Understand the upsides of an under drive pulley. But there must be a few downsides.

I have a 09 C6 daily driver with a G6X3 cam so a good idle is hard enough as it is.

Be honest !!

If it was that easy to pick up a few HP then why wouldn't the OEM do it.

 

They have been linking the cam chain failures to UD pulleys, not absorbing the Harmonic
vibrations and causing premature failures. mine is a 10% UD, but it's still rubber dampened.

 

Who is the manufacture of your 10% UD?

I agree that performance of the balancer is most important, so real user experience is important, but how about electrical issues of under speed of the alternator or AC?

 

Hey how is that 427 running? What were the final numbers?

 

They normally slow down the water pump and alternator hurting cooling and charging.

 

The 10% with 3.42 gears work great, with 2.56 your engine is turning a lot less and might be a problem.

 

I have 1500 miles on it, have 440rwtq and 505rwhp thru an A6 and
3.42's,with 2.5 exhaust and stepped headers, but I'm not finished.
I just installed a 3600 converter, PC calipers, Spin wheel mods 18x11
r888 305/35zr18, and I'm waiting for my Lg Super Pro's, with B B Fussion
3".
Then I'll spend more time on the tune!!!

 

Thanks I have a 3.42 being installed already.

 

The UD being the cause of the timing chain failures has not been fully proven as of yet. At this point it's a possibility along with a few other theories. There are plenty of members driving around with an UD pulley without issue. I know of no one complaining of cooling or electrical issues on their C6 with an UD pulley. The idle rpm can easily be raised a couple of hundred if there is an issue. Most likely if you have an aftermarket cam your idle was changed slightly anyway. The best time to do the UD pulley is during a cam install because of the labor involved. Most people don't see it being worth it as a solo mod because of this. You wont get a drastic bump in power, 5-9rwhp/tq is the average but a combination of all these "not worth it mods" can add up to 25+ horsepower when all is said and done.

 

I agree on the cost issue. Point is I am a week or so away from a G6X3 cam install on my LS3 and now is the time!!

Just need to figure out who has the best offering !!

I found these Powerbond SFI units, any comments from users on these or other options (10% is all I want):

http://www.adperformance.com/index.p...roducts_id=880

 

Dan
mine was a PowerBond Pn PB1480SS10
Phil

 

I've gotten an intermittent "Service Charging System" DIC warning since swapping in the UD during my cam install. I'm fine with my idle, and I'm lazy - so I just "reset" on the dash when I get it, which is usually once or twice during a prolonged drive.

 

I've never had that happen!!!

 

When you tune for the cam, you're going to increase your idle RPM. While your stock idle was at 600 you're likely to need 850 or more in order get enough vacuum to idle well. Big cams often need 1000 to idle well.

That said, you'll likely avoid any charging issue or cooling problem at idle. Guys that see those kinds of problems usually have a mild or moderate cam with near stock drivability and a low idle.

That ain't gonna be you.

 

I have a 25% UD and run an 800rpm idle with no issues on cooling, ac or charging. I even check the charging from time to time and today, siting at a light in gear (A6) it was bouncing between 13.8 - 13.9 volts. FYI.

 

I had TWO timing chain failures on my Lingenfelter 403 with ASP underdrive pulleys. When I arranged to have the engine modified I originally had not ordered UD pullys because of concerns with trade-offs. The LPE sales rep questioned why I had not ordered the option and assured me that there would be no issues. Well, I did not have issues with charging or warnings showing up but I did have timing chain failures requiring a complete rebuild of the engine.

The first failure was after about 9 months and 7000 miles. I sent the car back to LPE for repairs. I asked them about the UD pulleys since I had seen comments about them causing timing chain failures. I was told that they had looked into that possibility and determined that the timing chain failures were not related to UD pulleys. They told me I needed a stonger chain since I ran the car in track days. BTW, I had told them before they started that I was planning to run the car on the track as well as on the street. In addition to the cost of transport, I had to pay part of the cost of the repair since their warranty has a disclaimer for track use.

