fuel system suggestions

[kinter86]

I am going to turbo my 420a and have a few questions about what fuel system to run. I am building the bottom end this winter and want to upgrade the fuel system before I go turbo. My goal is 450-500hp and run 20-30psi. I just wanna make sure I build it right the first time. Any suggestions would help. Thanks.

 

[rstare]

For those numbers you will need MS for fuel control. Portfueler won't take you that far. You will also need some kind of ignition control, which you could just get MSnS and call it a day. Or get something seperate to control ignition such as MSD.

 

[kinter86]

I planed on the MSnS but i was wondering what size injectors, pump, fpr, lines, and if I would need a new rail for better flow. I was thinking of 880 injectors, 225 fuel pump, -6 lines, and the sfmu 12:1, and the Venom rail. Is this a good fuel set up to run in order to achieve 450-500whp? Thanks.

 

[bullettdsm]

I planed on the MSnS but i was wondering what size injectors, pump, fpr, lines, and if I would need a new rail for better flow. I was thinking of 880 injectors, 225 fuel pump, -6 lines, and the sfmu 12:1, and the Venom rail. Is this a good fuel set up to run in order to achieve 450-500whp? Thanks.

No sfmu. Get an Aeromotive regulator. -8an in. -6an out (for fuel rail). I run dual 255's, just to be sure. Use 880's only if you already bought them. Better off with something closer to 1000cc because MSnS can adjust.

Basically what I am running.

MB

 

[chris712vt]

Mark where would you estimate the cutoff to be before you need a second fuel pump?

I've got my Walbro 255 HP and I'll be installing PTE 880s with my MSnS as soon as the UPS man shows up... been waiting on these injectors for a while now...

Anyway I plan to run 20-25psi, hope to be in the 400-450whp range. Also along with when will the 255 will no longer cut it, when will the stock hard fuel line (supply) become a restriction? I never replaced the hard line for the supply, just the return so I could lower my fuel pressure enough with my SFMU/450cc combo.

 

[bullettdsm]

Mark where would you estimate the cutoff to be before you need a second fuel pump?

I've got my Walbro 255 HP and I'll be installing PTE 880s with my MSnS as soon as the UPS man shows up... been waiting on these injectors for a while now...

Anyway I plan to run 20-25psi, hope to be in the 400-450whp range. Also along with when will the 255 will no longer cut it, when will the stock hard fuel line (supply) become a restriction? I never replaced the hard line for the supply, just the return so I could lower my fuel pressure enough with my SFMU/450cc combo.

Ok, some of what I have done is based off my 4g63 experiences and also off my need to be safe. I have not used any big formulas or information from the vendors to come up with these (basically because I'd rather go with experience here, than some company's info).

Judging from my most recent foray on the dyno, I think you may be pretty close to maxing out the 880's at 450whpish. Now, maxing out to me is low 80's duty cycle. I don't like going above that (also remember that is on my engine set-up. Everyone's is different) . That's why I said if you already bought them, then use them (which I already had a set from the 4g63 ). But if you didn't already buy them, there really is no reason not to get 950-1000cc injectors because MSnS can adjust for them.

As for the walbro, its been my experience (as well as others that I "play" with) that when you get over 500whp, the 255 is not dependable. Which isn't to say that it hasn't/can't be done. Just that its not a great idea. Lean outs etc. Figuring that, in general, we run higher fuel pressure than 4g63's, I backed that safety level down to 450whp. Now I'm pretty comfortable with the 255 at 450whp. I'm just wussy when it comes to fuel (especially turbo). Lean spots in boost are death to pistons/ring lands, so I like to have safety pressures installed. Hence the dual walbros.

As for the lines, refer back to the dual walbros. -8an is safer than -6an. Its not about pressure here but volume. I installed the -8an with the idea of when I approach 600whp or more (yeah, we'll see ) I will already have the -8an installed. On our higher horsepower set-ups (again 4g63), we use this combo (unless you are over 800whp then we like to use -10an or more, ). Keep in mind that (I believe) the stock line is actually less than -6an (I use the stock line for my return line). But I would be comfortable with -6as a fuel line.

Just my "IMO"

MB

 

[kinter86]

So far what Im getting is that its best to go with 1000cc injectors and to replace the stock supply/return lines with -8/-6, o.k. so what about the fuel pump, Im a little confused.

 

[kinter86]

Also, I have searched for 1000cc injectors but cant find any, would 4g injectors work and would I have to rewire the harness?

 

[chris712vt]

Also, I have searched for 1000cc injectors but cant find any, would 4g injectors work and would I have to rewire the harness?

