Daffy

The C4 has a bad habit of starving for fuel during hard cornering unless the tank is full.Has anybody come up with a lighter weight solution to the problem???

96CollectorSport

I had that problem with my 96 and I thought (at the time) that it was a bad fuel pump, so I ended up buying a Racetronix fuel pump kit. What I found out was that the pump wasn't far enough in the tank.

There is a little plastic tray at the bottom of the fuel tank, that try is supposed to keep fuel around the pump during high g manuevers. All you have to do is pull your sending unit/pump assembly and pull it down. This way it sits further down in the tray and you will have fuel when you need it. Just be sure you have a new fuel sender seal before you start.

I can run my car until the reserve fuel ligh comes on at the track now without problems.

BTW - If your going to mod in the future the Racetronix pump isn't a bad way to go.

The Bus

On my 92 autoXing all I made sure was that I had at least 5/8 tank. Slightly less weight without a lot of work.

Slalom4me

There was a fairly thorough discussion in this thread
I emailed the Speed Merchant in San Jose, CA several times asking
about the sump kit mentioned by Vetracr and never had the courtesy
of a reply.

I corresponded w/ Rock Valley about having a custom tank built with
a sump. After seeing pictures of the C4 tank, they replied that they
felt the shape was too complex. I've seen other projects they've
done and I believe there may have been a different reason for declining.

Fuel Safe has a C4 tank, there is a picture on their website but I did
not pursue this possibility.

I intend to take the advice of the majority of people who posted saying
to just run with a full tank. I'll be putting a new sock on shortly and
I'll be checking to see that the little baffle mentioned in the thread
is in place, too.

.

Daffy

Good stuff

Slalom4me

Post back or PM me if you come across something interesting.

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96CollectorSport

If you are looking for a bolt in race quality unit take a look at Melrose T-tops. The have a set-up for the C4's, here's the link.

Melrose C4 tank

I still think that bending the sender down is the easiest fix.

Slalom4me

Does the Melrose mount underneath in the spare tire location or in
the passenger compartment under the hatch. One gallon (U.S.) of
gasoline weighs 5.8 to 6.5 lbs. So that tank represents 128 to 143 lbs
of fuel, plus whatever the tank, hardware and mounting frame add to
this. So I'd hope it mounts underneath, not inside.

I am not sure how the Melrose price compares with the Fuel Safe unit
which looks like a stock tank and mounts in the same location. I DO
know how much trade price is for an OEM tank and it is a heart-stopper
so I'd guess the Melrose unit might be the better bargain.

From the Fuel Safe catalog - pg 6 of 17, bottom right

Daffy

I was thinking of hanging a 5-8 Gallon cell in the spare tire location...maybe

Slalom4me

A bladder. It goes in MY tank.

This could turn the picture around in a big way.

While this wouldn't necessarily address the issue of fuel slosh, it does
promise to be an economical method of adding protection.

Something I'd learned while looking into tanks is that the OEM C4 tank is
a composite of a synthetic tank wrapped in a steel shell. I had initially
been under the impression it was just a steel tank as used in any
number of other GM vehicles in the past.

.

Slalom4me

After reading Vetracr's description of the Paul Casales unit, I came across
information showing a trunk-mounted fuel cell along with a separate
small ( 5 g) tank. I believe that set-up relied on two pumps: one to fill
the small tank with a by-pass back to the main tank and another pump
to feed the engine from the small tank, with the injection by-passing
back to the main tank.**

That may have been when I decided to take the advice about just
running with more fuel in the OEM tank.


(** pretty much similar to what Vetracr describes, only it was a plastic
5 gal ATL surge tank in the example of the sedan - IIRC)

.

Slalom4me

Here's the thread discussing the composite make-up of the OEM tank.
.

Zip Corvettes

First your stock tank has a bladder in it, they first started using them in 1975. I have the melrose unit in my 96 race car. The rear bumper support has to be removed and you install his. It holds and 22 gal. ATL cell that has a bladder as they all do plus a foam core, this keeps the fuel from sloshing around. The tank is mounted low to get the weight low behind the wheels.

Slalom4me

In the thread mentioned above, one person says it is plastic, another
says it is rubber.

