Alright rotary savants, I have fuel surge questions

speedjunkie · 10-15-2017, 10:14 AM

I've been looking for an anti-slosh solution for a while, but nothing so far has met all my wants and needs and I think I've finally figured out what I want to do. I'm currently using dual Walbro 450s and they each feed one of the fuel rails as of right now. I'd like to switch it back to both pumps feeding both fuel rails, but I need to sort out the pulsation issue I had before with that setup, whether it be a larger fuel rail or what. I'm not using flex fuel yet but the car is set up for it. I may not ever use it, I'm not sure yet.

I'm planning on building a little tank from stainless steel that sits in the stock plastic box, and I'll run a hose from each fuel pump to that tank. From both sides of the tank will run a line (probably stainless hard line) to a Holley Hydramat at the far ends of the tank on both sides, using a one way check valve on each line just before the tank. I will run a stainless hard line from the return line back to the tank as well, dipping down to the bottom of the tank so the return fuel can be cooled a little by the rest of the fuel in the tank. I will also put a lid on the top because I'll have to fill it with fuel first since it will be a sealed system, and because of all this I will probably also put a one way check valve going out the top so excess fuel or pressure can be leaked out into the main tank. I've also thought about scraping the protective coating off the bottom of the tank and attaching heat sinks to cool the fuel.

Because it will be a sealed system, it will be pulling the fuel back through the return line instead of just flowing normally. Theoretically, whatever amount of fuel I put into the surge tank to prime it, should be the amount it always has regardless of the load on the engine. Although it might not be a good idea running the return line straight to it, because the return will flow different rates depending on engine load. I imagine it will suck fuel out under heavy throttle, but light throttle or idle I wonder if it will back up in the line. However, whatever the flow in the return line is should mimic whatever the pumps are doing, so maybe that's a non-issue anyway.

Thoughts? What factors am I not considering?

JL1RX7 · 10-15-2017, 07:03 PM

Buy different pumps. Walbro should be called wallet blown. Aeromotive or the like will be better served. Expensive yes. But do couple hundred bucks vs redoing a blown motor.

The angry one knows surge tanks and that type of set up. Hopefully he will chime in.

speedjunkie · 10-16-2017, 12:55 PM

Well I've never heard much good about the old Walbros so I was nervous about using these. But I haven't heard anything bad about these and they've been good for me so far. I also got two so if one failed I'd still be OK. On top of all that, I have failsafes set up in the ECU using sensors just after the filters so that if I get low or no fuel pressure it shuts the car down. So I have redundancy after redundancy, but I want more safety HAHA. The reason I went with these is because I knew they'd be good with E85. I wasn't sure about AEM, Aeromotive, or the others. I had Bosch 044s that I was going to use but I sold those when I decided to do flex fuel. And now I'm concerned about using E85 anyway haha, I just feel like there hasn't been enough evidence yet that it's OK on the engine. Not to mention the flex fuel sensor doesn't detect water, ugh. I'm just on the fence still. I overbuild each system so that it protects the engine, but I wouldn't have it any other way.

I'd like to get some fuel pumps that are more known to be reliable that are also good with E85 (just in case I decide to use it eventually) and have a more solid way of connecting hoses to the inlet for this project. I've done some searching but I haven't seen much yet.

Yeah Brian PM'd me haha.

10-15-2017, 10:14 AM	#1
speedjunkie RCC Loves Me Not You Join Date: Mar 2008 Location: Colorado Springs, CO iTrader: (1) Posts: 2,089 Rep Power: 19	Alright rotary geniuses, I have fuel surge questions I've been looking for an anti-slosh solution for a while, but nothing so far has met all my wants and needs and I think I've finally figured out what I want to do. I'm currently using dual Walbro 450s and they each feed one of the fuel rails as of right now. I'd like to switch it back to both pumps feeding both fuel rails, but I need to sort out the pulsation issue I had before with that setup, whether it be a larger fuel rail or what. I'm not using flex fuel yet but the car is set up for it. I may not ever use it, I'm not sure yet. I'm planning on building a little tank from stainless steel that sits in the stock plastic box, and I'll run a hose from each fuel pump to that tank. From both sides of the tank will run a line (probably stainless hard line) to a Holley Hydramat at the far ends of the tank on both sides, using a one way check valve on each line just before the tank. I will run a stainless hard line from the return line back to the tank as well, dipping down to the bottom of the tank so the return fuel can be cooled a little by the rest of the fuel in the tank. I will also put a lid on the top because I'll have to fill it with fuel first since it will be a sealed system, and because of all this I will probably also put a one way check valve going out the top so excess fuel or pressure can be leaked out into the main tank. I've also thought about scraping the protective coating off the bottom of the tank and attaching heat sinks to cool the fuel. Because it will be a sealed system, it will be pulling the fuel back through the return line instead of just flowing normally. Theoretically, whatever amount of fuel I put into the surge tank to prime it, should be the amount it always has regardless of the load on the engine. Although it might not be a good idea running the return line straight to it, because the return will flow different rates depending on engine load. I imagine it will suck fuel out under heavy throttle, but light throttle or idle I wonder if it will back up in the line. However, whatever the flow in the return line is should mimic whatever the pumps are doing, so maybe that's a non-issue anyway. Thoughts? What factors am I not considering? Last edited by speedjunkie; 10-15-2017 at 10:41 AM..

10-15-2017, 07:03 PM	#2
JL1RX7 Rotary Fanatic Join Date: Feb 2008 Location: Front Royal, VA iTrader: (1) Posts: 487 Rep Power: 17	Buy different pumps. Walbro should be called wallet blown. Aeromotive or the like will be better served. Expensive yes. But do couple hundred bucks vs redoing a blown motor. The angry one knows surge tanks and that type of set up. Hopefully he will chime in.

10-16-2017, 12:55 PM	#3
speedjunkie RCC Loves Me Not You Join Date: Mar 2008 Location: Colorado Springs, CO iTrader: (1) Posts: 2,089 Rep Power: 19	Well I've never heard much good about the old Walbros so I was nervous about using these. But I haven't heard anything bad about these and they've been good for me so far. I also got two so if one failed I'd still be OK. On top of all that, I have failsafes set up in the ECU using sensors just after the filters so that if I get low or no fuel pressure it shuts the car down. So I have redundancy after redundancy, but I want more safety HAHA. The reason I went with these is because I knew they'd be good with E85. I wasn't sure about AEM, Aeromotive, or the others. I had Bosch 044s that I was going to use but I sold those when I decided to do flex fuel. And now I'm concerned about using E85 anyway haha, I just feel like there hasn't been enough evidence yet that it's OK on the engine. Not to mention the flex fuel sensor doesn't detect water, ugh. I'm just on the fence still. I overbuild each system so that it protects the engine, but I wouldn't have it any other way. I'd like to get some fuel pumps that are more known to be reliable that are also good with E85 (just in case I decide to use it eventually) and have a more solid way of connecting hoses to the inlet for this project. I've done some searching but I haven't seen much yet. Yeah Brian PM'd me haha.