i was on a mission to find the real truth behind whats available, what works and to see through some of the claims made by tuners. most of the tuners are very critical of other peoples work.
im not interested in pub bragging rights about max bhp figures - what really seems to count is the area under the curve of torque over the normal road driving revs range - no good if you only get power at some ridiculously high revs, or it fades off far too early like the factory setup.
most of this is related to the 2.0tdi 140 and some to the 170, as these are only just being tuned now that the cars are approaching 3 yrs or over.
dyno runs and reading is an art and can be interpreted to give the desired figures so before/after with the same settings is a far better representation of any improvement
ideally engine tuning for the tdi will increase the torque and extend it later in the revs range so the power doesnt drop off after 3500rpm, without losing too much at the bottom end, although the dsg boxes are very low geared for gears 1-3, so a bit of bottom end loss actually makes the car more drivable.
its the torque that breaks things not the bhp. the manual gearbox can handle loads of torque but the clutch may not - the dsg box has proven to handle 400lb/ft reliably so doesnt need any upgrading
tdi behave differently to petrol, they usually have lots of air and are limited by the amount of fuel, so tuning boxes and remapping usually alter the fuel and timing and even remaps dont often increase boost pressures that much. eventually you run out of air, particularly at the top end, so a bigger turbo will keep boost high at the higher revs, enabling more fuel to be added.
because the pd engines cant increase fuel pump pressure, the fuel will be limited by the injector size - in the case of the pd140 the fuelling is probably limited to about 2550hp give or take
options:
1) tuning box - some work as claimed, some dont and they seem to cost between £100 and £500. interestingly one tuner says they dyno'd a box from a very well known supplier for the pd170 and they got 2hp more only!
at least most seem to give 20-30hp gain and are easily reversible
2) flash tuning/reprogramming/chipping
cost seems to be between £300 and £600, some with a dongle to reverse or switch the tuning such as the superchips bluefin and revo sps. gains seem to be genuine upto about 180-185hp, some claiming more. the pd170 responds to about 200-205 but may have problems with the regenerative particulate filter.
3) bolt-on turbo upgrades - these keep the factory exhaust side of the turbo and its combined exhaust manifold but use a bigger compressor wheel to shift more air more efficiently with lower temperatures - commonly a vt20 compressor on the vt17 exhaust wheel. there seem to be main ones, the allard vt2 and the turbodynamics stage 2. allard claim their turbo is good for upto 220bhp, but it uses the factory water/oil/intercooler lines and just needs an exhaust upgrade to reduce back pressure and a remap.
the turbodynamics td2 hybrid is good for upto 240hp says turbodynamics and they have one north ireland tune who regularly gets 240-250 with an aggressive map. approx £2200-2500
4) really big turbos - these need a manufactured exhaust manifold and use a turbo with a much larger ratings - they care more efficient and capable of more top-end power and may last longer because they are not stressed, but as well as the turbo and manifold you also need oil/water/intercooler pipework as well as exhaust and remap so are a lot more expensive, approx £3500-4500
since the injectors limit the power to about 250hp, theres probably no point in going really big unless you are going to add propane or increase the injector size
5) injectors - larger injectors can add more power with a big-enough turbo, but they cost about £1000 and cause poor starting and poor efficiency cos the low revs flow pattern is poorer. economy may 1/2 compared to factory injectors
6) propane injection - this adds more fuel and improves the % of existing fuel thats actually burnt, from about 85% to 95-98%. propane is introduced as a gas in the inlet manifold to replace some air - doesnt involve injectors and you still run mostly diesel.
about 1:4 to 1:5 ratio of propane:diesel is used and it works at all boost pressures and all revs range, but for a big turbo with limited top end fuel will add most power at full throttle and high revs.
you may gain 20-40hp with propane and it costs about £1300 fitted
7) intercoolers - lots of tuners try to sell you a front mounted intercooler with their turbo upgrades, but for the pd140/170 a the factory intercooler is absolutely fine - after i asked them if it really did anything, most said it probably didnt add anything for road use.