What is your understanding - does the C4 have a molded, rigid plastic
tank protected with a metal housing or does it have a metal tank with a
pliable rubber/synthetic liner inside?

.

Zip Corvettes

The C4 has a rubber liner. They used a rubber liner from 75-77 and then went to a plastic liner with bad results. The plastic liners crack from the fuel. They went back to a rubber bladder in 84. That is not the problem though, one the tank allows the fuel to slosh around, the ATL cell will not allow this. I have seen the Fuel safe unit and it is a stock tank that they modified. I do not know everything they have done to it except for the obvious with is the new race sending unit. The ATL cell with the Melrose holder is the way to go if you race your car period.

Vetracr

I DISAGREE. If I had to do it over again I would not go with the Melrose setup and the ATL. On a C4 it puts the fuel cell as the rear bumper. Get tapped from behind and your fuel cell is the only thing being hit!! You have to remove the whole rear sub frame and partially cut the rear bumper cover to get it to fit. I had this installation on my 90 ITE Corvette. It was SCCA legal but I prayed I never got hit from behind. First thing I did after the fuel cell installation was install a full halon fire supression system.

I would buy the Fuel Safe unit with a bladder in the stock tank if I did it again. I don't think it was legal when I built my car. It may be legal now but the SCCA tech people, in some cases, are not the most enlightened. Forget about safety, meet the rules! Most guys I know use the ATl cell but mount it over the differential protected by the rear sub frame in case of a collision. It moves the CG higher but the safety is worth it.

Larry

melrose

Our fuel cell was designed to pass and exceed the specs put forth by the rules of the SCCA. One rule we wanted to take advantage of the cell could not be lower than the diff. Our is slightly adjustable but can be lowered to take advatage of the lower center of gravity. The bracket has been race tested and is actually made ot stouter steel than demanded by Nascar. It's made of 1" square tubing at .120 wall. As we wanted a certain percent of rear wieght at 50 percent fuel level the weight of the bracket was not importat.Chip Stabler was hit square on in the rear by a GT1 car and said he was never hit harder by anthing and no damage to car driver or cell. The other thing is that if you car is going to run fuel injection we have a design that has an ATL cell with a return line from the injection going to a center accumulator tank where the fuel is picked up. This allowed us to run a 383 and win the SCCA world challenge race in Minneapolis which was an hour long and we new we would need all of the 22 gallons we could legally carry

Slalom4me

Thanks for the information, Melrose. I wasn't aware that
that product was available before reading about it in this
thread and your comments have improved my understanding
of where it is positioned and how it is filled.

Vetracr, I had wondered about the SCCA legality of the
Fuel Safe unit, too, but the events I participate in are
not run under the auspices of SCCA so it was academic
I never looked into this tank further because I anticipated
it would cost well beyond what I was prepared to pay, based
on the price of an OEM tank. I understand your comments
about the other tank and defer to your greater experience
- however, the Roush-prepared Mustangs I drove at Bondurant
and many other race vehicles I've seen were set up with
fuel cells low and close to the back. Yes, the in-car
video of DE Jr. plays in my mind every time I think about
the fuel system - but the leak/fire wasn't due to a hit.

For my purposes (and I think Daffy427's, also), the goal
is to run hard for a short time with the least fuel. The
L98 powertrain in my dual purpose car is essentially stock
and I believe that there would be a benefit from any/all
weight savings.

I think the solutions posted in the other thread and this
one provide a range of methods to deal with slosh at the
hobby level and the fuel cells are there for me if/when
I'm ready to commit more seriously.

.

Corvette Kid

Great thread you started here, Andy. I learned a bunch!

DREGSZ

It may not be SCCA legal as a fuel cell, like they consider the viper's stock tank, (that point is moot since the 96 is no longer T1 eligible, but it is a fuel cell by design and construction none the less.

If you need a cell, Melrose has bolt in units. there are alot of parts from Melrose on C4R

I never had fuel starvation problems in hard cornering w C4R with the stock tank.
I don't believe there is a tank design flaw.


Maybe I wasn't cornering as hard as you guys?

Bwaa haa haa !! =P