86IROCZ4u2nv

iTrader: (1)

I had a similar question dealing with pully number 655-4020 in JEGS. It is the 2 piece crank and alternator pulley setup. I have read the above comments etc, but I had a question about wondering what size belts you need to use. In this case it would be for my 86' IROC 305 any feedback would help. Also again do people have many problems with proper charging or is everyone making a big deal out of it, whats the scoop thanks again for your time Dan-

86IROCZ4u2nv

iTrader: (1)

I had a similar question dealing with pully number 655-4020 in JEGS. It is the 2 piece crank and alternator pulley setup. I have read the above comments etc, but I had a question about wondering what size belts you need to use. In this case it would be for my 86' IROC 305 any feedback would help. Also again do people have many problems with proper charging or is everyone making a big deal out of it, whats the scoop thanks again for your time Dan-

TKOPerformance

Currently running underdrive pulleys on 4 vehicles. No charging problems on any of them.

FAST RS

Best bet would be to change the pully at the autopart store. Or you can install the pully take some string and route it like the belt would go mesure it or take it to the autopart store and you should be able to get a very close match. I went through 7 belts before i found one that would fit. The manual said i needed this belt when i really needed that belt

91TPI5.7

I got the march 3 piece alumnum kit on my 91. No problems whatsoever. There was no loss of performance, car feels a lil snappier, as a matter of fact the only actual diffrence i saw was the blinker light makes the battery guage dip each time it illuminates. I also have a GM replacement alternator on there, so that may be a lil more durable than those cheap rebuilts from pepboys...ect. I cant say that they alone gave me more power, i had installed an AFPR, injectors, and ported the plenum all at the same time. Those mods did drop my et by .4 sec, and give me a 4 mph increase in the 1/4

86IROCZ4u2nv

iTrader: (1)

thanks for all that have replied so far Dan-

BWW

iTrader: (2)

These pulleys seem like they are overpriced for the hp you will see but hey, what isn't? I think that you may want to remove your smog crap first to see a small gain.
Also I know a guy who was driving his car when the belt tensioner broke and his belt totally fell of so he had 0 parasitic drain. Even then he did not notice any increase in power. Maybe the fact that it was a 4.6l ford engine had something to do with it I dunno.

25THRSS

could be the fact that his alternator and water pump wern't operating either.

FAST RS

They pay for them selves after i put mine on i got about 80 miles more per tank of gas.

3rdGenBlackBird

Really? I barely get over 80 miles PER tank of gas.

Maybe I should take another look at those pulleys....

Laters,
Scott

FAST RS

i was gettin 220 miles per tank now i can get 300 out of a tank and have about a gallon of gas left. i have a 3.1 with 230,000 miles on it.

Wishmaster's87IROC

iTrader: (4)

is the underdrive alt pulley bigger than stock or smaller? The one that came with my set is...
crank: way smaller....
water: same size.....
alt: bigger...


is that correct for underdrives?

25THRSS

a bigger alternator pulley would underdrive it. Not the best thing for the street though.

jmd88iroc-z

You're right about that. Should probably stick with stock alt. pulley on the street.

FAST RS

I just use the crank pully i had the alt pully on but had bad charging problems. Put the old pully back on everything was fine and i didnt feel any loss in power.

vance

What do you guys think of this kind of a mod on a 305 TPI, in a 87 GTA.

A/C pump has been removed, was like that when i bought it.

Remove smog pump, air pump/diverter valve.

Replace cat with high flow cat with no air tube. Or possibly with different exhaust set-up.

Install aftermarket underdrive pully set and a higher amp alt than stock.

Install aftermarket water pump.

The engine has about 130 miles, the car has been stored for the past 5 years. Seeing as how I'm going to be taking the car out this summer, and the interior is almost done. I would like to do some upgrades to the engine, drivetrain and running gear. I was thinking about something along the lines of what i stated above.
plus a new steel driveshaft. I already had a new 700 tranny put in before storage.
All this is in planning, but i'd like to gain some knowalge about it before i start donig things that are totally wrong for these tpi engines.

25THRSS

I say before you do anything just read for a while on here and do a few searches on what you are interested in that way you can get a pretty good idea on what direction to take. Also, why a new steel driveshaft?

jmd88iroc-z

Yeah, 25th is right. do research before spending alot of money.
I spent alot of money for a very little difference.

vance

the new driveshaft because when i had the tranny replaced, I noticed the driveshaft began to viberate at high speeds, it looks as if it has a few dings in it. I'm assuming thats what is causing the prob. Just for peace of mind.

