Intriguing question about weight to power ratio and different engine swaps

[RCV7]

I've got a '97 328i 5 speed sedan as a dd that I'm very happy with but am very interested in getting a 318ti and swapping out the engine and tranny. I'd most likely use it for autox, track and dd it as well. I'm guessing the M3 engine is heavier than the 328. How do I decide which motor to swap in? I'm thinking the 328 would be less expensive to purchase and maintain and get better gas mileage than the M3. Wouldn't it also be lighter and thus handle better? Sorry for the noobness but not too experienced with this matter. Thanks in advance.

[BimmerBum]

Originally Posted by RCV7

I've got a '97 328i 5 speed sedan as a dd that I'm very happy with but am very interested in getting a 318ti and swapping out the engine and tranny. I'd most likely use it for autox, track and dd it as well. I'm guessing the M3 engine is heavier than the 328. How do I decide which motor to swap in? I'm thinking the 328 would be less expensive to purchase and maintain and get better gas mileage than the M3. Wouldn't it also be lighter and thus handle better? Sorry for the noobness but not too experienced with this matter. Thanks in advance.

Unless you land an aluminum block 2.8 from a Z3 the 2.8 and S50 or S52 M3 engine will weigh the same.

The cost to maintain the 2.8 and the US Spec S50 or S52 engines would be identical also. The real difference will come in the purchase price.