Pintle of injector

[Draco]

Some backround for those that did not read about it in club lounge...

I baught side feed 370cc side feed injectors from 300sx, when I removed it from the rail one injector pintle broke off, the point coming out of the nozzle forcing the spray pattern.

I have checked the net a few times because I was worried when this happend by mistake and could be bad coz the injector is screwed, all I could find is that the broken pintle increases flow rate and changes the pattern, there is many opinions on the net about what pattern is the best, till now some say more misty others say more streamy....

All I can say is the operation of the injector is still the same, it opens and closes the way it should, the only diffs is the spray pattern and the flow rate increasing....

I have not done this with all the injectors, so if you PFB or any one else can give me a solid fact based proven answer why this is bad, please let me know.....

[jon]

I'd like to see a comparative test on a proper injector testing machine thingy, one broken injector and the other not. Should be interesting to see the results.

[Draco]

What they do on a flow bench is connect the enjectors to a flow test machine....like dicktator....then they have marked containers showing the cc level per interval, normally they make one interval 30sec.

I don't have a flow bench, I used another method, my injectors are high impedience and opens with a 12v charge, so I took a normal injector mounted in my fuel rail, held it over a bottel so that no petrol is messed, connect 12v to the injector and took the amount of petrol sprayd in the bottle over 10 seconds, obviously the fuel lines had to be primed and petrol pump pumping(egnition on). I marked the amount on the bottle.


Then I took the injector with the broken pintle and put it in the fuel rail, did the same test, I found the spray pattern was less misty and obviously the flow was much stronger resulting in more flow, much more than the previous injector that had the pintle, there were no leaks through the nozzle, it opened and closed as soon as I applied 12v or removed it.

Also did it with old injectors, same thing...

So my finding, when the pintle is broken "opening" the injector nozzle, it altered the spray pattern to a steadier stronger "stream" and with an increase of flow.....

[Pinkfluffybunnys]

The machine doesn't measure atomization the single most important part of an injectors fuel delivery and it doesn't pulse the injectors at different duty cycles where the motor spends 99% of its life.

The test is is not really valid the pintel is there to help atomization removing it is crazy. Also injectors and atomization are chosen by the manufacturer and tailor for the spicific motor. pintel injectors like we have are valued for both good atomization and fuel delivery that why 70% of injectors are pintel

[Draco]

Thanks PFB, the atomazation is basically my only worry.....but now I want to ask, in cases where you add extra injectors(like Gary and Gremlin) the atomazation is influanced by the volume of petrol now injected.....

Even though the fuel is atomized, adding more fuel decreases the atomazation, it doubles it, the same with bigger injectors, atomazation is there but because of the amout of fuel injected it has the same effect as "hosing" stream or flooding into combustion chamber, now I can understand that if a car is set up for a certain amout of fuel and a bigger injector is used or lets say the pintle is stuck on open, it still atomizes the fuel but it is "hosing" the combustion chamber causing more carbon build up because of not being able to burn all the fuel.

If you then retune the car allowing more air for combustion, the mixture is praportionally adjusted, resulting in proper combustion.

The internet says the pintle is in use for 2 reasons, atomization and getting the requiered flow rate for the injector.

Now, as I said, or tried to say is the pintle is still there, it is only broken off inside the orifice, so there is atomazation, it is just not the origenal "pattern", the flow rate increases because of the point of the pintle does not regulate the flow rate as it should, therefore the fuel is exiting the orifice with more pressure, granted not as atomized as requered but still not one steady stream.

In the end, I am in the middle of a rock and a hard place, one injector is like that, I can not change that because of the accidental breakage, I am sitting now with a situation where 5 celynders are getting less flow rate with more atomazation and one with more flow rate and less atomazation.....this means no matter how well the engine is tuned, there will always be a open loop and one celynder will over fuel causing accesive carbon build up which means failier at some stage.....

the best thing to do is tho get another 370cc side feed fuel injector
that is basically impossible.....unless you import which will work me out well over R1000, I don't have that at the moment.

