Radium Engineering FST-R Fuel Surge Tank with Integrated FPR
 

FST-R Fuel Surge Tank with Integrated FPR

Any of you seen this ?

Specifically for returness systems and provides the same 1:1 pressure/vacuum

modifying the oe assembly is free...
Anybody who really needs a bigger pump should probably opt for a return system too...

But the OE system doesn't provide the 1:1 pressure/boost does it ?

Also, the reason I brought it up was because of this.

https://www.facebook.com/photo.php?v=10151053526323894

From Turblown

"Now we know why every Rx-8 regardless of drop in fuel pump never has adequate fuel pressure on the dyno. What you see is after 6 to 10 seconds of pump activation the pump drops pressure, then after waiting several seconds it recovers. Can anyone guess the problem and simple fix? Unit is walbro and there is nothing wrong with the pump."

The fuel pump assembly runs of fuel due to the high performance pump sucking more fuel faster than the housing can refill.

It's just that it so happens this surge tank comes with built in pressure regulator.

I will probably end with a surge tank for my build, im loosing hope in a good intank fuel setup

It's not a simple surge tank. It's a pressure vessel surge tank built like a reinforced concrete poop-house. It should work well as long as your pockets are deep enough. There are likely much less expensive options though

I thought it looked more like a fuel leak to me :)

a bomb might be a better description, it's well built though so it is no more prone to leak than anything else in the pressurized fuel system

A bomb ? Just to clarify, it isn't build by Turdblown. It's Radium Engineering.

I was looking at a surge tank just because of the issues brought up with the OE assy.

I was joking. It is a pressurized vessel full of gasoline though.

Its not under pressure btw...

Forgive my ignorance, but how does this prevent the stock fuel pump from running out? If the problem is the basket going dry under high demand, then the basket will still go dry since demand will be just as high. This will provide a few extra seconds until the surge tank goes dry as well, but that whole time the stock pump will be sucking air and reducing pump life.

Seems like a poor bandaid on the actual problem. Why not just fix the in tank problem and then do a return system with a fuel pressure regulator?

It prevents the fuel rail from running out because it acts as a reserve fuel source for the time that the stock intank pump is cavitating. I am not very familiar with the RX8 yet, but in the s2000 world the stock fuel pump cavitates on hard acceleration or hard sweepers, due to the fuel sloshing away from the pump. My understanding is the RX8 has the same issue(s), and that this is when the basket goes empty. When the fuel returns from it's sloshing around, it should almost instantly fill the basket back up. The FST provides an additional amount of time for the basket to fill up. S2000s do not have the fuel pump baskets, so forgive me if the issue is actually the basket filling up. If that is the case, I would remove the basket all together when running a FST. The FST should provide fuel much more than just a few seconds, and it should also fill back up very fast, because the in tank pump is now only pushing against head pressure (the distance from fuel level to the FST level, ~2 feet on average?), it is not trying to make up 50+ PSI pushing to the rail.

As for being a band aid.. yes, it is a band aid, it attacks an effect rather than a cause. The only way I see successfully attacking the cause is running a Baffled fuel tank/cell that has trap doors for the sump pickup.

I assume between fixing fuel pumps cavitating and OMP lines/injectors plugging, there will be much more reliability seen out of the Renesis motor.

Or modify the venturi to allow it to draw more fuel from the other side. Use that with a boost regulated return instead of the stock regulator and you might be able to get the best of both worlds.

How would you plan on doing that?

I don't plan on doing it, but if I ever need to this here's what I'd try:

Take the stock assembly and run the hose from the pump straight out the top bypassing everything. Run a new line through the top of the assembly for a return and connect it to the venturi. I don't have a stock pump handy, but if there is any restriction from the passenger side line through the ventrui I'd remove it. There are in line eductors that would probably work if the stock is still too small. I remember something on the fuel pump solution thread about enlarging the hole, but i think it was for the pressurized fuel not suction from the other side.

The point is that with a properly sized eductor/venturi you can draw more fuel into the bowl than what the the engine and the eductor uses. And if it sucks air it doesn't feed the air directly to the pump.

Then you can run a normal return system and have it boost regulated.