that we all shouild do to get 20 extra KW?

How much was the ne IC and did you change all the pipe work etc to silicon as well?