With all the talk about Miata ITA enduro cars...

[tyler raatz]

The stock tank is too small, the stock location does not really allow for cell installation with fast fill capability.
What do you think a 22 gallon fuel cell in the trunk would do to the handling of a miata?
Please discuss:D

[Greg Amy]

Why in the trunk, Tyler? Simply install it in that area right behind the driver, just aft of the vertical cockpit bulkhead and right behind where you have your rollcage mounted. All you need is a box around it to be legal, and it's right in the middle of the car...

Or if you want to get clever, what about in the passenger seat area? Use that ballast to balance that fat-ass sitting on the left side of the car. Again, all you need to do it cover it with a box to be legal...

GA, whose fat-ass is possibly driving this car for the VIR 13 this year...

[Knestis]

I've never cut a Miata up but it wasn't clear that we could get that big cell into the Golf either, until we did it. And in that case, there was exactly ONE place it would fit, given the rear axle location.

http://www.it2.evaluand.com/gti/images/mk3.2/fuelcell1.jpg

Kirk (whose not-quite-so-fast ass will likely be hot-swapping with Greg and Tyler)

[tyler raatz]

Why in the trunk, Tyler? Simply install it in that area right behind the driver, just aft of the vertical cockpit bulkhead and right behind where you have your rollcage mounted. All you need is a box around it to be legal, and it's right in the middle of the car...

Or if you want to get clever, what about in the passenger seat area? Use that ballast to balance that fat-ass sitting on the left side of the car. Again, all you need to do it cover it with a box to be legal...

GA, whose fat-ass is possibly driving this car for the VIR 13 this year...

Pass seat area is a possibility, the fast prod cars all have it there.
The factory tank fills from the side, if mounting a top fill cell of any decent size in the factory location there is no room to get a filler hose to the rear of the car. There is also nowhere in the passenger compartment to have a filler hose exit short of filling through the glass on the hard top. Can you cut a hole in automotive glass and would it be legal to do so?

[StephenB]

Does it still has to be within 12 inches of the stock location?

And remember additional reinforcement cannot be attached to the cage and in most cases the cell cannot be larger than 10% of stock.

Stephen.

[Andy Bettencourt]

and in most cases the cell cannot be larger than 10% of stock.

Stephen.

That is a local rule in our supps.

[StephenB]

Gotchya... my bad!

Stephen

[Greg Amy]

...if mounting a top fill cell of any decent size in the factory location there is no room to get a filler hose to the rear of the car...
So you use the stock filler hole to mount your quick-fill, run a tube to the cell.


Can you cut a hole in automotive glass and would it be legal to do so?
I don't think so, though one can argue you MIGHT be able to mount it into the hard top (but I'd hate for you to do that, destroying the top's value and making it a PITA to replace if needed).

However, if you mount the cell in the passenger seat area, you could have a "convertible" fill: one top-fill under the cover for regular sprint weekends, then an easily-installed "side fill" in the passenger window area or something where you simply open the passenger door and fill from there. As long as all components are isolated from the passenger compartment it would be legal....I'll look over a Spec Miata and give it some thought.


Does it still has to be within 12 inches of the stock location?
Yes. But that's not center-to-center, that's any part of the stock tank (even the flange) to any part of the new cell (including its mounting bracketry?) Hell, in a Miata just about EVERYWHERE is within 12 inches of the stock tank!!! ;)

[Greg Amy]

The more I think about it, the less I like the idea of a fuel cell in the passenger floorboard of a Miata. With the disparity of cars that enter enduros, there's just too much opportunity for a side collision that could compromise the cell, and the idea of 25 gallons of fuel spewing next to me while I'm flipping upside down is "unattractive"...

I think I'd pursue the idea of putting the cell in the stock location, as far forward and as low as possible, with the quick-filler in the stock location (remove the filler door).

