FD gas tank baffle and slosh problem
 

I could not find any discussion on this, only about fuel cell, which I don't want to buy.

I found out that my gas tank baffle is not in good shape anymore, it just float around in the tank, and even knock down the gas level sender.

New tank cost about $300, and you still have to run at least 1/3 or 1/2 tank full to prevent slosh.

Would it work if we stuff the gas tank with fuel cell foam?

They are pretty cheap compare to buying new tanks.
http://www.fuelsafe.biz/fuelsafe7.htm
http://www.fuelsafe.com/FAQ.htm

Anyone has ever try this? Any suggestion on how to do it? Any problem with foam getting sucked into fuel pump or clogging it?

just buy the fuel resorvior from rotary extreme for a fix, or make your own, it really is not that hard to do

The foam may be a good idea but you'll need a bunch of it in order to fill the tank. At that point I think the outboard sumps or fuel cells are competitive.

The foam will not crumble and go into the pickup.

I was going to do that, but I really want my level sensor to work. Might still do it, the level sensor doesn't want to work at the moment anyway.:mad:

Look at the price. The foam are cheap they could be as low as $10 from Summit racing.
I think I just need 4-5 of them.
http://store.summitracing.com/partde...t=SUM%2D290190

Compare $50 to new tank $300 or Fuel cell + stuff to make it work $500+? or Fuel Resevoir $500+?

And the foam would prevent the fuel slosh, and I can keep my old tank without the baffle.

You must fill nearly the whole tank. Just a few will do nothing for you, the fuel will just slosh "around" the few foam blocks. If your idea is to just surround the fuel pick up with a few blocks of foam it won't work well at all.

Yes, I will fill it up with the foam blocks, fill up the whole tanks. The only problem is the fuel level sender/float. It will not work.

The foam size is 4"x7"x15", right now I am estimating 4-5 blocks, do you think I need more? How many more?

http://www.speedwaymotors.com/produc...No=1&redirect=

With foam that large, you'll be decreasing your fuel tank capacity...

Not by much, the foam is mostly air. In a twenty gallon tank I'd be suprised if you lost more than half a gallon at the most.

Reza, I've neer measured the tank but just guessing I bet you'd need more like a couple dozen to nearly fill it? :confused:

You won't need that many.

The foam is only supposed to take 5% of your tank capacity.

The FD tank has a big bulkhead running through the middle in front of the opening. You should only have to fill the space behind it around the pump, as the bulkhead only has a few large holes in it and will keep the foam in place in the back half of the tank.

Is this bulkhead the baffle? My baffle is totally messed up, I can even take it out.

Not the plastic bucket. Look forward from the hole, you'll see it. I kept getting my fuel tank sender hooked on it when I was trying to put my pumps in the tank.:mad:

The foam only displaces a small amount of your gas capacity, but nearly fills the entire volume of the tank. You're still supposed to fill the whole tank.

I thought that means I can run less than 1/3 tank for autocross?

I know, but that might be a little tricky with the divider in there. Filling the back half will at least help with the fuel sloshing.

I wish someone made a fuel cell contoured the same as the stock tank.

Reza,

You can't do the foam mod and be legal for ASP. ASP only allows you to change the fuel pump and lines, not baffling or tank changes. You could run a fuel cell, but the allowance for that is based on safety and would require you to also run a rollbar.

Basically, you are stuck with the stock tank unless you want to spend $$ on a fuel cell and rollbar (I think you need a fire extinguisher too), or go to SM2 where you do other mods like the Rotary Extreme kit.

My goal is to reduce cost. Well the fuel cell foam is primarily used in the fuel cell boxes to prevent explosion. It absorb fire explosion. So in place of baffle will be this foams.
Thus safety and performance too :)

Is it in the rulebook about the foam?

If it's not in the rulebook, you can't do it. If you read the SP rules the only allowances are for fuel lines and fuel pump. Just because it doesn't mention foam doesn't mean you can do it. So, unless you can legitimately call the foam part of the fuel pump I don't see how it is allowed.