currently im using the superchips bluefin and am looking at the turbodynamics td2 with downpipe/exhaust and remap for 240hp or so
im not interested in pub bragging rights about max bhp figures - what really seems to count is the area under the curve of torque over the normal road driving revs range - no good if you only get power at some ridiculously high revs, or it fades off far too early like the factory setup.
most of this is related to the 2.0tdi 140 and some to the 170, as these are only just being tuned now that the cars are approaching 3 yrs or over.
dyno runs and reading is an art and can be interpreted to give the desired figures so before/after with the same settings is a far better representation of any improvement
ideally engine tuning for the tdi will increase the torque and extend it later in the revs range so the power doesnt drop off after 3500rpm, without losing too much at the bottom end, although the dsg boxes are very low geared for gears 1-3, so a bit of bottom end loss actually makes the car more drivable.
its the torque that breaks things not the bhp. the manual gearbox can handle loads of torque but the clutch may not - the dsg box has proven to handle 400lb/ft reliably so doesnt need any upgrading
tdi behave differently to petrol, they usually have lots of air and are limited by the amount of fuel, so tuning boxes and remapping usually alter the fuel and timing and even remaps dont often increase boost pressures that much. eventually you run out of air, particularly at the top end, so a bigger turbo will keep boost high at the higher revs, enabling more fuel to be added.
because the pd engines cant increase fuel pump pressure, the fuel will be limited by the injector size - in the case of the pd140 the fuelling is probably limited to about 2550hp give or take
options:
1) tuning box - some work as claimed, some dont and they seem to cost between £100 and £500. interestingly one tuner says they dyno'd a box from a very well known supplier for the pd170 and they got 2hp more only!
at least most seem to give 20-30hp gain and are easily reversible
2) flash tuning/reprogramming/chipping
cost seems to be between £300 and £600, some with a dongle to reverse or switch the tuning such as the superchips bluefin and revo sps. gains seem to be genuine upto about 180-185hp, some claiming more. the pd170 responds to about 200-205 but may have problems with the regenerative particulate filter.
3) bolt-on turbo upgrades - these keep the factory exhaust side of the turbo and its combined exhaust manifold but use a bigger compressor wheel to shift more air more efficiently with lower temperatures - commonly a vt20 compressor on the vt17 exhaust wheel. there seem to be main ones, the allard vt2 and the turbodynamics stage 2. allard claim their turbo is good for upto 220bhp, but it uses the factory water/oil/intercooler lines and just needs an exhaust upgrade to reduce back pressure and a remap.
the turbodynamics td2 hybrid is good for upto 240hp says turbodynamics and they have one north ireland tune who regularly gets 240-250 with an aggressive map. approx £2200-2500
4) really big turbos - these need a manufactured exhaust manifold and use a turbo with a much larger ratings - they care more efficient and capable of more top-end power and may last longer because they are not stressed, but as well as the turbo and manifold you also need oil/water/intercooler pipework as well as exhaust and remap so are a lot more expensive, approx £3500-4500
since the injectors limit the power to about 250hp, theres probably no point in going really big unless you are going to add propane or increase the injector size
5) injectors - larger injectors can add more power with a big-enough turbo, but they cost about £1000 and cause poor starting and poor efficiency cos the low revs flow pattern is poorer. economy may 1/2 compared to factory injectors
6) propane injection - this adds more fuel and improves the % of existing fuel thats actually burnt, from about 85% to 95-98%. propane is introduced as a gas in the inlet manifold to replace some air - doesnt involve injectors and you still run mostly diesel.
about 1:4 to 1:5 ratio of propane:diesel is used and it works at all boost pressures and all revs range, but for a big turbo with limited top end fuel will add most power at full throttle and high revs.
you may gain 20-40hp with propane and it costs about £1300 fitted
7) intercoolers - lots of tuners try to sell you a front mounted intercooler with their turbo upgrades, but for the pd140/170 a the factory intercooler is absolutely fine - after i asked them if it really did anything, most said it probably didnt add anything for road use.
currently im using the superchips bluefin and am looking at the turbodynamics td2 with downpipe/exhaust and remap for 240hp or so
