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Discussion Starter · #1 ·
I am in the early stages of building a gutted Prepared-class EF Civic for autocross, but I recently bought a new replacement fuel tank that I'd like to use initially. It's a nice tank with baffles like OEM, but it still requires running over 1/2 tank to avoid fuel starvation on long right-hand turns. I'd like to be able to run less fuel for weight savings.

The Subaru guys have figured out a solution, and I wondered if anyone has tried this on a Civic. It involves adding a small tank at the bottom of the fuel pump pickup and routing the return line into it to keep fuel on the pickup at all times regardless of fuel level. Anyone know if it's been done on one of our cars? Here's a link to the project for a Subaru: Shanes impreza fuel slosh mod - Ludicrous-Speed

Thanks for any help!
 

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88 hatch
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Ive never heard of this but I really like it and it is now saved to my computer.
 

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vw uses a similar system on their diesel lift pumps. except they use the return to act as an ejector pump to pull a constant source of cooler fuel from the tank and slowly overfill the canister.
 

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Look into foam baffle.
 

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Discussion Starter · #5 ·
Look into foam baffle.
I had considered foam, but I want something cheap and easily reversible. Besides, I've seen mixed results from people who have used it, and the existing baffles might make it difficult to place correctly.
 

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I really like this idea.

Also, there is a link to a different filter sock that sits at the bottom of the fuel tank in a 5th gen. I'm not sure how it would fit in a 4th gen. I'll look for the link.
 

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you may want to simply drop the oem tank altogether and simply run a fuel cell.


use an aluminum sheet where the fuel tank was, getting a nice cut out of air drag by flattening the bottom of the car.

EDIT in all honesty, keeping 1/2 a tank is only saving you roughly 6 gallons max worth of fuel (cuz no one can ever have a TRUE level reading). 6 gallons of fuel is roughly 36 pounds.


NOT worth much effort. you can remove nearly the same weight by simply removing quite a lot of brackets around the car and instead welding certain things for structural integrity (instead of needing nuts, bolts, brackets for something)
 

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Tape-R taper/driver
EC3, ED8, ED9, EE5
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The OE tank should already have a separated fuel pump area (baffle), and the return already directs the return fuel to the fuel sock.

While the OE tank already is baffled, it isn't very effective. I looked into it briefly, but I didn't not see a quick, simple fix.

I added a surge tank (not cheap, but cheaper than a fuel cell) and that resolved the pick-up issues.
 

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why so expensive I wonder.

The damn things are only a fitting away from a normal fuel sock, and of course the little extra material.

shit, a stock fuel sock for my 97 civic is $9 on rockauto or something
 

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Tape-R taper/driver
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You also need a positive displacement pump in order to use the Hydromat. A centrifugal pump (most of your OE pumps past the mid-90s) will not pull fuel through the Hydromat.
 

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Discussion Starter · #15 ·
Boom!!!!

https://www.amazon.com/Airtex-FS121-Fuel-Strainer/dp/B000ZN044Y

Maybe this would be a little more cost effective?
I picked up one of those recently after reading about it on this site. My plan is to drop the OEM tank and pull the pump to replace the sock. While that is out, I was going to hopefully address the starve issue.

There is a YouTube video that shows the internal baffles of an aftermarket Dorman fuel tank, which is supposed to be like the OEM tank. I will investigate this when I pull the pump, probably next week.

This internal surge tank idea should work, but I don't know if there is enough room in the OEM tank. I have the small tank and will play with this when the pump is out.
 

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Meat Popsicle
91 CRX Si
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Dunno man, the baffling on the OEM tank isn't bad. Here's the only shot I have of the inside of my CRX tank. The sock sits in the area to the right.



The strainer points towards the top of the above pic



I have pickup issues because the strainer/sock kit that walbro supplies with their pump sucks and fits loosely between the bottom of the pump and the strainer elbow. Like sucking a drink through a straw with a hole in it.

Jereme (xotic_crx) did or does work at advance auto and he told me that the airtex branded pump is identical to the walbro (is even stamped with a walbro emblem and has the same flow chart) so walbro/airtex stuff should be interchangeable
 

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Discussion Starter · #17 ·
Thanks for posting that picture inside the tank. That looks like it matches what I've seen previously. I don't suppose you know how deep or how long & wide that pickup pan is? Looks like we have starving issues once the level in the tank gets below the lip of that pan. I'm assuming there are fill holes at the bottom of the pan sides, but it may just not be enough.
 

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I spoke to Holley and they said it doesn't matter what kind of fuel pump it is as long as it can connect to the AN fitting on the Hydramat. They said it isn't a restriction to the fuel. They also said you'd want the mat big enough to reach both sides of the tank to pick up fuel. That'd be a huge mat for us.
 

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The problem with the centripetal pumps is that they will not lift. The pump needs to be submerged in order for the internal impeller to move fuel. The Hydromat isn't going to push fuel into the pump.

I have a wall of over 120 fuel pumps and assemblies from most performance related US market cars from the late 80's to current at my disposal.
 
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so you are saying if you were to put a hose on the end of the honda fuel pump and route it to a hydramat, it would not pick up fuel directly from the mat?

I think if it was 100% like that, we would see a lot more posts about fuel starvation from any aggressive driver on here.

Ive driven my bone stock 97 quite hard around corners, up and down hills, and its only starved for a second once or twice, just doing a massive backfire or detonation, then finding fuel again and running normal. After it had been below E on gauge for over 50 miles. when I filled up for gas, I was able to put in 10.8 gallons before nozzle shut off. I think tank capacity is rated to just under 12 gallons

Mind you, I have stock 170k suspension with no swaybars. Probably could finger the tarmac around a hard enough corner in my car. damn thing wants to roll over with any corner faster than 30mph lol
 
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