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Injector basics for LSJ

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Injector basics for LSJ

Old 01-21-2015, 11:45 PM
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Lower pressure helps with idle. If he runs out of fuel up top he can up it, but why not start low for a clean idle and see what it needs.
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Old 01-21-2015, 11:54 PM
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Originally Posted by ThexGovenor View Post
Lower pressure helps with idle. If he runs out of fuel up top he can up it, but why not start low for a clean idle and see what it needs.
Higher pressure assists in atomization, thats the sole purpose behind alot of these new injectors in new cars running pressures upwards of 100psi from the factory. That's the only reason I question dropping the fuel pressure from stock. Not saying its optimal for all injectors, but these newer style bosch injectors are designed for it. Older EV1 style injectors depending on the design, hate higher fuel pressure and will actually stop operating under certain high pressures.
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Old 01-22-2015, 12:46 AM
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I gather that the purpose of the BRFPS and the lower pressure on the LSJ was originally because the injectors "we" were using had crappy minimum pulse width characteristics, compared to what the LSJ was going to use, so the idea was to decrease pressure at low rpm specifically to increase pulse width.

Make the injectors happier, get better low rpm behavior

nowadays moving to an injector that has "better" minimum pulse width characteristics would render the "need" for the lower base pressure moot. the better atomization should lead to less fuel consumption / lower pulse width needed per rpm.
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Old 01-22-2015, 01:49 AM
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Originally Posted by wayfarer View Post
I gather that the purpose of the BRFPS and the lower pressure on the LSJ was originally because the injectors "we" were using had crappy minimum pulse width characteristics, compared to what the LSJ was going to use, so the idea was to decrease pressure at low rpm specifically to increase pulse width.

Make the injectors happier, get better low rpm behavior

nowadays moving to an injector that has "better" minimum pulse width characteristics would render the "need" for the lower base pressure moot. the better atomization should lead to less fuel consumption / lower pulse width needed per rpm.
yes exactly, which the newest generation of bosch injectors should be more then happy to provide. The injectors that the LSJ uses stock and for the stage upgrade are honestly, surprisingly older style injectors. Multec injectors well... not sure why anyone would buy those. Multec's are notorious for locking up at high pressures. But yeh your right, alot of those older styles have issues with low pulse widths. That's also the reason why i tell people not to over injector for (room to grow) so that you dont run into that. No reason to run a 1000cc injector in a car making 300hp and running it up to 30% pulse width.

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Old 01-22-2015, 10:31 AM
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Precisely why I am taking the Mototron 80's out and putting the Bosch "60's" in.
Well, that and my lack of knowledge on scaling a tune.
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Old 01-23-2015, 10:42 PM
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Originally Posted by Spawne32 View Post
Higher pressure assists in atomization, thats the sole purpose behind alot of these new injectors in new cars running pressures upwards of 100psi from the factory. That's the only reason I question dropping the fuel pressure from stock. Not saying its optimal for all injectors, but these newer style bosch injectors are designed for it. Older EV1 style injectors depending on the design, hate higher fuel pressure and will actually stop operating under certain high pressures.
Interesting. All the work Ive done is on the older style so the info is out of date. Good correction. As for scaling a tune its not too hard. The hardest part is the timing table.
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Old 01-23-2015, 10:56 PM
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That's the part I need to learn. I've searched for tutorials but can't find one.

I started putting together a new base tune for the 80's, but quit working on it in favor of the Bosch's.

I'd still like to learn the process
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Old 01-24-2015, 01:46 AM
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Lets say you are scaling it in half, you cut airflow in half and adjust from there. You also have to cut all timing in half and work up from there till you knock. More in depth but thats the basics. Also cut injector flow in half.
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Old 01-24-2015, 02:06 AM
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Canada Spray patterns

Spray patten,fuel droplet size and spray angle is very important.
Almost as important as the quantity of fuel delivered in cc/min or grams/sec..

All of these criteria have to be in close sync,to produce a near ,to perfect balanced fuel delivery into the combustion chambers to produce the "perfect"power delivery,or "blueprint" specification once the air fuel mix is ignited.

The internal combustion engine relies on three basic elements,and I reiterate,these three Basics !
AIR,FUEL and IGNITION ! Not quite as easy as it sounds making the perfect symphony of circumstances.
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Old 01-24-2015, 11:09 AM
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Originally Posted by ThexGovenor View Post
Lets say you are scaling it in half, you cut airflow in half and adjust from there. You also have to cut all timing in half and work up from there till you knock. More in depth but thats the basics. Also cut injector flow in half.
on the one i was working on, I cut IFR 50%, then started with GM stage 2 MAF and VE and cut them 50%.

rather than cut the stage 2 high / low octane tables advance by 50%, I thought there was a method of taking a specific manifold pressure row and moving it down the scale by 50%, but I wasn't clear on it, so that's where I quit. I suppose in my case, since I'm E85, the stage 2 gas timing would be soft enough I could just run it, until I was ready to start bumping it up. (obviously watching for KR and adjusting if needed)

I had also read "any table that has a MAP axis has to be scaled" and haven't looked into it to see what other tables.

otherwise, anything that is an "adder" i guess wouldn't ?
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Old 01-24-2015, 07:23 PM
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If you already have a completed timing table then yes you use that method. I can send you one if youd like. Its a scaled 50% timing table.
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Old 01-26-2015, 04:55 PM
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Originally Posted by lwrs10 View Post
Whoa....looks like people are looking for some answers. I have not been on here in over 6 months...sorry.