If you add a fuel cell the rules are very clear. It has to be at least 80%(maybe 75%) of the stock tank capacity, be located in about the same location (I think you can move it 6 inches, but I'm not sure), and you *also* have to do the rollbar and fire extinguisher. The only reason the fuel cell is allowed in SP is because of crossover rules with Solo 1.

I'd suggest reading through the rulebook though, as I'm only going from memory. SM2 rules are much more friendly than ASP.

Jeff Hoskinson has said on the RX7 List that he might produce the baffles which are found in the 96+ FD.

A few of us on the list have shown interest in this but he hasn't posted what his plan is.

Jeff, are you listening?

Baffles?
 

I would be in for some baffles.

Also Brian at M2 has mentioned that he has a "cure" for the starvation. Said he would post it on his site but I haven't seen it. It has been a while since I talked to him about this. At least a couple of years.

It would be nice to run events with less then a 1/4 tank.
What does a gallon of gas weigh?

Niles

Re: Baffles?
 

I think it's 6 pounds? (maybe 8? Think it's 6 for gas, 8 for water).

Running at a 1/4 tank would be nice. On grippy concrete I've had the car starve at 2/3 of a tank. My understanding was that on grippy surfaces you need to run 3/4 tank?

If you're on race rubber that's about right. For autox I just leave it full; at least that way I know my weight distribution is always the same. Road racing can normally get away with lower levels because you don't have the sloshing that goes on in slaloms etc.

Yeah, I run full or almost full for autocross. At the track I was starving with a little over half a tank. On street tires at the track I can run with less then half.

Niles

So what is the verdict? No foam allowed in ASP gas tank?
Anyway, what is the part number of the new 99+ gas tank? I tried to call Mazda Motorsports, and they close all day today. Strange its friday, and I am working in the office, so must me some japanese holiday.

um, so your not taking into consideration my suggestion about getting http://www.rotaryextreme.com/fuel.html??? even with baffles or a new tank which will cost a lot to make/buy, you can still get starved if you run too low.


at least take a look at rotaryextreme's fuel reservoir
http://www.rotaryextreme.com/fuel.html

I don't want to look into that suggestion, it is expensive, probably gonna cost close to $500+ (I thought I said this in the beginning!)

I know that system. I have seen in in use by a lot of japanese race car and even a US autocross RX-7.

A lot of wiring, tubing/plumbing, losing trunk space etc.
Arghhh too much work and money involved.

Putting in foam in the gas tank is much easier job, and on the wallet to.

Anybody knows the 99 gas tank part number from MazdaComp?

I just chimed in. I've got a 96+ tank in my FD. Previously I couldn't auto-x my car unless it was almost full or I'd get starvation. Since I installed the 96+ tank I ran it down to 3/8 and had one little blip of starvation on a 2.5 min run.

The "baffle" isn't really anything more than a piece of steel that fits over the top of the existing fuel "bucket".

My plan... Use up time:)

it cost 300 dollars just about

So Jeff,

Is it the 96+ tank or the "steel over the fuel bucket"
that's doing the trick? Or is it both?

What is the part number? Where you get it?

hey guys i have had to replace the tank on my '94 base because the baffling came loose too. it DID have the little metal cover for the the little plastic box the fuel pump resides in. comparing it with my mechanic's '93 cym he did not have the cover. i believe mazda made the change in between. however, when researching what to order i did get at least 3 or 4 different mazda part numbers because of different years and superseding parts. i ordered the replacement '94 from the parts diagram though and it had the little cover too.

i took a digital picture of the fuel tank. maybe i can dig it up later when i get home.

i've gone down to 3/8 to 1/2 a tank before getting some starvation on a really big fast sweeper toward the left in an auto-x.

i think the 96+ fuel tanks are probably pretty similar to mine if not the same. maybe we should all open them up and take pics....j/k.

reza, you are a crazy mofo....hahaha.

IIRC it was $320. I got it from Mazdacomp, my salvation:D.

