It seems like an inexpensive & easy mod, but I just can't seem to get reliable info from anyone about them...my car already has the air pump eliminated at Pettit by the previous owner, and I'm curious how beneficial it is to go with the full power pulley system.

TIA,

Ian

 

Pretty much depends on how you drive your car, there are a few guys that run under drive pullies on both the accessories and the crank, the bennifits are less power robbing at low end but requires a higher idle for the alternator to keep the battery charged, at the higher rpm range less likely hood of water pump cavitation, but reduced flow at lower rpm. There is a marginal gain of freed up HP so it pretty much comes down to "do you track the car and spend allot of time in the high rpm range" or is it more of a street driven car.

 

I don't drive the car a lot and when I do it is for less than 45 minutes. I have to use a battery charger to keep the battery charged. At night, at idle, the lights are noticeably dimmer. Just one of many sacrifices I made for more power.

I also don't have any emissions equipment-so it will make yor eyes water, and it is loud! I can't drive it to work early in the morning for fear of waking my 8 mo old daughter or the neighbors.

The air conditioner hasn't worked right since i added the PFC and other mods, so it's strictly windows down, even in 100 degree weather.

I got rid of the auto and put in a light weight flywheel and racing clutch combo. I stall it about 1 out of 10 times, and it grinds alot in protest if I try to ease it out, like when I'm pulling into the garage or in a parking lot.

Still, I always get out with a smile on my face!

 

So, what you guys are saying is that that it's pretty much:

little gain for lots of sacrifice (speaking purely about the power pulleys, not other mods)

 

I have the Greddy Pullies, Pettit power pulley, and no airpump. I can't see spending money on these unless it was one of the last mods you do. Mine happened to come with my car when I bought it.
Just an FYI, My A/C worked fine and I never overheated with all three of these pullies installed. The alternator charged fine too.

 

and BLING

 

Ah,

Someone willing to say that manuls are not all what there cracked up to be! Thanks weaklink for your honesty. Of course you have a highly modified car as well. I have always enjoyed your automatic adventures on this forum.

Also a good question with great answers! Thanks all!

Terry7

 

yeah.

 

Never overheated either, but the alternator wouldn't power my diy wb02 (v1.0) at idle.

 

As noted above, primary benefit is in preventing water cavitation at sustained high rpm. If you're not tracking the car, I wouldn't bother.

 

There is no "dain" in HP as is stated by most of the manufacturer's of these items. If you have 400 hp you will still have 400 hp, these pullies (like a lightened flywheel) free up the hp you already have. They are more for race applications than street use, if you just want the looks of aluminum parts Unorthodox racing offers all the stock pullies in stock sizes on there website.

 

Actually, manuals *are* all they are cracked up to be, esp in the case of FDs. Autos have the lovely 7k rpm redline and 3.90 final drive, and can't be modded reliably beyond a certain hp range. three strikes, they're out.

I have a 5 spd (r1) with a fresh manual tranny that was rebuilt 10k miles ago. short shifter, underdrive water pump and alt pulley, lightweight main crank pulley, deleted a/c and p/s. Spec sprung 6 puck clutch, lightweight 9 pound flywheel. Basically as 'racy' of a setup as you can get.

I never stall it, and it never grinds. The only problem that I have noticed that has been mentioned in this thread is the poor charging of the battery. A trickle-charger fixed that .

 

actually you can set the rev limiter as high as you want with the pfc. I ran mine at 8K just like a manual.

final drive can be changed.

I ran a single turbo behind my auto-although I did have to have the tranny rebuilt with better quality components.



That's cuz you got mad skillz yo! Actually I had my clutch flywheel combo installed at Gotham and Alex told me I was gonna hate it. He was wrong-I don't HATE it-but it is what it is. I have the requisite trickle charger as well.

 

I wonder why I haven't had poor alternator charging like everyone else. Could it be the smaller Pettit Crank pulley speeding everything up?

 

double post

 

The smaller the crank pulley the slower the aux. accessories are driven. The larger the aux accessories pulley the slower they are driven. Larger crank pulley faster, smaller aux accessories pulley the faster......getting the correlation yet ? ? ?

 

I have underdrive accessory & crank pulleys with an AGM (Westco Miata) battery and normal idle rpm with no problems and barely noticable light dimming at idle. The AGM batterys do charge quicker and more easily though. Some alternators are tired and don't charge as well anymore.

 

so hypothetically if you reduce all of the pulleys the same "percentage", they should operate in the same way as if they were the stock size, so long as they are all reduced at the same ratio...

are FD's very prone to WP cavitation? my FD was purchased as an intended track car, but i will also use it for cruising, and having fun with on nice days, if having an underdrive pulley will help out significantly on track days and i just need to watch myself while cruising this is something i will have to look into, but if its not a common occuring problem then i will probably leave it stock...

 

I've never experienced wp cavitation or high coolant temps for that matter and I've been running underdrive pullies for many years.

 

Making a WOT pull 15 secs at a time won't create cavitation (at least not noticeable). You have to be on WOT to really see the affect...... That doesn't include sitting in the grass while watching others go by for 10 mins. gotta bust your ***** on this one.

 

Sorry, but what is water pump cavitation?

 

Basically the impellor on the water pump spins so fast that it no longer does a good job of pushing coolant through the motor. With stock pulleys this tends to happen with sustained 7000ish RPM. Going up through the gears on the street won't do it, but blasting down long straightaways at a race track can.

 

Interesting...Thanks Damon