By "4g" I'm assuming you mean stock 4G63 injectors, which are 450cc. If you were to use those you will need to wire in a resistor box to run them, but that is simple and also can be had off a 4G63.

For your goals, similar to mine, I would recommend larger injectors though. I was planning at least 780-880s, but Mark says he would prefer 1000s (I agree with him, I just got a real good deal on mine ) They aren't too hard to find though man, lots of Vendors on this site have them, they're all over ebay... you should be able to get some 1000s for about $200 off ebay.




Also - Mark, thank you for explaining all that! I don't really plan to go above 450 wheel... it would be nice, but it is a street car, not a race car. And while it's cold as balls and the motorcycle is packed away, it is my daily. So the Walbro 255 and 880s should suffice for my goal. I am still concerned with the volume the stock hard supply line can flow... I don't want it to be a restriction. I may go ahead and upgrade that to avoid any risk (although I am curious now, -6AN is about 3/8", I wonder how large the stock hard line really is... 1/4"? If so that's a significant difference).

 

[chris712vt]

So far what Im getting is that its best to go with 1000cc injectors and to replace the stock supply/return lines with -8/-6, o.k. so what about the fuel pump, Im a little confused.

- You will need a Walbro 255 liter/hour High-Pressure fuel pump. They aren't expensive, and install is very easy.

- Also a 1:1 adjustable fuel pressure regulator, Aeromotive is a great choice but there are other brands too.

- Large injectors, as stated above already (with resistor pack most likely depending on high/low impedence)

- It's a good idea to upgrade your fuel lines as well, but not "required". I decided to run a larger return line because when I ran an SFMU with 450s, I needed to lower my idle fuel pressure way down and the return line was so small it actually created about 40psi of fuel pressure with the 255 pump running (even though my SFMU was wide open) - the larger line allowed me to drop the pressure as low as I needed. The supply line on the other hand on my setup is completely stock, but I may upgrade just to make sure it can flow enough fuel for 450whp. But again, I'm not sure if it is absolutely neccessary.

- And lastly, MSnS.

 

[rstare]

I am still concerned with the volume the stock hard supply line can flow... I don't want it to be a restriction. I may go ahead and upgrade that to avoid any risk (although I am curious now, -6AN is about 3/8", I wonder how large the stock hard line really is... 1/4"? If so that's a significant difference).

The stock hard feed line... I don't even think it's 1/4". I would definatley upgrade it. SlowBoy sells a -6an adapter for the OEM fuel rail. I can't remember if you upgraded your fuel rail... I actually got that adapter from SlowBoy already, because I know I will need it in the future...

 

[chris712vt]

I'm running a modified 97 rail right now. The supply side is stock though, it's the return side (well, the test port) that has a -6AN for my return to the FPR. I'll be looking into this though, might as well replace the supply line + filter while I'm installing my 880s.

 

[Car_guy_09]

Damn you guys...

Got me thinking about running some -8an from the pump to the rail.


I hate you...

 

[bullettdsm]

-6AN is about 3/8", I wonder how large the stock hard line really is... 1/4"? If so that's a significant difference).

Sorry guys, I didn't mean to throw you for a loop on this one. At the time, I measured out the ID of the stock line and it was just a hair tick under the line that I was using (just slightly smaller). So it would be considered -6an. But that's what I meant by being"smaller".

For most applications -6an would be enough. When you start looking at above 400whp, I would go with -8an.

I also used a modified 97 rail. In addition you can use the 95 rail. I have it on the turbo right now. I just removed the interior tube and welded in the fittings.

MB

And Chris, I miss my bike also, .

 

[rstare]

At the time, I measured out the ID of the stock line and it was just a hair tick under the line that I was using (just slightly smaller). So it would be considered -6an. But that's what I meant by being"smaller".

For most applications -6an would be enough. When you start looking at above 400whp, I would go with -8an.

I also used a modified 97 rail. In addition you can use the 95 rail. I have it on the turbo right now. I just removed the interior tube and welded in the fittings.

MB

And Chris, I miss my bike also, .

Wow, it seems alot smaller to me...
So basically upgrading to a -6an isn't much of an upgrade.

Mark, What fuel pressure do you run with that -8an line?

 

[bullettdsm]

Mark, What fuel pressure do you run with that -8an line?

Remember I only have 1/2 a tune on her because of the water pump pulley fiasco. I'm running 38 (blocked off vac line) right now, but it will go up when I dyno again.