I do have the correct data for these. And the voltage multiplier table was left in there as a leftover really. Alan is correct.....it does not work.
Nice to see you back here.
Can you update the information on offset halving etc. that you wrote here in the 1st post for what works in the LSJ and what not? Especially on the offset issues and your findings with halving IFR table / halving Stochiometric value?

Scaling a tune for big injectors is done and described for more GM platforms, only the LSJ has not all tables unlocked in HPT and some of these reference airmass...Therefore I lowered my base pressure so I had enough fuel with the Bosch without the need for scaling and possible idle/transient issues.
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Old 03-16-2015, 09:59 PM
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EV14 Bosch injector data

Originally Posted by lwrs10 View Post
First, let me state that I am in no way trying to step on anyones toes here. I am simply trying to educate the LSJ world about injectors. I do not want to see people deal with the frustration I went through.

There seems to be a ton of misinformation floating around about injectors in general, let alone in the LSJ world. There is a couple injector offset tables floating around for our cars, and I have done the math and improved upon them. First thing I have found is for some reason the advertised offset tables for injectors in our cars simply do not work. They somewhat worked for the Siemens 60's and 80's, but not for an injector with a higher offset approaching 1ms. I recently ditched the Siemens 60's because they are simply the wrong injector for our car. It should honestly never be used. More about that later.

I bought some Bosch EV14 630cc injectors to use with my car. The advertised offset at 14v was just over 1ms, according to the Bosch spec sheet. I even received GM offset charts with them in the normal LS1-E40-E67 formats. My IFR and voltage multiplier tables were setup correctly. I interpolated the data into the LSJ charts and started the car. It was pig rich. I could not remove enough fuel from the MAF and VE tables to make it even close, as the minimum pulsewidth of our computers is .3ms.

I know you are thinking I did not set something up right, but I assure you it was. I even tuned my car when it was stock so I have a solid reference to fall back on. I scaled my tune by 50%, just like the LS guys do for big injectors and for hitting the 1.36 G/cyl wall. Nothing changed. On paper you should be able to swap injectors, and as long as your injector data is correct, you should not have to change any trims. In reality nothing is perfect and at max you should not see more than a 2-3% change in fueling if nothing else was changed but injectors.

What I have discovered and verified is the LSJ computer(P12) uses exactly 50% of the offset values. I cannot figure out why, and I hope someone can figure it out. I have verified these offset values are correct, and I will show you how. Try it. Bet you it works.

This is an exert from a Megasquirt document modified for our cars, since we do not have secondary VE table.....



I have performed this test for the stock injectors, 60lb Siemens, 80lb Siemens, and my Bosch 60lb injectors. With the offset tables exactly half, the change was 10% every time. I tried this at idle and at WOT, and results were the same.

Injector Selection.....and reasons why


The stock injectors are a split pattern dual cone spray injector. There is a huge reason for this, since our motors are a 4 valve design. There is an intake runner splitter right in front of the valves. The proper injector will spray right on the back of both valves for maximum fuel atomization and efficiency....just like the factory injectors does.

Stock injector:


Bosch injector I have:



Not an LSJ head, but same concept here:



basic spray patterns:



Siemens 60lb Deka specs including spray pattern:




And here is a good read too...
Fuel Injectors

Problem here is most people slap in the Siemens 60 and 80 pound Deka injectors, which are a single pattern cone spray. This intake split is about an inch and a half away from the tip of the injector, so this single 26* cone is spraying right on the split before it is even broader than an inch. This is very very bad, as it causes the fuel to lose its atomization and leads to fuel pooling in the intake as well as very inconsistent transient fueling. This single factor right here is why the idle is so poor with these injectors. Many people tell me they got their car to idle great with these injectors, and I simply have to call bullshit. No way you can get this style injector to idle as smooth as stock. You can get them to idle OK with no surging, but not perfect.

The injector I chose is a Bosch EV14 injector, part number 0280158123. You have to use an adapter on the nozzle to make it work, but many injector shops have this adapter. They are slightly longer than 60mm(stock length) at 64.5mm, but I had no trouble since the stock fuel rail is at a 45 degree angle. The spray pattern is a split cone 25* just like the factory injector. They flow 60.5lb/hr @43.5psi, and [email protected] which is the stock LSJ fuel pressure. Another good point is the minimum linear pulse width is .711ms, compared to the 1.4 for the Siemens 60's. This is HUGE for our tiny motors, since idle is typically around 1.2, and deaccel is .7ish. My idle is as good if not better than factory right now, and transient fueling is very smooth with these.

