dE.fUsEd

Will be using a gt35r and need to know which injectors I should get.
Should I just go with 1000cc's or will 750's be enough?

LocoJoe

Simply no. You never wanna run an injector more than 80-85% duty cycle. 1000ccs should be around ~60-70% depending on fuel base pressure.

dE.fUsEd

Appreciate it.

lilcoolguy90

id go w/ id 1000cc injectors

Muckman

iTrader: (2)

I maxed out 750cc's at 425hp on gasoline.

scottdh20

dont know why it wont make it a link.....but highlight and put it into your browser.....it will give you the information nessecary to make your own decision on what size injectors to use

http://rceng.com/technical.aspx?UserID=11447970&SessionID=mQeuzAY62 KM{ZI0gvPXp

sanman000719

explain the issues with running injectors at 100% duty for us plzzzzzzzzz

m3tech95

^ good info.....

Builda'Teg_92

Dosent sound good! but i see in your sig you run 1000s at 100% w/ E85. Does the E85 allow you to run higher duty cycles? just tryin to learn something new.

sanman000719

no higher base pressure alows your injectors to flow more

1000's at 80-90psi are more like 1300's well 1299 to be more acurate.

i have always heard people say this or that duty cycle isnt good and just thought ide ask why lol

sanman000719

and e85 still robbs power over gas

Schister66

If you ever need to make a quick guess-timate for fuel injectors, use Schister's Rule of 6

You need 6cc of fuel injector flow per whp. That way, since you already have a power goal in mind, you can plan your fuel system accordingly. This is only a ballpark by the way and be sure to round up.

500whp x 6cc/per whp = 3000cc total flow
3000cc / 4 injectors = 750cc

Those injectors will be almost completely maxxed out at that power level. This is where the 'round up' suggestion comes into play. You know that 750s will be cutting it too close; therefore, move up to the next available size...like an 880cc.

If you want to calculate for E85, you simply multiply by 1.3 as E85 takes ~30% more fuel for the same power. Hope this helps

Builda'Teg_92

idk but the RC website says dont run past 80%..maybe just safty precaution so they can warrenty the injectors??? hope we get a real answer to that question


Schister66: now thats math i can do, great info.

sanman000719

probly to protect them in case of failure, but mine have been ran this way for 3 years now lol

900 bux is alot of money for some ID2K's

Schister66

^^RC's strategy just shows that they're not entirely confident in their product...aka unreliable manufacturing/ quality control. A good company, with high standards, is going to tell you to push the injector beyond the limits they have set for it. The catch is, these injectors are going to cost substantially more. ID's are a great example of this. They can easily flow more than they're rating but they also cost 2x as much as the standard fuel injector.

If you buy an 800cc injector and can only use it to ~80%, isn't the more like a 640cc injector? I would rather spend the money and get a set of ID's or Precisions if nothing else...

sanman000719

lol

so can you actually explain what happens when you run a set of injectors at 100% duty i mean do they heat up due to pressure/blow seals/ whats the real deal

Muckman

iTrader: (2)

The "rule of 6" is a little on the small side. How about we go with the "rule of 6.6" and that way its a closer calculation IMO and matches your name better.

And of course that rule only applies for gasoline. Rule of 9 for E85 but it doesnt have the same namesake.

Builda'Teg_92

It makes it easier to add/divide in the head lol....then just add a little on top

sanman000719

so noon knows the answer to my question huh

Schister66

Lol...i like it. I just always figured 6/4 or 1.5x the power will yield the injector sizing. It is on the small side, i'll give you that, but that's why i round up.

1158

From: http://www.hondata.com/techduty.html

We have not seen any problems with engines running rich or lean once the stock injectors get past 80-85%, but it is not recommended to exceed 80% duty cycle with replacement injectors. Otherwise you will run the risk of the injector not being able to open and close quickly enough, which causes the injector to float half open. This will lean the mixture out, which is not going to healthy for an engine at high revs and under full load.

sanman000719

awsome i have always heard its not good, but noone could actually answer why. th word recommended is a funny one to me because they say hey look it might not be good haha.

1158

Yeah, I'm the same way. I need to know why, I can't just let it go at this what you do.

Schister66

Me too...I need to understand why/how something works rather than taking someone's advice and accepting it.

EddieCRX

I sat the EFI 101 and asked why we shouldn't run DC on some injectors up to 100%, my interpretation of the answer was heat created through the injector at these DC's would effect the way the fuel is utilized.
Obviously, I see many people running DC higher than recommended and I'm not a tuner but for piece of mind I personally build in enough buffer in all areas of my build.