under drive pulleys
 

funny how i ask about these after i moded the entire engine, tranny, rear end, blah blah...

i always thought of these as a joke...a waste of money...

what are typical hp gains off of under drive pulleys , 3 piece serpentine system.

crank water pump and alt.

I'd say about 10-12hp gain. Some people have noticed a better
"pull" on accel. Some have noticed nothing!

It's a true hp gainer. It's not really a joke. It's like as if you
never had any accessories put on the motor. Because it
reduces the drag that the accessories produce. So, if you have
all the accessories on your motor, like take away like 10-15hp.
Swap in a set of under drive pulleys, and you gained it back.
They also claim to extend the life of your accessories too.

Not trying to step on any toes - just wanted to add something to the originally asked question. I've seen both 3-pulley sets and 2-pulley sets out there. Which is better? For instance, March has the set with crank, h2o pump, and alt pullies while Motorvation make a set with just the crank and h2o pump pullies. Why would one choose one set over the other??

one is not neccessarilly "better" than the other. It just depends on your situation. Sometimes its not a good idea to slow down the alt., which I'm assuming is the reason the motorvations kit you are refering to doesn't include the alt pulley. If you slow down the alt too much, you could notice a drop in voltage @ cruising speeds, making headlight brightness, battery charging,ect. a problem. You definitly do not want to slow down the alt. if you have any large amperage drawing accesseries.(audio amp, fog lights, ect.)

i had a huge argument with someone on here if slowing down the alt was a bad idea....

i still say its a bad idea for systems because it puts more load on the alt, and eventually kills it quicker......

just my 2 cents though

and 10 hp isnt worth 150 bucks to me.....ill use that money for roller rockers....

altho i hweard more modified engines respond alot better to pulleys than stock ones...

Don't use an underdrive pulley for your alternator if it's a street car. I highly doubt that you'll want to compromise your charging system for the extra 1 or 2 rwhp. Stick to the 2 pulley sets.

Aluminum pulleys would give you a better gain, but people are saying they'll wear out eventually.

If you think getting an aluminum flywheel and driveshaft is worth the money, then you'd probably want aluminum pulleys for the same reason. Lighter rotational mass.

Laters,
Scott

I agree with the alternator situation. I wouldn't risk using
the 3 piece with the alt. pulley. Especially if you have like
aftermarket stereo system added on ( sub(s), amp(s), etc.)
You will just be "undercharging" your charging system!

The point of the alternator in the power/amp underdrive pulley set is to keep the alternator at its original speed. You underdrive the crank which spins all the accessories slower than stock, but you overdrive the alternator which keeps it spinning the same speed at stock. Some people have still had issues w/ charging though.

Right, the alt. is an "overdrive" pulley and the rest are
underdriven. But, so many people complain about the
alt. not charging right after the pulley change, that I would
not recommend to spend the $150-$300 for set that
may cause charging problems and only free up like 10hp.

I have a March steel 2 piece set. I picked up a .1 and 1 MPH at the track and had no charging problems. The power steering got a little stiffer but like has already been said, the Alt. pulley is overdriven so my charging stayed the same. I've put about 20,000 miles on the car since I added them. If charging was an issue, you could probably step up to a better alt. and solve the problem that way. I believe the B4C Camaro's had better alternators due to all the extra electrical needs for police cars.

Yes, It would make sense to upgrade the alt. I would
recommend that if you do have a charging issue after
the pulley swap.

If I remember right even CHP said underdrive pulleys are not a good idea for street car that do mostly curising Rpm's to low for charging and steering.

We installed pulleys on a formula and a trans am and saw nothing in hp or torque at UTIs hot rod u program.

I've run them on several vehicles, all with good results.

My buddy's '95 F150 Lightening dropped a full tenth and picked up 1MPH in the quarter with a three pulley kit installed. He has had no problems with charging or cooling either.

My old 5.0 Mustang had just a smaller crank pulley. That was good for .15 second and 1 MPH in the quarter.

When I swapped the serpentine system onto my '86 IROC Z28 I needed pulleys anyway, so I bought the aluminum March ones. It's the 3 pulley set. I have no charging problems. The alternator pulley is either the same size or bigger than stock, so I don't see how it could affect charging.