Now, I have found the VG30 n/a side feed fuel injectors, which is redaly availible at scrap yards, but only flows 170cc, I took these and tested what happened when I puposely broke off the pintle, they all brake off just inside the orifice, creating a less atomized but still atomized pattern but more flow.

Even though the 170cc flow more, it is still not enough for the turbo VG30,
now logic tells me, I have a few choices, put in to small injectors and my turbo z can not boost safely without damage, useless, let the car park off for a very long time because my money will go towards my baby expected in July and all needed after birth, so lets say maybe next year, useless, or I do the same with all the injectors, retuning the car, which I have to do anyway and drive it like that till I can buy 6 bigger working injectors(importing will cost me a pretty penny so that will not happen very soon), or going for a top feed fuel injector setup, which is not only very difficalt because of space issues with the design of the plenum but will also cost me thousands....useless....

So in the end all I can do is try and get all injectors in the same cind of condition.....although it is not recommended, I am forced to tread along the unwalked path.

[Pinkfluffybunnys]

It’s your motor I would save up and buy the right stuff hill billing your injectors if not the way to do things and they are one of the most critical items in your motor.
Fact is the pintel end is used to cone and atomize the fuel by removing it you will get uneven burn in the combustion chamber resulting in lean spots and making the motor prone to detonation, also possibly bore wash adding to the fun also the car will lack power and any type of fuel economy the part was placed there by the manufacture for a reason.

It’s risky and I wouldn’t do it at all.

PS I have 6x injectors for sale they are top feed but you could convert to top feed or just convert and buy two sets of CA18DET injectors or what ever but R1000 for injectors is nothing. Speck to Ian or jerry they might have old SR or Rb injectors injectors. If RB25SX take my set of 6x440cc he might be selling his 6x370cc side feeds

[Guy]

Fact is liquid petrol doesn't burn, its the vapour that burns. Hence the petrol has to be atomised. Any excess liquid petrol that makes it into the cylinder will not burn completely and will in all likelyhood wash the oil from the cylinder bores causing excessive cylinder wear.

I think subarus have side feed injectors, since they're reasonably common you may be able to source an injector from a subaru, if its the correct size etc.

[Draco]

As I said, saving up is hard to do, I am not willing to let a car stand for over an year that I just paid 26K for and fitted new tyres and and and....

I also said converting to top feed is a problem because of space, my injectors sit underneith the plenum, a top feed injector with a fuel rail do not fit, no space, the other problem is impediance, Hi have high impediance, converting won't cost an arm and a leg but still is a problem. I also said it will cost to much, R1000 for injectors, plus a fuel rail....don't have the money, that means the car will stand.....

SR and RB type injectors do not fit in the zx rail.

[Pinkfluffybunnys]

My SX stood for 5 month 3 weeks after I bought it and I paid R 50-000. Your risking your motor here.


“IF” RB25SX take my injectors or some one else’s and converts over I’m sure he will sell the fuel rail and the RB25 injectors are high imp also the SR injectors are high imp

[Draco]

RB engines and V engines are not the same, RB's run the injectors all one side, I have 3 one side and 3 the other.....

There is a big diffs between 5 months and the car standing for over a year, the point is I am not willing to let it stand, I have spent enough time without my sx, the passion will not allow me to wait....waiting is not my best atrebute....

Thanks to the guys that gave me info, I will do some more tests with the old injectors to determain whether the spray pattern will be a huge problem.

[Draco]

Fact is liquid petrol doesn't burn, its the vapour that burns. Hence the petrol has to be atomised. Any excess liquid petrol that makes it into the cylinder will not burn completely and will in all likelyhood wash the oil from the cylinder bores causing excessive cylinder wear.

I think subarus have side feed injectors, since they're reasonably common you may be able to source an injector from a subaru, if its the correct size etc.

Thanks Guy, makes sence.

still now I wonder....



Mine sprayes like the one on the right, it is not as well atomized as the other 2, yet these injectors are used, specially in high flow needs.....why will mine not work?

