Tim Comeau

Can anyone confirm that and can you swap it into a 924 or early 944/924S? If you can, how about the gas gauge and sender compatibility?

924RACR

I take it you're looking for a smaller gas tank for racing? In that case, you might prefer to use a 924NA (2.0L) gas tank. Per the spec booklet, the 2.0L NA 924 has a 62L tank (w/ 5L reserve), whereas the 931 has an 84L tank (w/ 9L reserve). Also, from the 944/924S spec booklet, the 924S shows a 66L/9L reserve tank, whereas the late 944's show an 80L/8L reserve tank.

62L is 16.4gal, 84L is indeed 22.2gal.

Senders will be compatible; the '81 931 I just recently sold had a bad gas gauge sender, and I swapped in one from a 924S (after confirming the cross-reference in PET).

For install, I do expect they would be interchangeable. The #1 concern would of course be trans clearance, but all these cars use the same trans except the 2.0L NA cars, in which case, for the 4-speed trannies, the trans is smaller... some potential for lack of fitment, but unlikely. If the 4-speed and 5-speed 2.0L NA 924's all use the same gas tank p/n, then no worries. The only other concern then would be to ensure you have the tank mounting straps that came with the tank you're installing - they might be different (though again should be easy to confirm with part #'s).

Tim Comeau

Ok, thanks, Vaughan.
I got all that. What I want to do is put the larger 931 (22.2 gals) into a 924S (stock is 17.4 gals) for endurance racing. The 931 tranny is the same unit except for the missing top mount tunnels used in the late cars. I figured I'd need different straps but just needed to ask if I was missing something else that would prevent me from putting the larger 22 gal tank into a 924S.
I could then just swap the 931 sender and gauge over to the 924S chassis?

924RACR

You shouldn't even need to swap the gauge, just the sender with the tank (or keep your existing sender) - just make sure the "new" tank is cleaned thoroughly, they're usually full of rust, of course!

Tim Comeau

Shouldn't the sender have to stay with the tank? A half tank tank reading in a 22 gallon tank isn't the same as a half tank reading in a 17.4? Different resistance signal to the gauge?

knfeparty

I don't know what type of sender it is, but float-style senders work on level and the angle of the sender, so it would be right still. Right enough, at least.

Tim Comeau

No. I mean if the tank is shaped differently, which it must be because it's almost 5 gallons larger, it makes sense that the sender would have to stay with THAT tank.