M20 2.7

[Darren325is]

Sorry if this is a daft question / repost etc bur what actually is a 2.7 engine for an E30 ?

Is it a bored out 2.5, different head, stroked or a completely different engine ?

If its a messed about 2.5, what are the advantages / disadvantages and likely costs etc ?

Thanks

[Speedtouch]

See E30 Zone Wiki:

http://www.e30zone.net/e30zonewiki/inde ... ding_a_2.7

[Grrrmachine]

Also, have a read of this:

http://www.e30zone.net/e30zonewiki/index.php/M20

[maggspower]

It has at least a crank from the eta or m21 turbo diesel engine, the entire bottom end can be used, but it is sub optimal, IMO.

When using just the crank, you will need m20b25 pistons, and head.

Advantages: More powaaaaaaaah........

As long as its set up right, there are few if any disadvantages.

Its hard to give a cost because there are so many ways of doing it. I have just built a nice spec bottom end with new everything, bores, bearings, rings, conrod bolts, crank reground, m20b25 pistons, a good spec. That was well over £1000, the only bits provided were the crank and rods.

[Grrrmachine]

I've realised the confusion now. There are two types of 2.7 M20.

1) Factory original. These had the same 84mm block as the 2.5, but used the shorter rods from the 320i with a special crank that had a longer throw than either the 2.0 or the 2.5. They were asthmatically strangled by their unique head which was designed more for economy than power. They kicked out about 140hp.

2) The home-made stroker engines. These use the same combination of block, rods and crank, but with a better head taken from either a 2.0 or 2.5, which necessitates further engine work as outlined in the Wiki. They are normally built from standard 2.5 engines whose heads have cracked. These stroker engines can pump out 190hp fairly easily.

Hardly anyone on here has a Factory 2.7 because the car they were fitted to, the 325e, wasn't heavily marketed in the UK.

[Kedge]

I've realised the confusion now. There are two types of 2.7 M20.

1) Factory original. These had the same 84mm block as the 2.5, but used the shorter rods from the 320i with a special crank that had a longer throw than either the 2.0 or the 2.5. They were asthmatically strangled by their unique head which was designed more for economy than power. They kicked out about 140hp.

That's the ETA engine.

2) The home-made stroker engines. These use the same combination of block, rods and crank, but with a better head taken from either a 2.0 or 2.5, which necessitates further engine work as outlined in the Wiki. They are normally built from standard 2.5 engines whose heads have cracked. These stroker engines can pump out 190hp fairly easily.

This is basically what Aplina and Hartge did back in the day I think, Alpina also added in fancy pistons as well, not sure what lengths Hartge went to.

Hardly anyone on here has a Factory 2.7 because the car they were fitted to, the 325e, wasn't heavily marketed in the UK.

I don't think the 325e was available in the UK was it? These engines over here are usually pulled from E28s.

You could always go down the 2.8 route using an M52B28 crank as well

[bab-91]

190 bhp... a lot of work & money for little gain.

[maggspower]

190 bhp... a lot of work & money for little gain.

+20bhp and a simular amount of torque?

[bab-91]

190 bhp... a lot of work & money for little gain.

+20bhp and a simular amount of torque?

For a grand?

More torque would be nice mind.... but

HOW MUCH!!

[maggspower]

I've realised the confusion now. There are two types of 2.7 M20.

1) Factory original. These had the same 84mm block as the 2.5, but used the shorter rods from the 320i with a special crank that had a longer throw than either the 2.0 or the 2.5. They were asthmatically strangled by their unique head which was designed more for economy than power. They kicked out about 140hp.

2) The home-made stroker engines. These use the same combination of block, rods and crank, but with a better head taken from either a 2.0 or 2.5, which necessitates further engine work as outlined in the Wiki. They are normally built from standard 2.5 engines whose heads have cracked. These stroker engines can pump out 190hp fairly easily.

