best cam upgrade for m20b20

[SGP]

Any advice re. above ? I don't want to put in a m20b25 motor thanks, just thought that while the motor is out I could pop in a nice cam without removing the head. Somebody suggested using the cam out of a 2.5 ? Thanks in advance.

[Alex]

fit a 2.5 cam with the rest of the engine still attached to the cam

a 323i cam is better not sure a 2.5 one works with a 731 head

[Ajsingh]

2.5 cam goes with the 2.5 engine

[SGP]

As I said I'm not interested in a 2.5 engine. Thanks for the help.

[Kos]

2.5 inlet manifold and TB and cam with a "chip" can yield decent gains

but its not worth the aggro

[Grrrmachine]

The b20 was never designed as a performance engine and, as such, you don't see any mods for it that will yield any improvements. For any of the usual stuff to have any meaningful effect (BTBB, manifold, cam, chip) you need to increase the displacement.

However, if you want to throw money at your engine, then you can fit a cam that matches that used in the Hartge H23, H26 and H27, which had these degrees: 280/280/112

[B7]

I picked a fully main dealer historied (till 12/2011 ) 320i pre facelift up the other night. 118k on the clock and runs as it should. And GOD it feels sluggish compared to any 2.5 I've driven! It is positively "casual" in the way it performs.

I would say there is absoloutely no point in throwing money at a cam or upgrages when you can sling a good 2.5 in there for little money and get INSTANT worthwhile noticable gains.

[powelly]

Out of interest why would you not want to put a 2.5 in, it just makes so much sense, especially if you are taking the engine out anyway, you can get a decent 2.5 for the money you would spend on a cam for a 2.0 and you still won't be near the power of a standard 2.5.

[hongkongfuey]

Also your 320 will use the same amount of fuel as the 325

[Andyboy]

The b20 was never designed as a performance engine and, as such, you don't see any mods for it that will yield any improvements.

Really? 129 bhp was up there with the 2.0 Alfas and a long way from a 95 bhp Pinto. It has big bores, a very short stroke, big valves and big ports. If anything it's a performance engine strangled by a tame cam and a small throttle body.

But you're wasting your time with factory cams. If you're going to do it, you need something with more lift and duration (around 270 degrees) plus a remapped ECU to go with it. You'd probably get to 150 bhp at the possible expense of torque. Your best bet is to remap it as there is a bit to be gained there.

The best 320i I had was a 1984 car with LE Jet. With the timing set up properly and 97 octane fuel, it really went well.

[SGP]

Out of interest why would you not want to put a 2.5 in, it just makes so much sense, especially if you are taking the engine out anyway, you can get a decent 2.5 for the money you would spend on a cam for a 2.0 and you still won't be near the power of a standard 2.5.

I know it sounds nonsensical but in my country the annual motor tax on a 2ltr costs e660. The 2.5 costs a thieving e1005. and that is likely to keep increasing over the next few years ! That fact, coupled with the increased insurance premium explain my reasoning. The 2ltr 6 is a lovely smooth motor and as andyboy says (thanks for the sound advice ) 129bhp is not bad at all. many 2ltr cars can't match it. I'm going off the idea now, just thought it might be handy to lob a cam in while the lump is on the floor , no head-off costs etc etc. I'm restoring this car after12yrs of ownership and I want it to be good for another 20

[Ajsingh]

Keep the engine as is then...

But while its out, re fresh it. New gaskets all round, a good clean up in the engine bay, check all the intake hoses and make sure there in top condition and to finish it, a proper service and injector refurb.

Put it all in & it will last another 20 years....

[e301988325i]

I know it sounds nonsensical but in my country the annual motor tax on a 2ltr costs e660. The 2.5 costs a thieving e1005. and that is likely to keep increasing over the next few years ! That fact, coupled with the increased insurance premium explain my reasoning.

Most E30 owners couldn't tell the difference between the two engines visually, how do you expect your insurance or government to find out there's a 2.5 fitted?

[SGP]

They'd only find out in the event of an insurance claim, rendering the policy null and void.

[Ajsingh]

I doubt an insurer will take out the engine to inspect its code, especially when its a 20+ year old bmw

[SGP]

I don't think you need the engine out to read the number off it, but anyway I've learned the error of my ways, and will leave the b20 alone. Will see if I can come up with a 2.5 and a lsd in the meantime. The engine will be the last thing to go into the rebuild. Still though, it would be nice to have the right numbers on the book.
(post number 320 )

[HairyScreech]

it may be a 320 block on the outside.......

[e301988325i]

it may be a 320 block on the outside.......

How terrible would results be with the b20 head & inet manifold but plonking a b25 bottom (bored out b20 safest) end underneath?

[HairyScreech]

best results would be seen by using a bored 320 block and some flat pistons with a 2.7/2.8.