Speccing bmw tarmac stage rally car - thoughts?

[sideways_stu]

I'm currently very happily rallying a rwd conversion which is highly custom but it has a natural life which may end in the next year two either through regs, big accident etc and I'm looking at a bmw route for the next car.

Keen to hear from people with much more bmw knowledge than me on the rough direction outlined below - your thoughts and guidance really appreciated...

E36 compact base shell - seems to be light, probably needs wide arches for required track; there is some talk of the rear suspension not being as good as E46 compact - any views? I presume there is a fair weight penalty to going to E46 base model but any big + points?

Diffs, ratios and driveshafts seem to be fairly interchageable so hopefully avoid custom. Are std plate LSDs up to the job for tarmac and 220 tyres?

gearbox - would really like to stay with sequential box - could carry over Elite IL300 (bellhousing will be a faff); SMGII is heavy and loads of electronics (and is just an automated syncro manual); anything else to think about?

engine - S50B30/32 and S54B32 engines seem very heavy - strictly can only go up to 3 litre under current rules. M52B25 is alloy and has an attractive bore/stroke but not sure if you can drop top-end from something else to produce some serious go - would be running DTA or similar so not using std ecus. I do like high-revving natasp engines

suspension - I'm quite a fan of (and local to AVO) so would head that way

I'd be aiming for a pretty light car so lighten where possible, don't go OTT on the cage spec, start afresh on wiring, heated screen / no heater, polycarb windows.

Am I on the right track?
Any idea where this would come in on weight (or examples of similar cars).

I'm quite happy building rally cars and have some pretty good facilities / contacts so none of the above is an issue although I prefer to do it right first time!

Big thanks in advance and please don't expect this to turn into a build thread this month!

Stuart

[is-si]

E36 compact base shell - seems to be light, probably needs wide arches for required track; there is some talk of the rear suspension not being as good as E46 compact - any views? I presume there is a fair weight penalty to going to E46 base model but any big + points?

E36 is well used, Martin Stockdale is probably the man to approach regarding the e46

Diffs, ratios and driveshafts seem to be fairly interchageable so hopefully avoid custom. Are std plate LSDs up to the job for tarmac and 220 tyres?

if you use the e46 back end, theres no std lsd's and swopping internals seems unchartered.

gearbox - would really like to stay with sequential box - could carry over Elite IL300 (bellhousing will be a faff); SMGII is heavy and loads of electronics (and is just an automated syncro manual); anything else to think about?

read thro martine30 posts, he's using an elite

engine - S50B30/32 and S54B32 engines seem very heavy - strictly can only go up to 3 litre under current rules. M52B25 is alloy and has an attractive bore/stroke but not sure if you can drop top-end from something else to produce some serious go - would be running DTA or similar so not using std ecus. I do like high-revving natasp engines

yes they are heavy, a powerful m52 is possible but your info and parts will be from america/europe.

I'd be aiming for a pretty light car so lighten where possible, don't go OTT on the cage spec, start afresh on wiring, heated screen / no heater, polycarb windows.

just lighten the std loom by removal

Any idea where this would come in on weight (or examples of similar cars)

depends on engine, i'd say no lighter than 1150 kg with 6 pots, less than 1100kg with a 4-pot. If you are doing bigger rallies (not s.v's) add 10% - only a rough guide as it depends how much cash you spend on your bits.