I see no reason not to use these on a street car. They are a bit pricey for the 10-15 HP gain, but they are fairly easy to install, which is why I think a lot of people opt for them.

The benefits of altering pulley diameters to get more power and also lower accessory speedsa t high RPM is even documented in Smokey Yunicks book on the SBC. He was playing with this stuff back in the 60s, because he saw the possibility to one up his competition.

Underdrive pulleys work really well on most applications, the only application I've seen it be unsuccessful is on TPI motors. I've seen as much as a 15 HP increase on fox body mustangs.

How did you measure the difference?

We dyno the cars before the bolt-ons to get a baseline then do it again after the mods and note any change. It's been a while since I've had that class so I don't really remember that well but we did a crank pulley on an LT1 Z28 and picked up about 2 hp and 5 ft lbs.

Red WS6 Ram Air, I assume you're at the Houston campus too correct?

waste of money...true cars that would require such units typically have special versions made. those cars of course have hardly any electrical components.

:)

I have to agree that they are a waste of money.
For anywhere from a 1 piece crank pulley for like $50
to a polished 3 piece aluminum pulley kit for $300 is a
total waste. I would put that towards a nitrous kit
or a cold air/ram air intake set up.

there are other reasons other than just boosting power that you use the underdrives...


slowing the alternator, and waterpump down on an engine that turns a lot of rpms...


stock alternators do not like getting spun up to 6800rpm on stock setups.. they tend to explode

Also, slowing down the water pump keeps the impeller from cavitating at high RPM, which ensures adequate cooling. Lock at a NASCAR engine sometime and you will see a huge water pump pulley designed to keep pump RPM down at 9,000 RPM.

What's a waste of money to one person isn't to another. That's a matter of opinion. Some people would never dream of subjecting their engine to nitrous, and only want a little extra power from a few bolt ons. Underdrive pulleys fit nicely into this second persons plans.

If you want to go by a dollar per HP gain then it is impossible to beat nitrous or rear gears (granted they don't actually add HP, but your ETs will sure think they did).

for what the majority of people use their cars on this site for they are a waste of money....nothing more then hurt your performance.

Again, thanks for your opinion. There is no right answer, so quit trying to argue the point. Also, all of the stuff that's been said on this thread has already been said on another thread, so we're all guilty of putting a bunch of redundant information into the site.

lol...you can't be serious.

my statement that underdrive pulleys are a waste of money on the majority of cars they are put on may be opinion to you but its a fact. the only reason they are still on the shelves is because people buy them that don't know any better. look all around on the internet and you'll find the very same point.

you can say and claim to argue all you want but it's not opinion...it's fact.

"Also, all of the stuff that's been said on this thread has already been said on another thread, so we're all guilty of putting a bunch of redundant information into the site."

Well, no kidding about redunant info! New people come here
all the time, and will ask help or questions that has been
answered or done with before. NO one can help that! People
constantly start a thread with a question that has been
answered before. But again, a new person here or even
someone who has been here a thousand times, will end
up making comments or threads that has been done before.
So what's your point?

Also, we are NOT talking about NASCAR engines either!
That's a TOTALLY different thing dude! 99% of people here
do not run a stock body Camaro/Firebird with a 10,000 rpm
NASCAR motor/drivetrain. So, again, what's your point here?

people seem to get really hostile when something doesn't go there way. happens alot more then it should here. :rolleyes:

i think that its great there are different opinions and some of the above makes sense for why you would want to use this sort of setup. guaranteed though that 9 out of 10 people who are actually asking about them have stock or slightly modified engines and could better spend their money elsewhere.

which is nice that there are sites like this so those who aren't aware or haven't been through some of the ordeals can read up and form their own opinion of what to do. i wish i had it back when i started. would have saved me alot of hassle.

so for those who are looking into this sort of thing believe what you want. i personally have used them on various tpi cars as well as other makes and models like ford and the rest and they have done little to nothing but cause problems. it isn't fun when your stuck on the road due to a dead battery because your charging system isn't good. it's also not fun to pay the money only to see no gains......

think what you will i guess, eventually you'll learn.

:)

Well, several people that have posted, myself included can attest to the fact that underdrive pulleys can add a measurable amount of power to a car. Obviously this may not always be the case, but based on the numbers of replies on this thread and the others that have come before it I would say that there is a pretty good consensus going about the benefits of these parts. Your experience may differ from mine, and that has lead to your opinion of these parts. That's all well and good and I'm sure the initiator appreciates your input into this matter.

