Fuel Delivery Question

[Underboost]

Hey guys I have a Question.

I have 72lb injectors and Red Armstrong's XP Plus Double Pumper in the tank but I have been only running one pump with stock fuel rails, and lines.
I have a TurboTweak chip and do all my turning off the scanmaster & EGT's
I run a 70GTQ 85. housing @ 28psi and the Static Fuel Pressure is at 46psi w/ O2's at 780. My question is I'm putting Alum. Heads on the car. To stay with an injector duty cycle of 80% I will need to run 83's and a Static Fuel Pressure of 43psi.

Will my stock fuel lines, and rail handle the fuel delivery?

Will the motor be overwhelmed with fuel when the second pump kicks on at 10psi ?

Will my ECM with bigger drivers having a hard time correcting?

Could I hook both internal pumps up together with a new hob switch?

At what point do I need an external pump, and bigger fuel lines?


Thank you for your help on this.

I know I need an XFI. What would you do in this situation????????

 

[bison]

I had a similar setup (see sig). Just put on an adjustable Hobbs switch and turn it on at 20+ psi. Ive seen guys go well over 135mph through the stock lines. The 72 are low Z just like the 83's so control shouldnt be a problem. My ecm handled the 83's with no problem. Duty Cycle % was in the low 60's. A/f on dyno was very linear (11.2-11.3) at WOT at 25 psi. The FAST will make a lot of difference though.

 

[Underboost]

I had a similar setup (see sig). Just put on an adjustable Hobbs switch and turn it on at 20+ psi. Ive seen guys go well over 135mph through the stock lines. The 72 are low Z just like the 83's so control shouldnt be a problem. My ecm handled the 83's with no problem. Duty Cycle % was in the low 60's. A/f on dyno was very linear (11.2-11.3) at WOT at 25 psi. The FAST will make a lot of difference though.

Thank you bison but I'm at 134mph now and will be prob around 137mph with the new heads. I would love to have the fuel injectors pulse width at there most efficient percentage "80%". So if I run a adjustable Hobbs switch the stock fuel rails and stock fuel lines will the fuel psi regulator act as a dam?

 

[Dusty Bradford]

Every car can be different. I have also seen cars go 135 with stock rails and lines. On the TSM car with a FAST system we tried stock lines and 72's with RA double pumps and went 136 but a/f was getting lean near the 1/4 mile.........enough for us to try 83's. Same story, same duty cycle of near 95% and the a/f dropping at the end of the run. It blew #1 headgasket. Swapped to -an lines and same story only this time it got #1 piston as well. Rather than taking short cuts we put the Champion rails on with an external pump and solved the issue.

I have seen it several times now once cars reach the mid-high 9 range and start hurting #1. Everyone seems to agree the stock rail is too small and #1 is the last to get fuel which causes it to go lean when the other cylinders are using all the fuel up.

 

[Underboost]

Every car can be different. I have also seen cars go 135 with stock rails and lines. On the TSM car with a FAST system we tried stock lines and 72's with RA double pumps and went 136 but a/f was getting lean near the 1/4 mile.........enough for us to try 83's. Same story, same duty cycle of near 95% and the a/f dropping at the end of the run. It blew #1 headgasket. Swapped to -an lines and same story only this time it got #1 piston as well. Rather than taking short cuts we put the Champion rails on with an external pump and solved the issue.

I have seen it several times now once cars reach the mid-high 9 range and start hurting #1. Everyone seems to agree the stock rail is too small and #1 is the last to get fuel which causes it to go lean when the other cylinders are using all the fuel up.

LOL!!! $h!t!!!!!

Dusty "YOU AR THE MAN!!!!" I have had nothing but problems with my HG blowing between #1 & #2 mainly #1 it all makes sense now!!!!! I always thought I had a HG problems. RJC's, Cosmetics, Stockers etc. I always thought maybe my block was decked wrong or the heads were warped or the Irons danced to much. I am the master of HG's NOW! I can blow them at 10am then B!tch and moan and start the tare down at 12pm stop at 6pm get up at 9am next day and have the car running by 12noon. LOL I'm so happy to here this news. Now that I'm going with Alum. Heads I'm running the SCE HG's.

