240z Fuel Cell Install...looking for advice

[spawpoet]

Ok guys Tim ran the school at Homestead two weekends back and did well and was signed off, but we fought a fuel delivery problem all weekend. The car has a stock tank which was refurbished, but it was still full of garbage that is clogging our fuel filters. In addition we think our more signfigant problem from the weekend was vapor lock as the tank was building up a load of pressure. The car would go out and run great for 3-4 laps, but once the vapor lock built up he had to come in because it couldn't draw enough fuel (pressure dropping from 3 lbs to less than 1). Open the cap, and prime the pump, and we were back in business at 3 lbs. After all this we figured it best to bite the bullet and put a cell in for both safety and reliability.
What I wanted to know is what sizes/kinds of cells and what fuel pumps you guys recommend for the 240 and if you have any specific install advice? Also do you use surge tanks with your racecars, or is the foam in the fuelcells sufficient to prevent fuel pickup problems in a z? We do plan on running enduros so we need enough fuel for more than a sprint event. Our thoughts were a 12 gal cell, but if a 10 gal cell was big enough I'd hate to put in a 12. I also was wondering if anybody has seen a well-cell installed in a z before? Even though the weight would be a little higher with it we thought it would be an easier install, and it would leave the rear hatch area uncut and wouldn't affect chassis rigidity. Thanks in advance for any advice.

chris

[Ron Earp]

I'll shoot some pictures over of mine later today. I've been told it is a nice setup, and it looks it. Dual pumps, dual filters, one way valves, fuel return from carbs/regulator, and dual pickups in a 15 gallon cell down where the spare tire was. I didn't build it though, came with the car and seems to work well. Also has a well-done fuel sampling port back there that works with the turn of a valve that is pinned for safety.

[spawpoet]

How far can you stretch the 15 gal cell? We looked at and considered that 17 gal cell that was on the classifieds here, but thought it might be too big. By the time we went to measure the car to see if it would fit it had sold.

[Parrish57]

Chris...

I run a 12 gal cell in my car. It's perfect for sprint races but I wish it was a 15 gal for the enduros. Especially when it is a 2 hour.

I use a surge tank in mine and am very happy with the amount of fuel that I can pick up. As a result I only use a single Summit Racing 130 GPH pump regulated to 6psi. That, of course, is the weak link in my system. If that pump fails I'm done.

[Ron Earp]

Sorry about the pictures, I forgot! But I will get them tonight.

I have notes in my book with gallons per hour use and will double check it. But I think that it is right at one gallon every six to seven minutes.

One downside of my complete system is weight. I am 115 lbs over min weight in my car and I know I could get 15 lbs out with a more carefully constructed and simpler fuel system. 15 lbs needs to come out of me for sure.

[betamotorsports]

If you cut out the spare tire well and build a 1" square tube frame welded to the existing rear frame rails, the maximum fuel cell size is 26"W x 20"L x 10"D. This gives enough room to get to the rear diff mounting bolts and keeps the can above the ground per the rules (at the ITS legal ride height). I typically install the ATL SP115 Sport cell (15 gallons) in ITS and Vintage 240Zs for my customers. If you're willing to cut the side frame rails you can run the ATL SP122C cell and get 22 gallons for an additional 8 lbs of weight (not counting the fuel).

[spawpoet]

Chris...

I run a 12 gal cell in my car. It's perfect for sprint races but I wish it was a 15 gal for the enduros. Especially when it is a 2 hour.

I use a surge tank in mine and am very happy with the amount of fuel that I can pick up. As a result I only use a single Summit Racing 130 GPH pump regulated to 6psi. That, of course, is the weak link in my system. If that pump fails I'm done.

Steve,

I thought we needed to keep fuel pressure down below 4.5 lbs. to prevent from overloading the fuel bowls in the SU's. Are we running fuel pressure to low at 3.5lbs of pressure??? If so it may have been parts of our fuel delivery problem as we wouldn't be keeping our bowls full if our pressure was too low. Thank you for posting.

chris

[spawpoet]

Sorry about the pictures, I forgot! But I will get them tonight.

I have notes in my book with gallons per hour use and will double check it. But I think that it is right at one gallon every six to seven minutes.

One downside of my complete system is weight. I am 115 lbs over min weight in my car and I know I could get 15 lbs out with a more carefully constructed and simpler fuel system. 15 lbs needs to come out of me for sure.

