Underdrive pulleys [ merged 1/6/07]

[larryd]

Worth it or not? I'm thinking of going with the AEM tru-power pulley kit. Anyone used them?

 

[karbon]

is there any other one for like $100 to $150 bucks that is dampened?? what kind of performance increase will i get from the buschur pulley....is it very noticable???

For the "10 hp gained" from an underdrive (not to mention the lights dimming at idle and your battery taking longer to charge), you could just add a couple more pounds of boost. Go with the stocker. It's a lot cheaper than the Buschur one.

 

[98FWDSM]

ok, well i dont NEED a new one, i can just reuse my stock one but i was just thinking that if the gains were impressive then why not upgrade, but if it isnt worth it then i will just change my belts

 

[gsx951]

It's just not worth a busted crank or worn out bearings. Go O.E.M. or go with the Buschur/Fischer concepts pulley.

 

[dis_ill_usion]

if you are just going to junk the stockers...use a pipe wrench to hold the pulley still

, loving the new smileys
oorme: WTF

 

[dis_ill_usion]

I know this subject has most likely been discussed so many times but I figured I would ask anyway

I have heard about how nice underdrive pullys are but I have also been told that it is not good to replace the alternator pulley, they said that it doesn't allow the alternator to charge enough...is this true?

besides the undampened crank pulley, any other drawbacks? I know you can get a dempened crank pulley but can expect to pay out the a$$ for one

any sugjestions?

 

[doug]

If you're already using an underdrive crank pulley, I wouldn't use a different pulley on the alternator too. You'll already be turning the alternator slower from the smaller crank pulley. I have an underdrive crank pulley and at idle, my wipers and power windows run noticeably slower than at cruise, so I'm thinking that any more "underdriving" wouldn't be that good. Besides, the miniscule HP gain just isn't worth it. I have no hard evidence to back this up, but that's just my take.

 

[espinelli]

Wasn't as bad as I thought, impact gun worked great on the alternator pulley. Its always hard when taking things apart the first time. After that everything becomes easy.

The only pulley that can be a problem is the water pump pulley. Put a flat piece of plywood under the oil pan and use a floor jack. Make sure you undo the front and rear motor mounts along with the driver side mount. I'm not sure which works best raising it or lowering it. I think I raised mine but that was a long time ago.

 

[JiveMasterT]

i hope you're not using some solid UDP on your crank. they have been known to cause problems because they dont have the dampner built in and that means more engine vibration, which is not good when you are in the upper rpm range. save your time and money and invest in big power adders.

 

[skinnypimp]

i hope you're not using some solid UDP on your crank. they have been known to cause problems because they dont have the dampner built in and that means more engine vibration, which is not good when you are in the upper rpm range. save your time and money and invest in big power adders.

do you have proof to back up your statement?? i used the machv set for two years and had no problems. i've seen two other members who used udp's and had no problems. ta lon

 

[doug]

Eventually, every underdrive pulley thread on this board turns into an argument over whether an undamped pulley is bad or not. It's like religion-- you're unlikely to convince someone else of a differing opinion that they're wrong, so the best thing to do is just let it slide.

That being said, I've also used a solid pulley for over two years with no problems.

 

[JiveMasterT]

do you have proof to back up your statement?? i used the machv set for two years and had no problems. i've seen two other members who used udp's and had no problems. ta lon

think about it for just a second. chances are the engineers put the dampner in there for a reason. that reason? when the motor is at higher revvs it is more vulnerable to engine vibrations. that little bit of rubber in there is to help prevent those vibrations from being transferred all over the place. im sure i could explain this better but im at work, and there is a search button for this. enjoy.

 

[boostedinaz]

I found and article that explained this very well. If I can get my scanner to work I will post it up for everyone to read for now I will kinda summerize.

The pulley counteracts twist in the crank. When one piston is on the way down an other is on the way up. When they get to there respective spots they change direction very fast and do it again. All of this actually twist the crank and that can cause engine premature failure. The harmonic dampner, not a balancer at all really, helps to minimize or completely eliminate this twist. This helps two fold. One it helps to keep the crank from premature failure and, two, since it keeps the crank from twisting it helps keep the timming as accurate as possible.

Fot those that have run one and had no problems, good for you, but I have never liked the argument that it works for me, so its fine. Sure it may work but it that the best way to do it?

I have know people to drive around on 510's, no AFC, no fuel pump rewire, and 18# on a 20G. Did it work? Yes. Is it the right way to do it? Not at all. So that reasoning is laughable at best.

Ask Buschur why he wont run an undampened pulley on his cars and see what he says.

 

[doug]

I found and article that explained this very well..

You're probably talking about that article from Dinan BMW, correct? If so, I tend to discount that article somewhat since it deals with a different engine-- one having two more cylinders and a much longer crankshaft.

Ask Buschur why he wont run an undampened pulley on his cars and see what he says.

Yeah, I'll call him up right now-- I'm sure he'd love to talk to me at length about it.

