BUILD THREAD 86 GP 2+2~Blown 6.0

[81cutlass]

I was thinking the same until I re-read his post. Is he having issues with finding an input that reads .5-4.5v on the ECM?

I'm learning more about HP Tuners and stock ECM's following along here than I ever have :0

Yeah Jim worded it more concisely. I have enough 5V supplies, I needed 5V inputs which I initially used the wrong ones. I switched the input pins to fuel tank pressure input and AC pressure input and it works! Although the fuel level sensor pins are 5V signal, they aren't inputs like I thought.


Good news is swapping the pins works. All my added sensors are fully functional now.
Bad news, I had mentioned my interest in going to the track for Wednesday night street drags but I'm postponing that. My fuel pressure is too damn low.

58psi base fuel pressure and 173kpa is 10.5 psi of boost which means the fuel pressure should be 68, its 42, which is like 32 effective when it's really in boost. Ish. Yuck. Bad. Danger. Warning.

Already at 88% injector duty (which is because the fuel pressure isn't keeping up) on e60. There is very low likelihood I will have enough fuel with more boost, more RPM, or true E85. I need more pressure. It holds fine with injector duty cycle is below 70% but it starts falling off pretty fast once I get into the 80% duty cycle range.

I have -6 from the tank to the filter, and filter to the firewall, where it goes to -8 as it Y's into the fuel rails before it Y's back to the regulator. I am going to replace the stretch of -6 with a new piece of -8 from the filter to the firewall and see if that helps. If that isn't enough I will pull the walbro 450 out and swap to a 525 HC pump and go -8 from the tank to the filter also.

There are cases where the pressure is keeping up 1:1 with boost, but you can see in this pull past the snapshot white line where the fuel pressure starts trailing down as it revs through 3rd gear.

I'll get my fuel system patched up and reassess.

Lesson of the day is -6 AN hose and a 450 pump isn't enough to keep up for fuel requirements of a 6.0 with 10psi and 60% ethanol. That's why I spend the time getting these sensors set up. I always THOUGHT it was fine when I would glance at the gauge I had but it's really valuable to see the results as it runs through a pull.

 

[64nailhead]

Wow, dodged that bullet!

Moments away from joining the bent rod club.

 

[motorheadmike]

Yeah Jim worded it more concisely. I have enough 5V supplies, I needed 5V inputs which I initially used the wrong ones. I switched the input pins to fuel tank pressure input and AC pressure input and it works! Although the fuel level sensor pins are 5V signal, they aren't inputs like I thought.


Good news is swapping the pins works. All my added sensors are fully functional now.
Bad news, I had mentioned my interest in going to the track for Wednesday night street drags but I'm postponing that. My fuel pressure is too damn low.

58psi base fuel pressure and 173kpa is 10.5 psi of boost which means the fuel pressure should be 68, its 42, which is like 32 effective when it's really in boost. Ish. Yuck. Bad. Danger. Warning.

Already at 88% injector duty (which is because the fuel pressure isn't keeping up) on e60. There is very low likelihood I will have enough fuel with more boost, more RPM, or true E85. I need more pressure. It holds fine with injector duty cycle is below 70% but it starts falling off pretty fast once I get into the 80% duty cycle range.

I have -6 from the tank to the filter, and filter to the firewall, where it goes to -8 as it Y's into the fuel rails before it Y's back to the regulator. I am going to replace the stretch of -6 with a new piece of -8 from the filter to the firewall and see if that helps. If that isn't enough I will pull the walbro 450 out and swap to a 525 HC pump and go -8 from the tank to the filter also.

View attachment 175230

There are cases where the pressure is keeping up 1:1 with boost, but you can see in this pull past the snapshot white line where the fuel pressure starts trailing down as it revs through 3rd gear.
View attachment 175231


I'll get my fuel system patched up and reassess.

Lesson of the day is -6 AN hose and a 450 pump isn't enough to keep up for fuel requirements of a 6.0 with 10psi and 60% ethanol. That's why I spend the time getting these sensors set up. I always THOUGHT it was fine when I would glance at the gauge I had but it's really valuable to see the results as it runs through a pull.

Yeah, I wouldn't think that running at your power level through a 3/8" line was sufficient. That should be the minimum for a return.

That said, I'd be curious to know why a single 450 couldn't keep up at your current power level. If E85 really is cause the drop off I don't think a single 525 is going to be sufficient either. You are going to need twin pumps.

https://www.realstreetperformance.com/blog/fuel-pump-test-2018-real-street-performance/

EDIT: Forgot to qualify my statement about a single 450 being sufficient. We are both making similar power on a single 450. The difference being mine feeds directly into a -10 AN line that get split into twin -6ANs at the rail with a -6AN return line. I have the provisions for a second pump already in place for the transition to E(60).

A -8AN feed is plenty even on E. I just suspect a revamped system designed for the volume and pressure may be in order.

 

[81cutlass]

Yeah, I wouldn't think that running at your power level through a 3/8" line was sufficient. That should be the minimum for a return.

That said, I'd be curious to know why a single 450 couldn't keep up at your current power level. If E85 really is cause the drop off I don't think a single 525 is going to be sufficient either. You are going to need twin pumps.

https://www.realstreetperformance.com/blog/fuel-pump-test-2018-real-street-performance/

You present a good question if the pump really is large enough.

TLDR: If I switch from 3/8 hose to 1/2 hose I can reduce my pressure drop between the pump and fuel rails from 61psi to 15 psi, and increase the fuel pump flow from 20-30 GPH to 65-80 GPH. My injectors require 56GPH. 450LPH is sized about right if you keep line loss low.

