M20 into a 318i, best of both worlds?

[ali123]

Hey guys I was wondering what you guys think about dropping a M20 into a early 318i? with the 500 pound weight difference it sounds like it'd be an awesome car to drive but I read a comment that said they were the least desirable e30's? was it only till 85 that they weighed in the 2300 range?

[Liquidity]

They weigh less because they have a really small engine, matching tiny gearbox and 168mm differential. Once you put the heavy M20, G260 and 188mm differential it's not gonna weigh 2300lbs anymore.

[JinormusJ]

Wet M10 weighs like 190lbs
Getrag 240 weighs like 50lbs
Small case diff weighs like 35lbs

Wet m20 weighs close to 285lbs
Getrag 260 is about 80lbs
Medium case diff is about 70lbs


You're looking at almost 200lbs gain in just driveline alone
Definitely not 2300lbs anymore, but definitely still light

[Jaxx_]

My 318i with gas, driver and spare is 2340lbs. It has stripped interior, no PS, no AC, and a medium case LSD.

Sent from my LG-E980 using Tapatalk

[ali123]

So it's about a 300 pounds diff then if you added a m20? is this because of interior or were the frame of the later models more stiff?

thanks

[MattAvino]

So it's about a 300 pounds diff then if you added a m20? is this because of interior or were the frame of the later models more stiff?

thanks

You literally just answered your own question. The m20 is a BIGGER engine, it is heavier. Therefore, once installed in the vehicle, the total weight is increased.

science.

[thebutterson]

There's no need to upgrade the diff or axles. I forget if the getrag 240s from the 90+ 318i's will fit but that could be another way to avoid adding weight.

The early 318's came with no abs, thinner carpet padding, no sound deadening in the trunk, no check panel and extra wiring, and with a battery up front. That's where the weight savings comes from other than the drivetrain.

[AndrewBird]

The drivetrain is the only thing different between a 318 and a 325. Early 318s had drum brakes, so there might be a difference there, and they didn't have the tar in the trunk like 325s, but otherwise the unibody, suspension, interior, etc is all the same. I guess early models had smaller diameter strut tubes as well, but some early M20 cars had those as well.

So in short, swapping the drivetrain is going to make it just as heavy.

[2mAn]

My 84 318 weighed 2400lbs with a full tank AND it had a 2.7i in it. Do it! Theres a lot of other little things that are different. No power options definitely cuts down on weight. My 86 eta weighed 2750lbs with a full tank. It was fully optioned ES, VS a bare bones 318 car. There is a difference. Both cars had full interior

[slammin.e28]

M60 it or go home.

[varg]

Well the light weight of the early 318 drive train is certainly beneficial to handling and braking, and from what we've seen with certain individuals here the stock M10 can take enough boost to propel a 318 down the strip faster than a new M3. If you got 250whp out of the stock drivetrain with a mild build and worked on the handling and braking you could make an "undesirable" early 318i into a seriously fast car without even needing to do a swap.

[dirty30]

M60 it or go home.

boom

with bottlecaps and stock suspension

[slammin.e28]

boom



with bottlecaps and stock suspension

Wouldn't do it any other way.

[anabolice30]

Well the light weight of the early 318 drive train is certainly beneficial to handling and braking, and from what we've seen with certain individuals here the stock M10 can take enough boost to propel a 318 down the strip faster than a new M3. If you got 250whp out of the stock drivetrain with a mild build and worked on the handling and braking you could make an "undesirable" early 318i into a seriously fast car without even needing to do a swap.

Idk all about beating a new m3 down a quarter mile.. But yea the m10 can handle boost like a mother.

[jeffnhiscars]

My 84 318i lacks power window & sunroof motors. I also think the rear drums weigh about as much as a rotor but the wheel cylinde is lighter than a caliper. I haven't looked in ages but I also think the ebrake activates the brake shoes so no extra hardware there.

Then there's the style 42 battery that's a good 12 lbs less than what's in an m20 car.

The engine swap doesn't just add weight but it puts most of it in front the of the axle which magnified the impact on handling.

Do the math