TDI, better MPG from hard acceleration?

[Rango318]

I decided to start checking out the load on the engine today. Even at 50% throttle, I hit 80% load. I'm not to worried about it. I plan on putting larger injectors and a tune sometime this year.

[j12piprius]

By the way, as the rpms increase in the EX in 5th gear at a certain % engine load, the instant mpg likewise keeps increasing, meaning the mpg is higher at a higher rpm. I think the reason is because the EX is most efficient (BSFC?) at 5500 rpm.

[ecomodded]

Originally Posted by mcbota

I have made also a chiptuning to my car, an economical one, but I am afraid to accelerate briskly under 1800 rpm, to not provoke some lugging!

You can shift from 1st to 2nd to 3rd to 4th to 5th all within 250rpm if you like, its slow but sure sometimes i do it when I am in slow mode / no rush.
But it seems more load is Better so shifting every 500rpm increase should be more beneficial.

What I mean is you take off in first till you reach 1500rpm shift to 2nd your rpm will be about 1100 then accelerate to 1500rpm,again , shift up to the next gear repeat until your in 5th gear at 1000rpm. You should be able to accelerate from 30mph using 5th gear to what ever speed you require.

I never lug my car , its takes 900rpm to lug mine, at 1000rpm I can accelerate up to speed with no lugging from any gear.

*But* this is more my style then the 80% load theory , my technique is more like 40-50% load.. I can not handle high rpm driving for low speed driving it just seems wrong to me. It might be a mental Block.. but I think high rpm is not the right direction to go for fuel economy.

[ecomodded]

Originally Posted by johnlvs2run

By the way, as the rpms increase in the EX in 5th gear at a certain % engine load, the instant mpg likewise keeps increasing, meaning the mpg is higher at a higher rpm. I think the reason is because the EX is most efficient (BSFC?) at 5500 rpm.

I think your mixing performance and economy up and your mpg gauge is whacked !

As it does not agree with my religion ... . of the snail

[JasonG]

Originally Posted by ecomodded

You can shift from 1st to 2nd to 3rd to 4th to 5th all within 250rpm if you like, its slow but sure sometimes i do it when I am in slow mode / no rush.
But it seems more load is Better so shifting every 500rpm increase should be more beneficial.

What I mean is you take off in first till you reach 1500rpm shift to 2nd your rpm will be about 1100 then accelerate to 1500rpm,again , shift up to the next gear repeat until your in 5th gear at 1000rpm. You should be able to accelerate from 30mph using 5th gear to what ever speed you require.

I never lug my car , its takes 900rpm to lug mine, at 1000rpm I can accelerate up to speed with no lugging from any gear.

*But* this is more my style then the 80% load theory , my technique is more like 40-50% load.. I can not handle high rpm driving for low speed driving it just seems wrong to me. It might be a mental Block.. but I think high rpm is not the right direction to go for fuel economy.

But your waste gate turbo spools differently.
When the skinny pedal is pushed on an ALH the n75 valve commands the vnt to open thereby spoiling the turbo higher.

[oldtamiyaphile]

Originally Posted by mcbota

I try to use the same briskly method of acceleration, since I have discovered this website, but I cannot understand how can be done this under the 2000 rpm. If I have to use around 80% throttle method, then I will reach around 2800 rpm, before I will change the gear, because I cannot accelerate briskly starting form low rpm! So how do I have to do?

I have 455Nm at 2000 rpm so wheelspin is the bigger problem than lugging

I try to keep load at 80% below 1200 rpm, after that it's pedal to the metal. I shift at 2000-2500 rpm, keeps the turbo, egr, dpf etc clean.

[oldtamiyaphile]

Originally Posted by ecomodded

*But* this is more my style then the 80% load theory , my technique is more like 40-50% load..

My SG shows 40% load at idle (neutral), very slow indeed

It takes very little throttle to max out the load gauge at the low RPM of which you speak. I typically cruise at 80% load at 40MPH/ 6th gear.

[ecomodded]

I don't want to be augmentative but I think your scan gauge is misleading you , 1dle is not 40% load

[ecomodded]

Originally Posted by JasonG

But your waste gate turbo spools differently.
When the skinny pedal is pushed on an ALH the n75 valve commands the vnt to open thereby spoiling the turbo higher.

I think my ko3 Turbo spools fast and pushes good psi , on hills it maxes out at 20psi and settles at 15 psi @50mph. I can go from 0 psi to 15 -20 psi in about in a couple of seconds if I floor it.

I found this reference to the ko3 that speaks of it linear and max power and gradual..

Quote from tdi forum:
with the K03 setup its around 275 hp to the crank...... I really like the horsepower curve though as it does not peak early but gradually increases to redline......

[ecomodded]

The ko3 is the better Performing Turbo of the two given my little diesel the advantage / fast 20 psi of boost.


I should take a video of the Boost gauge going from 0-20psi , it seriously only takes about 2 seconds. Using my normal 1/2" of pedal to accelerate it maxes out at 5psi instantaneously or 1/10th of a second.