ok after finally getting my new distributor in and messing around with timing and fuel pressure im pretty sure i blew out an injector or multiple ones. when i first tried adjusting fuel pressure i dint know to unplug and cap the vacuum line, so once i did that i found the real reading was like 62 psi. then it started stumbling and running rough and smells so strong of fuel. is it possible to overpressurize and ruin injectors? any insight appreciated!

 

depending on the year.. if you have a multec injector they will lock up at that pressure. In other words the high pressure is too much so the ball seat valve wont pull up. The early style bosch are able to handle the pressure. Plus your pump will probably fail soon.. Go fix it!

 

well its a 91 gta and the injectors are about year old summit brand replacements if that helps. how would i know if it is a multec? would you recommend a different brand injector ? any ideas im open minded thanks

 

Bosch injectors will be no problem. We can supply them in either rebuilt or new.

I'm not sure who was supplying summit a year ago, could have been any one of a few companies.

Maybe we can just set you up in a bigger injector so you can drop your pressure, There's no advantage to running that high. Call me and we can discuss your options, there's a number of ways to go.

 

Im of the thought that higher fuel PSI (to a point) = finer fuel droplets and that = better/cleaner/more complete burn.

 

Nope. Old wife's tale. You turn up FP when you need more flow. Engineers design these to atomize at 39 lbs and 43.5 lbs. They do not atomize any better at 60.

 

Yup I understand that completely, however, On cars that have been tuned (say @39 psi) I have seen a lil power/mile an hr increase from bumping the PSI 2 50ish even tho the AFR stays the same because its controled by ECM and sensors.
Cranking the fuel PSI to cover a lean fuel curve seems like a band-aid 4 a to small of a fuel system to me.
Even the LS stuff is running 58 plus PSI and a bigger INJ these days. (some of the old injs wont take that)

I seem to remember a inj test somewhere about this very thing.. It was just a test in a inj stand to show the diff of the spray pattern @ dif PSIs

There is def 2 schools of thought on this matter and Im not saying Its a law but ever combo is a lil diff..
PSI=better burn and INJ size,pulse width,ecm and fuel pump controls how much fuel.
again just based on what Ive seen on the dyno over the years.
Im no expert by anymeans but Ive seen the results both ways..
Basicaly set your fuel PSI and tune to that PSI. Whichever ya choose.

 

I don't believe there is any daylight between us here. Adjusting fuel pressure is all part of the tuning. Increasing it may help in some situations.

Bottom line is what happens when the fuel hits the top of the hot valve and how the fuel is suspended in the intake port.

So basically I think we agree.

 

Any specific reason the LSx went to 58 psi? Did they just have left over 24lb@3bar injectors from the LT1 cars and just bump pressure to flow enough for the LSx?

I run new style Siemens 80-83lbs High-Z injectors with good success so far. I see them advertised as 80 to 83lbs at 43.5psi but I run them at 46-48 plus up to 18 psi booost so far and they seem to spray just fine That would be around 66 psi. My buddy used Motron 60's at lsx pressure (I think they were advertised as 72lb injectors on ls1) and ran 23 psi to make 700whp and those ran fine although tapped for power at 100% cycle duty. Thats 81 psi pressure

 

LSX aren't the only ones, the Chrysler Hemi's run four bar too.

Just newer technology and engineering design.

It allows for more flow with the high impedance injectors where low impedance gives up.

Morton 60s are probably Seimans. (I never heard of them) Seimans does not like high fuel pressure, the pintles tend to go. I just had a guy melt a piston doing that. Be careful. Do you mean MORAN?

 

It's Motron. They are made by Siemens according to this site: http://www.forcedinductions.com/product6.htm

 

Ah, those are seimans. Morton doesn't make them. This is why I don't bother putting my name on anything. We talked about it, but I find it's misleading.

I sell BOSCH injectors for $95 that my competitors put their name on and sell for $125. Same injector.

As a consumer, which would you rather?

I've mentioned before, there's only a few manufacturers of injectors, the rest put their name on it.

 

ARe you refering to the latest Siemens models? I got these newer style thin body injectors that are suppose to be better at low pulse widths and such and they come in 3bar and 4 bar ratings. They do well but I need the pressure for the extra flow. I"m already at 80-84% cycle duty according to my logs and I"m looking for even more power

 

Yeah, it's not a hard and fast rule, but when running higher fuel pressure, I perfer BOSCH. We see less problems with them.

DOn't get me wrong Seimans and BOSCH represent a huge portion of my business. They are both EXCELLENT injectors.

Just saying in an application running high fuel pressure, like forced air, I'd recommend BOSCH if you asked. Or just go to a bigger injector.

4 bar is only 58lbs. I'm talking 80,90, 100 lbs of pressure.

 

Ok i may have some more room then. Do you have a 90ish lb injector at 3 bar just incase I need to upgrade? Even a 4 bar would work i suppose but I thought guys were making much more hp than I am on 80's.

 

Yep. Can do that. Basically we can make just about anything within the physical limitations of, well physics...

Running forced air is a good case for more fuel pressure. My comments above were within the frame work of NA.