Fuel Injector Spray Pattern

Post Reply
User avatar
75evo
Verde
Verde
Posts: 855
Joined: Tue Oct 11, 2005 8:56 am

Fuel Injector Spray Pattern

Post by 75evo » Sun Feb 17, 2019 10:29 am

Hey Guys,

Have you thought about what injectors to use? I've had problems with the Bosch 947 injectors (4 holes) 24 lb/hr. At 2000 rpm and above it suddenly becomes overly rich and I have to reduce the fuel map by 20%. I then mistakenly buy a set of Dodge Dakota V6 (1998) injectors rated at 21 lb/hr. This one is better. Single hole, disc type nozzle, but the hole was not at the center. Hmmmmm....... so this ran a lot better but requires a LOT more fuel in the map! But it didn't have the problem of going rich at 2000 rpm. But by 4000 rpm I had to have the fuel map at 90, which is almost maxing out the injector. So the flow rate or the nozzle type doesn't seem to work for the 3.2 engine with cams.

I then started to look at other bosch injectors. The CF2 GTV V6s have the EV1 0280 150 701 single hole pintle style nozzle injectors and the 156 GTA has the 0280 156 038 injectors EV4 4-hole disc nozzle. Flow are both about the same. But it looks like the 986 Porsche Boxster has a twin hole design. I think that will spray nicely to the two intake tracts for each cylinder.

If you have a single cone it and stock heads, the spray will hit the separator where the intake tract splits to go to the 2 intake valves. Might be ok for the V6 12V engine. If you modify the heads and re-shape the separator, then a single cone spray might work well. These is just my hypothesis. For a road car, the injector hole numbers (more the better) will be good. It will improve cold start and maybe give a slight advantage in terms of improved mpg. For a track car I don't think there will much of a benefit. Although I just can't think of how a single spray cone spraying into the separator is a good thing.


I have some youtube links below showing why some older injectors meant for 2 valve engines wont work well with 4 valve engines: Remember the 4-valve engines have split tracts once it gets close to the valves.

E30 BMW 2-valve injectors
https://youtu.be/Q87ZVkzTPME

E46 M3 BMW 4-valve injectors
https://youtu.be/hQBkB7YKjzo
105gta.
Gold
Gold
Posts: 65
Joined: Fri Oct 23, 2015 4:15 am

Re: Fuel Injector Spray Pattern

Post by 105gta. » Sat Feb 23, 2019 4:39 am

Hi 75evo. There are many factors that dictate the correct injector for an application as you we discovering, not just flow rate.
I have a few questions which hopefully help you along your path. Are you remapping the factory computer or an aftermarket ecu
How big are your cams, inlet manifold design, system or more importantly injector voltage...
For example. With a different plenum and large cams you may be experiencing a lot of reverberation in the manifold that leads to faulty fuel readings then suddenly things come together and you need to add fuel to achieve the desired afr's
But in reality you were throwing heaps of fuel at the engine of which most was just blowing through...
in my opinion the more holes the better for atomization but you must also factor in injector dead times, spray pattern at certain pressures and voltages etc...
on my 2.5 24v I'm experiencing the exact opposite running the factory 4 hole injectors, I'm reading lean around 2500-3000 but also larger modified plenum and exhuast manifold with bigger cams.
Soo much comes into play when you start getting accurate.
Just some food for thought.
Oh and don't underestimate the smallest of exhaust leaks. And the role it plays on the O2 sensor. Prior and even after in some cases if you're using something decent. The factory spend many hundreds of hours coming up with a base map that will work in most situations but starting from scratch is a real headache if your have even the smallest of imperfections.
User avatar
75evo
Verde
Verde
Posts: 855
Joined: Tue Oct 11, 2005 8:56 am

Re: Fuel Injector Spray Pattern

Post by 75evo » Mon Feb 25, 2019 8:48 am

I'm starting almost from scratch. Got a base map from Beninca.

You're right about the exhaust leak. I read that on another forum about the same thing, even a small leak will have an impact on your A/F. I knew I had a small leak. Even after tightening a loose downpipe bolt and eliminating the small exhaust leak, I had to lean out the mixture by 6-7%.

Now I need to find out what the stumble is at around 1500/2000 rpm. What I need to do is create RPM cells at 1500-2000 rpm in 100 RPM increments and log all the relevant data (MAP, AF, ignition angle, injection angle, charge temp, crank & cam signals), then try to figure out what the problem is. I will send it out to Joe Beninca as well. He's been helping me a lot.
User avatar
75evo
Verde
Verde
Posts: 855
Joined: Tue Oct 11, 2005 8:56 am

Re: Fuel Injector Spray Pattern

Post by 75evo » Sat Mar 02, 2019 7:28 pm

I installed the 832 injectors and the idle is smoother than the 701 injectors. I think my setting with the 832 injectors in the software was incorrect, may have cause that problem where it would stumble. Once I fix my coolant issue, I will put the 832 injectors back in with the correct setting (I think). Also did an engine compression test, all around 220 psi.
Attachments
B1FDC491-CD73-4562-A0F4-99228C9B84BD.jpeg
B1FDC491-CD73-4562-A0F4-99228C9B84BD.jpeg (11.97 KiB) Viewed 539 times
User avatar
75evo
Verde
Verde
Posts: 855
Joined: Tue Oct 11, 2005 8:56 am

Re: Fuel Injector Spray Pattern

Post by 75evo » Sun Mar 10, 2019 9:00 pm

For these injectors to seat properly, you need to shorten the 164 or CF2 injector rail brackets. There are 2 brackets per rail. It needs shortening by maybe 5mm or so. If you don’t, it’s possible that the injectors won’t fully seat and you may have vacuum leaks.
KevinR
Platinum
Platinum
Posts: 309
Joined: Sun Mar 20, 2016 2:46 pm

Re: Fuel Injector Spray Pattern

Post by KevinR » Fri Mar 15, 2019 12:57 pm

And a fire :)
What’s happening with your coolant leak /issue ?
User avatar
75evo
Verde
Verde
Posts: 855
Joined: Tue Oct 11, 2005 8:56 am

Re: Fuel Injector Spray Pattern

Post by 75evo » Fri Mar 15, 2019 8:15 pm

Coolant leak solved.

Put K-Seal, to make sure liner seal leaks are covered. They were probably ok from the beginning
Check compression (all good, 220-230 cold dry), so not a head gasket issue
Oil not in coolant, so not head gasket issue
Opened the cam cover. Found traces of fresh coolant close to the water plugs and studs.
Pressurized the coolant system to about 14 psi. Saw coolant dripping into the cylinder head from 4 studs and 2 water plugs
Undid all the water plugs, all had no washers! Put in copper washers and high-temp sealant.
Cleaned head stud washers and nut surfaces and put sealant on them.
Re-torqued heads to 81 ft-lbs (did not use the angle)
Re-pressurized the system twice. No leaks. So I guess it's ok.....for now.
Post Reply