The baffles looked the same to me as my 93 R1 but I didn't closely inspect them. In addition the baffles in my R1 were broken. The design of the 96 baffles looked very similar or the same as my baffles. I've had 3 R1s built in 2/92 and I still have 2 tanks from them, I'll do some investigating.

I've had a 94 and it didn't have any steel over the fuel bucket but I'm sure Mazda could have changed it mid-year. I DO know that if you order a tank for a 95 it has a different part number than a 96.

I don't think the foam will work to prevent fuel starvation in the stock tank. The baffling doesn't help it so the foam really won't either. The problem resides in the design of the plastic box. I tried to create a cover for ours, but it still would starve. My solution was to build a 12 inch tall polyethylene cylinder that fits down the opening of the fuel tank. I then used a ATL 3-door trap door surge tank, having to cut it down smaller to fit inside the tank. I mounted this in the left hand corner of the tank, after taking out the plastic box. I installed a separate fuel pump to draw fuel out of this surge tank and it fills the polyethylene cylinder, where the main fuel pump resides. I installed a fuel cell type fuel level pickup that is a float in a aluminum sleeve, used for Ford application (6-80ohm) I think. It is not as accurate, but close enough to tell you the tank is getting empty. Basically, this system is similar to the Rotary Extreme system, but resides inside the tank. We can run the tank near empty without starvation. It cost about $300 bucks(extra fuel pump, ATL surge tank, fuel level pickup) and time to put the system together.

well if you buy the rotary extreme version, you dont need to custom make anything, its right there, just buy it and hook it up!

So this pump that feeds the surge tank would be a low pressure pump, right?

Erik,

Great idea!.....Sounds somewhat complicated to do....was it? Do you have any pictures of the process?

How did you mount the the surge tank inside the tank?

The rotary extreme unit is nice but I don't like the idea of being in the car with fuel lines and pumps. Setting it up in the tank is great.

ANy more info or advice on how to do this would be great.
Thanks
Niles
ps. Now we know why you were so fast is that car!:-)

Another problem with fuel pick up can be as simple as a vacuum leak. Make sure everything is sealed well. In my case there was a hole in the tree/housing for the fuel pump. The previous owner had drilled a hole for some type of modification and then patched it with shoe goo :)

My fuel was sloshing back up the fill neck and leaking. Also could not maintain good pressure once fuel was below about 5/8 full. I replaced the tree and now I'm not throwing gas all over the track on hard turns. No more fuel cut either unless below 1/4 tank.

Just something to think about. If anyone needs a new pump, tree, or tank, I of course have a couple ;)

Fritz, you have fuel tank? Are the baffle good?

You still have to buy the external fuel pump, an lines and probably some fittings for those lines.
Add the little things up and it'll come out over $400 for sure.

The Rotary Extreme is selling the CAN only, not the lines, nor the pump, nor any other installation item.

So, it's not a "buy it and hook it up!" deal. It's buy the other items, find a location for installation in the car (I've thought about another method of installing it outside the car), measure it out and install.

It'll be cheaper to have my friend weld a can that is similar and still have flexibility in the reservoir design.

Like the others, I would like to see a solution that resides in the fuel tank.

I think foam would work, but you would significantly eat into your capacity. Thus, the foam block would have to be pretty huge.

J

Have any of you looked at other OEM fuel tanks like from an Acura?

J

hmmm i now see yoru point, i assumed that the rotary extreme version came with everything but can now see how it can nickle and dime you to death. I knew someone selling a his old kit for jsut about 300 bucks which came with all the lines, pumps and can and just figured that rotaryextreme's one would come with the same.

Nah..not on the rotary extreme kit, it will definitely put me into the SM2 class at autocross.
Otherwise, its good for drift car. I am pretty sure with you being in Hawaii, must have seen a lot of drift car with that kind of contraption. :) I wish I am in Hawaii.

