wtf is up with m42swaps?

[Vivek]

You two had/have some overdue maintenance or something that severely destroyes(d) your efficiency.... because i'm getting a constant ~29MPGs on mixed driving in winter and best i got is 31.4 in the fall.

What could it be? I know this is a bit OT but I've done all my vac hoses and have no leaks to my knowledge, spark plugs are a few k's old, etc. I always assumed it was just crappy aero+4.27 diff. It gets fine mileage highway, I did about 120 miles one day and calculated it at 24mpg, and that was a cruise to a meet an back, so I was mostly going 80+ in 4th gear, fucking around and maxing out every gear many times, flooring it half the time, etc...24 was damn good for what I did that day.

[E30 Wagen]

I'm with the OP on this one.

Instead of spending the money, time, and effort on swapping an m5x, I'd rather rebuild a tired m42 with some of the upgrades that have been mentioned. I'm not sure what kind of power output is possible, but it can't be that far off from an m20 or m50? Plus, you get to keep the original engine and handling characteristics, and the engine would be like new again, only better, and not used.

How much power do you really need to have fun?

[///M42 sport]

m42 turbo >m20

[CrusherCurtis]

^ My first m20 e30 bone stock 5 speed got at least 27 mpg. The only m42 benefits are 50 lbs and 2 mpg. MEH

[eur04lif3]

Just about none. I get around 20 city (daily) and 24 combined. I've never tried all highway but my mileage blows.

When I had my m42 I was highly disappointing with the gas mileage, It was honestly about the same as my m20. I go maybe 26 and I said earlier its rated only 1 mpg better. There goes practicality.

EDIT: Any one know the official weights of both motors?

You two had/have some overdue maintenance or something that severely destroyes(d) your efficiency.... because i'm getting a constant ~29MPGs on mixed driving in winter and best i got is 31.4 in the fall.

[JinormusJ]

EDIT: Any one know the official weights of both motors?

M42 - 220 lbs; 280 lbs w/ tranny
M20 - 255 lbs; 330 lbs w/ tranny

These are estimates, but the figures are around 5 lbs error projection

what i meant was if my m42 were to take a shit i would either put another m42 in it or go big with an s50, expecting it to be a totally different car in the end. if my m42 blew i'd never put a m20 in it... a m20 swapped 318is seems like a waste since m20 cars are dime a dozen. while a s50 swapped 318is wouldn't have the same feel, its definitely not a bad feel; its just different.

I see said the blind man
If your m42 takes a dump, then I can understand the need for a swap; Even then, I'd try to resurrect the m42 to keep originality, but I see your point



I'm with Creeper; this thread needs to die...

[CrusherCurtis]

When I had my m42 I was highly disappointing with the gas mileage, It was honestly about the same as my m20. I go maybe 26 and I said earlier its rated only 1 mpg better. There goes practicality.

EDIT: Any one know the official weights of both motors?

[iamsam]

what i meant was if my m42 were to take a shit i would either put another m42 in it or go big with an s50, expecting it to be a totally different car in the end. if my m42 blew i'd never put a m20 in it... a m20 swapped 318is seems like a waste since m20 cars are dime a dozen. while a s50 swapped 318is wouldn't have the same feel, its definitely not a bad feel; its just different.

i put an M20 in my 318is simply because it was far cheaper to do so than to buy a head gasket kit for the M42...

[Tismael711]

318is should never be swapped. If you want to swap an iS chassis, at least swap the 325iS. There is nothing that can't be done weight-wise to the 325iS to make it the same as an 318iS, but the handling characteristics you can never replace and you will destroy them by dropping another huge boat anchor in it. At least 325iS already had less composed handling so dropping a bigger engine in is no big deal, but please: don't molest a 318iS

what i meant was if my m42 were to take a shit i would either put another m42 in it or go big with an s50, expecting it to be a totally different car in the end. if my m42 blew i'd never put a m20 in it... a m20 swapped 318is seems like a waste since m20 cars are dime a dozen. while a s50 swapped 318is wouldn't have the same feel, its definitely not a bad feel; its just different.

[Ryann]

^^I was disappointed with my 318ic's fuel economy as well, 26 at best. Heavier car + poor aerodynamics? My 16v 4d would get as good as 28 if I kept it at 70. The stock diff ratio is the primary contributor to relative shitty fuel economy on the freeway.

Edit: forgot the vert diff ratio is 4.27, so likely the main cause of crappier mileage.

[iamsam]

Just how practical is an m42 over an m20 in terms of gas mileage? Maybe 2 mpg better if that?

Just about none. I get around 20 city (daily) and 24 combined. I've never tried all highway but my mileage blows.

my 318is got 30 mpg avg before i swapped in the M20B25, now it gets 26 mpg average. I'd say that is pretty significant.

That said, I kept a 4.10 with the M20, but went to bigger tires, 195/70/14, whereas with the M42 I used 195/60/14 and the 4.10.

[Vivek]

Just how practical is an m42 over an m20 in terms of gas mileage? Maybe 2 mpg better if that?

Just about none. I get around 20 city (daily) and 24 combined. I've never tried all highway but my mileage blows.

[CrusherCurtis]

Just how practical is an m42 over an m20 in terms of gas mileage? Maybe 2 mpg better if that?

[irish44j]

HAHAHA yeah I drove with the m10 for about a month before I swapped it. i lost to a 95 corolla and that was really embarrassing

should be more embarrassing that an e30 and a corolla are drag racing. They're both slow, with any stock engine ;)

Hell, a V6 camry these days would probably walk an e30m3 in a drag, lol....

[unevolved]

But this is the internet! I want to argue!