Originally Posted by ThexGovenor (Post 7477445)

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.

Originally Posted by wayfarer (Post 7477460)

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.

Originally Posted by Spawne32 (Post 7477448)

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.

Originally Posted by ThexGovenor (Post 7478711)

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.

Originally Posted by lwrs10 (Post 7474416)

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.

Originally Posted by lwrs10 (Post 7118707)

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:
https://i.imgur.com/JMaDlePl.jpg

Bosch injector I have:

https://i.imgur.com/fjXRfbdl.jpg

Not an LSJ head, but same concept here:

https://i.imgur.com/xYqSVAg.jpg

basic spray patterns:

https://i.imgur.com/Cj34f2a.jpg

Siemens 60lb Deka specs including spray pattern:

https://i.imgur.com/mVhVa1Ol.jpg


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 72.02@58psi 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:
https://i.imgur.com/sWiDDdQl.jpg

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.

Originally Posted by wayfarer (Post 7510052)

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

Originally Posted by wayfarer (Post 7509850)

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 !

Originally Posted by wayfarer (Post 7510968)

yep. I work SLOOOOOOWW!!!!

but its going great so far

Originally Posted by ccundiff72 (Post 7511324)

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...

Originally Posted by wayfarer (Post 7511372)

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

Originally Posted by blueLNFftw (Post 7559134)

What you tuned your car to prior to new injectors wont matter.