 

[skinnypimp]

not trying to start an argument, just stating my experience. i just want to see where someone had an bad experience with an udp. well my friend did an engine swap on his civic, i looked for a dampener and it didn't have one. civics are known for there quality, so why we don't hear about them crankwalking or bearings going bad like on our cars???? maybe a dampener is added protection ta lon

 

[boostedinaz]

You're probably talking about that article from Dinan BMW, correct? If so, I tend to discount that article somewhat since it deals with a different engine-- one having two more cylinders and a much longer crankshaft.


Yeah, I'll call him up right now-- I'm sure he'd love to talk to me at length about it.

It was actually in a Drag racing magazine I get. It was written with the help of some tech's from ATI. They make all kinds of after market dampners.

Yes, the length of the crank will play a roll, but any motor can benefit from a dampner. I have been looking around lately and have seen that some cars dont have them and most of them are not performace oriented vehicles.

 

[doug]

OK, cool-- yeah, post that article if you can scan it. I like to think I'm open-minded enough to be convinced otherwise if the data supports it. Too many of these threads turn into name-calling flame wars, so I'm glad to see that we can engage in some healthy debate without it degenerating into something juvenile.

 

[MitzMadness]

You can go the UDP route if you want I just suggest using one that has a dampener on it. People still don't have a true answer to why crankwalk happens, there alot of theorys some more believeable or researched than others. I think the reason why you hear some DSM's running UDP's without problems is probably that they have no experienced crankwalk yet because the UDP has not caused enough damage internally yet or that the crank in their engine was built to spec. One of the more popular theorys is that Mitsubishi put out a large number of cranks that werent of the correct spec causing the crank to wobble. All in all I'd go with a dampened one to be safe. Now on your note about the alternator pulley why don't you just get a lightweight one. Companies like Unorthodox Racing sell pullies that are not underdrived and just made of lightweight billet aluminum which does not cause pullies to spin slower. Thus no charging problem

 

[dis_ill_usion]

Now on your note about the alternator pulley why don't you just get a lightweight one. Companies like Unorthodox Racing sell pullies that are not underdrived and just made of lightweight billet aluminum which does not cause pullies to spin slower. Thus no charging problem

finally, someone answered my question

 

[MitzMadness]

no prob

 

[oldman]

I have read many threads like this over the years and most of them focuses on the cons. I have not seen real comparison dyno numbers that tells us exactly what the gain is for this mod. I mean dyno the car, replace the pulley, immediately dyno again. If we are talking about 1 to 2 whp, why even have this discussion?

 

[boostedinaz]

I have read many threads like this over the years and most of them focuses on the cons. I have not seen real comparison dyno numbers that tells us exactly what the gain is for this mod. I mean dyno the car, replace the pulley, immediately dyno again. If we are talking about 1 to 2 whp, why even have this discussion?

Its not always about HP and what your car runs. Sure it wouldnt be worth it if you only gained 2 WHP, but what if your motor lasted an extra 15k. That would be a huge benefit to anyone I know. This is in regards to the harmonic dampner not underdrive pulleys. As far as they go I also would like to see a back to back dyno run.

So my scanner took a shit and my new one wont be here until the morning. Hopefull I can get thet article up in the next few days if Fedex comes through.

 

[GSTnewbie]

I too have UR pulley and has been using it for couple of years now. At first, I didn't notice any drop in the voltage until I got Blitz Turbo Timer installed. Since our cars do not come with voltage reader, this extra feature of the TT is very useful . It had helped me with warning of low voltage (I snapped the alt. belt once) so I stopped the car before severe damage to the engine. Anyway, back to the topic. Yes, if you installed all the pulleys which I believe there are 4 of them in the set, you would notice some drop of the voltage during idle. Mine was at the lowest at 11.1 V (eyeballing the TT) with stereo+head lights+log lamps+stepping on the brake while in drive. It is fine during crusing.

Solution: I replace the largest pulley (heh I don't know much car lingo so I wasn't sure if that's called crank pulley or not ) with the OEM and replace the alternator pulley with smallest pulley I can find. The result is much improved voltage level at about 12.8-13.1 V at idle. The lowest is 12.3V during the same condition above.

Seriously though, I didn't notice much of HP gain at all but hey, I'm no expert and I haven't dynoed the car. So, I wouldn't say it's worth the price tag. Although, the looks under the hood improves quite a bit though .

 

[doug]

Its not always about HP and what your car runs.

Totally agree. To me, the reason to use a one-piece pulley is because it's just that-- one piece. It won't separate on you at some random, probably inopportune, moment.

 

[oldman]

Totally agree. To me, the reason to use a one-piece pulley is because it's just that-- one piece. It won't separate on you at some random, probably inopportune, moment.

Good point, but there are usually enough warning signs.

 

[skinnypimp]

Good point, but there are usually enough warning signs.

like what??? mine seperated and i had no clue what happened