Real-world data, ain't it great?
KERMA ( http://www.kermatdi.com ) supplied me with a set of his Bosio POWERPLUS 357 nozzles so that we could see what the story really is. The PP357s are the "similar-class" replacements for the stock 0.184 manual nozzles. Bosio claims a slight fuel flow increase and a slight mileage increase.
So what's the real story? Here it is...
Two sets of dyno runs were made with my 2001 5-speed Golf with stock chip. The first dyno was with the stock nozzles with approximately 35k miles and the second was with PP357 nozzles with approximately 500 miles. The only mods to my car are the VagCom EGR adaptation and a Dawes device to limit boost spikes. Stock airbox, OEM paper air filter, snorkel with screen in place.
I feel that my old nozzles, although having 35k miles, were still in good shape. Mileage has been consistent (I got 62mpg at the TDIFest mileage rally on ~B80 about 5k miles ago) and my stock dynoplots correspond with other stock plots. So any differences due to the age of the nozzles (old vs. new) shouldn't be too significant.
Atmospheric conditions during the two sets of runs were VERY close. 1-3*F difference in ambient temp, and 0.15 in-HG difference in barometric pressure.
Fuel used is standard Atlanta diesel on both runs. The stock runs were with standard dosage of PS Diesel Kleen, and the PP357 runs with standard dosage of PS Diesel Fuel Supplement.
Gary Miyakawa was present for both sets of dyno runs and he lent his RPM measurement equipment. Thanks to him for his help.
All runs were in 4th gear.
So... here's the data:
First, stock nozzles without dawes versus PP357 nozzles without dawes. 002 is stock/no dawes, 005 is PP357/no dawes.
Max increase over stock is 9 HP and 15 lb-ft. That's approximately a 10% increase over stock in both values. Also notice that the power increase is across the board. This results in a nice, even increase in power at all speeds and throttle settings.
Now, let's look at the PP357 nozzles with and without the dawes device. 005 is PP357 without dawes and 007 is PP357 with dawes.
Peak power's about the same, but I gain about 4 lb-ft of peak torque. The big thing here, though, is the shape of the curve. While doing the dyno run without the dawes, boost spiked to 18psi, undershot to 12psi, and finally settled to constant 14-14.5 psi at around 3200 RPM. WITH the dawes, boost spiked to 16psi, and barely undershot before immediately stabilizing at 14-14.5 psi.
Note that both plots are identical above 3200 RPM... both configurations have steadied out to 14-14.5 psi by that point. Now compare the responses between 2000-3200 RPM... the no dawes run (005) has two dips... the first comes from the overshoot (turbo is being driven higher than it needs to be... power is taken away from the wheels to drive the turbo), and the second from the undershoot (lower boost means lower MAF reading, and the smoke map cuts fueling).
So... conclusions?
Upgrading from stock nozzles in a manual to the "similar-class" POWERPLUS nozzles will give you approximately 10% increase in peak power and torque, and will give you MORE power across the entire operating range of the engine. Results in an automatic using the smaller POWERPLUS nozzles should be similar. With the nozzles (and with even bigger nozzles and with chips or tuning boxes), the Dawes device not only limits boost spiking, but makes more power available to the wheels during turbo spool-up.
Qualitatively, I definitely felt a little more power after about 50 miles with the new nozzles in. I get NO visible smoke at all, even WOT at night with lights behind me. I would recommend doing the VagCom EGR adaptation if you go to bigger nozzles to make sure that extra air is available in part-load situations.
Discussion?
(edited to change topic name)
<small>[ February 03, 2003, 12:31: Message edited by: DavinATL ]</small>
KERMA ( http://www.kermatdi.com ) supplied me with a set of his Bosio POWERPLUS 357 nozzles so that we could see what the story really is. The PP357s are the "similar-class" replacements for the stock 0.184 manual nozzles. Bosio claims a slight fuel flow increase and a slight mileage increase.
So what's the real story? Here it is...
Two sets of dyno runs were made with my 2001 5-speed Golf with stock chip. The first dyno was with the stock nozzles with approximately 35k miles and the second was with PP357 nozzles with approximately 500 miles. The only mods to my car are the VagCom EGR adaptation and a Dawes device to limit boost spikes. Stock airbox, OEM paper air filter, snorkel with screen in place.
I feel that my old nozzles, although having 35k miles, were still in good shape. Mileage has been consistent (I got 62mpg at the TDIFest mileage rally on ~B80 about 5k miles ago) and my stock dynoplots correspond with other stock plots. So any differences due to the age of the nozzles (old vs. new) shouldn't be too significant.
Atmospheric conditions during the two sets of runs were VERY close. 1-3*F difference in ambient temp, and 0.15 in-HG difference in barometric pressure.
Fuel used is standard Atlanta diesel on both runs. The stock runs were with standard dosage of PS Diesel Kleen, and the PP357 runs with standard dosage of PS Diesel Fuel Supplement.
Gary Miyakawa was present for both sets of dyno runs and he lent his RPM measurement equipment. Thanks to him for his help.
All runs were in 4th gear.
So... here's the data:
First, stock nozzles without dawes versus PP357 nozzles without dawes. 002 is stock/no dawes, 005 is PP357/no dawes.
Max increase over stock is 9 HP and 15 lb-ft. That's approximately a 10% increase over stock in both values. Also notice that the power increase is across the board. This results in a nice, even increase in power at all speeds and throttle settings.
Now, let's look at the PP357 nozzles with and without the dawes device. 005 is PP357 without dawes and 007 is PP357 with dawes.
Peak power's about the same, but I gain about 4 lb-ft of peak torque. The big thing here, though, is the shape of the curve. While doing the dyno run without the dawes, boost spiked to 18psi, undershot to 12psi, and finally settled to constant 14-14.5 psi at around 3200 RPM. WITH the dawes, boost spiked to 16psi, and barely undershot before immediately stabilizing at 14-14.5 psi.
Note that both plots are identical above 3200 RPM... both configurations have steadied out to 14-14.5 psi by that point. Now compare the responses between 2000-3200 RPM... the no dawes run (005) has two dips... the first comes from the overshoot (turbo is being driven higher than it needs to be... power is taken away from the wheels to drive the turbo), and the second from the undershoot (lower boost means lower MAF reading, and the smoke map cuts fueling).
So... conclusions?
Upgrading from stock nozzles in a manual to the "similar-class" POWERPLUS nozzles will give you approximately 10% increase in peak power and torque, and will give you MORE power across the entire operating range of the engine. Results in an automatic using the smaller POWERPLUS nozzles should be similar. With the nozzles (and with even bigger nozzles and with chips or tuning boxes), the Dawes device not only limits boost spiking, but makes more power available to the wheels during turbo spool-up.
Qualitatively, I definitely felt a little more power after about 50 miles with the new nozzles in. I get NO visible smoke at all, even WOT at night with lights behind me. I would recommend doing the VagCom EGR adaptation if you go to bigger nozzles to make sure that extra air is available in part-load situations.
Discussion?
(edited to change topic name)
<small>[ February 03, 2003, 12:31: Message edited by: DavinATL ]</small>
