Light-weight Crank Pulley's

**JetspeedCamry** · 12-02-2007, 08:10 AM

Hey guys,

Just a quickie, friend over on another forum installed a lightweight alloy crank pulley from a Scion tC onto his Camry 2AZ-FE. Seems that it gives decent power and response increases (about 12hp). However, i was a little concerned that being light weight, it would not share the same balancing properties as that of a full steel harmonic balancer, especially seeing as the 2AZ-FE balancer is a 2 piece design with a rubber insert.
It would seem to me that this would cause increased stress on the crank and wear the main bearings faster. Throwing it out of balance.
Your thoughts?

Cheers.

**Aust162** · 12-02-2007, 10:29 AM

When people get a performance engine rebuilt they have the total rotating mass blueprinted and balanced. (including the crank pulley/harmonic balancer). I'd image a factory assembled engine would have to be balanced too..

if you were rebuilding your motor (eg.had it apart), you'd probably grab the lighter pulley. if it wasnt, then i'd be hesitant to just put it on.

**Norbie** · 12-02-2007, 11:36 AM

First of all, I call BS on 12hp from swapping a damn pulley. And secondly, you're right most of these lightweight pulleys are not harmonic balancers at all which leaves your engine susceptible to harmonic vibrations in the crank. I recommend against it.

**JetspeedCamry** · 12-02-2007, 11:58 AM

Yeah exactly what i thought. The harmonics is what triggered my worry...i'd imagine it could cause havoc on the bearings, unless as Aust162 said, you balance and blueprint with the new pulley (which he hasn't done)...
Heres the pulley comparison he posted...

And the dyno comparison he posted...

**o_man_ra23** · 12-02-2007, 05:18 PM

Is that pulley the only thing he changed?? Was there a difference in ambient air temps/air humidity?? Did he change the oil, filter, fuel filter, air filter etc between runs?? So many variables. Even the uber expensive GFB pulleys only claim a 4hp increase, and that one is a load of crap.

Not having a harmonic balancer is ok for a well balanced motor. Many 18RGs didnt have them and didnt have harmonic problems. Putting it on a camry motor on the other hand, IMHO is just asking for troubles.

I second Norbie's call of BS.

Cheers, Owen

**Billzilla** · 12-02-2007, 05:21 PM

I find it hard to believe as well, and I've tried some pretty radical pulleys.
Whilst they may or may not actually increase the power of the engine, there's no doubt they will help the transient response, and so let it rev a little easier.
That's what I found with my set.

**Screamn_Sleeka** · 12-02-2007, 05:30 PM

also, "lighter" doesnt always mean better, heavier balancers will usually give more torque (if any change), as it adds to the inertia and therefore turning power. But that dyno graph shows more low end torque and high end hp, complete BS i say as well.

And yes some old toyota's have no real balancer, just a very thin pulley like the 4M as well, but they will have differently designed cranks and bearings to account for that.

**JetspeedCamry** · 12-02-2007, 05:34 PM

Yeah didnt really make sense to me either. And i second, asking for trouble on a production run Camry engine.

**o_man_ra23** · 12-02-2007, 05:34 PM

Oh yeah, and also note that now the front oil seal is rubbing on aluminium instead of what appears to be treated cast iron... so it will leak out the front before too long also.

Cheers, Owen

**Joshstix** · 12-02-2007, 06:15 PM

The front oil seal rides on the crank not the front pulley.

Those dyno runs are number 5 and number 13 and done without shoot out mode, in reality with 8 runs to play with and no locking of the parameters the dyno could have told any story they wanted.

**o_man_ra23** · 12-02-2007, 08:24 PM

I stand corrected, but it does look an aweful lot like the earlier stylez where the oil seal rode on the front pulley... might be worth ppl looking at similar items for earlier engines to note.

Cheers, Owen

**mullett** · 12-02-2007, 08:40 PM

I call crock. Full stop. The only way to increase actual HP by changing the pulley is by changing the drive ratio to the accesories. The crank pulley could weigh 30kg, it'd make no difference to power or torque, just to engine response. A heavier pulley will give you greater rotational inertia, like a heavier flywheel, but this will not increase torque in the slightest, that's a computer-game driven myth. The power is a function of the torque and the engine speed, and the torque is a function of how much fuel and air the engine is burning, and how much of that energy is wasted elsewhere defines power which leaves the engine. So without changing the drive ratios (and thus parasitic drag), you can't change the HP/torque. And of course by doing that you change the efficiency range of the alternator/AC/PS, etc. The GFB pulleys were a complete set, and they did change the ratios, so I guess the 4hp gain they claim is plausible.

RM.