Max sump under car.
 

Cant find any reference anywhere as to the most sump/bellhousing that can be below the floorpan when installed before something takes a lump out of it?

Bob

Instant sump reduction
 

That may depend on the height of the object you hit :o

I'd say anything below floorpan level is a likely target:(

3" clearance under the sump would be a good figure to aim for. ( If the ideal height under the rail is 5").

Make sure that at full down suspension travel there is still air under the sump!!

There is no point in cutting the sump shorter than the bellhousing.
Then it's about how high the rocker cover is to the bonnet.

But how much?
 

Have tried to get the answer to this a couple of times, I am about to take engine and box to talon for chassis mock up and need to know what can stick out under the car before it becomes a problem. The answer will determine overall chassis height as that can changed . Is 2" sorry 50mm to the young ones to much?

Bob

2" would be OK.

7ishnz have you ever seen our roads? The unmade ones in the aussie outback are smoother.Potholes that people abseil down and speedbumps through towns that people with vertigo have to avoid. Are you sure 2" is ok?

Bob

my sump is about an inch below the bottom chassis rail. the gb is about 1 1/4 inch lower than the bottom chassis rail. i have managed to touch the gearbox down a couple of times when pressing on over bumpy roads.

personally i would say any more than an inch under the chassis rail is going to end in tears at the side of the road

Better if you can have it level with chassis rails, as Ash mentions DON'T go lower than an Inch or you risk taking a chunk out of it on our crap roads!!!

The best solution is sump level with the chassis. This is not usually possible even with a dry sump, as the bellhousing will now be the lowest point.
The best result is a compromise between bonnet height and bellhousing. 3" clearance under the sump/ bellhousing is the usual for 7's here... some have more, some less.
If you are worried, make a skidplate that will protect both the sump and the bellhousing.
Alternatively... fit airshocks :)