[i30niko]

Hi guys,

Done 10,000k on the auto i30 diesel. I have noticed when I overtake and push the car for example doing 90km/h and then downshift to 3rd gear and overtake while RPM from 2000 to 3500 I can see white smoke coming from the rear view mirrors.
I know the diesels if pushed do not burn fuel as well resulting in black shoot (as evident mostly in trucks etc).

Any ideas as to when I should start worrying?

REGARDS

[Dazzler]

Gee I'd be a bit worried if your mirrors are smoking 

But seriously I don't think I remember any smoke from our CRDi when accelerating 

I think that needs investigating 

[peon2t]

I haven't noticed anything like this on my i 30. But it also wouldn't come to my mind to downshift into 3rd gear when doing 90 km/h...

[FatBoy]

I haven't noticed anything in the i30 like that, but I have noticed the wife's Terracan "puff" black smoke occasionally (usually going up hills when it downshifts).  I'd get it checked out by a mechanic. 

What revs does the engine get to when it dumps to third?  Remember that the diesel doesn't work like a petrol engine, the more you rev it, the less power and torque you get.

[constipated]

I commonly see some smoke if accelerating vigorously from an intersection even with revs only 3000rpm or so. I think it depends on throttle position. It's not that the vehicles behind are shrouded in smoke, but usually at night I notice the smoke by its effects on the headlights behind.

Some diesels are worse than others, I know the Ford Territory diesels look awfully dirty to me. Even routine acceleration at traffic lights causes smoke.

[FatBoy]

..... even with revs only 3000rpm or so.

3000 rpm in the i30 CRDi is fairly high.  Torque drops off at around 2700 or so.  Go much above that and you are losing efficiency (which could be the smoke behind).

It is nice to drive getting the most out of it though!!

[constipated]

..... even with revs only 3000rpm or so.

3000 rpm in the i30 CRDi is fairly high.  Torque drops off at around 2700 or so.  Go much above that and you are losing efficiency (which could be the smoke behind).

It is nice to drive getting the most out of it though!!

A bit off topic but I've often wondered what is the best strategy for optimal acceleration. I know it is a factor of rpm as well as throttle position.

I know max torque is from about 1900-2700. But max power is not till 4000rpm. Max power is where I believe the most "work" ie things happen the quickest.

Is it faster to accelerate by changing gear early and use the max torque from 1900rpm but with more throttle so things happen quickly

OR

Is faster acceleration gained by operating in the higher rev range 2500-4000rpm where the turbo is spinning fastest and you may not need as much throttle?

I know Alan Ho did some acceleration tests where he matched the claimed 0-100km/h acceleration stats. I wonder what strategy he used?

[Phil №❶]

There wouldn't be too many members suggesting that 4k RPM is a good place to be in a diesel engine, certainly not me, i30RSA maybe. 

[The Gonz]

I do all my driving between 1500 and 2000. Some gear changes might swing into the 2K+ but not for long. I aim to stay sensible and have it last. 

[Doggie 1]

I do all my driving between 1500 and 2000.

But what if you need to go out earlier in the day or after 2000 hours? 
Do you have a driver?

[The Gonz]

But what if you need to go out earlier in the day or after 2000 hours? 
Do you have a driver?

[FatBoy]

I do all my driving between 1500 and 2000.

But what if you need to go out earlier in the day or after 2000 hours? 
Do you have a driver?

 

[The Gonz]

I'd like to issue a lame retort like "Laugh it up, FatBoy" but it sounds like some famous quote. Anyone know the origin?

[Shambles]

You leave Bushy Boy out of this

[constipated]

I do all my driving between 1500 and 2000. Some gear changes might swing into the 2K+ but not for long. I aim to stay sensible and have it last. 

I'd challenge anyone to keep up with Sydney Traffic in a CRDI without going >2000 rpm in 1st or 2nd. People behind you just wouldn't be appreciative.

By no means do I rev the car to 4000rpm but by the same token, it's quite common for me to go to 2700-3000rpm in 1st or 2nd.

[The Gonz]

The joys of NOT driving in Sydney 

[Asterix]

You sure won't hurt your engine by revving it up to 3500-4000 now and then, but no need to do it every day.

I find a quick acc is easy done by revving up to 3000-3500.

