Stock Injectors

[Alpha D]

Yeah most go for a hundred bux a set, i was just curious as to how well the theory would work in practice. Things always seem alright on paper untill you try it...and yep it was stock fuel pump .... hmmmm

[Alpha D]

Also for you gus with all the tuning software and know how to self tune or dyno tune, its not often almost ever I hear of fuel pressure being increased to get more flow out of an injector once its reached max duty cycle or w/e maxxed out injector means...how do you figure out what is to much pressure for an injector? because for example: If i just buy a set of injectors... the company dosnt know what pressure my car runs....Is there a standard or so? Never bought brand new injectors (i assume the instructions would shed light on that?)

In school we learned that most modeen vehicles have like a min of i think it was 60psi...its been to long i do not remember the generalized psi spec that was given..however the point is there was a standard which most new cars hovered around..

I know direct injection cars like the newer cobalts run a much higher base fuel pressure, granted the injector design might be different and cant be exchanged ...with a dsm injector clip..or that of a toyota..... So lets just say... hypothetically speaking they could fit...wouldnt yu get a different cc rating or fuel flow? lol if you purchased a aftermarket injector

[Shane@DBPerformance]

Standard pressure is 43.5 psi aka 3 Bar, which is the pressure that most injectors are rated at. You usually aren't going to have problems with running too much pressure on a fuel injector or them starting to act weird until above 100psi.

We sometimes raise or lower fuel pressure on cars on the dyno to either get more out of the injectors or more out of the fuel pump. For example if someone has way too much injector, but not enough fuel pump, then we might run a lower than normal base, but if you go too low then atomization suffers and you can start getting a funky idle/low throttle.

Often people don't play with it much though, because it requires making changes to the entire tune whenever you change the base pressure. Like if you run out of injector towards the end of a tuning session, then decide to raise the base 10-15psi to make the injectors bigger, then you need to go back and retune the idle and part throttle again.

Direct injection cars run fuel pressure in the thousands.

[asshanson]

Most injectors are rated at 43.5psi. However, some specific to a platform can be rated at that pressure, like a lot of vette injectors are sold with a flow rating at 60psi, probably just for marketing purposes.

[Shane@DBPerformance]

Yea, GM injectors are often run and sold at 4 bar. So a 60lb/630cc injector for GM would be a 550cc injector if run at 43.5 psi base fuel pressure.

[19TsiAwd90]

Most injectors are rated at 43.5psi. However, some specific to a platform can be rated at that pressure, like a lot of vette injectors are sold with a flow rating at 60psi, probably just for marketing purposes.

s10's(aswell as all 4.3l vortec motors)use a weird type of injectors called spider injector, and they run 60+psi of fuel pressure. They are VERY picky about fuel pressure when a pump starts getting weak they WILL NOT start(i know from experiance T.T). im sure there are other platforms that use higher pressure too, i guess Vettes use the modern day injector so this might not even be related. just thought i would share something.:spin:

[Alpha D]

This is amazing, thank you guys :) ! I feel like i actually learned something hehe! In conclusion with all the input: ''It is NOT a smart idea to raise my fuel pressure nearly 26PSI to get more injector !'' Reason being it will throw my whole Tune of balance...which makes perfect sense ! Theory is proven to be none practical in this scenario...sucky !

Most injectors are designed around a 3bar spec that answers the question i had!

[Alpha D]

Most injectors are rated at 43.5psi. However, some specific to a platform can be rated at that pressure, like a lot of vette injectors are sold with a flow rating at 60psi, probably just for marketing purposes.

Marketing? Which sort of marketing are we talking about? Like aftermarket or dealer...im assuming aftermarket since i dont see why they would use that in the performance spec as a point of sale dealer wise? Sounds like it would be over the head for most consumers?

I consider my self an enthusiast and i didnt even know head from tail well...

If i do ever feel adventurous though, im safe playing around with fuel pressure up untill or close to 100psi roughly...granted the whole tune will have to go hand in hand. With this new knowledge gained, I will have to decide on an injector size, for the up coming E85 season... since i sold my 1450 FIC i wonder if 1000CC will support 400WHP...but thats a discussion for another day. Not to mention i know for sure there is an equation for figuring injector size out...

I remember the first book i read called ''How to build a high performance mitsubishi engine or 4G63T'' had all kinds of interesting math in it. Again Thank you guys !

[asshanson]

Marketing? Which sort of marketing are we talking about? Like aftermarket or dealer...

Aftermarket. If they rate them at 60psi they look like bigger injectors.

If i do ever feel adventurous though, im safe playing around with fuel pressure up untill or close to 100psi roughly...granted the whole tune will have to go hand in hand. With this new knowledge gained, I will have to decide on an injector size, for the up coming E85 season... since i sold my 1450 FIC i wonder if 1000CC will support 400WHP...

1000cc injectors could probably get you close to 400whp on Shane's dyno. Your Walbro pumps won't like 100psi, they start to really taper off after 75-80psi. Look at this flow chart (13.5v brown line):
http://www.stealth316.com/images/flowtest-walbro.gif

[Alpha D]

Aftermarket. If they rate them at 60psi they look like bigger injectors.



1000cc injectors could probably get you close to 400whp on Shane's dyno. Your Walbro pumps won't like 100psi, they start to really taper off after 75-80psi. Look at this flow chart (13.5v brown line):
http://www.stealth316.com/images/flowtest-walbro.gif

Where did the graph go? or are you referring to the previous link...didnt see one there either? Yeah its time to look into a new fuel pump set up as well i think...not to mention all the nightmare story's ive read about with one pump throwing in the tower mid pull through causing a sudden change in afr's sometimes to fast to let of and engine damage occurring.

What monster pump's do people even run now a days. I know map sells those DW300 or something weird pumps...and i also hear of import image selling some sort of Bugatti veryon pump that gtr's seem to like ect ect