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Boost a pump was on my radar, but seems expensive and adding more points of failure. Not sure it will correct the issues with the s2 pump when running a stock ecu that cant correct for fuel pressure.
Mine idles at 62, quickly comes down to 58 then plummits to 53 around 5psi and hold that until 10ish psi dropping to 47 by 12psi.
At best i believe with a boost a pump it will maintain 53psi as per the regulator
As far as I'm concerned anything over 300hp you should start looking at a surge setup as well.
You need rock solid fuel pressure and ideally a rising rate regulator to keep things from going boom... and that's difficult when the fuel pressure does what it wants.
If the pump can't keep it at the regulated pressure you have a big supply problem..... and that isn't something you want to try and tune around...
yeah it gets into a bunch of things I just don’t care to get into the same old argument with the danged and determined to do it wrong crowd
and the S2 module is documented and discussed in my S2 pump testing thread; Mazda intentionally backpressures the pump/FPR at 60 psig to power the siphon for pumping fuel over from the RH saddle. So you have to understand all that and how to work around it in some form. There are different ways to do it, but I don’t really care to get into that discussion/argument again. Just like overheating radiators, running the wrong spark plug heat range, etc. you can all just go figure it out and do it your own way.
To mildly resurrect this thread, is there any room inside of the assembly to install a larger fuel pump? IE a hellcat fuel pump (F90000295)? I don't have an S2 basket to look at yet, I feel they have become difficult to find.
I think removing the reg is also an option since i'll be running an external reg so if that is a cause for fitment aside from dia, then that can be altered.
If not, I assume I'll need to look for a custom basket, or just a surge tank.
So I admit I'm an idiot, I didn't think I posted that question yet. And even more embarrassing is I missed your response initially. My apologies.
And to get it to fill, I am hoping with a radium ventri kit, it will pull enough to not go dry. Not sure an exact solution yet, just want to avoid a surge tank if possible.
No, you’re not. This particular thread always bothered me, is all.
It can siphon from the other side if there’s fuel over there, but it certainly won’t provide that amount of flow any more than the fuel inlet flap on the basket. For that kind of flow you really need a surge tank setup and/or pump modules on both saddles with check valves and a Y-merge into the main fuel line to the engine. Because even with a surge tank it has to be kept filled from the fuel tank as well depending on how long it may be operating at peak flow rate.
Obviously that will be different for a 1/8 or 1/4 mile drag car than a road race or 1-mile top end speed car.
For sure. I did see B2A used to sell a 3d printed surge basket. I never really looked into the design much but it may be worth looking at designing and printing one. I don't know a whole lot about surge or basket designs, but am a design engineer by day and have the 3d printing capability. The only other in tank baskets I've seen are out of stock and north of $500 - $700 before taxes or shipping.
I wonder if I'm over thinking it, and should just do dual baskets with dw300's, and have a venturi on each one to siphon from either side of the tank?
So do we actually know how much the venturi siphons will flow? Do they in theory flow more with high pump flow rate? I know the radium one says it's designed with common after market pumps in mind. Venturi Jet Pump Kit
This is the one you have flickert? I have a venturi siphon created by B2A.
One thing to note is the both the S1 and S2 sumps have two venturi pumps. One feeds from the right tank, the other picks up fuel from under the sump to keep the sump full
The S1 setup below:
The picture below is a quick and dirty mock-up showing the configuration I used in my S1 sump. It splits the return which feeds both venturis in parallel, the Radium venturi didn't like being in series with the second venturi and transfer from the right tank went to near zero. I have my fuel system setup as a return style. The return from the regulator at the fuel rail goes to a 6an Y fitting and one side goes to the Radium venturi which pulls from the right tank, and the other goes to the second venturi in the bottom of the sump.
I can't say how effective this is for certain, but I haven't had any starvation issues yet.
Also It's highly unlikely the Hellcat pump will fit. I tried to fit a DW400 (the pump on the top with the green sock in the picture above), and it will not fit in a S1 sump as the fuel line from the pump outlet interferes with the sump lid, the S2 lid is even shorter . The DW400 is 138mm tall and the Hellcat pump is 131mm tall. Better choice if you need the flow is the DW440 brushless, it's more compact, draws less amps and is speed variable.
@Warrior777 I don't have the venturi kit as of yet but yes that was the kit I was planning on buying. Trying to work out any plans that can prevent me from having an external surge tank.
