Fuel Tank Foam

ddozier · Aug 29, 2016

UPDATE -

Tried option 1. from the post above, and had fairly good success. Prior to the foam being added to the center hump of the tank I could not get through the long left hand banked oval without fuel starving at the end of the turn if I ran with much less than 3/4 tank. Added the foam and now I can run to nearly 1/4 tank before the fuel starvation shows up.

On a normal road course that does not include a series of left handers before a long banked left hander I would be surprised if this issues really showed up. Since my local test track happens to be a counter-clockwise roval it showed there in testing.

I used a piece of fuel cell foam from RCI, 7050A is the part number and it is 16" x 6" x 3". Since it is highly compressible I was able to pack in in very tightly above the center hump of the fuel tank by accessing the opening for the passenger side sending unit. Once you remove the sending unit you have to work it into the space between the two sides of the tank. I would assume you could get it into place by removing the drivers side fuel pump but there are more lines and connections on that side so the passenger side should be easier. It was not difficult and would be very easy in an un-caged car. It was a little harder having to fight the cage but was not too bad. Took about 30 min total. I did not take any picks of the install as it was fairly straight forward.

If you run a lot of counter-clockwise road courses you may want to try this to keep from having to run a full tank of fuel.

Dave

Plimmer · Aug 29, 2016

ddozier said:
UPDATE -

Tried option 1. from the post above, and had fairly good success. Prior to the foam being added to the center hump of the tank I could not get through the long left hand banked oval without fuel starving at the end of the turn if I ran with much less than 3/4 tank. Added the foam and now I can run to nearly 1/4 tank before the fuel starvation shows up.

On a normal road course that does not include a series of left handers before a long banked left hander I would be surprised if this issues really showed up. Since my local test track happens to be a counter-clockwise roval it showed there in testing.

I used a piece of fuel cell foam from RCI, 7050A is the part number and it is 16" x 6" x 3". Since it is highly compressible I was able to pack in in very tightly above the center hump of the fuel tank by accessing the opening for the passenger side sending unit. Once you remove the sending unit you have to work it into the space between the two sides of the tank. I would assume you could get it into place by removing the drivers side fuel pump but there are more lines and connections on that side so the passenger side should be easier. It was not difficult and would be very easy in an un-caged car. It was a little harder having to fight the cage but was not too bad. Took about 30 min total. I did not take any picks of the install as it was fairly straight forward.

If you run a lot of counter-clockwise road courses you may want to try this to keep from having to run a full tank of fuel.

Dave

Awesome

Thanks for the update. Sounds like a relatively cheap and easy fix to solve this problem.

higdominator · Apr 15, 2017

Looks like I'm getting the foam too. I thought I had accidentally enabled advance track but even after I filled up I still got some sputtering coming hard out of Turn 3 at Heartland Park- even on the new asphalt.

Brent Dalton · Apr 16, 2017

Good to know. Sorry I missed you today. I had work come up and didn't get to make it out.

higdominator · Apr 16, 2017

No worries, it was a interesting day to say the least. Once a little rubber and heat got in the track it was pretty fun, but the first and most of the second session was pure carnival ride, lol.

I'll be at Hallett this coming sat but I think we're headed up to NASA at Heartland soon after.

sigintel · Apr 16, 2017

Check your pickup. The stock pump actually has a cross feed tube running from the passenger hump to the pump. I will be switching to dual stock pumps feeding independent rails checkvalved w siamese return. Either pump starved drops bank instead of running whole motor lean.
Has anyone tried the new micromesh tank bottom pickup material?
Hydramat?
I was thinking hydromat plus foam plus dual pumps, dual lines, check valves, single return.
Surge tank sounds like end all solution but sounds much more expensive and complicated. Will be looking for surge tank setups next track day.

ddozier · Apr 16, 2017

sigintel said:
Check your pickup. The stock pump actually has a cross feed tube running from the passenger hump to the pump. I will be switching to dual stock pumps feeding independent rails checkvalved w siamese return. Either pump starved drops bank instead of running whole motor lean.
Has anyone tried the new micromesh tank bottom pickup material?
Hydramat?
I was thinking hydromat plus foam plus dual pumps, dual lines, check valves, single return.
Surge tank sounds like end all solution but sounds much more expensive and complicated. Will be looking for surge tank setups next track day.

The cross feed tube is used to draw fuel from the passenger side to the drivers side through a venturi pump that uses the bypassed fuel from the main fuel pump to draw the fuel over to the drivers side tank. The issue is that as the fuel demand raises less fuel is bypassed and then there is less fuel to create the venturi and draw off the passenger side.

The M3 crowd have a very similar setup to ours and have the same fuel starvation issues we do. They use a 2nd fuel pump in the opposite tank from the main pump to move all the fuel to the side of the tank with the main pump. This is likely the best solution and much simpler than what you are describing.

I do not think it is a good idea to split your fuel delivery system. You will likely end up running a bank leaner than the other should the fuel starvation issue not be solved. If you do not want to add a surge tank then make sure all the fuel in the car is always in the drivers side tank by adding a secondary low pressure electric pump to move the fuel to that side.