[i30sean]

I give mine a good rev normally when joining a motorway up to 4-5K through the lower gears and I also see a little smoke out the back, I think when you are poodling around at 1-2K it does it good to clear it out. My 2010 Crdi puffs out more than my 2011 Crdi does.
i30Sean.

A bit off topic but I've often wondered what is the best strategy for optimal acceleration.

Maximum torque revs are where best efficiency occurs; where the engine is extracting the most energy out of the fuel burnt. Maximum power revs are just that, the revs where the engine is creating the greatest force.

Torque and power are two different measures of the same output. Torque is the strength of the crankshaft twist. Torque does not consider revs directly although of course it varies with revs. Think of an arm wrestle, plenty of strength but insignificant movement - this is torque. Torque by itself does not adequately describe the engine output as its power clearly increases with revs, even when the torque is reducing, simply because there are more explosions per unit time. So power and not torque is generally the more useful measure. Power is effectively derived by multiplying torque by revs.

Looking at the power curve can predict where you ought drive for maximum acceleration.  The band between maximum torque and maximum power is close to where your best option is. So rev out to and change up at max power and the revs should then drop to somewhere near or above max torque. Repeat.

In our diesels the turbo modifies the torque/power curves greatly and the point of maximum power is so broad making it redundant to rev all the way out. You only need to rev out to a point that allows the lower revs (after the change up) to still stay in the power band (not below 2-2.5k say).

[Asterix]

Great post.


Thanks Pip. 

[i30niko]

I haven't noticed anything like this on my i 30. But it also wouldn't come to my mind to downshift into 3rd gear when doing 90 km/h...

Actually yeah it would downshift to the 3rd gear by itself anyway.....uphill motorway 100km/hr speed limit, so doing 90 and accelerating so
I can overtake. As soon as the engine jumps from 2000 revs to around 3000 it downshifts to 3rd gear (Mind you I do not have the throttle
floored - probably around half way) it starts smoking - Mostly evident at night as someone mentioned above (from the headlights of cars behind me).

Also I found it smokes sometimes on traffic lights when taking off (again not full throttle and evident at night).

[i30niko]

 

What revs does the engine get to when it dumps to third?  Remember that the diesel doesn't work like a petrol engine, the more you rev it, the less power and torque you get.

In a ~10% uphill from 90km to 100km overtake from around 2000Revs it downshifts to 3rd gear and the revs reach 3000 so I can overtake. (This is on the 4 speed auto btw). I try not to go more than 3000-3500 revs anyway on the diesel, but I was surprised by the smoke because I wasn't even pushing so hard (throttle about half way pressed) and I thought a diesel would have more than enough power to overtake uphill.........

[Phil №❶]

All diesel engines without DPF are certainly capable of producing smoke. Usially, black smoke is an indication of injector problems, (correct me if I'm wrong Kom). As good as fuel injection / ECU's are, downshifting is causing havoc with many components all at once, (which is acceptable and what they are designed to do), let's see

-throttle position changes, change and rate of change goes to ECU for increase of fuel algorithm.
-ecu calcs new fuel injection quantity required based on engine revs, load and turbo VVT settings  & injection timing is then altered.
-egr valve does something.
-VVT turbo is altered.
-trans downshifts, which in turn alters all of the above.

There's probably a lot more too, like air temp & pressure monitoring etc.

All this is happening multiple times per second.
Diesel oil, unlike petrol is harder to ignite and burn.
All engines, in order to produce power, must have a higher fuel ratio, higher than the engines Stoichiometric ratio.

All these things add up to some smoke IMO.

[sootytorques]

You sure won't hurt your engine by revving it up to 3500-4000 now and then, but no need to do it every day.

I find a quick acc is easy done by revving up to 3000-3500.

Agree 110%,diesel's need to be worked hard, im no boy racer, but regularly bounce mine of the rev limiter &  have done from day one, BTW never used a drop of oil unlike our other I30 diesel that was driven gently from day one, personal choice i guess.

[rustynutz]

 

Good luck with doing that, diesel's aren't designed for that sort of abuse..... 

[The Gonz]

I worked a 1.5 ton Diesel which was armoured to 4.5 tons very hard every day in a dangerous and dirty place. Not because it was good for it but because it was necessary. I wouldn't be tracking that particular vehicle at any auctions any time soon