smaller alternator for a 1.9tdi - anyone know?

CarlosVanDango · May 9, 2020

anyone know of an alt that will bolt up to the factory mounts but is just a bit smaller body size

ive got the 90 amp one in my 1.9 ASZ conversion but it fouls on a chassis leg (not by much) ive got a few options but my preferred one is a smaller alt

ive ditched the air con and my car is very basic so i think i could get away with less than 90a

cheers

Mozambiquer · May 9, 2020

Is the goal less power drain or fuel economy drain, or what's your goal? I plan to use something like a denso racing alternator or delco 5si or 7si on my caddy. I could set you up with something. It would probably require custom mounts, or I may be able to find something which would be bolt in.

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eddieleephd · May 9, 2020

Less output would be a gasser alternator, not sure about housing size though.
I'm curious what your desire is as well.

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CarlosVanDango · May 9, 2020

the engine is in a Reliant Scimitar this is where it would fit although it doesnt look like it in the picture it touches the chassis leg upright
i just want a smaller physical size alt
less drain isnt an issue its just i dont think i will need any more the car has no electric gadgets it's very basic so a 90A will be overkill anyway

i would ideally like a factory alt that will bolt to the tdi mount

CarlosVanDango · May 9, 2020

just realised thats an earlier picture the engine needed to go 2" to the right to be mounted in the right place - thats why it looks like there is loads of room

eddieleephd · May 9, 2020

I would measure and check if the dealership or auto store has gasser alt on hand and measure theirs to compare them.

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AndyBees · May 9, 2020

Physically, the Gasser 90Amp Alt and the Diesel 120Amp ALT are the same size........ no difference.

eddieleephd · May 9, 2020

AndyBees said:
Physically, the Gasser 90Amp Alt and the Diesel 120Amp ALT are the same size........ no difference.

I was thinking they likely weren't being how they're mounted. I'm not sure if VW used any different sized physically. And if they did it would be a different bracket holding them in most likely.
One key that you must remember is the diesel alternator has a freewheeling pulley hub so the engine speed doesn't destroy it. So no matter what alternator you use, you'll need to use the same type of hub.

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Mozambiquer · May 9, 2020

eddieleephd said:
I was thinking they likely weren't being how they're mounted. I'm not sure if VW used any different sized physically. And if they did it would be a different bracket holding them in most likely.
One key that you must remember is the diesel alternator has a freewheeling pulley hub so the engine speed doesn't destroy it. So no matter what alternator you use, you'll need to use the same type of hub.

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Only the 120 amp version has a clutch pulley. I don't know if there's any which would bolt in the stock location without modification that is smaller in diameter than the 90 amp, which is the same for the gasser or tdi.

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eddieleephd · May 9, 2020

Mozambiquer said:
Only the 120 amp version has a clutch pulley. I don't know if there's any which would bolt in the stock location without modification that is smaller in diameter than the 90 amp, which is the same for the gasser or tdi.

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No, I know the TDI is supposed to come with the clutch pulley. Daniel at ADW told me about it and that it was installed on the TDI because the varying RPM of the engine killing the alternator otherwise. I believe that both the 90 and 120 amp alternator can have the clutch pulley installed.
https://kermatdi.com/i-668-alternator-pulley-mk4-mk5mk6.html

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Mozambiquer · May 9, 2020

I did some searching, and there was a 70 amp alternator which was used in the mk4 TDI and the vr6 which could work. I don't know if the diameter is smaller though, since my supplier doesn't give physical dimensions. There's the one used on the 1999-2005 beetle with the 2.0. Bosch part number 0124315003 it's 133mm diameter stator. I can't find the dimensions of the 90 amp version currently, except for the 2002-2005 which is 125mm diameter. That may be the way to go if you can get ahold of one of them. That's Bosch part number 0124325149.
Hope that helps.

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Mozambiquer · May 9, 2020

eddieleephd said:
No, I know the TDI is supposed to come with the clutch pulley. Daniel at ADW told me about it and that it was installed on the TDI because the varying RPM of the engine killing the alternator otherwise. I believe that both the 90 and 120 amp alternator can have the clutch pulley installed.
https://kermatdi.com/i-668-alternator-pulley-mk4-mk5mk6.html

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I was thinking on the mk3 TDI, which only had the clutch pulley on the 120 amp version. The newer ones have the clutch pulley on all of the sized ones.

