More Suck, Less Starve

It's a problem with both the MS3 and MS6 - fuel starve under various conditions. If you have a high powered drag car, you'll suck the basket dry. If you have lots of lateral grip, you'll starve the basket if you're running low on fuel. Either way, fuel starve is a problem for many of us.

Option 1) Run a surge tank/swap in a fuel cell. Fine solution for lots of people, and they aren't terribly expensive. If you don't live by a rulebook, this is a great solution.

Option 2) Holley Hydramat. That's what we'll be talking about here.


Check out this video if you don't know what it is: Link






My rule set doesn't allow surge tanks, so that's out. It does allow fuel cells, but they have to be located within 6" of the original fuel cell location and can't be much smaller than original. With the stock tank being low in the car and made of plastic, it's in a good location and is already very lightweight. We've been running it full for pretty much forever to prevent fuel starve - 16 gallons of fuel is heavy. I'm hoping we can start events with 3-4 gallons of fuel, which would lighten the car by ~70lbs. That's huge.

On to the actual work - Pull the fuel tank and figure out where the hydramats need to go.

MS6 fuel tank layout:


With the pump being at the forward position of the tank, and only on the driver's side, it's easy to see where the problem comes in. I'm going to focus on two areas, though, since it's a saddle tank. Acceleration and turning in either direction puts fuel in the rearmost corners:


The saddle tank drives a need to pick up fuel from either corner, so I'll be using two hydramats. You can bend these things around a bit, so I want them to wrap up onto the sides of the fuel tank. I decided to use two of the 15x15" hydramats, sort of like this:





Sort of like this:














Keeping it secured in that location is pretty easy. You can do this two ways, and I'll be doing it both ways. Holley makes little magnet adapters that sandwich the tank. These magnets are incredible strong:



Hydramats have attachment holes on the corners:



What that looks like on the inside and outside:



I will also be adding foam into the tank for two reasons - 1) securing the hydramat and making sure it stays pushed into the rearmost corner. 2) Help prevent fuel slosh. Big box of foam:





I'll talk about the fuel pump and plumbing situation in the next post.

 

Nice! I bet these pads will make a huge difference.

Though, never seen foam added to a tank before. Is that specifically made to be used with fuel?

 

Yeah, the foam is compatible with gas, ethanol, and methanol. I picked them up from Speedway Motors.

 

so these are basically a surge tank you can put in the gas tank?

 

That's not its main functionality, but it does pull from its internal reservoir before it will suck air. The real benefit is that if any part of it is touching fuel, it will pull it in without sucking air from the exposed areas. I think this video shows it better than the first one:

 

That's freaking cool! Video definitely helps

 

Alright, so plumbing this should be easy, amiright? Like most things, it's not.

Here was my original concept.



The Holley ITFP adapter (16-137) should have been the easy button. I would love to keep the ITFP because it simplifies the plumbing. Issues I have right now:

1) The Holley adapter doesn't work with OEM, Deatschwerks (DW300C), or AEM pumps (50-1200). Seemingly, it doesn't work with any typical 255lph ITFP that isn't Holley brand - and the Holley brand isn't compatible with E85. The adapter doesn't allow the pump to seat against its O-Ring for the fuel pump inlet - the raised channels/nubs prevent it from seating all the way down.

I prefer using OTS parts, because it simplifies quick fixes that we sometimes do at events. I could modify the pump by removing the nubs. I could also modify the adapter so it accepts the nubs/channels. TBD on that front.






2) Pressure regulator. The OEM setup has the pump in a plastic sleeve that has a regulator attached to it. I can't use that sleeve anymore because of the Holley adapter. This is going to require an external regulator that I haven't decided on or figured out how to plumb yet.



More to come on this front.

 

I think we have a winner - Walbro GSS342G3 if anyone wants to venture into this. I'll submerge this and test to make sure it doesn't pull air past the O-ring.

If the other fittings get here this weekend, I'll plumb it and do some testing.

 

We did some testing with the hydramats over the weekend to get a feel for how they worked and if they had any weird issues we need to be aware of. We mostly did this with the mats in a couple large bins, and we just started to test it in the tank.

1) The hydramat pickup will pull air pretty early if the pickup angle isn't perpendicular to the mounting surface. I think this will be solved by supporting the area with the Speedway foam.

2) Early testing with the mats in the Mazda tank show it sucking air from what would be the inside half under turning conditions. More to come on this, we need to work with mat placement more before we can conclude anything.

3) Most surprising to me - the fuel pump can suck some air, but it doesn't transmit to the downstream fuel line unless it's sucking a BUNCH of air. Check out the 2nd video.


Showing how sensitive the mats are to pickup angle:





Running 1 dry, and sucking some air without pushing it downstream





Angle testing 1 mat to see how it picks up from a single corner touching fuel:

 

The fact that it can pick up fuel from just that one single corner of contact, is pretty amazing!

 

Things are getting...complicated.

I can't trust that the hydramats won't allow air through in dynamic situations. They suck air during transient tests by lifting up one side of the tank and sloshing the fuel around when there's low fuel. Transient maneuvers is about 100% of autocross, so that won't work. Let's complicate this shit.

Before, I had a lift pump on the passenger side into the stock basket before, so I'm doing a more robust version of that now combining it with the hydramats. Effectively, I'm making a larger basket that the hydramat system will pump into, then pull from the basket with a second pump:



And I just got the materials in for the basket:






I'm nearly finished sorting out what hardware is required to make this all work, and I'll post up some details once it's all set.

 

Progress. This is the final conceptual drawing (hopefully):



I've been busy making the new basket. Disregard the rest of this post if you don't care about the fabrication, but I like to make stuff so I'm going to show how I did it (lol).





I just started with the pics from my post above - 6061 tube and flat plate.

Turn the OD and ID so it fits into the stock fuel tank opening and you maximize internal volume.



Get a rough idea of how you'll cap the thing with the flat plate. I chose a bolt pattern of 12 screws, with a 13th so it can be aligned the same way every time.



I opted to start with a thinner tube than what I could have, because I'd rather weld on some little pads and machine them, instead of having to turn the ID down a whole bunch. In the end, probably didn't save a ton of time, YMMV. Weld blobs:



Machine those bad boys down -




You could drill all the holes in the cylinder, and then the top plate and hope they line up perfectly. Or the method I chose - tack weld the top plate on, drill the holes through both to ensure alignment. I tapped through both the plate and cylinder at the same time, then opened up the plate holes to have clearance for the threads.






You probably noticed that the top plate isn't round. I chose to turn the top plate down after having the attachment complete so I could ensure concentricity:




The top plate needed a bunch of work. There's 3 fittings, and I chose to put a level sensor in it for future datalogging purposes, and just a gauge for now. Not a lot of pics here, but here's the top plate with a bunch of holes in it:




The level sensor is just a simple reed switch type.



The 6" version just barely clears the bottom of the basket:




Anyway, I wanted to be able to pull the level sensor if needed. That allows a view port if I want to see what's happening in the basket. So that requires some more machining...

Make square things round:



Transfer the fuel sender bolt pattern and drill holes (SAE 5 bolt patterns are not equidistant...)



Tap:



Test:





Attach your donut to the bottom of the plate. Tack in place:




I cut the donut hole undersize so I can make the top plate hole and donut hole concentric (seems to be a theme). Swap over to the 4-jaw chuck and cut both together:



Top plate is done:






Time for the bottom plate. Similar idea to the top plate, but the bottom will be fully welded:



Turn it:



I turned that on a bevel, so not unexpectedly I cut into the seam and had to reweld:



And turn again:



Now it holds liquids


Quick work to make a weep hole in the basket so it spills back into the main tank. I put that on the front side of the basket. There's pros and cons to putting it anywhere, but I figured I wanted as much fuel as possible during acceleration.





Assembly. From here, we just attach the bulkhead fittings and fuel level sender:





And drop it into the tank: