Underdrive for Alloytec 190 twin belt setup?

[routier1642]

The saga of my 2005 VZ Adventra continues.

I became entranced with idea of under-drive pulleys, bought PBK-007 20% underdrive kit, supposedly the right one.
But it won't fit, because some VZ Adventras, like mine, have a twin belt setup, with a 2-track harmonic balancer.

Powerbond, unfortunately, only make a straight replacement for the 2-track HB, not a 20% underdrive one.

Does anyone know of a 20% under-drive harmonic balancer which would suit a HFV6 (Alloytec 190) ?
Maybe one made for a Buick or Cadillac LY7?

In the meantime, I have a spare 20% underdrive kit for a single belt Alloytec; includes harmonic balancer, 2 pulleys and a belt.
Offers?

 

[routier1642]

A post in this link seems to suggest that the 2 belt system was used in the Cadillac CTS:

Mad Scientist Fridays: Underdrive pulley, new perfomance part [Archive] - Cadillac forums : Cadillac Owners Forum

(search for "dual crank")

They also say the "the Australians" are going to make a kit for it.

Anyone know anything?

 

[routier1642]

Spoke to Powerbond (who make the underdrive kits), and a few other companies.
Basically, I'm out of luck. They make a replacement 2-crank HB, but not an underdrive one.
Probably not enough dual-crank HB'sd around to generate the demand.

Maybe the dual-crank harmonic balancer came over from the Cadillac CTS and other US builds?
Maybe it's more efficient? Hoping there's an upside to this...

I've seen the PBK-007 kit with the single-track HB advertised as being suitable for the Adventra.
But of course, if you have the double track HB, it won't fit!

Do only some Adventras have this HB? I'm curious to find out!

Meanwhile, I have to be disappointed. :-(

 

[routier1642]

For future reference:

Most VZ Alloytecs use a single-belt HB, Part No. 12565992.
Powerbond make a replacement for this, the HB1177-N.
They also make the 20% underdriven version, PBU1177-SS20.

My 2005 VZ Adventra (and I don't know if it's all Adventras, or just a few) use completely different layout of alternator, water pump, etc.
This is a double-belt system, using a different HB, Part No. unknown, but probably HB's Part No. 12603180, similar to Part No. 8973615621, used in the HFV6 Alloytec and Turbo Diesel versions respectively, of the 2008 Holden Colorado!
Powerbond make a direct replacement, HB1506-N, which fits all 3 applications (the Adventra and the two Colorados) but there is no 20% underdrive version.

A similar HB 2 belt system was used on many Alloytec-equipped Cadillacs, Chevys and Buicks, but I don't know where it originated.

Perhaps it was a more robust system, so it was used on the Adventra, and later re-used on the Colorado.
It does seem to resemble the LS1 system, (HB 12553118, Powerbond HB1480-N) which Powerbond make a 25% underdrive for (PB1480-SS25), so I'm having crazy thoughts that I have to suppress.....

:-(

 

[XioiX1983]

hey routier1642,

I have PM you.


Cheers

 

[_R_J_K_]

I guess the big question I have is, why do you think you need an underdrive kit? They're really only for cars that high rev for long periods of time.

 

[Husky]

I guess the big question I have is, why do you think you need an underdrive kit? They're really only for cars that high rev for long periods of time.

Underdriven pullies can be handy in day-to-day use, for example an auto engine will be turning the Water pump, PS pump and alternator a lot faster than a manual doing to same speed. Add diff gears and they are spinning a lot faster that needed. An underdriven pulley slows them back down to normal which reduces drag on the crank and frees up a few kilowatts that can be used elsewhere.

 

[routier1642]

Yep. Also, my LX Adventra weighs 2 tonnes!
Having under-drive pulleys frees up some torque, and faster rev up means that the torque is available down low more rapidly.
It would also do this at a lower fuel cost.
The Adventra is great once it's going, but acceleration to running speed from standing or slow burns a lot of fuel.
It's a killer in heavy traffic.

But unless someone can advise me on a compatible underdrive harmonic balancer, I'm stuck.

I've searched the Internet and looked through whole catalogs. The LS1 HB is similar, but weighs more, has a driveshaft hole 0.5mm thinner, and seems to be asymmetrically weighted, which would be a big no-go.
I won't completely give up until I have physically seen the balancers side by side so I can compare them, but it doesn't look hopeful atm.
The Alloytec driveshaft is 38mm, and I haven't found even one double-crank HB (except for the original one) with exactly the same diameter drive hole.

I guess I could address it from the other end and look for larger pulleys for the alternator, power steering, aircon and water pump...