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eddieleephd · May 10, 2020

Mozambiquer said:
I was thinking on the mk3 TDI, which only had the clutch pulley on the 120 amp version. The newer ones have the clutch pulley on all of the sized ones.

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I believe that should be able to change, but, good to know. Might be a good upgrade for the older alternators.

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CarlosVanDango · May 10, 2020

thanks guys - plenty for me to go on
mine does have the clutch on
i've measured up my alt - it's the 142mm dimension that could do with being about 10mm less

the search is on

jimbote · May 10, 2020

what about moving stock alternator up and fabbing a bracket (in red) to connect upper mount.

oilhammer · May 11, 2020

The amperage of the alternator has nothing to do with its physical size. The 70A, 90A, 120A, and 140A Bosch alternators are all the same case size.

Bosch does make smaller units, but I doubt they would bolt up. Our John Deere compact tractor has a cute little Bosch alternator. But I am pretty sure it uses the side mount setup, not the type the VAG engines use.

Lots of Japanese engines in smaller applications have even smaller alternators. The JD garden tractor (Yanmar 3 cyl diesel) and the Kubota RTV (Kub 3 cyl diesel) both use itty bitty Denso alternators not much bigger than my fist. But they probably do not have much output...I'd guess less than 50A.

CarlosVanDango · May 11, 2020

oilhammer said:
The amperage of the alternator has nothing to do with its physical size. The 70A, 90A, 120A, and 140A Bosch alternators are all the same case size.

yes i know, what i mean was i want a physically smaller alternator but if it happens to be a lower amperage output i'm cool with that as my car is so basic i doubt i'd need the same as the golf does

CarlosVanDango · May 11, 2020

jimbote said:
what about moving stock alternator up and fabbing a bracket (in red) to connect upper mount.

yes this is an option i had to do this with my mk1 transit pd conversion the alt was in the way of the radiator so i had to drop it underneith

i just like the factory mount this one has the tensioner on it too, but i must admit moving it up there will help with my cooling pipe routing

eddieleephd · May 11, 2020

Honestly, it sounds like moving it is your best bet. Cheaper and less time consuming looking for the unicorn alternator.
You could probably use the original mount holes in the block and fab a different mount to change the placement.

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CarlosVanDango · May 12, 2020

found that the 70amp alt from a Skoda Octavia 2003 1.6 8V PETROL BFQ 028903028C

has all mount measurements same and the 142mm one is 135mm and the 155 one is 148mm

i think that may fit - just need to be 100% sure before i buy one

Mozambiquer · May 12, 2020

CarlosVanDango said:
found that the 70amp alt from a Skoda Octavia 2003 1.6 8V PETROL BFQ 028903028C

has all mount measurements same and the 142mm one is 135mm and the 155 one is 148mm

i think that may fit - just need to be 100% sure before i buy one

The number I posted was the Bosch number of the same alternator. If you can take yours to a parts store and compare them, that should work.

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jimbote · May 12, 2020

oilhammer said:
The amperage of the alternator has nothing to do with its physical size. The 70A, 90A, 120A, and 140A Bosch alternators are all the same case size.
Bosch does make smaller units, but I doubt they would bolt up. Our John Deere compact tractor has a cute little Bosch alternator. But I am pretty sure it uses the side mount setup, not the type the VAG engines use.
Lots of Japanese engines in smaller applications have even smaller alternators. The JD garden tractor (Yanmar 3 cyl diesel) and the Kubota RTV (Kub 3 cyl diesel) both use itty bitty Denso alternators not much bigger than my fist. But they probably do not have much output...I'd guess less than 50A.

90 amp has a smaller case than the 120...not by a a lot but is definitely smaller diameter...and i'm pretty sure the 140 is slightly larger still than the 120. EDIT; so i did measure the 120 and 140...same case diameter @ around 143mm but don't have a 90a here to compare.

Nozzleman · Jun 29, 2020

I ran into a clearance issue and ended up removing the A/C mount and running the stock 2002 Ford Ranger 2.3L alternator. It is mounted to the original alternator top mount and had to be spaced between the outer mount with about 0.080 shim washer. The lower mount is a fabricated bracket off of threaded bosses on the block.

That let me tuck it in close to the block.

smaller alternator for a 1.9tdi - anyone know?

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