More info about the injector I went with:
http://www.bosch-motorsport.de/en-US...2775993867.pdf

Pic of the Bosch injecter with the adapter:


I bought them from Fuel Injector Connection in Georgia for about $60 each. That makes them about $100 more than the Siemens, and it is money well spent. Ask for Jon there, and he will know exactly which injectors you need. He will put the tip adapters on them and they will be a direct drop in.

I started with the Siemens 60's, and I can tell you those are a terrible injector for a 4 valve motor. You want the injector to spray on the back of the valves, not at the intake split. Please do some research before you follow everyone else and purchase the Siemens.

If you are interested in the 100% correct and verified injector data for the LSJ send me a PM and I will provide it.
Hello, Im new to this forum, Ive been using info from CobaltSS to build a 2.4SC. I need that injector data, ( I purchased the 630EV14 split) but I have not figured out this forum. How do I private message you to get the data?
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Old 03-17-2015, 06:52 PM
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I finally got these injectors installed in my car (got them in December ! ), and got the fuel pressure set correctly.

Drove it for the first time this afternoon. Immediately noticed a vast improvement in idle quality over the Siemens 80's. Can't wait to get the tune going !
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Old 03-17-2015, 10:15 PM
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I bought the bosch EV14 60's from Fuel injection connection, John tells me to get the set up info from you guys. (lwrs10, armcclure)
This discussion makes perfect sense to me.
Can you help a fellow newb cobalt tuner.
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Old 03-18-2015, 01:40 AM
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I can't PM you, don't know if that's a setting thing or what.

I have the info you need, but I'll need an email address to send it to you
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Old 03-18-2015, 09:30 AM
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Originally Posted by wayfarer View Post
I can't PM you, don't know if that's a setting thing or what.

I have the info you need, but I'll need an email address to send it to you
I think he needs 5posts before he can send or receive PMs
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Old 03-19-2015, 08:29 PM
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Originally Posted by wayfarer View Post
I finally got these injectors installed in my car (got them in December ! ), and got the fuel pressure set correctly.

Drove it for the first time this afternoon. Immediately noticed a vast improvement in idle quality over the Siemens 80's. Can't wait to get the tune going !
Ha, you got everything working?
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Old 03-19-2015, 10:23 PM
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yep. I work SLOOOOOOWW!!!!

but its going great so far
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Old 03-20-2015, 08:24 PM
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Originally Posted by wayfarer View Post
yep. I work SLOOOOOOWW!!!!

but its going great so far
I'm assuming this applies to the LE5 head also?... I'm getting ready to pull the trigger on the Mototron 80#ers for my build next month....would you guys suggest these Bosch? Thanks...
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Old 03-20-2015, 10:36 PM
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Originally Posted by ccundiff72 View Post
I'm assuming this applies to the LE5 head also?... I'm getting ready to pull the trigger on the Mototron 80#ers for my build next month....would you guys suggest these Bosch? Thanks...
I removed Mototron 80's (purchased new from ZZP,ran them less than a year) in favor of these Bosch 630cc's

But... You gotta get injectors that are up to the task. I didn't need the 80's to begin with

Last edited by wayfarer; 03-22-2015 at 10:46 AM.
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Old 03-22-2015, 04:24 PM
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Originally Posted by wayfarer View Post
I removed Mototron 80's (purchased new from ZZP,ran them less than a year) in favor of these Bosch 630cc's

But... You gotta get injectors that are up to the task. I didn't need the 80's to begin with
I noticed on FIC's site that they have a Bosch 720cc that will fit the bill for me...I sent an email over the weekend inquiring whether or not I can get them with the extended tip (4.5mm) to fit like the 60# in this thread...probably won't be a problem...Man! I'm glad I came across this...But this is why I try to do my homework and get as much info as I can before I make a decision when building and purchasing...
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Old 08-26-2015, 11:12 AM
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Installed these injectors last night. They replaced gm stage kit injectors. I had already tuned the car to within 1% and after these injectors my tune is off. My trims are 10-18% rich now. I'm guessing the info for these is not correct. It certainly didn't look right as some of the values wouldnt work in HP tuners. Does anyone know where we can get the proper info for these? I believe I've read before that there are companies that flow test injectors but I have no experience with that.
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Old 08-26-2015, 11:36 AM
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What you tuned your car to prior to new injectors wont matter.
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Old 08-26-2015, 11:44 AM
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Originally Posted by blueLNFftw View Post
What you tuned your car to prior to new injectors wont matter.
First time replacing injectors, but I thought all I had to do was copy the data and the injectors would flow the same. I apologize if I misunderstood.
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