m20/b20 to m42 1.8

Mon Mar 13, 2006 12:33 pm

Hi I'm planning to chuck m20/b20 with the auto gear and plonk in a m42 from e36 318IS, i'm getting the manual trans too.

What r a few things I should take note have when doing such a conversion?

Mon Mar 13, 2006 7:00 pm

Expensive, for not much of an upgrade.

Go for the 3.5 conversion, it should be cheaper for much more power!

Mon Mar 13, 2006 7:18 pm

After being out in randomdaves car on sunday, the way ahead is a 525i engine! 192BHP standard, and i think it had a short ration box, it went like stink around the track. He bought a complete donar car for Ãƒ”šÃ‚£400...

Tue Mar 14, 2006 3:44 am

E30Mark wrote:After being out in randomdaves car on sunday, the way ahead is a 525i engine! 192BHP standard, and i think it had a short ration box, it went like stink around the track. He bought a complete donar car for Ãƒ”šÃ‚£400...

Is that the e28? I was thinking of petrol savings

too... i'm getting my engine from a donor car for about 390 ... can the transmission fit into my car (e30)?

Tue Mar 14, 2006 9:08 am

We're not all power mad out there! Some of us just want to bring the E30 a bit nearer to the 21st century.
We already have an excellent chassis and near perfect interior, but it's let down by the primative M20 engine. I think an M42 conversion would be well worth doing on a 320, for thje fuel economy alone if nothing else.
No idea what problems are involved though.

Tue Mar 14, 2006 9:26 am

fuel economy

I wouldn't change an engine just for fuel economy. If you want to save money on fuel, I would think it would be better to go LPG. Or put in a 2.5 engine on LPG.

Tue Mar 14, 2006 9:36 am

Petrol wise I get about 320 miles out of 40 quid in my M42 touring which works out about 33 miles to the gallon, thats mostly short journeys 15 miles ish with mixed driving.
If you thrash the engine(which it loves

) you get low twenties.
I didn t think it was that good to be honest.

Sometimes having a bigger torquey engine give you better economy because you can drive in a higher gear at lower rpm

Tue Mar 14, 2006 10:05 am

A friend of mine suggested buying a 2.7 ETA engine (the non motronic one, i don't know if there was one). Then he asked me to retain my b20 top but using the ETA's lower portion. He said i'll make much more power than the b25 but retain the jetronic that i have in my car ... haha but fuel eff. will be near to zero hahaha.

Tue Mar 14, 2006 10:13 am

That's the more straight forward route to take... use the Eta bottom end and retain your 320 head, etc. To use the 'cheap and easy' route, use your existing head, but bolt on the 325i inlet system, and re-chip the ECU. Job done. 190bhp and little work involved really.

Tue Mar 14, 2006 10:21 am

CorollaRWD wrote:Petrol wise I get about 320 miles out of 40 quid in my M42 touring which works out about 33 miles to the gallon, thats mostly short journeys 15 miles ish with mixed driving.
If you thrash the engine(which it loves ) you get low twenties.
I didn t think it was that good to be honest.

Sometimes having a bigger torquey engine give you better economy because you can drive in a higher gear at lower rpm

alex dunno why you do so badly on fuel out of the m42. I normally get just over 300 miles out of the tank doing town driving and having a heavy right foot etc. so just over 30mpg. I've never really had worse than 30 out of the factory ECU, or about 28/29mpg with the chip. and i've had the car for years and i do have a heavy right foot.
on a motorway run I'll get nearer 350/400 miles out of a tank, or even doing mixed roads/A roads like when i went around wales a few wkends ago. I would expect on the M'way or A roads to get 35mpg minimum, 40 is a bit hopeful though.
If you're really doing that badly out of fuel, I'd consider getting the fuel system checked out.

Tue Mar 14, 2006 1:44 pm

Geeman wrote:That's the more straight forward route to take... use the Eta bottom end and retain your 320 head, etc. To use the 'cheap and easy' route, use your existing head, but bolt on the 325i inlet system, and re-chip the ECU. Job done. 190bhp and little work involved really.

Geeman, you meaning changing the manifold and throttle body ain't it? But mine is a Jetronic so i think there is not much I can do ain't it? but if you're referring to the jetronic system then tell me more

Tue Mar 14, 2006 2:30 pm

Not sure what the real differences are with Jetroni and Motronic.

All I know is that for a facelift model you can use the Eta bottom end, 320i head with either standard cam or uprated, 325i inlet manifold complete with injectors still fitted, 325i TB and AFM and re-chip the ECU with a 2.7 Zone chip from Ant. The exhuast manifold is the same, but the system 'could' do with uprating if you really thought it neccessary.

Sorry, but I'm not up to scratch with the earlier engines and what implications that would have...

Tue Mar 14, 2006 2:57 pm

the 525e is motronic so i dont know why you would want to use jettronic ?

Tue Mar 14, 2006 3:07 pm

to chip it I guess... pretty useless using the stock 320i mapping for a 2.7 litre engine...

Tue Mar 14, 2006 3:27 pm

m-dtech wrote:the 525e is motronic so i dont know why you would want to use jettronic ?

m-dtech, my car is jetronic, so I can't really go far with this. But someone told me that there was a jetronic 2.7 ETA engine that could be fitted in my car by using the bottom with my head and get 19X plus horse.