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(Post Link) post #1 of 28 Old 18-12-11 Thread Starter
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Lighter and smaller alternator - 2.5V6

I'm using my 2.5V6 for trackday proposes only, and when on track lighter car is always good.
Stock alternator is huge, bearing in mind that i have removed all unused wires and power supplied devices unrelated with engine and driving the car(headlights, interior lights and so on), i can really be good with smaller alternator.
Friend of mine uses for his Fiat Coupe an daihatsu altetnator cause it's smaller, lighter and leaves space on the tight 20VT engine bay.
That's why i'm asking if someone used different alternator, and knew how hard is to fit it????
Thanks.

Rear Wheel Drive Mid - Engined Alfa 156 3.0 V6 '99 - trackday car
Alfa 156 2.0 TS '00 - daily car

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Last edited by Speedmaster; 10-01-12 at 18:02.
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Do you still have AC?
If not I would suggest fitting a smaller Alternator where the AC pump used to be.

I am sure you can fit a smaller unit in the OE place but it is a bit of a mess to fabricate mounting brackets while the motor is in the car.
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Quote:
Originally Posted by turbonutters View Post
Do you still have AC?
If not I would suggest fitting a smaller Alternator where the AC pump used to be.

I am sure you can fit a smaller unit in the OE place but it is a bit of a mess to fabricate mounting brackets while the motor is in the car.
No AC......maybe it's worth to find out if alternator can be mounted in the place of AC, you give me really good idea.
Thanks.
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Please keep us informed on the small alternator idea with no A/C, be interesting to see.
On the idea of this could you not also reduce weight and diameter of aux pulley to give a slight better response? ( i think it is easy on tspark engine? but not sure if could be done as easy on v6?)
You prob would have to go for smaller battery aswell and you could get away with that on a track car if you not needing to power all the electrics.

If your are using only for the track are you going to upgrade the ARB's for adjustable units and put some coilovers on it? (Sorry to change subject there)

i am sure there are a few areas where you could reduce front end weight

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On the v6 the pulley is part of the balancing so it is not as simple as replacing it with a smaller pulley like on a ts
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Yes, pulley cannot be changed.....
I'm using lightest battery available.......have Koni Sport all around, with 4 DIY coilovers.....custom made stiffer front and rear springs, Eibach ARB as well......
Problem with 156 2.5V6 is that if you removed all unused stuff, lighten it as much as possible and rear end becomes too light compared with front end......that's why i was forced to DIY coilovers - rear becomes too high from the ground.
P.S - Some curious info - there is almost 6.5 kg wires that can be removed from the car, when leaved only ones needed to run the engine and it's sensors.....

Last edited by Speedmaster; 03-11-13 at 05:01.
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The 2.0 JTS alternator is much narrower than anything else in the Alfa range, if you could get hold of one of those perhaps you could fabricate a mounting bracket.

I did wonder about waterpump drive, could you replace the belt driven pulley for a toothed-gear, which could then be driven by an electric motor? That way you could limit the waterpump rpms to the equivalent of something like 3,000 crank rpm to help reduce the load on the crank.
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It's a really big risk to run WP with electric motor, and AFAIK gain did not worth the risk.
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Plenty of track cars with electric waterpumps.
Not normal pumps rigged to an electric motor though!
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Quote:
Originally Posted by David C View Post
Plenty of track cars with electric waterpumps.
Not normal pumps rigged to an electric motor though!
I think without the waterpump in the correct location on the V6 you wouldn't get proper coolant flow around both banks, but having an electric waterpump made to fit in the original location would be impossibly expensive. Breaking the link between engine rpm and waterpump rpm is key to releasing additional power as well as retaining better control over cooling. Perhaps belt driven off an additional electric motor might be better than gear driven.

I've seen the electric waterpumps people install in the top radiator hose, but I've never seen one installed as the engine's sole pump, only as additional pumps for extra cooling.