Honestly just threw the fuel system together when I did the swap 5 years ago on a budget and didn't look past it. I didn't understand how to calculate line losses at the time and I only (finally) learned in the last two years when I was getting my Master's.

Since I am a few months from having a piece of paper saying I have a master's in engineering specializing in fluid power so I guess I can do some math.... I do this for my 'job' so I can do this for fun too. I spent an hour and a half on this that I should have spent typing my thesis so I can graduate and get a real paying job again, so priorities.....

Caution: Math

Calculated the density, kinematic viscosity, Reynolds number, flow velocity, pulled out the moody chart, found the pressure drop equation, blah blah blah.

80lb/hr injectors at 58psi base pressure flow 92lb/hr which is 14gal/hr per cylinder or 428lph for the entire engine. I need 428lph of fuel flow (at the pump) to max out 80lb/hr injectors.

But, that's assuming the injector would be firing all the time, which it can't. If the engine is running at 6000 rpm its making 3000 combustions per minute, and you only have half the cycle to use because one half is intake and the other is exhaust, which means essentially the injectors run at a max duty cycle of 50%, even if they are at 100%. Can't inject fuel on the exhaust stroke. Really I need 214lph to max the injectors out on a 4 stroke engine. That's 56 GPH which according to this chart is achieved below 105psi on 12v or 115psi on 13.5v.

Gotta keep the pressure AT THE PUMP below ~100 psi on a 450 lph pump with 94lb injectors.

So assuming the pump is totally maxed out at 335lph which is the flow at 58psi base pressure.
-With 3/8 hose that is 3.42 PSI/ft pressure drop, lets say I have 18ft of hose that's 61 PSI of pressure drop from the pump to the regulator. To get 68 psi at the regulator I need 68+61psi =129psi at the pump. Zoinks.
-With 1/2 hose that is 0.81 PSI/ft of pressure drop, so 18ft of hose is 15 PSI of pressure drop. I need 83psi at the pump. Realistic.
-With 5/8 host that is 0.3 PSI/ft so 6psi over the car. 74 psi at the pump.

Basically the math says at 129psi of pressure at the pump I am only getting 20GPH of fuel flow and I need 56GPM to max the injectors out.

I saw as low as 42 psi at the rail which if I still had 61psi of pressure drop through the hose, the pump pressure would be 103psi which if the pump really has 12V is basically right on the curve at 56 GPH Some correlation.

Due to the high line losses, I was running the 450lph pump way past it's efficient zone.

I can really see how this issue compounds on high boost setups and why people put such big lines in now. I never understood why people put -10 fuel line in stuff, and I don't believe most other people understand why, they just do it be cause 3/8 doesn't work and 5/8 works. Coming from industrial fluid power, 3/8" hose flows WAY more than 450lph and I never took the time to look at it. When you have 4000 psi in a hydraulic ram, 50psi of pressure drop during high flow doesn't matter.

It's not that the fuel system needs the flow. A 3/8 line can flow enough for a 2000hp engine on e85, It's that you need to keep the line losses VERY low at high boost to prevent the electric fuel pumps from falling off the flow curve. If you had a 300psi supply gear pump to make fuel pressure, you could run 3/8 and never care. But, these electric fuel pump flows die after 100psi and if you run 60psi of base pressure and 25psi of boost, you need 85psi at the pump PLUS whatever line losses you end up with. -12 lines just so happen to have really low line loss.

I should put an excel chart together that auto sizes fuel lines and pumps based on base pressure, number of cylinders, and injector size.

 

[Supercharged111]

Or you could be lazy and bump IDC to achieve the desired AFRs.

 

[64nailhead]

Don't overthink this. You're pump and line size are too small., Of all things to be on the edge with, the fuel system is not it. #8 line with a true 1/2" inside diameter and two AEM 340's or Walbro 450's will get it done.

For reference, Happel couldn't make 900whp with two in tank 450's. I'm going to bet you're knocking on the door of 500whp if not more. I'd add another 450 and be on my way, and also convert to either #8 or #10 line.

 

[Supercharged111]

Don't overthink this. You're pump and line size are too small., Of all things to be on the edge with, the fuel system is not it. #8 line with a true 1/2" inside diameter and two AEM 340's or Walbro 450's will get it done.

For reference, Happel couldn't make 900whp with two in tank 450's. I'm going to bet you're knocking on the door of 500whp if not more. I'd add another 450 and be on my way, and also convert to either #8 or #10 line.

I would expect his setup to be mid-high 500s at the tire spinning that blower as he is.

 

[motorheadmike]

I never understood why people put -10 fuel line in stuff, and I don't believe most other people understand why, they just do it be cause 3/8 doesn't work and 5/8 works.

Not quite sure how to respond to that? Oh wait!

 

[64nailhead]

Actually there is a lot of documentation about this stuff. Whatever size line will work with gas needs to be two numeric numbers larger. If you have -6, then you need -8

 

[81cutlass]

Don't overthink this. You're pump and line size are too small., Of all things to be on the edge with, the fuel system is not it. #8 line with a true 1/2" inside diameter and two AEM 340's or Walbro 450's will get it done.

For reference, Happel couldn't make 900whp with two in tank 450's. I'm going to bet you're knocking on the door of 500whp if not more. I'd add another 450 and be on my way, and also convert to either #8 or #10 line.

But I like to overthink everything! My car is a rolling example of overcomplications and overthinking

I have already decided to convert to #8 line. I'll see how the pressure signal looks after I change the line. If its still wishy washy I'll throw a second pump in.

Not quite sure how to respond to that? Oh wait!

Hey I said a few weeks back that 'Mike is right', I gotta crawl back to sanity a little