GA

[Knestis]

...and if one were to go with a NASCAR-style solution that built the steel cell box into the structure of the car, with framing and reinforcement as appropriate, it could be hell for stout. Might be that the bladder could be poked up from the bottom, with the "lid" not in the driver's compartment.

I'm curiouser and curiouser on the fuel mileage question for the Miatae.

K

[JeffYoung]

Didn't Andy say once you enrichen them to make "ITA" or "ITS" power, they drink fuel badly??

[tnord]

i don't know about "badly" but mine does seem to use about 1/3 again more fuel than my SM did.

[JeffYoung]

Seems badly to me, especially for an enduro car.

[tnord]

i haven't quite figured it out yet, as the car is still new to me. i *THINK* my old 1.6 SM used ~3 gallons for a race, and got ~12mpg. I dumped in *something* over 3.5 gallons last race at the same track and ran out on the last lap. so i guess i need to dump in 4 gal next time. rough calculations have me at 8mpg now instead.

[JIgou]

Over the couple of years that I really tracked it religiously, my 1.6 SM hovered between 10 and 10.5 MPG. YMMV. :D

That's based on the odometer mileage, though - I don't know how that compares to the real world / GPS.

[Andy Bettencourt]

Yes, it full-bore IT trim they suck gas VERY quickly. I swear mine uses more fuel than my ITS RX-7 did.

Greg qualified it correctly...bolt ons for a touch more power, stock ECU, a slightly upgraded SM suspension and some R-comps and you should be able to lead the SM crowd without issue and get similar MPG.

[Eagle7]

Well, I'm confused. Doesn't
In any automobile where allowed removal of rear seats, upholstery, etc., creates an opening between the driver/passenger compartment and an exposed gas tank, fuel cell, or part thereof, a metal bulkhead which completely fills such opening shall be installed
mean that the cell and those non-metalic hoses need to be behind a bulkhead?


I've never cut a Miata up but it wasn't clear that we could get that big cell into the Golf either, until we did it. And in that case, there was exactly ONE place it would fit, given the rear axle location.

http://www.it2.evaluand.com/gti/images/mk3.2/fuelcell1.jpg

Kirk (whose not-quite-so-fast ass will likely be hot-swapping with Greg and Tyler)

[Greg Amy]

Well, I'm confused. Doesn't [snippage] mean that the cell and those non-metalic hoses need to be behind a bulkhead?
Kirk has a box over all that; it's only open for the photo.

[Eagle7]

Kirk has a box over all that; it's only open for the photo.
Ahh. Thanks Greg.

[JeffYoung]

That blue car = best built/designed enduro car I've seen.

[Greg Amy]

That blue car = best built/designed enduro car I've seen.
...which, sadly, can't seem to get enough paying drivers to justify running it, forcing its owner to rent a Mee-Otter...hey, just sayin'...

[Knestis]

http://www.it2.evaluand.com/gti/images/mk3.2/fuelcell2.jpg

Sorry for the confusion - this is what it looks like with the box, but the lid off. Box was built by an HVAC guy in Greensboro, NC, then finished by yours truly. Round tube on the right is a piece of semi exhaust tube, to give the hose a conduit rather than knife-edged holes to run through the multiple layers of chassis sheet metal out to the quick fill.

K

[Eagle7]

Sorry for the confusion - this is what it looks like with the box, but the lid off. Box was built by an HVAC guy in Greensboro, NC, then finished by yours truly. Round tube on the right is a piece of semi exhaust tube, to give the hose a conduit rather than knife-edged holes to run through the multiple layers of chassis sheet metal out to the quick fill.

K
No need to be sorry. I responded in a different context than you posted in. Thanks for all the pretty pictures. Good stuff.

[StephenB]

Granted it was only a three Hr. but it was a miata 1-2 at NHMS yesterday. Their was a super fast ITE car running as well.

On a side note... how long does a miata run on 1 tank? Any RX7 drivers want to share how long those will last and how much fuel they carry?

Stephen

[924Guy]

Nice box! ;)