mr viper
Viper Owner
X2 I also plan on going with a supercharger. And this info really helps out. Thanks guys. I think I will run a twin pump set up.
BOTTLEFED, I Have the same plans for my 98 GTS. 10# with some nitrous.
Post your Upgraded Fuel system
- Thread starter BOTTLEFED
- Start date
X2 I also plan on going with a supercharger. And this info really helps out. Thanks guys. I think I will run a twin pump set up.
BOTTLEFED, I Have the same plans for my 98 GTS. 10# with some nitrous.
Russ M
Enthusiast
Its 55psi, just like all the other vipers. On the newer cars the regulator is in the pump on the older ones they seem to have that metal piece. Not sure at what point they switched but for sure a 99 is internally regulated, no metal regulator.
EllowViper
Enthusiast
x3..but I want to stay with a returnless system regulated at the tank...like OEM. Project for later this fall.
BOTTLEFED
Enthusiast
Eric, you're going dual pumps but in a returnless system? how?
EllowViper
Enthusiast
Need to see how the stock bypass works and how it is fitted to the top of the OEM pump...and also line in/out sizes/limitations. Some of the pics I've seen show a large black metal mechanism the fuel out line attaches to. Again might be year specific if later pumps have an internal bypass...or if there is space on the tank, put an external regulator co-located there and pump excess right back into the tank at that point. I have to believe those smarter than me have gone down this road before (presumably unsucessfully given the systems people have thus engineered) so I don't know what I'll end up with when all is said and done. Great post in trying to pull the rug back on some of this and like you, I appreciate those that have responded with details. Worst case...single Walbro 255 using stock lines/BAP. Better case, dual Walbros bypassed at the tank with improved lines to the filter...and fuel rails.
BOTTLEFED
Enthusiast
I'd like to hear some opinions from those that know the stock system about the reasons for upgrading the pump.
What HP does the stock pump max out? does it matter if the car is n/a, nitrous, Roe, Paxton, TT?
Why does it max out? flow? psi?
Is the Walbro the better choice just because it can be regulated to higher psi?
What HP does the Walbro max out? why?
What HP does the stock pump max out? does it matter if the car is n/a, nitrous, Roe, Paxton, TT?
Why does it max out? flow? psi?
Is the Walbro the better choice just because it can be regulated to higher psi?
What HP does the Walbro max out? why?
i know there is always talk of the OEM pump being good till 600rwhp but id like to see some facts to back it up personally.
im sure there are a bunch of tuners or guys who have some bad stories at that power level, maybe they can chime in.
i think its flow that the problem
im sure there are a bunch of tuners or guys who have some bad stories at that power level, maybe they can chime in.
i think its flow that the problem
Russ M
Enthusiast
Plum,
I have personally seen a factory pump make 640rwhp on a viper without a boost a pump or anything, this was a nitrous car.
Bottlefed,
The stock pump is good for about 700crank hp if you run it at factory pressure, the higher the pressure the less power it can support.
It makes a big difference if your car is NA, or forced induction/nitrous. For instance an NA car typically will be tuned to 12.5-13.1 air/fuel, while a turbo/nitrous car would be 11.1-11.5 air/fuel which is much more demand on your pump.
There are much bigger and better pumps than the walbro, but for the price/longevity/noise of the walbro its hard to beat it.
I have personally seen a factory pump make 640rwhp on a viper without a boost a pump or anything, this was a nitrous car.
Bottlefed,
The stock pump is good for about 700crank hp if you run it at factory pressure, the higher the pressure the less power it can support.
It makes a big difference if your car is NA, or forced induction/nitrous. For instance an NA car typically will be tuned to 12.5-13.1 air/fuel, while a turbo/nitrous car would be 11.1-11.5 air/fuel which is much more demand on your pump.
There are much bigger and better pumps than the walbro, but for the price/longevity/noise of the walbro its hard to beat it.
BOTTLEFED
Enthusiast
Very true, I didn't think about the tune.
So the stock pump could, theoretically, go farther on a forged piston car than a cast piston car since the tune is typically richer on cast pistons. This is only hypothetical since cast piston cars can barely max out the stock pump because of engine strength issues, not pump limitations.
I guess most built n/a cars can be tuned just fine on the stock fuel system then.
dansauto
Enthusiast
Russ M
Enthusiast
If your running 14:1 compression you will be also running race fuel, since that is no longer a street car that can run on pump gas. Which means you will still be running 12.5-1 air/fuel. But you are correct if your motor is that high compression then you will be richer than your normal NA motor.
Bottlefed,
Forged or cast makes no difference, you cant have detonation on any of the pistons. The only difference is that if its cast it can break much faster than forged, but make no mistake either one needs to be treated like its extremely fragile.
Bottlefed,
Forged or cast makes no difference, you cant have detonation on any of the pistons. The only difference is that if its cast it can break much faster than forged, but make no mistake either one needs to be treated like its extremely fragile.
1TONY1
Enthusiast
BOTTLEFED
Enthusiast
thanks Tony
questions:
how are the lines inside the canister connected to the pumps?
what are the lines going to the Y-fitting?
do the Walbros sit all the way down in this configuration so that they can pick up fuel at low tank levels?
questions:
how are the lines inside the canister connected to the pumps?
what are the lines going to the Y-fitting?
do the Walbros sit all the way down in this configuration so that they can pick up fuel at low tank levels?
1TONY1
Enthusiast
thanks Tony
questions:
how are the lines inside the canister connected to the pumps?
