Home
What's new
Latest activity
Authors
Store
Latest reviews
Search products
Forums
New posts
Search forums
What's new
New posts
New listings
New products
New profile posts
Latest activity
Members
Current visitors
New profile posts
Search profile posts
Log in
Register
Cart
Cart
Loading…
What's new
Search
Search
Search titles only
By:
New posts
Search forums
Search titles only
By:
Menu
Log in
Register
Navigation
Install the app
Install
More options
Change style
Contact us
Close Menu
Forums
SVTPerformance's Chain of Restaurants
The Distillery
Time for e85.. Have a few questions
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Bad Company" data-source="post: 13940341" data-attributes="member: 141815"><p>It isn't about pressure drop. It is about unstable pressure changes at the fuel rail, due to a restriction in the return fuel line at low fuel demand conditions of the engine</p><p></p><p>Take 2 Walbro 465 pumps at 13.5 V, these flow 430LPH of E85 at 40 psi. 430 x 2 = 860 LPH from the tank to the engine. To give you a better idea of how much fuel this is lets do some more math. </p><p></p><p>ID1000 injectors flow 95Lbs of fuel an hour. E85 weighs roughly 6.8 lbs per gallon. 95 divided by 6.8lbs =13.97 gallons of fuel per hour at 100% duty cycle of the injector is the max fuel flow the engine can burn x 8 injectors = 111.764 gallons of fuel the engine can burn at 100% duty cycle of the injector each hour the engine is at max power and fuel delivery. Now we have pumps capable of moving 830 liter per hour of E85 at 40 psi. 830L divided by 3.785 = 219.28 gallons per hour of fuel flow from the tank to the engine at all times. 219.28 of fuel pumped -111.764 of fuel used = 107.516 gallons of fuel that must be returned to the tanks each hour at 100% duty cycle of the injectors. </p><p></p><p>Now to use a smaller return fuel line then the supply is to cause a pressure rise in the return line when you aren't using large amounts of fuel. Cruising at low speeds and engine loads the fuel return has to carry almost all of the 219.28 gallons of fuel back to the tank each hour. If the car achieves 13 mpg at a steady state cruise condition at 60 mph. That is the equavelent of 13 GPH of fuel usage. 219.28 GPH delivered to the engine, the return line must carry 206.28 GPH of fuel back to the tank each hour. To have a smaller return line during this condition is asking for a pressure rise in the whole system. A pressure rise in the return line also cause turbulence in the fuel as it returns to the tank. Turbulence causes aeration of the fuel, which will over time aerate the fuel in the tank. Aeration of the fuel in the tank causes unstable fuel pressures. </p><p></p><p>The cost difference between 20 feet of number 8 and number 10 return hose isn't enough to try and diagnose the problems at a later date in my mind. </p><p></p><p>This is also why I recommended the Fore FC3 Fuel Controller. You use this to shut the second pump off during these low fuel usage conditions. Why do you need to pump 219.28 gallons of fuel to the engine each hour, when you're only going to use 13 gallons of that? Shut one pump off and only pump 109.64 GPH. This will lower the heat rise of the fuel over time.</p><p></p><p>Edit</p><p></p><p>One thing to remember is that nobody would run the injectors at 100% duty cycle. So the numbers I'm using are being generous versus the actual amount of fuel being used by the engine. So the return line will have to handle more fuel then what my math is showing at 100% engine power output</p></blockquote><p></p>
[QUOTE="Bad Company, post: 13940341, member: 141815"] It isn't about pressure drop. It is about unstable pressure changes at the fuel rail, due to a restriction in the return fuel line at low fuel demand conditions of the engine Take 2 Walbro 465 pumps at 13.5 V, these flow 430LPH of E85 at 40 psi. 430 x 2 = 860 LPH from the tank to the engine. To give you a better idea of how much fuel this is lets do some more math. ID1000 injectors flow 95Lbs of fuel an hour. E85 weighs roughly 6.8 lbs per gallon. 95 divided by 6.8lbs =13.97 gallons of fuel per hour at 100% duty cycle of the injector is the max fuel flow the engine can burn x 8 injectors = 111.764 gallons of fuel the engine can burn at 100% duty cycle of the injector each hour the engine is at max power and fuel delivery. Now we have pumps capable of moving 830 liter per hour of E85 at 40 psi. 830L divided by 3.785 = 219.28 gallons per hour of fuel flow from the tank to the engine at all times. 219.28 of fuel pumped -111.764 of fuel used = 107.516 gallons of fuel that must be returned to the tanks each hour at 100% duty cycle of the injectors. Now to use a smaller return fuel line then the supply is to cause a pressure rise in the return line when you aren't using large amounts of fuel. Cruising at low speeds and engine loads the fuel return has to carry almost all of the 219.28 gallons of fuel back to the tank each hour. If the car achieves 13 mpg at a steady state cruise condition at 60 mph. That is the equavelent of 13 GPH of fuel usage. 219.28 GPH delivered to the engine, the return line must carry 206.28 GPH of fuel back to the tank each hour. To have a smaller return line during this condition is asking for a pressure rise in the whole system. A pressure rise in the return line also cause turbulence in the fuel as it returns to the tank. Turbulence causes aeration of the fuel, which will over time aerate the fuel in the tank. Aeration of the fuel in the tank causes unstable fuel pressures. The cost difference between 20 feet of number 8 and number 10 return hose isn't enough to try and diagnose the problems at a later date in my mind. This is also why I recommended the Fore FC3 Fuel Controller. You use this to shut the second pump off during these low fuel usage conditions. Why do you need to pump 219.28 gallons of fuel to the engine each hour, when you're only going to use 13 gallons of that? Shut one pump off and only pump 109.64 GPH. This will lower the heat rise of the fuel over time. Edit One thing to remember is that nobody would run the injectors at 100% duty cycle. So the numbers I'm using are being generous versus the actual amount of fuel being used by the engine. So the return line will have to handle more fuel then what my math is showing at 100% engine power output [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
SVTPerformance's Chain of Restaurants
The Distillery
Time for e85.. Have a few questions
Top