Thank you Ron. I'm curious to see your system....sounds like a real professional setup. My uncles EP car (Datsun Roadster) is setup like that with duel feeds, pumps, etc. Your fuel consumption rate sounds about what I would have guessed the z's get. I helped with pitstops for Ira & Marvin a couple of times at Homestead's 12 hr race and I believe they were running stints around 1.5 hours, and I thought they had a 15 gal cell so that would work out to 6 gal/hr. As for car weight we are in the same boat as you...maybe a little heavier. I wanna say we are around 200 lbs overweight now. I hope we don't add much with a cell cuz there isn't much more wqe can take out. Our cage is overbuilt with 1.75" tubing so we have alot of extra weight there that can't really come out of the car on our budget.

chris

[Parrish57]

Steve,

I thought we needed to keep fuel pressure down below 4.5 lbs. to prevent from overloading the fuel bowls in the SU's. Are we running fuel pressure to low at 3.5lbs of pressure??? If so it may have been parts of our fuel delivery problem as we wouldn't be keeping our bowls full if our pressure was too low. Thank you for posting.

chris

That is true if you are running the stock needle and seat. If you upgrade to Gross Jets you can bump up the fuel pressure some. The real trick these days is finding a set of gross jets. There has been a lot of discussion on this issue over the years. I'm just reporting what works for me......

[spawpoet]

If you cut out the spare tire well and build a 1" square tube frame welded to the existing rear frame rails, the maximum fuel cell size is 26"W x 20"L x 10"D. This gives enough room to get to the rear diff mounting bolts and keeps the can above the ground per the rules (at the ITS legal ride height). I typically install the ATL SP115 Sport cell (15 gallons) in ITS and Vintage 240Zs for my customers. If you're willing to cut the side frame rails you can run the ATL SP122C cell and get 22 gallons for an additional 8 lbs of weight (not counting the fuel).

Thanks John, and nice website. I've somehow never seen it before in my websurfing on Datsun enthusiast sites. We will be needing some Koni's in the next year or so (currently using Illuminas which I know aren't the best IT setup), so when the time comes we will give you a call. As for the cell setup is it safe to assume since you use 1" square tube that HD angle iron just isn't beefy enough to hold a fuel cell then? Also do you find you gain weight when you go from a stock tank to a cell setup?? Thank you again.


chris

[Mike Mackaman]

I run a Fuel Safe 15 gallon cell with two pumps, one filter and a return. I have two duck foot pick-ups and the return tee's inside the cell and goes into the duck foot area. When the car stumbles, you have a lap to a lap and a half. When you come in, the bottom of the cell will be wet, but no measureable fuel. I use a standard Holley regulator where the hood latch used to be and have a 1/16" restrictor in the return line. The return line, and especially the tee into the duck foots is a huge plus for being able to run all the fuel out.

Mike

[betamotorsports]

As for the cell setup is it safe to assume since you use 1" square tube that HD angle iron just isn't beefy enough to hold a fuel cell then? Also do you find you gain weight when you go from a stock tank to a cell setup?? Thank you again.

No, I use the 1" x .063" wall square tubing because its strong enough and a bit lighter then 1" x .125" angle iron - plus Rivnuts are easier to install in the square tubing. And yes, a fuel cell setup is heavier then the stock tank. You don't add a fuel cell to gain a performance advantage, you add a fuel cell to reduce the chance of fire in a wreck.

[tim240z]

With in the next few days I'll try and whip up a diagram on how we have our setup(including line size.) Perhaps the issue is right under our nose and a fresh(or experienced) brain can point out a flaw and give us a temporary solution.

Thanks Guys!

[Ron Earp]

Here are a few pictures, maybe that will help explain a bit.

[betamotorsports]

Here are some images of the work Bill Savage of T-Mag (and NPTI fame) did about 10 years ago for my non-IT 240Z:

[Mike Mackaman]

I used 1-1/4" square tube for the cross lateral braces and then 3/4 or 1" for the one side to side and two front to back. This made a box strong enough to jack the car from. Comes in real handy!

Mike

[kthomas]

Nothing beats the stock tank for location. You'll want to put the cell as low and to the right as possible. I think the GCR still gives you 6.5 inches from ground to bottom of tank. Our 15 gallon cell was completely under the tire well deck.

[ITZ34]

Can anyone explain the reason for the return line? I don't have one, should I?

DC

[Mike Mackaman]

Yes, you need a return. With a return, the bubbles that will get into the line can escape through the return line. Otherwise they can only get out through the float bowl. This can have significant negative impact on performance! If you return into the duck foot or a surge tank, then you can use almost all the fuel in the tank.

The only negative I see is that you must change your filter more often, not like every month, but like every 6-8 races.

Mike

[ITZ34]

Thanks for info.
Isn't that the reason for the vents on the carbs?
Where do I start the return? Between the regular and the carbs? Not sure what the duck foot is either. Are those the things at the end of the pickup hoses in the fuelcell which I just replaced?
This is my current setup:
12 gal cell, 2 Facet blue top cylinder pumps in parallel running into a regulator under the hood at 4.5psi.
Have used 1 Facet pump also, but decided to hook up the spare in parallel since I had it anyway.

Thanks