Author Topic: injectors (Read 3768 times)

turborabbit · « **on:** October 29, 2008, 08:32:51 pm »

Hey, virtual gurus, thanks for the tach tips. Now I need help with my injectors. The engine is a 1.6T diesel out of an '86 Jetta. #2 and#3 are leaking, though I did get 51.7 on the second tankfull. I have some injectors from my other caddys, but they are 115bar and 130bar. My spare 1.6T has 155bar injectors. Can I mix and match? Will I get better or worse economy? Can they be re-built or do I need new ones?? huh? huh? are we there yet??arewethereyet??

jtanguay · « **Reply #1 on:** October 29, 2008, 08:57:00 pm »

i wouldn't mix and match, although the engine would probably still run, it will most likely run rough. however it is better than running with a leaky injector (as a leaky injector can damage the motor severely)

turborabbit · « **Reply #2 on:** October 29, 2008, 09:17:56 pm »

Thanks for the reply. What is the significance of the bar rating??

jtanguay · « **Reply #3 on:** October 29, 2008, 09:28:11 pm »

Quote from: "turborabbit"

Thanks for the reply. What is the significance of the bar rating??

its the pressure at which the injector opens. the higher the pressure, the longer it takes to build, the lower pressure, the less time it takes to build. turbo injectors have higher to ensure a 'safe' atomization with all the boost.

by mixing, you'll be affecting the timing. a few bar difference between injectors isn't so bad, but more than 20 will really make it run rough and 'weird'.

turborabbit · « **Reply #4 on:** October 29, 2008, 09:33:01 pm »

Will the 130bars give me more fuel economy??

cyrus #1 · « **Reply #5 on:** October 29, 2008, 10:36:24 pm »

Potentially they could since it would take less power to compress to 130 instead of 155. It's hard to say if you would actually notice any difference though. I suspect the biggest difference you would see would be from a nice set of rebuilt injectors.

The injector nozzles can be replaced as they are wear items. This is probably a good idea if the mileage is high. If you check the for sale section, there is a group buy for injector nozzles right now.

jtanguay · « **Reply #6 on:** October 29, 2008, 10:54:07 pm »

there was a post done a while back by i think subsonic with regard to pop pressures and fuel economy... and i think that 130 bar was the most economic. higher breaking pressures = parasitic drag. but those pressures are there for a reason. i would love to see experiments of injecting fuel into regular atmospheric pressure, and then seeing the effects of going 10 psi, 20 psi, 30 psi, etc...

beew · « **Reply #7 on:** October 29, 2008, 11:39:53 pm »

a higher opening pressure would reduce the injection period and will also more easily overcome cylinder pressures. im not sure of the effect of this on performance or fuel economy if it is even noticeable.

cyrus #1 · « **Reply #8 on:** October 29, 2008, 11:58:40 pm »

Quote from: "jtanguay"

i would love to see experiments of injecting fuel into regular atmospheric pressure, and then seeing the effects of going 10 psi, 20 psi, 30 psi, etc...

I think it would also be interesting to build a see through pressure vessel for testing injections. Pressurize it to 500 psi and see if the fuel sprays any differently than into the atmosphere. That could get pretty dangerous though. :twisted:

jtanguay · « **Reply #9 on:** October 30, 2008, 01:18:18 am »

Quote from: "cyrus #1"

Quote from: "jtanguay"
i would love to see experiments of injecting fuel into regular atmospheric pressure, and then seeing the effects of going 10 psi, 20 psi, 30 psi, etc...

I think it would also be interesting to build a see through pressure vessel for testing injections. Pressurize it to 500 psi and see if the fuel sprays any differently than into the atmosphere. That could get pretty dangerous though. :twisted:

500 psi hmmm you'd need some diving aparatus or something :lol:

i guess going 10 psi 20 psi or 30 psi isn't going to be the same :oops: i forgot that it needs to be multiplied! so... 14.7psi is normal. now if you go 30 psi, does the compression numbers rise to 1000 psi??? thats pretty insane...

AdAm84 · « **Reply #10 on:** October 30, 2008, 10:55:56 pm »

Quote

500 psi hmmm you'd need some diving aparatus or something

I have some full SCUBA tanks. They are 2250psi :lol:

jtanguay · « **Reply #11 on:** October 31, 2008, 10:00:02 pm »

Quote from: "AdAm84"

Quote
500 psi hmmm you'd need some diving aparatus or something

I have some full SCUBA tanks. They are 2250psi :lol:

so using that, and a small cutout for a sight glass, this could work... BUT i forgot the fundamental flaw... the diesel will autoignite!!! :shock: :lol: unless the air is let cool long enough...

AdAm84 · « **Reply #12 on:** November 01, 2008, 03:43:09 pm »

Yeah slight flaw in the design. But would be cool to see...... from across the shop :lol: