when do m20s wear out?

[ChrisBarns]

I was thinking about some bolt on performance goddies for a 2.5. In my budgeting i allowed for a rebuild (like i did as a youth - rebore, oversize pistons, reground crank, lap the valves etc, etc) as there is no point in spending £500 on a new manifold then attatching it to a crapy engine.

however something Brian Moore said on the "what oil?" thread suggested that M20s don't wear for interstella milages. I realise it depends on how its been driven and serviced but roughly how long do they last before performance drops off?

[munky30]

forever.

[dom-1984-320i]

forever.

Agreed

[ChrisBarns]

seriuosly?

[dom-1984-320i]

certainly good for 200k+ if well looked after ii would say

[tari]

i suppose with the right owner looking after it, it could last forever???

[hairydave]

As long as your cars performance is still strong and dosen't use oil and or smoke, it shouldn't need any more than regular servicing.

Having said that if you can stretch to a rebuild then you should look at a 2.7/2.8 and then get the bolt on bits.

[ChrisBarns]

Yeah but my question is slightly different - i don't want to keep it going with out clattering and smoking - i want it to be making its 170 bhp before I spend well over a grand searching for another 30bhp.

[hairydave]

I understand and agree you should have your engine in fine fettle before modding, the only way to tell what power it's running now is to get it on a dyno.

Once you get a figure then you can decide what route to take.

[ed325i]

roughly how long do they last before performance drops off?

I bet there is not many 325's making 170bhp.

[munky30]

roughly how long do they last before performance drops off?

I bet there is not many 325's making 170bhp.

How dare you?!

These angines are built by bmw... therefore they will never break, run low on power, or change in any way from the exact spec they were when they left the factory. They ARE the best engines ever made, ever.

[ChrisBarns]

rolling road good idea but i was hoping to clean and build-up a new engine, add the performance parts and then swap it in (current engine is 2.0).

On the other hand... Would be interesting to add parts one by one and assess improvements. Expensive if i use rolling road each time though!

[jamesh1977]

if your wanting to do that why not go for the 2.7 or 2.8 theres plenty of discussions on here on how to build them

[ChrisBarns]

if your wanting to do that why not go for the 2.7 or 2.8 theres plenty of discussions on here on how to build them

because i wanted an engine that likes to rev (like my 320) and recon i should be able to get close to my target 200bhp with a BBTB, BTB, a cam and a remap. But not if I'm starting with, say, 155 bhp.

[320Touring]

quoted from

exxonmobil.com/corporate/files/corporate/mobil_1_fact_sheet.pdf

One Million Miles on Mobil 1
As one example of the level of testing undertaken, a
1990 model BMW car was tested for 1,000,000
miles (1,600,00 km) with Advanced Formula Mobil 1
and showed extremely low wear. Oil drain intervals
were 7,500 miles (12,000 km), as specified by the
manufacturer, and Mobil 1 was used from the very first
day of testing.
After the end of the test, with 1,001,120 miles
(1,601,792 km) on the vehicle, the engine was
removed and internal components were inspected and
measured. Overall engine wear was extremely light. In
fact, with the exception of light to moderate wear on
the camshaft and followers, no other significant engine
wear was noted. Oil consumption over the entire test
was equivalent to just one litre every 40,000 kilometres.

[Jhonno]

Sweet!! Thats well built!!

[Brianmoooore]

If you are keen, then replace the big end and main bearing shells with standard ones, although it is likely to be far from necessary.
As for the top end, the exhaust valve guides are likely to have a little wear and should be replaced, along with tidying up and lapping all the valve seats.
Camshaft and related bits should be assessed for wear visually and replaced in necessary.

[dom-1984-320i]

quoted from

exxonmobil.com/corporate/files/corporate/mobil_1_fact_sheet.pdf

One Million Miles on Mobil 1
As one example of the level of testing undertaken, a
1990 model BMW car was tested for 1,000,000
miles (1,600,00 km) with Advanced Formula Mobil 1
and showed extremely low wear. Oil drain intervals
were 7,500 miles (12,000 km), as specified by the
manufacturer, and Mobil 1 was used from the very first
day of testing.
After the end of the test, with 1,001,120 miles
(1,601,792 km) on the vehicle, the engine was
removed and internal components were inspected and
measured. Overall engine wear was extremely light. In
fact, with the exception of light to moderate wear on
the camshaft and followers, no other significant engine
wear was noted. Oil consumption over the entire test
was equivalent to just one litre every 40,000 kilometres.

AMAZING!!!

[orangecurry]

quoted from

exxonmobil.com/corporate/files/corporate/mobil_1_fact_sheet.pdf

One Million Miles on Mobil 1
As one example of the level of testing undertaken, a
1990 model BMW car was tested for 1,000,000
miles (1,600,00 km) with Advanced Formula Mobil 1
and showed extremely low wear. Oil drain intervals
were 7,500 miles (12,000 km), as specified by the
manufacturer, and Mobil 1 was used from the very first
day of testing.
After the end of the test, with 1,001,120 miles
(1,601,792 km) on the vehicle, the engine was
removed and internal components were inspected and
measured. Overall engine wear was extremely light. In
fact, with the exception of light to moderate wear on
the camshaft and followers, no other significant engine
wear was noted. Oil consumption over the entire test
was equivalent to just one litre every 40,000 kilometres.

sorry but that is marketing nonsense.

We all know that most engine wear occurs at start-up, and before the engine reaches temperature - THAT engine was warmed-up once (I bet they even pre-warmed the Mobil1 before each oil change), and then the engine ticked over in perfect cooling conditions with minimal load for the 1.6M.....meaningless... unless they had an identical engine running mineral oil next to it, and compared wear? I think not.

[Brianmoooore]

sorry but that is marketing nonsense

Of course it is - but they aren't claiming 1,000,000 miles is the life of the engine. No significant wear, except for cam.
In the real world, and from what I've seen of M20 internals, there's no reason why 500,000 miles shouldn't be realistic with minimal engine repairs.

[miniblob]

My 325 engine was putting out between 150 & 160 bhp (iirc) when i started tuning it. I spent a lot and had BBTB, BTB mani and straight through 'zaust, ITG filter, MAF conversion, Unichip (rr setup) - everything you can bolt on (didn't get round to a cam!). When done, it was putting out 185bhp!!! Defniately a big difference!!!

I do remember at the time, posting up and saying i was going to bolt on all the bits and get 200bhp and everyone saying there was no chance of hitting that - and it would seem they were right!!!!

Now got a 2.7 in there with most of the bolt on bits and i reckon it's the way to go!!! Way more bhp, but most importantly, a whole shedload more torque!!!!!

[ed325i]

because i wanted an engine that likes to rev (like my 320)

Get a 2.3 engine.

[pnd]

what brian moore says should restore the engine to fine fettle if its done high mileage I have driven cars with this treatment after 200,000 and they were definitely up to power.

[Simon13]

sadly a 2.7 won't ever rev like a 2.5 does. and a 2.5 with 190bhp would be great engine but will cost alot of money

i broke a rocker on my 325 touring on around 215,000miles due to a worn cam and rocker. Which all started from a blocked spraybar at some point. I changed this when i bought the car but was obviously too late and possibly delayed the inevitable!

Anyway to my point! i rebuilt the top end with nice new rockers and eccentrics and a shiney cat cam 273/273 with 11.6mm lift, added a racing dynamics exhaust manifold. I cleaned up all the valves on my old mans lathe and re seated them by hand and new stem seals. The guides all seemed ok so i didn't change them

The only work i've done on the bottom end was a new sump gasket and cleaned up the tops of the pistons with tooth paste! works wonders. Theres no smoke from the bottom end so it's probably ok for 220,000 plus miles now

On paper this should go a bit better! but on the rollers it had 2 runs of 164bhp and 175bhp. As it needs badly re mapping as it's too lean below 3500rpm and way to rich on the top end. The only consolation was it was still making power at 6800rpm! I'm sure a remap would sort all this out and i would end up with a solid 180-185bhp no messing.

It's lost torque low down as the cam has moved it all up top but it revs like a lunatic now, noticibly better than a stock 2.5.

I've got a nice little mod to do on the intake side of things but i'll do this later in the summer and maybe see about mapping it properly just to see if i can make a proper engine of it all.

[jimson]

my 325 is on 163k, engine never been to bits, its has been driven carefully but reved, dont go labouring them around at 1500 rpm, its had oil/filter changed every 5000 from new. it does 143mph (gps) indicating 150 on speedo, dont even take that long to get there. if you got time it still creeps up.
its worth having a bit of a strip measure sesion with bores and bearings, this will tell you if its been maintaned proper, then go from there.

[zaust]

They don't ware out.!!!

People brake them...

[dazleeds]

They don't ware out.!!!

People brake them...

[Rosc0PColtrane]

They wont wear out so long as an m42 is sacrificed to the BMW Gods every once in a while. It's why the 4 pots were built

[pnd]

m20 's may last a long time but before we get carried away lets remember not many get to 200k without an expensive new head ergo there are tougher motors out there made by bmw and others.

[dimebag_from_hell]

They would last alot longer if they didnt sound so good!!! I find it hard to get it out of third........glorious sound

[aus325]

They would last alot longer if they didnt sound so good!!! I find it hard to get it out of third........glorious sound

Agreed !!!

[munky30]

m20 's may last a long time but before we get carried away lets remember not many get to 200k without an expensive new head ergo there are tougher motors out there made by bmw and others.

No there aren't. everybody knows the m20 is the finest strongest engine in the whole worl;d, ever.

BMW made it, it must be.

If it breaks its the drivers fault.

[Rosc0PColtrane]

m20 's may last a long time but before we get carried away lets remember not many get to 200k without an expensive new head ergo there are tougher motors out there made by bmw and others.

They wont wear out so long as an m42 is sacrificed to the BMW Gods every once in a while. It's why the 4 pots were built.

The m20 breakage is down to lack of sacrifice. More m42's and m40's need to be killed off to appease to Gods of M20's.

[Barx325i]

Quote:
because i wanted an engine that likes to rev (like my 320)


Get a 2.3 engine.

Or one of those meths steam engine kits

[munky30]

m20 's may last a long time but before we get carried away lets remember not many get to 200k without an expensive new head ergo there are tougher motors out there made by bmw and others.

They wont wear out so long as an m42 is sacrificed to the BMW Gods every once in a while. It's why the 4 pots were built.

The m20 breakage is down to lack of sacrifice. More m42's and m40's need to be killed off to appease to Gods of M20's.

I sacrificed an M40.

The result was a swift death for my M20.

I think I angered the bmw gods.

I then sacrificed the dead M20 for a new M20 which has issues.

I dont believe your sacrifice rule. Either that or I have angered the bmw gods by using wheels that aren't BBS and smoking my lights.