BMW M52/2.8 - ITB's?

[e21Mark]

I run an M52/2.8 in an E21 BMW and noticed both Dbilas and now Jenvey offer ITB kits. Looking a little deeper, it seems that many people are of an opinion that the gains just don't warrant the not inconsiderable expense, with the kit at about £1 900 plus the same again for standalone ignition and mapping. You could do £4k yet only see another 20 bhp! An s54 can be had for half that amount.

Is there a reason that ITB's release so little from the M52/2.8?

Were I to make up an inlet manifold and use S50 ITB's etc, could the standard ECU cope if it was live mapped?

Has anyone managed to get more than 240bhp without going turbo / supercharger?

Any advice / insight would be much appreciated.

[Sensibleboy]

They are expensive but they open the door to longer duration cams that won't work too well with the standard inlet.

[e21Mark]

More so than the M50 inlet conversion, which I've already done? (I've also fitted 'fast road' cams from Cat.)

[reggid]

dbilas kits are rubbish, they dont seem to comprehend runner diameter and length and the importance of those.

[e21Mark]

reggid said:

dbilas kits are rubbish, they dont seem to comprehend runner diameter and length and the importance of those.

Never owned them myself, but certainly give disappointing results on M20 engines.

[Evoluzione]

When tuning an N/A observe the law of diminishing returns.

[reggid]

even negative returns with the dbilas stuff.

best throwing in a bigger bottom end to the M52 block to make gains more useable

[e21Mark]

Is 3.0 litre as big as you can go?

[reggid]

how deep are you pockets?

strokes available
86mm
89.6mm
97mm

a few other rare pieces around from Alpina and HIOP in between

3L is most practical with stock bore but most is 3.5L with new $4000US crank and add $1000 pistons and perhaps rods to it gets pricey and definitely diminishing returns territory

Edited by reggid on Thursday 3rd April 21:40