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So, who's running pulley kits ? (Naturally Aspirated thread content)

6K views 44 replies 26 participants last post by  saedrin 
#1 ·
Heya everyone,

Still undecided on running pulley kit or not for my 1999 1.8L swap.

I don't want to hear about the turbo issues from running pulley kits, but would like to hear if any engine/water pump or anything ever broke on a naturally aspirated car from running a pulley kit ?

My friends running 1.8 protege swear by this mod, so I'm wondering if I should try it or not.
 
#3 ·
But the big question is: did it ever fail on a naturally aspirated car ?

I'm pretty sure Fuji Racing shop car had the pulley on their high hp/high rpm car.
 
#4 ·
I'd be interested in knowing this as well. All the searching I've done seems to be people extrapolating an experience they heard from so and so etc.. Never any well documented first hand thoughts.
 
#6 ·
so... if these light weight pulleys are not good for the car why are they made some one at one point and time had to of researched this and made it work. i think they have a bad rep. because of just stupid people not knowing what the f@%$ they are doing.
 
#7 ·
so... if these light weight pulleys are not good for the car why are they made some one at one point and time had to of researched this and made it work. i think they have a bad rep. because of just stupid people not knowing what the f@%$ they are doing.
of is not a contraction of have.

With that out of the way, by that logic ebay electric turbos would be something you would want to put on your car.
 
#8 ·
#9 ·
I've had an under drive pulley on my 2000 for 3 years and no problems. And its not stock. It has, intake, headers, timing advance, power card for fuel, 2 1/2 inch exhaust, Stage 2 intake cam, adjustable cam gear on exhaust cam, Walbro 190 fuel pump and a lightend flywheel.
 
#11 ·
i have a unorthodox racing crank pulley,faster revs and less strain on crank, Mopar folks over at DTforums live by the UDP(Under Drive Pulley) i had one on my modded 99 neon and could tell alot on the revs and the takeoff,i have not had any issues on either carwith running pulley kits.
 
#15 ·
I think I'll read minkara/carview reviews about those who bought the Nakajima pulley kits and see if any of them had problem and what abuse they gave their car.

Still wondering if all the failures we heard were because of forced induction, cheap pulley kit (bad standards) or it's really the oil pump who can't take it at all.

If I remember correctly, Emilio @ 949 is running a pulley kit on his 160whp N/A race car, Jimmy from FujiRacing was doing that, too.
 
#25 ·
If I remember correctly, Emilio @ 949 is running a pulley kit on his 160whp N/A race car, Jimmy from FujiRacing was doing that, too.
Probably should be pointed out that both examples you gave are on RACE cars.... not street cars. Depending on where in the rpm range the natural frequency of everything is, race cars may or may not be revving in this range when on track. Therefore the ramp through resonance quickly (entering or exit off track).

On the other hand, street driven cars usually go through the whole RPM range quite a bit so if the natural frequency and it matches the resonance frequency, then you have some pretty damaging harmonics.

I wouldn't take it lightly, removing that tiny bit of mass isn't worth it IMO. If you got money to spend by then by all means :)
 
#16 ·
i have the pulley kit from sr motorsports. pulley kit was for the crank, alternator and water pump. i installed them about three years ago and running NA. the gains were moderate but i've never had a problem with them after the install. from what i've read (i think from m.net), changing the crank pulley won't do any damage to the engine unless you're running 200 hp or over. so if installed correctly you should be fine. i like them a lot
 
#17 ·
#21 ·
fair amount, meaning at least once a week for specifics
 
#23 ·
good deal, hopefully you'll enjoy them as much as i do
 
#26 ·
I've had an unorthodox pulley sitting in my garage for like two years.
I've always been skeptical about putting it on even though I've only read about problems from them with higher horsepower cars like someone else mentioned.
 
#31 ·
Just went back and looked at Slevin's build thread, Invert posted there on the pulley subject.
Invert, you've been thinking about this a long time...
 
#29 ·
Well, I talked to RS Aizawa and they told me they put them on their built engines (for customers, too), however, they say they are balanced perfectly.

Now, back to thinking about putting it or not.
 
#30 ·
Why bother running the risk whether or not it would ruin your crankshaft, when you know for sure that it currently does nothing harmful? :dunno:

You'd need a little more information on those RS Aizawa crankshafts to know if the resonance occurs or not.... Factors like knife edging change the natural frequency too. Again unless you have someway of determining natural frequency for crankshafts, there is no way of proving that it wouldn't damage it. You could probably approximate it quite closely if you measured the crankshaft, but then again I highly doubt you'd do that on a street car anyways for 0.4hp or so.
 
#33 ·
invert, i found the link that i mentioned earlier. it was on solomiata, not m.net
not exactly our engines but he has a street motor with a 2000 head.

http://www.solomiata.com/street.html
 
#35 ·
well like i stated before i have had mine on for almost 3 years with no issues,if i was new to the pulley kits i would be skeptical as well,but i have used these pullies on 3 different cars with success,i just never bought a cheapy set i always bought decent brands like Mopar performance, and Unorthodox.On cheapy set i would be leary due to poor workmanship and maybe them being off balanced and causing some issues.
 
#36 ·
im curious if the underdrive pulley affects the water pump? theoretically it would put less strain on the alternator, and if horsepower gain is your interest it shouldn't make much of a difference if your alternator doesnt churn as fast since you should have a lot of electronic loads stripped, as well as no PS or A/C for that matter. everything affected seems to be luxuries, i'm just concerned about certain manufacturers screwing with the pulley that controls water pump operation. with an underdrive on a small SC pulley you could still boost 8-10 PSI and have a lighter pulley... am i missing something?
 
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