JBrady

This is of course your choice. That said there is a REASON every car manufacturer spends the money to use harmonic balancers. Trust me, if they were not required manufacturersl would NOT spend the money. Just because YOU have never had or seen/noticed/realized the damage that occurs does not mean it does not occur. There are TONs of online reports of both engineering reports on why to use them and damage as the result.

For drag race only applications where the RPM range is not at a critical harmonic you can get away without a HBD for a while. Even so, except for the slight gains of running a smaller diameter pulley, WHY?

BTW, there are quality underdrive crank pulley HBD combinations for a number of performance vehicles including C5 Corvettes. If one were made for the Lexus engines it would be fine. Otherwise, buyer/user beware.

RRocket

I picked up 12RWHP with my underdrive pulley on another car...hardly a "slight" gain. GS400 owners would be thrilled to death with a 12RWHP gain for about $100. I /we have used both types. The type that I had used you bolted the stock dampener back onto the pulley. So you were underdriving while at the same time keeping the dampening. And here's the kicker...A friend of mine was a powertrain engineer for Ford's, then went on to become a powertrain engineer/program manager for Rousch. Anything powertrain was his. I asked him of the dangers of an underdrive pulley. He said the tolerances are so close and modern engines, that the likelyhood of damage from a pulley was "minimal if at all". While I certainly do appreciate Jbrady's opinion, I suspect my friend has had just a tad more experience in this area. The to double check, I talekd to March Performance while my buddy was having a prototype pulley made for his truck. I asked the same question. He said they had seen a grand total of 2 failures. (and they've sold hundreds of thousands) But the failures were crank bearings on very highly modified engines, so it would be dificult to pinpoint the cause. So let's assume that it WAS the pulley's fault. 2 instances in a hundred thousand units sold. Not bad odds at all. ..While I do agree that damage COULD result, the chances are slight. LIke I said...we've been using them for years. Several dozens of us track people. Either we have somehow miraculously been "lucky" or the chances of damage are in fact minimal. I'm sorry, but I'm not one of those guys who listens to some story a "friend of a friend of a friend's sister's boyfriend heard second hand" story.The last vehicle I had with the pulley had 257,000kms on it when I sold it, and was still running strong. Many many pulleys are sold every year, and if they were that horribly unreliable, car guys like myself simply wouldn't buy them as these failures would be rather prominent and happen quite often. In truth, that isn't the case....The last time I e-mailed Todd from TM engineering, he had over 40,000 miles of testing on his GS400 with an aluminum crank pulley, and no failures yet...Perhaps you could defer further questions to him??

JBrady

RRocket,

Please do not take my post as insulting you or in any way arrogant or condesending: BUT, your advice could cause many people unneccesary damage and expense.

Your friend the engineer could have MANY reasons for his answers but honestly the ones you list are not valid. Ask him WHY manufactures spend millions every year on harmonic balancer/dampeners (HBD).

Now, your cited experience with a smaller diameter PULLEY bolted on to a stock damper is not a good example and is not as problematic as it still has the damper. My statements center around using NO damper.

Now, using a smaller diameter pulley will increase RWHP. This is due to less parasitic loss. BUT, interestingly enough, a properly designed damper will actually make MORE RWHP vs. no damper. This of course assumes the same pulley size. Here is a good read from David Vizard on dyno testing this statement:

http://www.popularhotrodding.com/eng...06mm_windsor2/


Here are someother good links including first hand experiece and other tech data.

http://www.atiperformanceproducts.co...mper_dinan.htm

http://www.pacarsearch.com/stealth/buschur.htm

http://www.pacarsearch.com/stealth/udp.htm

http://www.atiperformanceproducts.co...s/dampers/101/

http://www.fluidampr.com/torsional_vibration.htm

RRocket

I stand by my statements. I'm comfortable using them, but others may not be. If they failed as frequently as you make it out, I surely would have seen one by now. I'm not sure how much time you spend at tracks, dyno runs or stuff like that. I have spent many hours at each. Could pulleys cause crank damage?. I suppose. Do they reduce engine life. Maybe. But by how much is the big unknown. 1000 miles? 2000 miles? Nobody really knows. As I said...Todd from TM has 40,000+ miles of testing using his pulley with no damper on it. I had a car with 255,000kms on it, of which 200,000 had the pulleys on it. I had another one with 100,000kms with pulley use. And the list goes on and on. This is mod that really comes down to personal preference. I did my homework, talked to engineers, saw results at the track and dyno. I decided to do the mod. I did use almost exclusively pulleys by March Performance. They now make pluid damped pulleys. SInce they live so close to me, I am considering leaving my car with them for a few days to have them make me a set...no doubt I will ask for the fluid damped pulley. So here's my discalimer: Pulleys worked for me, but they may not work for you. I think it's a great mod for the money ($125= 12-15 RWHP). So I guess it goes back to what JBrady said 1st..if you do this mod be sure to use the highest quality parts that you can to prevent a risk. As I said..personal preference mod...

Lexbox

Does anyone know if the underdrive pulley on Ebay, or any of them, allow you to reuse the dampener on the stock one or come with their own. Or should we just listen to the people in the know and scrap the idea?

jgscott

iTrader: (1)

OK so let's get together and have a 1UZFE pulley made that is a lightweight NON underdrive pulley with a proper Damper that will provide performance gains. At $ 200 or less it should draw a big response.
I have a extra stock pulley that I would be willing to donate. Who can make one for us ? Anyone know ?

LXOGOOD

Just to clarify, are we taking about a crank pulley right?

GSteg

iTrader: (15)

I had an lightened Underdrive crank pulley on my old car (acura legend). Ran over 3000 miles without a single problem. 95% city drives with traffic everywhere (socal) so the engine stresses a lot more than 5k worth of highway mileage.

I've heard of people who had problems, but none of them could document why the pulley caused the engine to break down. They only "suggested" that it's the pulley's fault.

I figured it would be okay for me to get the pulley because my engine came with a 1-piece pulley (w/out harmonic balancer) straight from the factory, and the engine was known to go over 300K miles without trouble. The newer legends came with harmonic balanced pulley, but many people have changed it out to the 1-piece without the harmonic balancer for added performance. The engine between the years were virtually unchanged so I see no problem using a single piece pulley on an engine that never came with a harmonic balancer.

Now on the GS300/400, that could go either way. I'm not suggesting it would work, but until someone can actually confirm the pulley works, I will stay away from it.

Lightened (not underdrive) alternator and power steering pulleys will be nice. ASP are able to custom make pulleys for us if we send in our stock pulleys. I've seen the work done and they come out very nicely.