The second failure occured even sooner, at about 10,000 miles with just 4 1/2 additional days on the track. I contacted LPE and they just said that it sounds like I over-reved it (I did not) and I could send the car to them. I had a local engine builder look at it this time since I did not trust LPE to find the real cause of the failures. He found a few issues with the engine build, with the most likely causes of the timing chain break being the UD pulleys and insufficient piston-to-valve clearance. I communicated the findings to LPE and then talked with them at the completion of repairs. They are now saying they believe there is a problem with using the UD pulleys and told me that other owners have been instructed not to drive their cars until they can be corrected. And although LPE had previously stated that they would provide some help if a problem was found with their build, they would not pay one cent of the 2nd repair or reimburse any of the amount they charged me the first time. They made it clear that they did not care about the problems they have caused me and their interest is in minimizing warranty claims. Obviously I am not happy about the whole experience.

And if anyone wants to try an ASP underdrive pulley set, I would give you the parts for free if you are local - but I don't recommend using them.

 

UD pullies have been around since 1997 on LS powered vehicles and no such rash of timing chain breaks were ever reported. The crank, pistons (although differing diameters but still made by Mahle), and connecting rods are identicle. Given the rotating assembly has been little changed, I fail to see why all of the sudden the timing chains are breaking from a metal part that represents so little of the rotating mass and exactly how its supposed to be responsible for the breaks when they never happened before. Guys running 100k miles on such set-ups and stock chains makes me think tuners with more than one break on the same engine has something so much more wrong with it than a pulley on the front and there is nothing more than a theory to support it. When bad things happen we always look for a scape goat to point the finger and get closure. Its part of us. We want justice and to isolate the bad thing so we can focus anger and move on. The problem is that too often its misplaced and little support to actually prove the theory. My proof is the number of them in service. I understand that the failures are the data points counted but until there are a huge number of cars out there with no UD pulley, we wont be able to get a statistic of failures with stock balancers since most cars use them when swapping a cam.

Personally I think the problem is the power the current motors make is off the scale higher than the LS1 and LS6 and thats why the breaks are more common.

I think the HPI superdamper is a far better direction and offers dampening that a solid metal unit cant offer. It comes in a 10% underdrive version. There are also different brands of UD pulley.

Addressing the voltage issues of yesteryear, more often than not a 25% underdrive puylley is attached to a car that has a cam and the idle speed for cammed cars is raised 20-25% to get the cam to idle. The net change in charging is therefore zero since a 650rpm idle raised to 800-850 rpm will be spinning the accessories at the same speed they always were at. The accessories are not spinning 25% slower. Further, the car is higher in rpm than that all cruising/driving so charging isnt an issue. Thats said even a A4 or A6 running a cam can raise the idle a bit and regain the same speed. The Alternator can be overdriven with a different pulley ro regain accessory speed for automatic cars if it was an issue. Auto guys state they dont have the charging issue and the nay sayers are guys that dont have one on this car who used one on their 1979 6.6 liter pontiac trans am with dimming lights at idle.

I had UD pullies on all my builds and never saw a charging or A/C issue even on the hottest days.

 

Pistons in strokers are all clearanced with valve reliefs and there is no way a stroker running any hydraulic roller cam doesnt have sufficient P/V clearance. Even a 2cc relief could run a 250 intake duration and still have plenty of room.

What are your cam specs? Lingenfelters cams are all small.

I didnt see the motor in question, but I would need to know a few things before I would make a statemet about a tuner like that on an open forum.

We will have to see if the new balancer solves your problems after the same track service time. I hope it does but it seems to me the more common link to these breaks is the type of racing the owners of these engines do. Its apparently more deadly to chains.

 

Spin, I was called by Jason at Katech right after I finished the 427, and he asked about the UD Balancer, I told him it was a PowerBond PB1480SS10 which is a 10% under drive,
he said good, now I have no idea what that meant.
I've had UD pulleys in all my small blocks never had a problem.

 

The conversation to me, would suggest there is a brand specific issue.

The powerbond is the best looking anyway.