It is not that complicated. It took me a day to put it all together. I don't have pictures, so here is quick explanation of the process. First, you need 1/8" thick sheet of polyethelyne or similar polymer plastic that is resistant to gasoline. Cut out an oval using the gasket for the fuel pump assembly cover, making it slightly smaller by 1/8" around. Go to Home Depot or similar and buy some 1/16" aluminum L shaped material 1/2" X 3/4" and a piece of 1 1/2" flat. Pop-rivet multiple 1" or widepiece of the L shaped material around the periphery of the oval template, so that the 3/4" inch side is flush with the outer edge. Then create the tube by pop-riveting a 12" tall piece of the 1/8" polyethylene plastic around the oval that has the L-bracket around the periphery. Pop-rivet the 1 1/2" wide flat aluminum up the seam, and your tube is finished, except for slight leaks at the bottom. I sealed the bottom of the tube with a 2-part epoxy that was would stick "somewhat" to the polyethelyne. Nothing sticks very good. I think in retrospect that the tube would work fine without sealing the bottom, as the bottom is resting at the bottom of the tank, and it is in a small amount of gasoline anyway. The seam did not leak significantly, if you place the rivets close enough. I bought a 3-door trap door surge tank from ATL (Aero Tech Laboratories), and cut it down (I had to cut a section out, and shorten it also) to be able to fit into the oval hole. After you remove the stock plastic tray, there are some metal tabs that are welded to the bottom of the tank, that can be used to wire tie the surge tank in place.
Certainly, as others have mentioned, you can buy the external system from Rotary Extreme, but I didn't want all the hoses in the back hatch, or running outside the tank under the car. This system works, it just takes some time to put it together.

Thanks for the write up.
NIles

Thanks EriK. I assume that you're THE Erik Strelnieks who's ProSolo driver extraordinare? Congratulations on your victories! At some point, can you please send us a note on track comparisons between a your Z06 and an FD?

There are many other ways to do this mod as well. IMO, the simplest way is:

1. Detach the lower plastic baffle (or the only one if you have a 95 or older)

2. Fab or buy the baffle cover from Mazda ($220). I can get you the part number if you like.

3. Fab and rivet a small cover for the large hole on top out of poly (easy to figure out once you've got it in hand).

4. Cap or plug the outlet from the lower baffle (also easy to understand if you're looking at it- it's on the upper right hand side when looking at the baffle from the rear of the car).

5. By three 1" one way ball/chack valves from ATL or fuel safe (about $80) installing them on the right, left, and rear sides of the lower baffle. You'll need to cut 1" holes into the plastic baffle to do this. Be very careful to avoid using a drill or anything that will cause a spark if you're working on a full or partially full (or even an emplty tank with fuel vapor) fuel tank! Use a knockout punch or a hand-crank drill to do this.

6. Reattach the bottom baffle and cover. Snap/bolt everything back together.

I've run my car down to 2 gallons with this mod on the track. It really works!

Gene

Gene...
Is that the instruction/order of making a mod or several mod option to do. I assume you did option 5 then 6. Any photos?
Reza

Gene, I wish I knew of this modification, as it is what I initially was trying to accomplish by buying the ATL surge tank. I knew the plastic tray was the problem, and I even tried to attach higher sides to the stock one. Certainly a cover and better in-lets is what it needed. I am still curious how you were able to get those 3 metal tabs to reattach the bottom part of the tray to the tank. They are a bitch to try and bend back into position.

As far as the comparison, it comes down to one word, torque. Hoping to narrow that gap with a 3-rotor that is on its way from Florida, as our SM2 RX7, will still not beat a SM2 Z06, until we can get off the turns at lower RPM.

All parts need to be done to do this mod correctly. They're roughly in order, but don't have to be.

Most difficult part is removing the lower baffle, cutting holes, and replacing it.

My digital camera was stolen with the pics. I hope to get some time in the near future to replace my Supra pump with a Bosch Motorsports unit. I'll snap some more with the new camera. I'll let you guys know and put them on my website.

Gene

I got lucky with the tabs, but suffered lots of bloody hands and forearms in the process. Not sure that I could do it again!

Good luck with the 3-rotor. I concur on autocross re: Z06 vs FD torque. That's why I do track-only stuff now :)

Wonder how Steve O'Blenes manages to fight off the 'Vettes in BP?

Gene