V6 oversized pulleys.

[vlad01]

Has anyone had experiance with the oversized pulleys for the V6, was there any negative effects that should be considered?


On my restro-modded red VP a lot of you may remember, well the pulleys are trashed from rust now and I was thinking, I need a better corrosion resistant material and recall the raw and anodised billet alloy ones on the market.

When I had a look, it was good to see quite a few options for Buick and also two manufactures cover the two types of alternators as well.

The only thing is, neither offer standard sized ones, but after doing some limited research it seems overall they have more benefits than draw backs and some of these drawbacks were for the Mustangs as it's a common mod on them. These were less cooling and poor charging.

With the V6 however, cooling has never been an issue, their cooling systems are over kill, it takes some serious issues to allow them to overheat.
I have also read and talked to one of the manufactures, cavitation is an issue at higher rpm and that is where they benefit the most in speedway etc... Prob never going to be an issue on my cars, the VP S for sure it will be, but all the current cars not really.

With the red car, my idle is 15% higher so the pulleys being 20% larger, it's much for muchness.


PS has always been an issue on these cars, and I feel they have been over driven from factory, so I expect it to help there.

The alternator, for a stock engine, not sure if this is a hindrance or still will work ok with an oversize but I can always leave this stock.

There are well known power gains and dyno back to back, at least on mustangs for similar 20% reduction and approx 15-18hp recovery at 5600 rpm, exactly where the stock and mild V6s operate. I know most argue that it depends on the engine, but it doesn't, engine has nothing to do with the accessory losses, it's a fixed value that depends on the accessory load and the stock accessory rpm and the rpm reduction with the pulleys. So given the fairly consent scenario amongst most cars and the available pulley rpm reduction, the power gains will be much the same. Which is about 15-20hp at the 5-6K range and this gets bigger at higher rpm. This is assuming the 20 ish % reduction for all accessaries except AC.

I think this is mainly from the PS pump and water pump, the alternator would be minimal as the load of the alternator is proportional to the electrical load plus some small efficiency loss. But there would be an inertia gain going to the larger pulley.


I think those gains are worth pursuing and having nicer pulleys that don't rust is a massive bonus. But I figured I'd ask if anyone has had issues.

Also keep in mind, I drive my cars, even when cursing around more aggressively than the average person and I keep gears much lower for a given speed.

[Chr0m3]

I run them on my N/A eco drift car, can't say I noticed any power difference, two different Dynos but each dyno was completely different setup, went 260 Rwhp on a hub with factory ecu and no pulleys, went 254 on a roller with haltech and the pulleys.

I only did it as the constant high rpm was killing alternators (rev limiter was 6500), all I've noticed is idle is harder to maintain (doing things like turning the wheel etc while idling does drop rpm a bit), also higher rpm steering gets a little heavier, that's about all I noticed (while drifting).

I never had aircon either so can't comment on gains from that, cooling has never been an issue (good radiator and 82 deg thermostat) and I'm on e85, I doubt you'd see the sort of gains you're thinking however.

If you're gonna do it, do it for the look and the fact they won't rust, you'll gain something from it but I just don't believe you get a 18-20 HP gain (unless you're talking at the flywheel and even then I think that's a bit much).

If you weigh up the side effects, the look, and the performance gain they're worth it anyway.

[vlad01]

Well that's good to hear nothing too negative in the compromise side of things.

I suppose any power gain is a power gain, without doing back to back dynos runs with and without, you can't make conclusions from using different dynos really.

Hub dynos always are more to true power than rollers as tyres are a massive loss and even within the same set of tyres vary depending on road surface, temp and pressure.

The dynos I watched for the pulley testing were all rollers ones. Power for that mustang went from like just under 200hp at 5600 ish to somewhere around 215 hp. They also tested in between pulley sizes from the OEM under drive, and then after market which were about the 20%

For me, it's the PS that always die prematurely, overflowing, overheating etc... I run a cooler on my red car, that made a big difference, but running it slower should help prevent the issues, rather than a bandaid such as a cooler, but I will keep the cooler either way.

I don't think the idle should be affected, should be easier due to less load, I'd say that from the Haltech as most after market ECU don't have anywhere the same level of idle control as OEM plus things like voltage compensation might be off given the alternator probably drops some voltage during idle.

[immortality]

I ran the complete set on my VN for years and never really had any negatives as well as our old VS ecotec.

PS might be slightly heavier, I actually fitted the 20% OD pulley on the missus Calais with variatronic steering because the steering is so light there was no feedback with the OEM pulley. I always fit coolers to PS systems now if there isn't a factory fitted one.

It might run slightly warmer, our L67 does with the larger pulley fitted but mostly at idle, cruising it runs too cool so I compromised and how have a 10% OD pulley on the water pump.

Never had any major issues with voltage either, not unless it's bloody terrible day, cold, raining etc when you have all the electrical systems running.

you might save a hp in parasitic losses but I don't think there are huge gains.

That old car would do 7L/100km when driven nicely. (3.45 gears/T5) so it does all add up.

[Chr0m3]

I actually haven't had any PS issues, was alternator and is still gearboxes haha (unrelated obviously), you're likely correct about the idle and the hub dyno being more true, it's likely I picked up 20 or so more Rwhp before the roller dyno runs and that'd mainly be from the haltech and tuning changes. The 260 on the hub was just a street tune I did myself, haltech was dyno tuned, I really don't think you gain a lot but the negatives are near unnoticeable so I'd just go for it.

[vlad01]

I'll get myself a set when I get to that job.

[immortality]

I have a full set of non ecotec 20% OD pulleys from Clarko's I no longer need if you are interested.

[vlad01]

Are they in good nick?

[immortality]

They should be fine.

I'll dig them out in the next few days and check em and take a pic for you.

[immortality]

There not too bad after sitting in a box for almost a decade. They would look really good with a buff on a wheel but this is with just a rag and polish.

The alternator pulley is brand new, never fitted.

On the VN I had charging issues as I never ran it long enough and it would sit unused between shifts at work so it needed a battery charger constantly.