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The energy to drive the pump has to come from somewhere. It makes small difference whether you take that power from the engine direct or via the battery. Unless you run the battery flat that energy has to be recovered.
On full load the pump is going to be running at max power, at part load it will require lower speed - much as it behaves when connected to the crank with a belt. It can be done with electric pump, but more complexity and more to go wrong........
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I remember using an electric pump on a sidecar which we plugged to a seperate battery in the pits as we had problems with cooling between race heats. But we let the battery run flat so had no problems of extra alternator load.
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The net energy effect is zero (provided you lock waterpump rpm to crank rpm), as the engine charges the battery and the battery would power the electric waterpump. But the effect at 7,000rpm when there is zero load on the engine from the waterpump, and the electric pump is turning maybe 3,000rpm from the battery, I think the power difference measured at the crank would be substantial.

Don't forget waterpumps are geared to provide adequate cooling at idle when the engine is doing 800rpm and the car is stationary with no cooling airflow through the engine bay, so even when driving hard at high speeds and high engine rpms the waterpump will be spinning far more than required. You could get adequate cooling at much lower waterpump rpm than crank rpm.

Another added benefit would be that you could have the pump spinning at a higher speed than crank rpm when the car is idling, to help keep temperatures down in traffic.

I think its definitely a good idea for a track car, its just the implementation which would be difficult on the V6, because the waterpump is splitting the flow to both banks, and space is so tight.
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Well, i had an alloy aftermarket front rad, containing 1.7L coolant more that OE(same weight as OE one), and when tested in hot summer with air temps from 30C and track 45C, my coolant temp rarely exceeds 86 - 90C, so for now cooling is not problem, and i can live with this little extra power loss from the WP...
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Little update......
Bought new refub alternator today, used on some unknown Daihatsu model. Light and 40Ah.....will fit perfectly where originally A\C sits.
As always there is a little problem. This alternator may not handle well 6-7k rpm, and i risk melted bearing in the middle of a trackday. That's why i'm planning to do 2 different pulleys for.......OE for 2.5 is 60mm, Daihatsu one has 63mm......my idea is to have at least 75mm and another with 85mm OD, and will see if there is any problem.
Maybe it wont be a big problem if idle charging is poor, car wont stay at idle for long.

Last edited by Speedmaster; 03-11-13 at 05:01.
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Keep us updated, this is interesting
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Off course i will ......it's a real pain to remove the OE alternator with engine in stu, last night it takes me 2 hours hard work, and it can't go out until right engine mount loosened, and engine few inches forward. And having in mind that around the alternator i have oil thermostat, 2 oil pipes to the oil cooler, oil filter, water pipe, oil pressure and temp sensors i really, really need my alternator out of this place.
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(Post Link) post #19 of 28 Old 28-02-12 Thread Starter
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Engine started today, with the new alternator and custom made allow pulley.
OE pulley was 65mm OD, new is 85mm - my biggest concern was that in high revs(6-7k rpm) the alternator may fail, cause its not produced for such high rpm's.......
When idling i measured 11,7 - 11,9V current, lamp on the rev counter is off......when revved above 1500rpm its all ok, 13,5 - 14V.......being trackday car i really don't care about idling......
Here is some video -http://www.youtube.com/watch?v=gjzEN...887&lf=mh_lolz

Last edited by Speedmaster; 28-02-12 at 12:43.
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Does it feel any different?
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Quote:
Originally Posted by Pud237 View Post
Does it feel any different?
Well i still didnt drive the car around cause it look very road illegal and with almost no exhaust i'll be caught immediately if drive it on the street.....anyway in few days i'll tow it out of the town, and will do few WOT runs....will inform as well.....
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it's very interesting!!
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(Post Link) post #25 of 28 Old 17-03-12 Thread Starter
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First of 3 days in Serres Int Track, almost 35 laps knowing and learning the track with street tires, and alternator performs great, no worries......
Serres Friday 16.03 First Run Street Tyres. - YouTube
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