25THRSS

Why not upgrade to aluminum or even carbon fiber?

FAST RS

What is the benifit of an almunium driveshaft? I bought one to put on my 68 firebird since it was cheaper to buy then have a new yoke put on. I have not yet driving the car nor do i remeber driving it since i only drove it 15 minutes and it threw both front rods.

vance

Why not upgrade to aluminum or even carbon fiber?

I heard that the lightweight ones were prone to splitting and whatnot.. or would that just be a concern for a car with alot of mod's on the engine? After all its only a stock 305 tpi.

25THRSS

You'll find everything you need to know on the drivetrain board or by doing a search. If you still have questions feel free to post about it.

tpiroc

Just to get back on topic here and stay away from good vs. evil of them here's my experience;

TPI Car, Subs + Amp, Daily Driver.

March 2 piece set; Alternator pulley was BARELY larger so I didn't install it.

Number of problems; zero

Same alternator, it hasn't died or anything, and I've never discharged the battery. As far as gains, I did a WHOLE heap to the engine so I couldn't tell you, but I certainly plan on putting them both on my new engine when the time comes. I give them a thumbs up

TKOPerformance

3rd gens don't fare well with aluminum or carbon fiber shafts, unless they are totally stripped down race cars. The torque arm's proximity to the shaft makes it impossible to run a really meaty one, so the aluminum ones are too weak and break on a full weight (portly) street car. Carbon fiber is even worse.

FAST RS

I was talking for a 68 firebird with a 455.

Any ways the pullys will pay for them self in increased gas milage.

johnjm22

I disagree. I have an ls1 aluminum driveshaft and it is quite a bit meatier than the stock steel one and clears the torque arm just fine.

Also, If a 3.5 inch ls1 driveshaft is strong enough for a 4th gen SS, then I'm sure it's more than strong enough for any thirdgen.

Camaro_nut

I have to disagree on aluminum driveshafts.

They are made of a lightweight, flexable material.
They will not last on a serious race car. I would trust
a heavy duty steel driveshaft ( like Spohn's) over any
aluminum one. My friend's 98 T/A had a driveshaft break
apart on him. It was the factory "Three Rivers" aluminum
driveshaft. His car is only around 330RWHP. He beats
on his car. But the driveshaft should not break!

Those aluminum driveshafts are better than the thirdgen
stock steel ones. But, I would not trust it on a high horse
power car. You guys can say all you want about the
aluminum driveshafts. I know that they might free up
like 10 hp because of the less rotational mass. And they
are lighter than steel. But for the guys who run 12s or
quicker may experience some breakage!

johnjm22

I agree that a very high horsepower car should probably use a stronger steel driveshaft. But what I meant was that any stock thirdgen or slightly modified thirdgen is better off with an aluminum driveshaft over the stock steel POS.

TKOPerformance

Steel is considerably tougher than aluminum. On a street car you probably don't have the traction to apply enough force to break the driveshaft, because the tires will breal loose first.

On a car that sees strip duty on slicks, but still weighs what a production street car does I wouldn't run anything but steel. The production driveshaft is meant for a production vehicle. They will work fairly well on mild race cars, into the 12s, as long as the u-oints are relaced with high quality aftermarket parts. Ultimately an aftermarket steel shaft is a better choice though.

On a dedicated race car that weighs 2,800 pounds or less I wouldn't think twice about using a quality aluminum shaft. The car would have to be 2,500 or less for me to think about carbon fiber though.

Camaro_nut

Yeah, I kinda figured you meant that. I'm just giving my
opinion on it.

25THRSS

On my LS1 that weighs about 3600 pounds and has about 550 flywheel hp. I have a carbon fiber driveshaft with 10 inch Hoosier slicks out back launching off a 3200 stall, that acts more like a 4000+ stall in reality. No problems here. And even if I did, it's the safest shaft to break as all it will do is "broom" and not destroy the floor pan like a metal shaft would.

3rdGenBlackBird

I agree. If I'm going to break something, I'd hope that it wouldn't be steel! That might cause some damage... and I don't think DS loops will hold back flying steel.

Laters,
Scott

TKOPerformance

Driveshaft loops aren't supposed to prevent damage to the car. They're designed to keep you alive. The goal is to keep the mangled shaft from smashing through the floorpan and taking out your legs, or digging into the pavement and catapulting your car.