Hardly anyone on here has a Factory 2.7 because the car they were fitted to, the 325e, wasn't heavily marketed in the UK.

Has someone hacked your account? There are some inaccuracies in there

[maggspower]

190 bhp... a lot of work & money for little gain.

+20bhp and a simular amount of torque?

For a grand?

More torque would be nice mind.... but

HOW MUCH!!

Speed is a question of money, how fast do you want to go?

More power and an engine ready to do another 200000 miles, yes its a rip off.

Sorry forgot this was the e30zone.

[bab-91]

and just out of curiosity what does that do for fuel consumption?

[daimlerman]

E28 525e is the source of parts for a stroker build in the UK.

However,as 525e was only available up to cira '84,good condition cranks now rank alongside rocking horse poo in the availability stakes. Using a crank from an M52 2.8 starts to make sense.However,this is not a straightforward build,as the nose of the crank differs from it's earlier relation,meaning that a sleeve needs to be machined to enable things to work properly.

'Economy' 2.7 is easy enough if one can get the parts needed at the right price and in usable condition.A complete 'eta' short motor mated to a '320/520' cylinder head,using a '325' cam,injectors,inlet manifold,AFM will give about 175bhp,but more importantly,will boost torque from 2000rpm to 5000rpm.Torque is what fires a car out of a corner,or past the pensioner dawdling on an A road,bhp is what we used to boast about down at the pub...

[maggspower]

and just out of curiosity what does that do for fuel consumption?

Little or nothing, some even say an improvement. The additional torque at lower engine speeds means the throttle needs to be open less, and you can change gear sooner, effortlessly trundling along a 1000rpm if you want.

Higher compression resulting from increased capacity, gives greater thermal efficiency, more of the latent energy within the fuel is turmed into motion, kinetic energy.

Of couse it is hard to take advantage of this, what with the extra power an' all

[daimlerman]

and just out of curiosity what does that do for fuel consumption?

Little or nothing, some even say an improvement. The additional torque at lower engine speeds means the throttle needs to be open less, and you can change gear sooner, effortlessly trundling along a 1000rpm if you want.

Higher compression resulting from increased capacity, gives greater thermal efficiency, more of the latent energy within the fuel is turmed into motion, kinetic energy.

Of couse it is hard to take advantage of this, what with the extra power an' all

I have seen up to 38mpg from my 2.7...but a more usual figure is 31/32mpg,as the extra torque cry's out to be used....

[bab-91]

Something to do in the future. maybe....


Just maybe.


The wiki should be updated with some of this info

[daimlerman]

Something to do in the future. maybe....


Just maybe.


The wiki should be updated with some of this info

Well worth considering when your engine needs a re-build.

These days,going 2.8 does make a lot of sense,you get to keep a 'stock' look under the bonnet,with the grunt offered by extra capacity,running costs are possibly reduced and your grin gets bigger!

M20 is not cheap to re-build properly,the same grunt is available from a straight swap using an M52,but when you open the bonnet,you give the game away

[bab-91]

The pretense of oem wholeness is appealing


Much difference is the 2.7 & 2.8 rebuild?

Sorry for the bombardment of questions. I'm an inquisitive little cherub this morning.

[daimlerman]

I've only fallen to 2.7 rightness,which is pretty much a 'parts bin' build.

2.8 requires more engineering imput for a small capacity gain,but careful attention to detail does give impressive results.Several zoner's(stonsie,goosegander to name two)have built 220+bhp engines that put the 175/180bhp 2.7 well in the shade,but remember,to get that sort of output,it is nesessary to imput considerable funding and attention to detail in the build.

Remember also,that an M52 furnished with an M50 inlet will give similar results for less outlay,but again,you need to imput the engineering skills to get the results.

At the end of the day,some need the 'stock under bonnet' look of a stroker build,some prefer the cheaper option using the newer engine.
Both,however,need commitment and funding to achieve results.