Dave

higdominator · Apr 22, 2017

I tried the foam out today and without fail I would still get hesitation on the very last lap ona 25min session after topping off to the top.

What I think my issue may be is the increased demand of E85. My fuel level was stil showing near full when the issue would pop up and only on the last lap.

I'm going to pop the pump and verify that the crossover tube is good to go then I'll just try running regular gas next track day and see if it clears up.

Was kind of a killer as I was laying down personal bests in 55* weather- tires never got up to their temp but that aero was on point!

Brent Dalton · Apr 22, 2017

Interesting. I ran HPT on Thursday evening all the way down to 1/4 tank(of E85) without any fuel starve.

ddozier · Apr 22, 2017

higdominator said:
I tried the foam out today and without fail I would still get hesitation on the very last lap ona 25min session after topping off to the top.

What I think my issue may be is the increased demand of E85. My fuel level was stil showing near full when the issue would pop up and only on the last lap.

E85 means higher fuel burn rate, means less reserve pump volume, means less fuel bypassed at the regulator, means less fuel left to drive the venturi pump and draw fuel over from the passenger side.

You can not trust the fuel gauge to tell you what you have in the tank while running hard. It is supposed to be an average of the two tanks since each has its own sender but the car gets confused and will not be accurate until you get back to the pits and let the car sit for a few minutes.

If you are running E85 and are running hard for 25 min I would expect a fuel burn rate of around 9 - 11 gals per session. That means starting at a full 16 gal tank you will be ending a session with 7 to 5 gallons left. That will not be enough to prevent the starvation unless all the remaining fuel was in the drivers side tank, and that is not likely going to be the case.

You will likely be fine on pump gas because the fuel burn per session would be more like 6 - 8 gal per session, but if you want to run E85 or have the problem permanently solved add a secondary electric transfer pump to move more fuel from the passenger side to the drivers side.

Dave

Plimmer · Apr 23, 2017

Brent Dalton said:
Interesting. I ran HPT on Thursday evening all the way down to 1/4 tank(of E85) without any fuel starve.

It seems to depend on which track you are at. Definitely COTA will cause a problem in the left hand turns when fuel is 1/4 tank. At TWS I never had any problems.

mnmike59 · Apr 23, 2017

And here we go with another item to think about.
I'm changing the name of my car to "the money pit"

Brent Dalton · Apr 23, 2017

Plimmer said:
It seems to depend on which track you are at. Definitely COTA will cause a problem in the left hand turns when fuel is 1/4 tank. At TWS I never had any problems.

Hey Rob, my comment was in reference to Higdomimator being at HPT last Saturday(I was there the following Thursday), where he first reported the issue. Sorry, should have been more clear. It reminded me when I saw his comment about Hallett. I guess I'm lucky to have not experienced fuel starve anywhere yet.

higdominator · Apr 24, 2017

Seeing as I have had the issue more frequently and at higher fuel levels than others, I'm going to pull my pump and basket and verify it is in good condition. There very well could be an issue in there, maybe a kinked transfer tube or something. By my fillups, I think I'm actually closer to 4-5 gallons per session at most tracks (the trend so far this year). I start with a completely full tank and top off with a 5 gallon jug and it's at the top of the filer neck most times.

As long as I kept the car topped off, I was able to run Heartland without issue (although it did pop up here and there, I think it was similar in occurrence to Hallett- last lap, etc). I was also not running a fast pace due to the uber green surface (2:10's/2:11's). I was pushing Hallett a bit for the conditions (55* and slippy slidey 1:32's) but Hallett has 5/6 which at a decent speed keeps the fuel to the left through 5/6.

I may run a low pressure pump on the passenger side to feed the DS basket but I want to check out the pump/transfer/and possibly the tank vents first.

Something is AMISS! lol

ddozier · Apr 24, 2017

higdominator said:
Seeing as I have had the issue more frequently and at higher fuel levels than others, I'm going to pull my pump and basket and verify it is in good condition. There very well could be an issue in there, maybe a kinked transfer tube or something. By my fillups, I think I'm actually closer to 4-5 gallons per session at most tracks (the trend so far this year). I start with a completely full tank and top off with a 5 gallon jug and it's at the top of the filer neck most times.

Get a code reader and check your codes, most fuel related codes will log and not cause any lights to come on, if you have a clogged vent line ot will throw a code but may not turn on the light.

Wow, a 25min session on E85 and you are only burning 5 Gal, I wish I could get that kind of fuel economy on track. At a track like NCM, Road Atlanta, COTA, or Road America I burn 7-7.5 Gal of 93 in a 25 min session. My E85 burn would be 8.5-9 Gal easy. Last time at NCM I burned 80 Gal of 93 in 11 sessions.

What RPM do you have your rev limiter set at, and what RPM do you shift at when rowing through the gears?

If you want to check the transfer tube drive the car to under a half tank, avoid any high G left handers, then check the passenger side of the tank it should be bone dry. If there is fuel in there start the car and let it idle for 5 min, recheck the passenger side. Should be bone dry after that long of an idle.

Dave

Fuel Tank Foam

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Plimmer

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higdominator

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sigintel

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ddozier

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higdominator

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Brent Dalton

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Plimmer

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mnmike59

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