What type of pump should I run? Aeromotive W/ Champion fuel rails what size AN lines??? If so what type Aeromotive pump? Sorry Dusty for the 20 q's. You made my day!

 

[Dusty Bradford]

Glad to help.

Do you street drive the car?

We have used aeromotive eliminator and a Weldon 2015 or 2025. If you street drive the car with any of these you will need a pump controller. These pumps move so much fuel without a controller the fuel will heat up and vapor lock after about 20 minutes of run time. The controller will still allow street driving.

A -8 supply and -6 return is plenty big. I have seen a local V8 car make 1200hp with -8 supply.

 

[Underboost]

Glad to help.

Do you street drive the car?

We have used aeromotive eliminator and a Weldon 2015 or 2025. If you street drive the car with any of these you will need a pump controller. These pumps move so much fuel without a controller the fuel will heat up and vapor lock after about 20 minutes of run time. The controller will still allow street driving.

A -8 supply and -6 return is plenty big. I have seen a local V8 car make 1200hp with -8 supply.

I street drive the car to car shows. I don't jump on the Fwy's do to the TH400.


PM me a cost on the pump controller, and pump that would work best with my application when you get a chance. Thanks Dusty

 

[Scott Atk]

Brent,
I know you have TSM aspirations, where ALKY isn't allowed. But in the meantime your ALKY system will extend those 72's a long way. I've been 139 with 72's and ALKY, thumbwheel set at "D" not sure what that corresponds with in duty cycle but I had two more postitions to go.
Interesting thoughts on the stock fuel rail. I melted #1 two years ago at the West Coast Nats. (the last one in Vegas) Never gave much thought to the stock fuel rail contributing.

 

[cruzn57]

brent

talk to me about fuel lines, as I need to upgrade also,
from tank to rails,
let me know what you find, or plan to upgrade to,
thanks
Lee

 

[bison]

Every car can be different. I have also seen cars go 135 with stock rails and lines. On the TSM car with a FAST system we tried stock lines and 72's with RA double pumps and went 136 but a/f was getting lean near the 1/4 mile.........enough for us to try 83's. Same story, same duty cycle of near 95% and the a/f dropping at the end of the run. It blew #1 headgasket. Swapped to -an lines and same story only this time it got #1 piston as well. Rather than taking short cuts we put the Champion rails on with an external pump and solved the issue.

I have seen it several times now once cars reach the mid-high 9 range and start hurting #1. Everyone seems to agree the stock rail is too small and #1 is the last to get fuel which causes it to go lean when the other cylinders are using all the fuel up.

$hit. My #1 got too hot last time too and burned the gasket out. Luckily i heard the dead cylinder and let off before melting the piston. The homogenous mixture of all the cylinders was around 11.4:1. Maybe #1 was at over 12:1. -8 feed will be going in.

 

[Dusty Bradford]

$hit. My #1 got too hot last time too and burned the gasket out. Luckily i heard the dead cylinder and let off before melting the piston. The homogenous mixture of all the cylinders was around 11.4:1. Maybe #1 was at over 12:1. -8 feed will be going in.

Louie Lopez and I talked about this issue a while back. It seems he still had issues even with the -an lines on a stock rail until he put a Weldon pump on. I still fill an intank pump and -an lines still can't move enough volume through the rail to support 9 second power.

 

[Turbo1dr]

These aluminum fuel rails came off of my full race ported Champion GN1 intake as delivered to me.

I can't get a grasp on how the Champion fuel rails supply the engine with more fuel when they are actually slightly smaller internally than the stock fuel rail? In the pictures below I have drawn a line identical in length to the max bore size of the aluminum rail and put the same red line on top of the stock rail. I can't find a piece of scrap stock fuel rail to actually measure the internal diameter. I'm guessing the thickness of the wall is about .050" thick. Even if I take .100" away from the total outside diameter of the stock fuel rail it's still slightly larger than the aluminum rails internal passage.