I seriously hope that your LS1 car isn't a street car. The biggest problem with carbon fiber shafts is that they are much more suceptible to damage from outside sources (e.g. not power related). All it takes is a little rubbing and the shaft is totally compromised.

Camaro_nut

Right! Driveshaft loops are only for SAFETY of you the
driver! Just like the roll cage, it's only purpose is to keep
you intact and safe with minimal ( if any) injury. The stiffening
of the chassis is just a bonus ( roll cages).

Whatever you want to use for a high performance driveshaft,
I still would only recommend a steel one. Even you are only
doing 18s or even 8s in the 1/4, steel is the best route. Of
course, you can argue all you want. But it's a fact that heavy
duty steel driveshafts will stand up to more hard launches
than anything else. Why does Spohn only recommend steel
ones? He doesn't make aluminum or carbon fiber. He runs
the drag strip himself ( Steve) with his own steel driveshaft.
I'm sure he's doing at least 10s in the 1/4.

After the accident in my friend's '98 T/A with the factory
driveshaft breaking on him, I don't trust them. He could
have been killed.

3rdGenBlackBird

Uhm, what did you guys assume I meant by "...cause some damage...?"

It's called a driveshaft safety loop for a reason.

I'm sure there are strong DS loops around, but I still think they will hold back an alum or CF shaft better than they could hold back a steel one.

Reread 25thRSS' last sentence of his last post. I agree with that.

Under the right conditions, you can still break a steel driveshaft, and I'm sure that'll cause more damage than a broken CF shaft.

Laters,
Scott

IceManRS305

iTrader: (-1)

how bout with a aftermarket torque arm? does that make any more room?

drew86z28

Hey just installed a new underdrive pulley system as well. I put in the BBK 3 piece with crank, water pump, and alternator. Notice the water pulley is smaller, alternator is a little bigger, and the crank is about the same. This has made it impossible to use the factory belt sizes. Any idea what I can do? My mechanic and jegs (where i ordered the pulleys) has been less than helpful.

Wishmaster's87IROC

iTrader: (4)

there's really no way of telling what size belt or belts you need...just take the one you got now to an advance or AZ and get another smaller one.......by the numbers on the old belt they will know which smaller one to get ya....

trial and error....keep trying till you get the one your happy with.

AD or AZ will take them back til you get the right size.

drew86z28

Thanks for the reply. I'm going to tie a string around the pulleys to get the overall length and I guess my mechanic has a belt measuring device you wrap the string around, apparently it adjusts for tension and gives you a size afterwards. When I get belt sizes and part numbers I'll post them here for anybody else who purchases the bbk pulleys as I'm guessing they'll have the same problem.

burnout88

Why not just go to the auto parts store and buy a few sizes and test fit them. You can bring back the incorrect sizes. All of the part store retailers are understanding when it comes to belt sizing. Start with 2 inchs shorter then stock.

TTOP350

iTrader: (8)

You may want to use your stock Alt pulley if its a street car.
The new crank pulley should be quite a bit smaller than the stock crank pulley.

85Z28NOS

iTrader: (2)

I just went thru this about 3weeks ago. I took my old belt and marked how much shorter it had to be and went down to Oriely and asked the guy for one that length. He went off the number of my original belt and looked up a belt that was 3" shorter in my case. It was an odd ball size that ended up running me $49. Thats funny cause I only gave $55 for the under drive pulleys.

89shane350

iTrader: (1)

i had the march ones, 3 P. set. the instructions said what size to buy, after i bought it, it didnt fit but this stock one did, it was weird. i ended up thating them off for over heating and charging issues

Reid Fleming

iTrader: (2)

Something to consider is what location you live in in regards to alternator/charging issues. Look at who's posting good things and where their location is and where the people posting bad things have listed as their location.

When I lived near Vancouver, I had zero problems with battery voltage. As soon as I moved to Houston, all of a sudden I had low voltage. Why? Because up north, you can get away with vent. And I rarely had traffic situations. Summer weather was 75°/25% humidity. The system runs with ease.