MB

 

[Ajax]

Dont make the mistake I made. Initially I ran -6AN to rail and used my stock supply as return. But I switched to E85 so I had to upgrade my supply line to -8AN and used my -6AN for return.(So just go with -8AN from the beginning) Still use my stock rail just tic'd an -8AN fitting on the one end and still use the test port for return with a aeromotive 1:1 regulator. I also run duel walbro pumps with 1660cc injectors with MSnS running everything just fine.

 

[bullettdsm]

Hmm, I find this interesting. You guys seem to be using the test port for your return line. Gotta ask, why not the other end of the rail? Seemed like the obvious choice to me. Just welded in the fittings and blocked off the original feed line hole.

Just curious why the choice.

MB

 

[rstare]

Hmm, I find this interesting. You guys seem to be using the test port for your return line. Gotta ask, why not the other end of the rail? Seemed like the obvious choice to me. Just welded in the fittings and blocked off the original feed line hole.

Just curious why the choice.

MB

The test port is the other side of the rail... Not exactly sure what you mean.
I'm curious to see your rail Mark, I can't exactly picture it. If you could snap a shot of it when you get a chance that would be really helpful.

 

[knight007]

my question is how are you running two pumps, wouldn't 2 pumps mean you would want to run two lines? also curious on the dual fuel pump bracket

 

[bullettdsm]

The test port is the other side of the rail... Not exactly sure what you mean.
I'm curious to see your rail Mark, I can't exactly picture it. If you could snap a shot of it when you get a chance that would be really helpful.

Hmm, I think I see what you guys are doing. I just did what I thought was logical. I ran the -8an feed line to the passenger side of the rail (with an -8an fitting welded on) and then I welded a -6an onto the other side (because that's where my AFPR and stock line is run) for the return. Don't mind the crappy welds. I tried to braize this one together and it didn't work

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MB

 

[Ajax]

My duel pump is setup with one pump in the tank feeding another pump mounted outside the tank. I was more concerned with volume of fuel than pressure. Some people mount both pumps in the tank with a Y-fitting but I have read that that can cause early pump failure bc one pump ruins the other one.

 

[bullettdsm]

I caught your PM Knight. I was going to hit you up tomorrow.

But anyway, first off the pump side. Its actually pretty simple. there is no bracket, . We simply zip tie one pump to the other (using the stock bracket for one pump). Works fine never had problems with multiple set-ups. Now for the lines; Lots of different ways to do this. The way I did it was to pull both lines through the fuel cover plate (on 4g63's you have enough room to do the connection inside the tank. We don't). I ran a hard line through my plate (as well as using the stock line for the other pump). On the hard line I had a 90* bend on it that sent the line down to the Y connector that I had a buddy at a machine shop make (the ones on-line were WAY too expensive). The connector is mounted to the bottom of my car. So I used the stock line to come out for one pump, and I brought that down to the Y. Now that is two, -6an lines in, with an -8an line out and up to the rail (you can use SS but I just used push lock. Of course with a filter in between).

Pretty simple.

MB

 

[bullettdsm]

Some people mount both pumps in the tank with a Y-fitting but I have read that that can cause early pump failure bc one pump ruins the other one.

.....and I'm glad you brought that up. I ran into this with some conversations. Some people didn't seem to get it. I saw one pump failure because of this.

BUT here is the reason; some people look at this set-up like they would a boost situation. Need to put a couple of lines together? No problem use a T-fitting. Works fine for vac or boost but not for running fuel at each other. This is where they run into a problem with burning up pumps. Saw a buddy burn up 2 of his new walbros right at the track. He was running a T.

From what I was researching (and people I was talking to when I went to do this), lots of people ran a T. I had a hell of a time finding one at a reasonable price (of course I was also going {2} -6an's to {1} -8an) and I got a lot of just go with this T. No, its got to be a Y. And it should really be a 30* or 45* Y.

MB

 

[knight007]

I caught your PM Knight. I was going to hit you up tomorrow.

But anyway, first off the pump side. Its actually pretty simple. there is no bracket, . We simply zip tie one pump to the other (using the stock bracket for one pump). Works fine never had problems with multiple set-ups. Now for the lines; Lots of different ways to do this. The way I did it was to pull both lines through the fuel cover plate (on 4g63's you have enough room to do the connection inside the tank. We don't). I ran a hard line through my plate (as well as using the stock line for the other pump). On the hard line I had a 90* bend on it that sent the line down to the Y connector that I had a buddy at a machine shop make (the ones on-line were WAY too expensive). The connector is mounted to the bottom of my car. So I used the stock line to come out for one pump, and I brought that down to the Y. Now that is two, -6an lines in, with an -8an line out and up to the rail (you can use SS but I just used push lock. Of course with a filter in between).

Pretty simple.

MB

oh ok makes more sense now thanks for the walk through