ECMlink 1G Should I increase fuel pressure or do I need bigger injectors?

[AWD-Tony]

Fuel pressure is set to 40psi and I'm maxing out towards top of WOT. Should I increase fp? If so, to what? Or should I go bigger injectors? If so, what size? My goal is 350-380whp.
Big 16g w kiwunaga 17lb IWG
Rc550
255 Walbro rewired
Fuel lab 515

Thanks

 

[Dstarperformance01]

are we talking e85 or pump gas? This will help you determine what you need.550's aren't gonna get you there.

http://fuelinjectorclinic.com/flow-calculator

 

[AWD-Tony]

pump gas. Thanks!! That's a great calculator. What's a good/stable fuel pressure and duty cycle? Thanks

Forgot where I saw it but it said you don't want higher than 80% duty cycle.

 

[OH91awd]

go up to like a 43.5 psi base at least. that's what most injectors are rated at.

 

[AWD-Tony]

Ok. I'll increase to 43.5 and see where the injduty is. Thanks

 

[AWD-Tony]

are we talking e85 or pump gas? This will help you determine what you need.550's aren't gonna get you there.

http://fuelinjectorclinic.com/flow-calculator

Looks like I need something above 799. I had 2g w 660cc running fp green and it made 407 whp. So i'm kind of confused why I need bigger injectors to make less hp. I trying to hit 375 whp using that calculator.

 

[motomattx]

Bottom line: if you have to increase fuel pressure you need bigger injectors period, raising fuel pressure over stock is a band aid on something that needs stitches.

 

[AWD-Tony]

Thanks moto! Is 43.5 max bfp? I'm just curious where the limit is when setting bfp.

 

[lasthope05]

With the quick calculations I did. You can raise base fuel pressure to 60 psi, assuming you will be running 30psi of boost max. At 90psi of combined fuel pressure a walbro 255hp has just enough fuel to meet your goals. Injector sizing at that point would be 650cc.

But double check it on your end. I don't think bumping up base fuel pressure is a bandaid at all if you have enough pump to sustain it then why not?

 

[Vegas Smith]

I think it's just a case of there being two ways to skin a cat. As long as you're not abusing something in your setup, then what's the difference?

 

[motomattx]

With the quick calculations I did. You can raise base fuel pressure to 60 psi, assuming you will be running 30psi of boost max. At 90psi of combined fuel pressure a walbro 255hp has just enough fuel to meet your goals. Injector sizing at that point would be 650cc.

But double check it on your end. I don't think bumping up base fuel pressure is a bandaid at all if you have enough pump to sustain it then why not?

The problem is that at 90 psi your volume output is cut down, if turning up the pressure worked the same way, there would be no 2000cc injectors out there, for that matter the Evo wouldnt have come with 550cc injectors, they would have just used the dsm 450cc and turned up the base pressure.

 

[lasthope05]

The problem is that at 90 psi your volume output is cut down, if turning up the pressure worked the same way, there would be no 2000cc injectors out there, for that matter the Evo wouldnt have come with 550cc injectors, they would have just used the dsm 450cc and turned up the base pressure.

I guess you miss the part where I said that at 90 psi on a walbro 255hp has just enough flow volume to meet his goals. Look at the flow charts yourself. What oems do vs what tuners to is completely different. There's different ways to reach the same goal. Fuel pumps become less effecient at higher pressures thats a given, but if the pump can sustain fuel consumption at said pressure it is not an issue. The same is done with mechanical fuels pumps. The main point of mechanical is for the huge linear fuel output that allows you to increase BFP for more injector flow volume.

Run the numbers yourself and get back to me for his application. As I said, my quick number crunching says that he has enough headway.

-Fuel consumption @ rated hp for pump gas(60 base and assuming 30psi boost)
-Injector output of 550cc injectors at 60psi base
-255hp flow chart in gph converted to lph of fuel.

Personally, I'm already at the point of maxing out 2150cc injectors( bigger Moran's billets injectors flow like shit on our stock drivers) and my next mods are 4303 or mechanical and increasing my base fuel pressure.

 

[AWD-Tony]

I don't plan on turning this car into a full blown race car and I have another car plus I don't commute. And to be honest, I want it to have decent mpg...don't know if this is achievable??? Only time I'll be upgrading turbo is if this one goes or a few years later if I'm bored with it. Think I'll go with either 1000 or 1650s. I've read some previous posts and I'm confused on whether to get lowz or highz. Also, does a walbro 255 output enough for 1000 or 1650's? Thanks

 

[lasthope05]

It all depends if you're looking to future proof yourself but a walbro 255 would be fine for 1000cc on pump. High or Low its up to you. They arent big enough to have injector pulsewidth issues at idle anyway. However, I havent seen any reviews or feedback on highz 1000cc from fic. Most out there are for the 1650 or 2150.

 

[AWD-Tony]

Thanks, Alan!!

