M50 B25 Engine Info, can anyone please help?

[Motorshed]

Hello folks,

I'm trying to find out as much as I can about the 24 valve 2.5 ltr Straight six engine M50 B25.

I have a fairly high mileage (170K) non-vanos example in my 1991 5 series (E34) BMW that I'm turning into a track day car. I want to know how strong these engines are, how reliable they are, how rev happy they are (everything seems to happen above 3,500rpm)and any weak spots. Any hints and tips on improvements or things not to bother with would also be appreciated. The engine may eventualy end up with a turbo conversion if the bottom end is up to it.

In case you are interested/curious, details of the car can be found here:

http://www.escortupgrades.co.uk/BMW/Project%20Brat...

Thanks for any help.

[Motorshed]

Ooh, I haven't heard that one. Is this a known proven conversion? The only reservation I have about it is it'll reduce the engines willingness to rev. Considering that as with most 24valve 6 cylinder engines all the power is right up the rev range I can see this being somewhat of a problem.

Do you happen to know if the standard bottom end is strong enough to take a reasonable amount of turbo charging?

Thanks very much for the reply.

[sniff diesel]

Motorshed said:

Do you happen to know if the standard bottom end is strong enough to take a reasonable amount of turbo charging?

A lot of guys in the States run turbo'd M50s with standard internals. Regarding a rebuild this thread may be of interest:

http://www.ppcmag.co.uk/forum/topic.asp?TOPIC_ID=5...

[cashybai]

T'other option worth considering would be a supercharger...http://www.pistonheads.co.uk/sales/1082197.htm

[Motorshed]

Thanks for the replies.

I had been following that E30 estate build on there but then got engrossed in getting my own car sorted ready for the £999 challenge that I failed to get it to. I'll have another trawl through it later when I've got a bit more time (it's currently breakfast time at the 'Zoo', kids!).

Supercharging is a nice idea but I have limited funds and turbocharging appears the cheaper option at the moment. I also plan to eventualy run it on LPG so the variable boost option of a turbo charger for when switching betwen the two fuels is also a big plus point.

I also happen to have a T28 turbo sitting in the shed (bought for £15 as home rebuilt but considered an unknown quantity and deffinaetly not likely to be balanced) and have just been donated a smallish inter-cooler. The exhaust manifold is of course going to be a bit more work as is then getting the exhaust pipe back down past the steering shaft. I suppose I could always run it up out of the bonnet and over the roof!

Anyway, here's a few pics for your troubles.









And hopefully the finished article:



Lots more to see on my website:

www.EscortUpgrades.co.uk

Cheers!

Edited by Motorshed on Saturday 20th June 09:55