When it comes to spending money that's a matter of OPINION, nothing more, and nothing you say will make you right when it comes to how other people spend their money. Fortunately we still live in a country where freedom of choice is up to the individual not your sole discretion.

I don't give two lumps of fecal matter what it says on the internet either. All my information about this subject comes directly from experience, not from what some friend of a friend did, what I heard, or what I read once.

It's a fact that a 305 Chevy has 8 cylinders. It's a fact that a 700R4 has 4 forward gears. I can claim all day long that building a 305 is a waste of money or that automatic transmissions suck, but that doesn't make it so. Those last two claims are my opinion, even if they're based on what I've observed as well as some factual information. I can make recommendations based on my opinion, but they don't automatically override anyone elses recommendations based on their opinions.

Sorry this has been long, but I'm sick an tired of people arguing over stuff that can never be effectively settled because it is all based on opinion. Post your thoughts and then just let it go. If someone has a fact wrong then correct them, but don't try and impose your opinions on everyone in the forum. The goal here is to allow people to get factual information from informed sources, and to see what others have done and what success they have had. Getting into an ego war with people trying to come out as king of the 3rd gen forums is assanine, and more importantly it doesn't help the person who initiated the thread.

Everything you said here is true really. A few of my friend's
had cars with those kind of pulleys. They did nothing but
cause problems. Now, if you had spent like $300 for a good
set of pulleys, now your charging system is acting up. You
find out it's not working right. Now you need to cough up
more money for a high output alt. NOT saying ALL pulley
sets do that! But, in my experience and my firends, it's a
waste of money. They are even the ones that supposed
to be an "overdriven" alternater pulley in the set. :bs:

Sorry this has been long, but I'm sick an tired of people arguing over stuff that can never be effectively settled because it is all based on opinion. Post your thoughts and then just let it go. If someone has a fact wrong then correct them, but don't try and impose your opinions on everyone in the forum. The goal here is to allow people to get factual information from informed sources, and to see what others have done and what success they have had. Getting into an ego war with people trying to come out as king of the 3rd gen forums is assanine, and more importantly it doesn't help the person who initiated the thread.

I will admit that I have done this before.

It's so easy for me to do this. Although, I post both factual
info AND state opinions. I have argued A LOT with fly87gta
or whoever, and it got NO WHERE. Even if I stated correct
info, he was still arguing with me. :rolleyes:

Camaro_nut, are you talking about serpentine belt setups with respect to loosing charging ability or conventional v-belts?

All the experience I have had with underdrives are on serp systems. I've never had charging problems. I've also always used the ones that have stock size alternator pulleys, or slightly oversize ones. Granted, all the vehicles I've been using them on also have the bigest alternators that could be had for the application, or larger. My old 5.0 actually had an SN95 alternator, which is a substantial upgrade from the stock one. My Camaro has a 130 amp alternator to go along with my serp conversion. My friend's Lightening also has a huge alternator. Maybe charging problems are only common on lower output systems?

I'm also wondering about proper belt tension after the pulleys are installed. I know they say to just use the stock belt with most systems, but that could be for convenience and may not necessarily be the right way to go. I also think that pulleys may expose a marginal charging system on a higher mileage vehicle, but I'll admit that this is conjecture.

TKOPerformance,

All of the charging issues were on my old car and 4 of my
friends' old cars (range from 85' Capri, '90 T/A, '94 Mustang,etc.)
All had the stock alt. systems too.

All had the serpentine belt set up. All were stock too. All
had the same issue. Undercharged alt. due to pulley swap
with an aftermarket set. 2 of them were the March brand,
1 was an ASP brand, and another was a Ford racing brand.
So, this is experience and opinions. To each to his or her
own on those underdrive pulley sets. Good luck. I would
also not recommend an aluminum driveshaft either for
freeing up hp, but that's just my opinion. I would trust
a high performance steel driveshaft from Spohn or any
other company than to trust a flexable aluminum material.
Not worth the extra 10hp there also. But, everything has
it's ups and downs when it comes to aftermarket performance
parts and experiences with them. It's like a hit or miss really!