Thanks I know about the subaru injectors, have tried finding that aswell....have not been lucky yet....

[Draco]

the Lucas disc's spray pattern is a laser narrow beam and not the fan shaped dispersed mist like pattern that you see on the OEM pintle nozzles. The throttle response and idle quality ironically suffers though with the laser beam spray pattern. The Bosch disc nozzle has the same spray pattern (i.e. fan-shaped or cone-shaped) as the OEM's making it "better" for street applications in terms of atomisation at part throttle and for emissions.
The laser beam is good for race engines and engines using the fuel to cool the intake charge and the valve face backing to disperse the fuel.

[Draco]

It's a known fact that you can't burn fuel until it's atomized. It's also known that you can't burn fuel without air. The most important, of all known facts is that you can't burn anything, if it's not in the combustion chamber. The secret is to provide adequately atomized fuel with as much air as possible. Adequately atomized is the Secret Word of the day. Fuel does not have to be completely atomized at the injector tip (SMD of 10um - 20um) but it does have to get past the valve to do us any good. The more condensed the fuel delivery is the faster it will travel, (regulated by discharge area and pressure) and the more accurately it can be targeted. Resent (S.A.E.) "Injector Atomizing and Targeting" studies have provided us with one of the most prominent advances in High Performance Engine Management. These test programs have concluded that "accurate impingement onto the center of the valve head is vital for good vaporization" and "The targeting orientation of the injected fuel spray is a critical parameter in fuel evaporation" also that " Fuel injected directly onto the intake valve yields a significantly better engine response" (SAE950506) What all this means is, different engine designs require a different type of injector to operate efficiently and that 100% atomization is not always required or desired. In racing situations we usually have to do the best we can with what we have, or what's available

The Lucas injector maintains its pattern, cycle to cycle, the best under varying pressures and pulse widths. Diffuser/Pintle injectors have a rather tight, wetter pattern (more coalescence) than single discharge injectors. This is evidently caused by the impact of fuel on the diffuser surface causing the fuel to partially recollect. This provides a more concentrated liquid volume flux at the center of the cone, a tighter pattern angle, and a more accurate targeting capability

At 8000 RPM the intake valve is opening and closing at 66 times a sec. and is only open for an average of 9 Mil/Sec. At this cyclic rate the transient time to complete the delivery of fuel, from injector to valve, is critical. This is why; Indy car injectors are very precisely targeted and timed to provide a solid stream of fuel with non-existent atomization, LBDS, "Laser Beam Delivery System". In these engines the injectors can discharge fuel, at a "just prior to valve -open position", and get it all down the hole. As the fuel impinges the hot intake valve it virtually vaporizes and mixes quite well with the incoming air forming a very homogenous charge. This is one of the most extreme situations but it's a real interesting one. As an added benefit, the latent heat of fuel vaporized in the chamber also provides charge cooling that makes the mixture denser. A denser, heavier mixture (cold and thick) will produce more power then a thin (hot and light) charge. This is why Turbo intercoolers are so effective

[Guy]

While the Lucas type does have a tight stream it is probably more atomised than a pintle type with the pintle broken off.
To me it just doesn't seem good to be shooting a jet of fuel like that into the manifold. Have you checked with some of the places that refurbish/clean injectors, perhaps they would be able to disasemble your injector and replace the pintle with one off another non-working injector? If thats at all possible, I've never looked at disassembling an injector before.

[Draco]

While the Lucas type does have a tight stream it is probably more atomised than a pintle type with the pintle broken off.
To me it just doesn't seem good to be shooting a jet of fuel like that into the manifold. Have you checked with some of the places that refurbish/clean injectors, perhaps they would be able to disasemble your injector and replace the pintle with one off another non-working injector? If thats at all possible, I've never looked at disassembling an injector before.

I have tried and so far failed.....none of them indicated that the pintle can be replaced.....

Guy, I understand what you are saying, but please remember, I tested the injector and it is by no means just shooting a jet of fuel.....