Lightweight starter and alternators

[shorty73]

Anyone got any ideas where I can get these from? Tried looking on Brise and Tilton but don't seem to have any for BMW's.

Has anyone fitted a larger pulley to there exsisting alternator? If so what size is best?

Thanks

[agreen]

Has anyone fitted a larger pulley to there exsisting alternator

why would you do this mate

ps do you have aspoiler on your car if so what is it can i see it any pics

[maxfield]

It will sap less power from the engine... not really sure how as I would probably make myself look a twat.

[e21Jason]

Hi

The m10 e21 316 alts are about 4kg lighter than an e30 but only rated at 55amps (approx) if you upgraded them with an modern voltage reulator they would preform better. You could fit an nipondenso but you would have to fab the brackets.

The later m40 starter are also a few kg's lighter but but you need to make a hybrid one to get it to work.

Jason

[shorty73]

I've done away with nearly everything that you would have in a road car (power suroof, heated mirrors, cigarette lighter) so the alternator is not really required to run much other than the ecu/ignition and worse case heated screen and head/rain lights. That's not going to take much power so putting on a bigger pulley slows down the alternator meaning it uses less engine (BHP) power. Every day cars tickle along in the low to mid rev range and thats where a standard alternator works best but a race /track car is mostly up the top and by fitting a bigger pulley it allows it to work higher up.

Standard Alternator 6kg

Race Alternator approx 3kg and means smaller battery which means smaller/lighter starter.....

Good weight saving right up the front end.

Clicky

[shorty73]

Hi

The m10 e21 316 alts are about 4kg lighter than an e30 but only rated at 55amps (approx) if you upgraded them with an modern voltage reulator they would preform better. You could fit an nipondenso but you would have to fab the brackets.

The later m40 starter are also a few kg's lighter but but you need to make a hybrid one to get it to work.

Jason

Good to know. I'm going to see what my car draws worse case (everything on) and see what I can get away with.

Fabricating brackets shouldn't be too hard.

[shorty73]

Any ideas on starter motors?

[UweM3]

you can fit a smaller battery regardless of alternator size. The regualtor will stop charging once a battery is full.
The size of the battery is just the capacity of how long it delivers power without charging. But all withing reasonable limits. Batteries do also need a certain cranking power, so bigger deosn't always mean better.
The internal resitance is the important thing

If money is no object you can fit one of these GEL batteries as used by the audio boys. i.e. Optima Red Top.
A good acid lead battery is the BOSCH silver top (available form GSF). They only thing a conventional battery doesn't like is to be deep discharged. so avoid that if possible. GEL batteries are unaffected by this and can be mounted upside down without leaking. Not a bad idea for a track day car and a huge weight saving.

I run a 55amp battery in the M3 with still the stock alternator without any problems. Car is parked for 3 weeks and turns the starter with ease.

HTH

[cecotto_singh]

just had a custom hi-torque starter made for my cossie engine! its the dogs! went straight to the guy who makes them. got it at nearly half the price as what other companies advertise it as in the mags.

[shorty73]

Sounds good. Any chance of pm'ing any details?

[agreen]

shorty sounds like thats what you are looking or mate

Uwe - my battery in the front on my 318is wanna swap for samller one what do you recomend ie the cca of the bat needs to be ?

[UweM3]

shorty sounds like thats what you are looking or mate

Uwe - my battery in the front on my 318is wanna swap for samller one what do you recomend ie the cca of the bat needs to be ?

I wouldn't go less than 50amps (or 52 whatever they are coming)
45amps should be ok as well but they aren't getting much smaller under 50 amps. If you really want to save more weight, Optima Red Top or the like is your best bet. But they are £Â£Ã‚£Ã‚£'s

Have a look at demon thieves or GPR.

[agreen]

bloody hell they are expensive so i can still get a smaller normall one then righ >?

[miniblob]

Saw an ad in a vw mag the other day for hi-torq starter motors - meant to be a lot lighter apparently and there must be quite a few places that do them - try a google!!!

I've always found optima's to be very heavy - although never lifted a red top!! Ice batteries aren't what you want 'cos they're deep cycle and designed for a long large current to be put out and a fast recharge.
You just want something with a high cranking amps and that'll do ya.
Search for racecar battery or lightweight 12v or something on google and i'm sure you'll find some. There's some very small and light batteries available that will do you nicely!!

As for alternators, not really looked into those yet, but will be interested to know what you do - although i'll be looking to raise the output of mine!!!!

[shorty73]

Seen starters for VW's and Porsches but not BM's. Searched all the usual, wore google out! I'll have to do some measurements and try to find a suitable one. Who are the oem ones made by? Bosch?

I've seen 5 inch pulleys for e30 325's on Ireland engineering so I reckon 110-120mm is the biggest I can go.

Battery wise I'm thinking Varley or Powervamp. Not sure what size as yet. I'll have to do some calculations and see what's best.

With lighter battery,alternator and starter, I should get a good weight loss and some power gain so it will be worth a bit of dosh!!

[e21Jason]

Hi

To uprate the alt output you need a bigger supply from the alt and an uprated voltage requlator mod like so

http://davebarton.com/AdjustableVoltage.html

Jason

[shorty73]

I'm not trying to uprate the output but lower it! Alternators can rob a lot of horsepower. Thats why a lot of single seaters run total loss systems. Bigger pulley makes it run slower and rob less.

[cecotto_singh]

the company who did mine was called luke motorsport based in bucks 01296747722. he specialises in starters and makes them for other companies who sell them under their own name at double the price!!

[e21Jason]

Hi

A standard alt is 90 amps the 316 alt is 65 an early e21 316 alt is 45 amps and the lightest, but uprating the alt you get more output for size of alt by about 10%

Jason