That's why 90% of high peformance parts do not come with
any warranty!

I can only claim experience with March and BBK. All these have been good experiences. Asp is a relative newcomer, so I was waiting to hear some info on them before trying their products. Looks like that won't be happening!

I agree with you on aluminum drivehafts for heavy street cars too. The big problem on the 3rd gen is the torque arm prevents you from using a tube with a big enough diameter to make an aluminum shaft that is strong enough to withstand the low end torque of a TPI in a heavy car, particularly when coupled to a manual trans.

I'll toss in another piece of advice too. Stay away from aluminum flywheels on street cars. They make the idle instable because of the lack of interia. I'm running one now and am wishing I'd gone with the billet steel one instead. My car sounds much nastier than it really is, because it lopes at idle like it's got a big cam.

See, now we're providing useful information!

Thanks for that info on the flywheels too!

I am ordering a GMPP 350 motor and it comes with
an OEM style flywheel. I am also swapping in the manual
T-56. So, I guess I will throw out the idea of the lightweight
aluminum flywheel too!


FYI: My friend's 98 T/A was basically stock (as of Oct. 03).
He had split the driveshaft at the front yolk end!
Car was all stock minus air lid, K and N, and Borla cat back!
The driveshaft is aluminum, and comes factory on all F bodies
I believe from 93-02. I will never trust those after that
incident! He almost took out his new car. :eek:

The "loping" can't be a bad thing though! I think a
lopey cam sound is awesome!

another point that i didnt see mentioned: if you've upgraded your rear gearing then it makes more sense to use underdrive pullies since the overall revs will be higher and therefore shouldn't adversely affect charging unless all you do is sit in traffic.

Gears dont have much to do with it. Just about every underdrive set gives full charge at less than 1,000 rpm so once you tap the pedal you have full charge. If you have just a 25% crank pulley you should have full charge at about 800 rpm, or with a power and amp series set it should be fully charges at idle even with an auto. They are a worthwhile mod no matter what anyone says. They have been proven several times over.

I've just recently installed the three piece set of aluminum BBK ud's and I've noticed a little chance in charging at stop lights. Would raising idle speed help? As for power stereos and amps: use capacitors in your battery-to-component wiring. It stores power and uses it when its needed so as not to pull on the charging system.

yeap, raisig the idle would cure that. It'll prolly only take about 200 rpm max to get it back to stock.

the only problem is that the idle speed is set from the factory. hints not a good move to reset.

Yes it's set from the factory, but that doesn't mean you can't adjust it. You can either adjust it with the idle screw or with the computer. If you don't wanna do that then get an overdrive alternator pulley. It's nothing to worry about really as the only time it will drop is at idle and it's only a couple volts.

I have the overdrive alt. pulley.

typical results are 15rwhp IF and only if your tpi serpentine has smog pump, A/C, and power steering still hooked up. of course thaalternator too.

i just recently installed march pulleys, power steering, alternator, crank, ac, and water pump. i havent really noticed any lack of power, only at idle sometimes, but this weekend im installing a 140 amp alternator, which hopefully will help the idle problem.

but i was thinking about something else, in a 3 belt setup, which i just had, doesnt the alternator belt run off the crank anyway??? the crank is wut controls everything, i think at least. so a serpentine setup running off the crank with one belt shouldnt exactly harm alternator voltage. if anyone has had this problem, and solved it, please let me know

I have the March 3 piece 4010 on my car with no air pump and have never had any and I mean any problems whatsoever.

any1 kno where i can get just a crank and water pump UD pulley then? cuz all i have been able to find are 2 piece set of crank and alternator or 3 piece set of crank, alternator, and water pump. Because so far i've heard pretty much bad stuff about the alternator pulley, so yea any1 kno where i can find just eather a set of water pump and crank pulley, or the 2 seperate? and i'm talkin nice CNC machines ones not just stock replacements

Just get a crank pulley. Just about every underdrive "set" is stock sized except for the crank and maybe alternator.

where can i get just the crank pulley??

asp

whats asp?

check out thunder racing at the top of the page

I HAVE A crank pully on my 3.1 i tool the alt off due to charging problems noticed no difference when i took the alt pully off in power but the crank pully did give me better throtle response my car felt like it had more pull and i got ALLOT better gas milage to me this is a must do mod.