 

[Brembo]

My .02 cents. I am old enough to remember reading super street magazine in high school and back then people used injectors in like 750 area and now the norm is 1650. I highly doubt that most people even use the full potential of those injectors. I do understand that injectors are expensive and buy only once logic but most people don't need huge injectors. So with that said I bumped my fuel pressure to 48 psi base. The reason why is because it is much easier to set pressure at 48 psi then 43.5. My gauge reads in 2 psi increments. Is it the best way to do it, most likely not but does it work? You bet. Duty cycles went down but not a lot. I am in 90 with evo 560. I even went over 100 percent and when I took engine performance class for ASE, the prefossor said it's impossible. Well in my mind that duty cycle is calculated number and does not 100% show exact duty cycle. You don't want to be there but many people are their with no issues. Your not going for some dragster records here. Now if you want to spend money then yes buy injectors large enough that you don't have to buy again. Maybe even e85 compatible as you don't know what life will bring you in future. Not trying to start an argument just sharing my line of thought. Criticisms welcome. Flame suit is on. Hahahaha

 

[motomattx]

I guess you miss the part where I said that at 90 psi on a walbro 255hp has just enough flow volume to meet his goals. Look at the flow charts yourself. What oems do vs what tuners to is completely different. There's different ways to reach the same goal. Fuel pumps become less effecient at higher pressures thats a given, but if the pump can sustain fuel consumption at said pressure it is not an issue. The same is done with mechanical fuels pumps. The main point of mechanical is for the huge linear fuel output that allows you to increase BFP for more injector flow volume.

Run the numbers yourself and get back to me for his application. As I said, my quick number crunching says that he has enough headway.

-Fuel consumption @ rated hp for pump gas(60 base and assuming 30psi boost)
-Injector output of 550cc injectors at 60psi base
-255hp flow chart in gph converted to lph of fuel.

Personally, I'm already at the point of maxing out 2150cc injectors( bigger Moran's billets injectors flow like sh** on our stock drivers) and my next mods are 4303 or mechanical and increasing my base fuel pressure.

No one I know, including myself with mechanical pump setups bought the pump so that we could increase the base fuel pressure for more injector flow volume, its there to support larger injectors fuel flow. Either way its not the right way to increase fuel flow from an injector.

 

[AWD-Tony]

I increase to 43.5 or close to it since my gauge also is marked in 2 increments and set in link. Had to get groceries so just did a second gear pull and duty cycle is around 83.

 

[motomattx]

83% is getting too high, your losing safety margin and running your injector drivers more than they need to be.

 

[AWD-Tony]

My .02 cents. I am old enough to remember reading super street magazine in high school and back then people used injectors in like 750 area and now the norm is 1650. I highly doubt that most people even use the full potential of those injectors. I do understand that injectors are expensive and buy only once logic but most people don't need huge injectors. So with that said I bumped my fuel pressure to 48 psi base. The reason why is because it is much easier to set pressure at 48 psi then 43.5. My gauge reads in 2 psi increments. Is it the best way to do it, most likely not but does it work? You bet. Duty cycles went down but not a lot. I am in 90 with evo 560. I even went over 100 percent and when I took engine performance class for ASE, the prefossor said it's impossible. Well in my mind that duty cycle is calculated number and does not 100% show exact duty cycle. You don't want to be there but many people are their with no issues. Your not going for some dragster records here. Now if you want to spend money then yes buy injectors large enough that you don't have to buy again. Maybe even e85 compatible as you don't know what life will bring you in future. Not trying to start an argument just sharing my line of thought. Criticisms welcome. Flame suit is on. Hahahaha

That's what I don't understand. I had a 2g 10+ years ago w 660s fp green w super AFC and it put down 407whp with more than enough fuel. It was tuned on the dyno at turborix when they moved to south jersey. And now w 550s and a smaller turbo I'm running out of fuel???

 

[AWD-Tony]

83% is getting too high, your losing safety margin and running your injector drivers more than they need to be.

I thought 80% is where you'd want to be. So what is a safe injduty%?

 

[Vegas Smith]

Is it me, or is your fuel pressure set to 37psi?

 

[Brembo]

I haven't open the log. I am on iPad and don't want to start the PC. In my opinion and I am not great tuner by any means but 83% is more then enough. Also when you have less information their is less problem. For example: back in the day afc was the way to go and people went fast with it, and now ecmlink users have all of the info in the world and they spend more time getting these numbers perfect and not going anywhere. I am talking about myself here. I spend so much time making sure their is no knock or duty cycle was good or that wg flapper was tight and no boost leaks and blablabla to find myself realizing that my car is still slow as a turd. I am comparing it to my own evo here. I think like this. If it's 83% then forget about it and move on. That 1 percent plus or minus will not change anything as this number is calculated number.

 

[lasthope05]

No one I know, including myself with mechanical pump setups bought the pump so that we could increase the base fuel pressure for more injector flow volume, its there to support larger injectors fuel flow. Either way its not the right way to increase fuel flow from an injector.

You don't buy is specifically for raising BFP but what happens when you're out of duty cycle and I'm already maxing 2150s? Next logical thing in increasing BFP. I am trying to avoid dual rails at all costs.

Its a tricks to increase injector flow when you are option limited. If you or your friends don't know about it and think it's incorrect then that's your problem.

 

[Brembo]

You don't buy is specifically for raising BFP but what happens when you're out of duty cycle and I'm already maxing 2150s? Next logical thing in increasing BFP. I am trying to avoid dual rails at all costs.

Its a tricks to increase injector flow when you are option limited. If you or your friends don't know about it and think it's incorrect then that's your problem.

Wow maxing out 2150. Holy cow. That is most likely a scary ride. Good luck with the build.