Also, look at the small crossover with the 90* bends and the MUCH smaller openings in the fittings? How can that help flow to the drivers side cylinders unless people feed BOTH sides of the aluminum rail...which would cure the leaness of that bank of cylinders.

 

[1BADTT]

Good point Turbo1dr !

Double pumper, stock lines & stock fuel rail work for Jason Cramer (heaviest TSM car of all & runs 9.75 @ 140) why shouldn't it work for most of us ?

 

[Underboost]

These aluminum fuel rails came off of my full race ported Champion GN1 intake as delivered to me.

I can't get a grasp on how the Champion fuel rails supply the engine with more fuel when they are actually slightly smaller internally than the stock fuel rail? In the pictures below I have drawn a line identical in length to the max bore size of the aluminum rail and put the same red line on top of the stock rail. I can't find a piece of scrap stock fuel rail to actually measure the internal diameter. I'm guessing the thickness of the wall is about .050" thick. Even if I take .100" away from the total outside diameter of the stock fuel rail it's still slightly larger than the aluminum rails internal passage.

Also, look at the small crossover with the 90* bends and the MUCH smaller openings in the fittings? How can that help flow to the drivers side cylinders unless people feed BOTH sides of the aluminum rail...which would cure the leaness of that bank of cylinders.

That's odd.

 

[Underboost]

Good point Turbo1dr !

Double pumper, stock lines & stock fuel rail work for Jason Cramer (heaviest TSM car of all & runs 9.75 @ 140) why shouldn't it work for most of us ?

Jason and I weighed the exact same getting off the scales in Bowling Green.
That was weird. :smile:

 

[1BADTT]

Jason and I weighed the exact same getting off the scales in Bowling Green.
That was weird. :smile:

What have you done for weight savings ?

 

[Underboost]

What have you done for weight savings ?

No spare tire & Jack, and a glass front bumper. I put the bumper on after
the TH400 went in. Oh and Weld wheels.

 

[gnxtc2]

Like Dusty said, every car is different.

I was running a RA double pumper. Even though I had no problem with it, it was always in the back of my mind "what if the 2nd pump doesn't kick on"

I like the big single pump w/ controller for a piece of mind.

I am running a Weldon 2025 pump with their controller. I also have their FP regulator. Some say it's over kill but running from the cell to pump in -12 AN then -10AN to a "Y" in the engine compartment. Then feeding with -8AN to each side of the rail. Using a -8AN as a return.

You can see the controller mounted on the passenger side. The pump is sticking up.

Billy T.
gnxtc2@aol.com

 

[Dusty Bradford]

Also, look at the small crossover with the 90* bends and the MUCH smaller openings in the fittings? How can that help flow to the drivers side cylinders unless people feed BOTH sides of the aluminum rail...which would cure the leaness of that bank of cylinders.

There you have it. Feed each rail and you a have a single rail feeding 3 injectors. This is what we did on the TSM car. Just like Billy T.

Like mentioned earlier. I think the main issue is intank pumps and the stock rail. Louie eliminated his issue by running a Weldon pump with -8 feed to the stock rail. This large pump supplies enough volume and pressure to counteract the weakness of the stock rail. Some get by with this set-up....some don't. We burnt two headgaskets and 1 piston trying to make the stock rail work with intank pumps and never made it past 9.80's in a 3560# car. Even with 15 volts on the pumps.

Bottom line....If you're having issues with #1, this is most likely your problem. For those not having issues I wouldn't worry about it until you start making more power. Just because someone else gets away with it, it doesn't mean you can.

Another note....do not try double feeding the stock rail. There is no way for trapped vapor to vent from the rail. Another racer tried this and had issues.

 

[Dusty Bradford]

For everyone's info on line size and hp potential. It's based on what I see at the track every weekend.

A -10 is enough to feed 2000+hp

-8 is good to 1500-1700

On a buick you could run a -8 supply with a -6 to each rail and be fine. Billy T has a TA aluminum motor so he went with the larger size.