Braided line, hose clamp on the pump end, AN fitting on the top. Now I would use the specific type hose that is made to be submerged in fuel.
what are the lines going to the Y-fitting?
Those are the feed lines...pressure side of the pump. Two size -6 and out of the Y with -10.
do the Walbros sit all the way down in this configuration so that they can pick up fuel at low tank levels?
They sit as low or a touch lower than the factory pick-up. If you see the little round part on the bottom of the canister, that is the factory pick up location. Here is a picture I forgot that shows both pumps with the filters attached. In the previous picture when only one filter is on you can see how it compares to the factory pick up location. To hold the pumps in place you have the holes that they stick through on the bottom and also the slots that the hose clamps go through..the clamps go aroung the pumps. Small hole on the side is for access to tighten the clamp. This was a bunch of work. To do it over I would just by the RSI piece if it were on sale. Back then, it was not available.
questions:
how are the lines inside the canister connected to the pumps?
Braided line, hose clamp on the pump end, AN fitting on the top. Now I would use the specific type hose that is made to be submerged in fuel.
what are the lines going to the Y-fitting?
Those are the feed lines...pressure side of the pump. Two size -6 and out of the Y with -10.
do the Walbros sit all the way down in this configuration so that they can pick up fuel at low tank levels?
They sit as low or a touch lower than the factory pick-up. If you see the little round part on the bottom of the canister, that is the factory pick up location. Here is a picture I forgot that shows both pumps with the filters attached. In the previous picture when only one filter is on you can see how it compares to the factory pick up location. To hold the pumps in place you have the holes that they stick through on the bottom and also the slots that the hose clamps go through..the clamps go aroung the pumps. Small hole on the side is for access to tighten the clamp. This was a bunch of work. To do it over I would just by the RSI piece if it were on sale. Back then, it was not available.
Last edited:
BOTTLEFED
Enthusiast
Exactly what I was looking for, thank you.
It sounds like this will be the setup I will go with.
It sounds like this will be the setup I will go with.
dansauto
Enthusiast
kindo of what I did on my gen 1, I had a machine ship make me new "bungs" for the top of the canister and ran an fittings off them. I used the factory line as the return and (2) 8an lines of of the canister to a y block then 10an out of the y block. I used fuel injection hose to the pumps in the canister and just wire tied them to the sides of the canister with the pick up tubes down in the sump part of the canister. I used the factory power as a signal line for a relay to turn on the pumps.
1TONY1
Enthusiast
Very, very important IMO.
BOTTLEFED
Enthusiast
Yes, I was planning on this as well. I will use the factory wiring to turn on a large relay and run a large gauge (6-8ga) wire directly from the battery for the pumps.
So will the BAP not be necessary anymore with this setup?
So will the BAP not be necessary anymore with this setup?
mnviper
Viper Owner
From what I found researching this earlier, once you cut openings in the stock canister or bypass the check-valve at the bottom, you run into the "less than quarter tank" pick-up issue. One other thing I found out is that standard fuel line is not meant to be submersed and will fail over time. The only line I'm aware of that is certified for submersion is a Gates product available on through napa at about $20/foot.
SNKEBIT
Enthusiast
From what I found researching this earlier, once you cut openings in the stock canister or bypass the check-valve at the bottom, you run into the "less than quarter tank" pick-up issue. One other thing I found out is that standard fuel line is not meant to be submersed and will fail over time. The only line I'm aware of that is certified for submersion is a Gates product available on through napa at about $20/foot.[/quote]
That hose fails too if the hose clamp is too tight. Mine is basically the same as Tony's set up only I have mine feeding off the bottom of the canister. Return dumping into canister to keep fuel at pumps.
I made 3/8 hard lines with fittings at both ends to hang the pumps. Seems to be working w/ 16 lbs of boost on my crappy ol' gen. 1
ViperBing
Enthusiast
Does anyone have any idea if the RSI fuel pump hanger has the 1/4 tank issue? It seems like the RSI hanger would be the simplest solution.
1TONY1
Enthusiast
The way the pumps are in mine, the bottom of the filter screen is probably touching the bottom of the tank. I wouldn't normally race or autocross with less that 3/8 to 1/2 tank even with the stock set-up but the other day I had cause to do a 1/2/3/4 30mph to 140mph with less than 1/4 tank and with the drag radials it was hooking and for sure moving the fuel to the rear.....the a/f never fell off at all. I have also ran the tank about dry with no issues....normal driving though, not sweeping curves or such.
Simms
Enthusiast
Good thread.
Bob D
Enthusiast
I built my fuel pumps as per Tonys design a couple years ago and can confirm there is no issue with a low fuel level.
I bought the fuel-proof hose from Auto Performance Engineering - Walbro fuel pumps and more
I bought the fuel-proof hose from Auto Performance Engineering - Walbro fuel pumps and more
ViperBing
Enthusiast
Given that the RSI fuel pump hanger is on sale for $399, which setup do you think will work better? Modding the factory hanger per Tony's design, or the RSI billet hanger?
BOTTLEFED
Enthusiast
It probably comes down to $$
The RSI piece would be easier and prettier, but Tony's setup would be cheaper and, well cheaper
The RSI piece would be easier and prettier, but Tony's setup would be cheaper and, well cheaper
EllowViper
Enthusiast
Hummmmm...Man-O-Man...RSI hangar is pretty tempting...I just have this terrible character trait of self-induced "making it harder than it needs to be just to..in theory...save a buck...". Choices choices choices...
BOTTLEFED
Enthusiast
haha
I'm the same way
I think I feel more accomplished if I made something myself, than just buying it.
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