My Injector Project and What I’ve Learned

Mr.Bosio, just to make sure we are talking about the same matter: I think you are referring to actual nozzle tip hole angles, which have to be different from the burn marks on the pistons due to angled injector on our 8 valve engines.

At least I was (and I think robnitro was too) referring to those burn marks as they tell where the fuel actually is while combusted. From those burn marks it's easy to see that even though those 2R520 nozzle tip holes are targetted to give even fuel distribution, they aren't doing so if you look it from the piston's view.

2R520 gives ~70% of its fuel to 10-2 o'clock position (that's only ~1/3 of the piston area). That's the blue box on the picture.



These pictures don't represend actual nozzle holes, but actual burn marks on the piston. 2R520 has burn marks like the left one, but should be more like the one in the middle to share heat load more evenly over the piston. The right one (=septagon) is not bad, but not ideal for our pistons as they are asymmetric.

I do understand that it's harder for the fuel to take 90 degree angle than 30 degree angle when it travels through the nozzle, but can't that be taken care with the hole sizes so that 90 degree hole is larger than 30 degree one?

I think what Bosio is saying is that the holes at the top are purposefully more and larger and the lower ones less also on purpose. It seems that they intended on reducing crown heating at the weak part of the piston by reducing overall fuel spray in this area. Makes sense on paper. Though, it seems in practice(at least for many who have tried them) that this doesnt work out for power vs smoke.

The "Ideal" 7 hole will not work with an offset combustion bowl in the case of the VW TDI without a centrally located bowl like the CRI version.

The 7 Hole R520 is the best option to provide optimal heat distribution accross the piston. Using the 7 sided septagon would overheat one side of the piston bowl.

Another issue is setting the pressures and the trigger points for opening. If you delay the secondary pressure this can cause the injection to occur slightly later and you will have more fuel burning out of the bowl and lose combustion efficiency by losing the benefit of the high speed swirl while in the bowl. Once the piston moves downward the vortex rapidly loses its velocity and the mixing efficiency of the burning fuel and air are rapidly lost.

the middle one you draw doesn't correspondent with the 2R520 hole location..

mrchill said:

I think what Bosio is saying is that the holes at the top are purposefully more and larger and the lower ones less also on purpose. It seems that they intended on reducing crown heating at the weak part of the piston by reducing overall fuel spray in this area. Makes sense on paper. Though, it seems in practice(at least for many who have tried them) that this doesnt work out for power vs smoke.

Click to expand...

I fail to see this sense even on paper. Our piston crown is weaker from the 6 o'clock side, but not that much weaker. Now ~70% of the fuel is targetted to less than half of the piston crown (yes, it's the stronger half, but not that much stronger). It may also be that burning fronts (the outer edge of the fuel squirt which vaporizes and starts to burn) are so close to each other in the upper half of the piston, that they have no air available to burn efficiently. They overlap and "rob" air from each other, which is the reason for less power vs. smoke.

This should be an easy fix for the manufacturer (Mr.Bosio?)? I still think that seven smaller holes is better than five bigger ones and total flow can be even increased with increased hole number (5 vs. 7), but some re-engineering could be needed here.

I'm more than happy to try out these re-engineered ones on my engine...

Drivbiwire said:

The "Ideal" 7 hole will not work with an offset combustion bowl in the case of the VW TDI without a centrally located bowl like the CRI version.

The 7 Hole R520 is the best option to provide optimal heat distribution accross the piston. Using the 7 sided septagon would overheat one side of the piston bowl.

Another issue is setting the pressures and the trigger points for opening. If you delay the secondary pressure this can cause the injection to occur slightly later and you will have more fuel burning out of the bowl and lose combustion efficiency by losing the benefit of the high speed swirl while in the bowl. Once the piston moves downward the vortex rapidly loses its velocity and the mixing efficiency of the burning fuel and air are rapidly lost.

Click to expand...

I agree about the middle one being pretty close to ideal for our asymmetric piston. But I think you made an error naming that 2R520. IMO 2R520 is closer to my drawning (I know it's bad ):



Also those triangles in the middle picture should be all same lenght and width (even my red ones are too long and they should be as long/wide as the lower blue ones) as you don't want your fuel to hit the bowl wall. We can't use all the piston crown for distributing the fuel, just the bowl.

Here we see 6 hole symmetrical bowl loading in off centre bowl; engine is 2.5tdi 10v

Hello,
digging up this topic ...

There is also nozzles motor VP with a 0.260mm bosch, that has the same specs that the 520 RACE?

Greetings

R520's are .240 IIRC

Holy crap that took some reading and I'm still none the wiser lol. I think I'll stick to pimping my car

Read thru the posts. Just getting ready to get some PP764's and now I want a set of your Bosch injectors. Email me back with a website, email address and price.
Thanks much - Frank

hi Frank,

sorry nothing yet at this time. after waiting over a year for a turbo solution my car is in the shop and should be done in a couple days. then i can resume my testing at which point i'll still be a ways out before i make more units for sale. so far so good but i need to finish the last round of testing on my own car.

Not a year waiting for my kit! Only a few weeks! Just thought id clear that up, haha!

yes ryan you are correct. it was another kit i gave up waiting on