All you gurus out there, I was wondering what Fuel Pressure (vacuum line disconnected) you would recommend running on an Evo with a TME 6.5 Turbo running roughly 25psi (factory is roughly 43psi from my understanding).

I have a Walbro 255lph High Pressure Fuel Pump on its way and I am running the Injector Dynamics 1000cc Injectors that recommend running as much Fuel Pressure as possible for better atomization.

Their recommendation was to take the maximum fuel pressure your fuel system can handle then subtract the amount of boost you will be running (25psi) and set your fuel system pressure to that point.

So what is the maximum fuel pressure my system can run? I was thinking about 55psi as an educated (kinda) guess. Thanks in advance.

Dan

 

I just run stock FP on my ID 1000's.......I honestly wouldn't worry about it until you can go to a twin walbro or a inline bosch pump because you are limited to what you can do with FP on a single walbro.

 

I'm not familiar with those injectors, but I imagine you will have a hell of a time tuning if you use that method. You aren't trying to do anything crazy, so personally I'd recommend sticking with stock fuel pressure.

You also need to remember that your fuel pump will not be able to create as much flow at higher pressures, so it may not be able to keep up with 1:1 pressure near redline if you are really flowing enough for those 1000cc

 

Thanks for the insight. I am very new to the tuning world but do have a very good grasp on flow vs pressure and most tuning concepts. Are there any figures on what this fuel pump will actually flow at certain pressures? I have been searching the web with little luck.

With a little data and finding out how much fuel the car uses at peak torque I can't imagine it would be too hard to figure out how much pressure I can safely run. Also, considering I am running a stock size turbo, I don't think I will be pushing the fuel pump or the injectors to their limits.

Why would you think I would have issues with tuning with higher fuel pressures? I have all the latency information and can adjust scaling appropriately. I wouldn't be adding more or less fuel than at a lower pressure, I am just shooting for better atomization per recommendations from Injector Dynamics. But, I am more than willing to admit, I am not sure why I would need better atomization... I will research in to that more thoroughly. Thanks again.

Dan

 

I think for the headache you will get the atomization benefits will be negligable. Your latency will change significantly with higher pressures, and IMHO this is the hardest part of fueling to tune.

AMS Posted a thread about the Evo X fuel pump (and another thread about series/parallel) that should have all of the information you are looking for on flow rate in a nice little picture.

 

Unmodified 255 HP (thanks AMS and jayracing)
http://amsteam.net/files/8/fuelpumpgraph-1.JPG
http://www.jayracing.com/images/Bosc...lbro_255HP.JPG

Modified 255 HP (thanks AMS)
http://amsteam.net/files/8/fuelpumpgraph-3.JPG

Calculate your fuel demand. Add in boost pressure on your 1:1 FPR. Find the difference. Don't forget to add in 5-10psi due to fuel line and fuel filter restrictions.


Negative ghostrider. The ID1000's kick *** and kick more of it the higher the pressure you run. They aren't a design from the 80's, they have proper documentation, and they do indeed run better at higher pressures. It is the users job to provide the proper fuel system allowing these puppies to flow 1600cc/min at the peak differential pressure these injectors are designed for.

 

truf

 

Shut up FGT.

 

0xDEAD,

Thank you for all the info... Any more information on how AMS Modifies the Fuel Pump?

And whilst we are at it, if you have the information handy on fuel needs, that would be appreciated as well.

Dan

 

Modding a Walbro

https://www.evolutionm.net/forums/ev...ng-walbro.html

 

Thanks again for more info. I guess I will be modding the fuel pump and pushing the fuel pressure up.

But first things first, I will just run the stock fuel pressure until after the next Redline Time Attack. I don't want to go changing too many things before a race. I also don't have a fuel pressure regulator yet.

Dan

 

So if I am understanding this properly.....the idea is to raise the fuel pressure to help the injector have better spray atomization?

In theory, I can see how this will "work" but having a fuel pressure regulator will hold back any potential gains that the "modded walbro" might produce....right???

What about having rising rate fuel pressure by disconnecting the fuel pressure solonoid line from the regulator and hooking the regulator line directly to the intake manifold. Thus, as boost pressure increases so will your fuel pressure.

Just a couple thoughts.

Paul

 

The factory fuel pressure regulator rises at a 1:1 ratio to boost pressure. The only problem is, it's not adjustable and is set to roughly 40psi with the vacuum line disconnected.

I will add an adjustable fuel pressure regular with the same 1:1 ratio, but set the base fuel pressure to, lets say 55psi (estimate as of right now) with the vacuum line disconnected. Now the fuel system will act just like factory but with a higher base pressure.

Latency numbers will have to be adjusted, the fuel maps will have to be reworked and scaling (most likely) for the added flow the injectors are capable of due to increased pressures. Tuning should still be fairly standard, I would just have to keep an eye on the Walbro to ensure it is up to the task of handling the higher pressures consitantly. Luckily I run an AIM Sport MXL dash and can add a pressure sensor to keep track of fuel pressure and warn me if the pump were to fail in any way.

Dan

 

I would suggest reading through Injector Dynamics Site - good info if your looking to understand how they work and why they are badd a** injectors..

If I am reading what your saying it would be the opposite - even a modded walbro will hold back how much base pressure you can run. You would need to run a twin walbro, or a combination of internal walbro and external bosch pump to supply enough fuel to handle higher base pressures where these injectors will start working like 1600's. You are limited on a single pump how far you can turn your base pressure up....

The evo already has a rising rate FPR 1:1 and it already increases? The solenoid is only an assist for starting, does not do anything else from that point on from my understanding.

 

Well you can crush them a little and raise the fuel pressure that way - just have to baby step it. All it takes is a 1/4" drive extension, a vice and a hammer and then tap the top with some force and then install - start the car watch FPR gauge w/ vac. line off and repeat until you hit the desired base fuel pressure.....but you would be limited to how far you can go.