Thanks for the @Stubbs , I think that's part of my problem is that I don't have a hellcat FP on hand, nor a spare fuel basket to really sit down and play with. I should just get a S1 basket for cheap, 3d print a hellcat pump for mockup and go from there. Might the best choice.
My idea was to take the return line with the venturi connected to the right side of the fuel tank and place the discharge into the surge tank basket, so that the fuel from the right side of the tank goes directly into the surge tank to help keep this full. With this method you don't need two venturis, however I'm using JDL manufacturing in-tank surge tank/dual hanger setup.
How do you like it? Its been out of stock for a while.
It looks nice and certainly makes the process more simple with it's plug-n-play nature, except for wiring in additional fuel pumps which is intimidating to me. I posted some pictures on my build thread. The tank does come with a siphon but I'm not sure how well it will work or if it was bench tested for what, time will tell.
One thing to note is the both the S1 and S2 sumps have two venturi pumps. One feeds from the right tank, the other picks up fuel from under the sump to keep the sump full
The S1 setup below:
The picture below is a quick and dirty mock-up showing the configuration I used in my S1 sump. It splits the return which feeds both venturis in parallel, the Radium venturi didn't like being in series with the second venturi and transfer from the right tank went to near zero. I have my fuel system setup as a return style. The return from the regulator at the fuel rail goes to a 6an Y fitting and one side goes to the Radium venturi which pulls from the right tank, and the other goes to the second venturi in the bottom of the sump.
I can't say how effective this is for certain, but I haven't had any starvation issues yet.
Also It's highly unlikely the Hellcat pump will fit. I tried to fit a DW400 (the pump on the top with the green sock in the picture above), and it will not fit in a S1 sump as the fuel line from the pump outlet interferes with the sump lid, the S2 lid is even shorter . The DW400 is 138mm tall and the Hellcat pump is 131mm tall. Better choice if you need the flow is the DW440 brushless, it's more compact, draws less amps and is speed variable.
It looks pretty hilljacked together so I am not sure if it the path to go, but seeing its possible to get it in the basket is a bit more believable. The poor guy doesn't know how much fuel starving he will see though with that setup without any additional syphon setup. Wondering if I gut it out, do as you did with the radium venturi syphon, and the hellcat pump would be enough to get by. Then dump the return line right in to the basket.
Also talked to a guy that did a JZ swap that has a Hellcat 525 in tank with the stock basket. He mentioned tunedbyshawn has a video somewhere of doing the mock up and install of a 525 into the stock basket. Its a video on facebook that I cannot post from work. I will try to remember to upload it tonight.
so quick question since I don't know anything about cars, if I get a 255 lph for my 2005 rx8 will it run fine and still have the same 18mpg? in the city
so quick question since I don't know anything about cars, if I get a 255 lph for my 2005 rx8 will it run fine and still have the same 18mpg? in the city
as long as the fuel pressure is the same...or close the fuel pump capacity itself doesn't matter as long as it provides enough fuel
A bigger pump doesn't change anything till the engine needs more fuel than it provides... and a stock Renesis doesnt need a bigger pump than stock
okay I'm dumb but anyways your saying as long as the pressure is the close/same I can replace my dying fuel pump with a 255lph one and it will run like stock and not rich or would it just be better to get a oem fuel pump to replace it on a stock rx8, the only reason I want the 255lph pump is because its a little cheaper to get the 255lph pump then buying a whole oem pump assembly plus eventually when I save enough up ill put a turbo on it
because from what I think I know the stock rx8 that has a 115lph pump is only good for 250hp and below I think but if I get a 255lph it means I won't have to replace the fuel pump till like after 500 hp idk but considering the cars stock hp is 238 plus after I do some mods with it the hp would be over 250hp so wouldn't it be better to get a 255lph pump?
The only issue you could have is the OEM assembly includes the fuel filter and the regulator. If the old filter is OK then you can change the pump and be OK. If its old you would be better replacing the whole thing so you get a new filter
The stock pump has more than enough capacity for the stock setup. Anyone with fuel starvation issues with the stock assembly has something else going wrong
We race an RX8 with factory fuel pump. When we run tracks with hard left hand turns, or left hand turns with banking, like Daytona, we suffer fuel starvation. What is the solution? New pump? Different pump? Engine starts starving for fuel when there is still 5 gallons of fuel in the saddle tank.
01-19-2022, 05:50 PM
