Surge tank positioning

[jeremiahnz]

I am currently working on a surge tank setup in a datsun project car. The surge tank will be located in the boot of the car (it is a sedan).

In terms of positioning the surge tank, it makes a lot more sense from a fuel line perspective for it to be positioned on the side of the boot under which the exhaust runs. This is to pick up the original hard fuel lines (which will now be used as a return), and keep rubber fuel lines at a minimal length.

The surge tank wouldn't sit directly over where the exhaust runs however reading part 10.4.1 from the "NZ HOBBY CAR TECHNICAL MANUAL" (included below for reference) I want to make sure that there are no issues with certification base on drainage in case of a leak or rupture in the fuel system. To provide a bit more context, there are no drains in the floor surface above the exhaust. The exhaust is positioned well below the floor surface so will not heat the floor surface. In case of a leak or rupture, the surge tank setup will be no worse then the factory fuel tank setup which will spill all over the boot floor surface. The most obvious drain point for the fuel will be the drainage in the bottom of the spare wheel well. There will be a couple of holes drilled in the floor surface for mounting the plate which the surge tank will be attached to, however these will not sit directly over the exhaust, and will have bolts or rivets in them (plus could be sealed more if necessary)

I've seen a number of cars with LVV certs setup like this, but want to check before proceeding whether or not this is acceptable.

Thanks

Extract:

10.4.1
A low volume vehicle that has a fuel tank located on top of the
floor surface, must have the floor and surrounding area in which
the fuel tank is located, designed in such a way that any fuel, in
the event of a fuel tank leak or rupture: (see Diagrams 10.1 &
10.2)
(a) cannot come into contact with the vehicle’s battery or
battery leads; and
(b) will escape to the outside of the vehicle, without draining
onto either:
(i) any part of the vehicle’s exhaust system; or
(ii) any part of the vehicle’s electrical system.

[Justin]

Hi there

From your description, it sounds like a drain hole in the spare wheel well will satisfy 10.4.1.

[jeremiahnz]

Ok cool - thanks for your response.

So just to clarify - there would be no issue with the surge tank being mounted on the floor surface in the boot above the exhaust as there isn't a drain hole in the floor surface?

Thanks again for your help

[Justin]

Hi Jeremiah. So long as there's a compartment separating the tank from the exhaust, in this case the vehicle boot, and so long as fuel can't leak on to the exhaust (or the vehicles electrical system) should the tank rupture, it should be fine. So, it must have a drain hole, but it must not allow fuel to drain on the exhaust (or electrical system).

I hope this helps.

[jeremiahnz]

Yep - thanks for your reply. That clarifies it for me.

Cheers