Down south, I have constant air conditioner use. More traffic. And the weather is 95°/60% humidity. So you have hot underhood temperatures, hot alternator which invariably means lower output. A larger amperage alternator won't cure this. The only thing I could do was get high end battery/alternator/ground cables from Innovative Wiring. That fixed the problem for the most part. Wintertime, it's pinned on 14.5 volts. Summertime, it settles around 13-13.2 volts during rush hour. Before the cables, it would run about 11.5 to 12 volts during rush hour.

All the above is with the stock pulleys. Under drive would just make the situation worse. I can't see running the air conditioner compressor at a slower speed being a good thing at all.

If you had a dedicated race car. Or something without A/C that you drove in a northern climate, I could see going with pulleys. But not down here. Not in this heat.

TKOPerformance

I've never had an issue with my alternator charging and I'm running a set of March underdrives. In Delaware we regularly get 90+ degree weather during the summer with a heat index well above 100. No charging issues at all, I'm putting out a constant 14+ volts no matter what (I have an Autometer voltmeter in my car so I can monitor it all the time). One key might be that I run a later model alternator ('87-up style), and its the biggest unit available over the counter (sounds like drugs huh?). When I converted to the serpentine setup I bought everything through my local NAPA. When they asked what output alternator I wanted I just said, the highest one you've got. I'm pretty sure its at least 110amps, and could be as high as 130. The truck and car units are the same (the case clocking might be different, but that's easily fixed), so its easy to get a high output unit for a decent price. If you run the proper feedback wire (avoid 1-wire units, that's really BS, they typically have low speed charging issues) you should never loose charging ability, even with underdrive pulleys, because when demand hits the alternator responds as intended.

I just figured out belt length with a piece of string. In these situations I find you just have to go with what works and gives you some tensioner travel or adjuster travel. What works for one guy may not work for another, particularly when you get into deleting smog pumps, ect. Once you know the right belt keep the sleeve in your glove box, then you can't go wrong if you end up needing a replacement down the road.

UnderCover89TBI

iTrader: (25)

ive had issues. if you just run basic stuff but get into aftermarket fans, and stereo etc you will have problems. IMO these are more for cosmetic than actual performance. Also they made my belt make noise when the a/c is on. I will be ditching these this winter

HawkZ28

iTrader: (2)

FWIW, I had a set with a serpentine setup, and be it Nebraska winters or summers (-10* ambient to 105* ambient), I NEVER had a problem- alt, water pump, etc. In fact, I got just shy of 250k on that alternator- dumped the OEM alt at 78k- before the pulleys. Dumped the rest of the truck at 343k.

March steel set is what I had. On the 4.3L the Blazer had, it made a noticeable difference- best $90 I spent on that truck IMHO. Helped acceleration and MPG.

TKOPerformance

FYI, nothing in my car is stock anymore. I run a BeCool aftermarket dual fan setup, a full custom dash, and quite a bit of aftermarket stereo equipment. I still have no problems with charging. I'll add that I think part of it is also that if the charging system you already have is marginal then an underdrive pulley is going to exacerbate any issues you already have, even those you may not know about. The electrical system of our cars is typically the area that people know the least about. It's treated like there's voodo involved or something. To really fix cars of this vintage, or newer you need a good functioning understanding of electronics. Even a lot of good mechanics fail at this. I think this is why a lot of people have issues with the electrical systems in their cars, and then when something goes wrong they just start replacing parts hoping it will solve the issue.

Also, the earlier your car the lower the output on the stock alternator. If you look at cars from the 60's they typically had like a maximum of a 30 amp alternator. They had no electronics, so they didn't really need the capacity. Even a lot of cars in the 80's were still running 60-75 amp units, which if you had some aftermarket stuff and an underdrive pulley would certainly compromise charging. I'd consider a 100 amps minimum for a setup like that, and truthfully the more the merrier. The higher amp units do cost a bit more, but is it really a bad thing to have capacity that you don't use? I think not. I'd rather have a unit that only runs at say 75% of capacity that one that's trying to run at 110%. Its all about ensuring that the load demanded by the vehicle never exceeds what the alternator can put out, because if it does you are running down the reserve capacity of your battery. When a car is running it shouldn't even need the battery. The battery is to start the engine and to provide some reserve capacity so you can use the electronics in the car without the engine running, nothing more. Once running you should be able to remove it, because the alternator should be putting enough power into the system to run everything the car needs and then some. That's how its able to charge the battery, which does get run down a bit from starting the car. When the alternator can't put out enough to keep up with demand you've set yourself up for failure.

Reid Fleming

iTrader: (2)

All the above is correct. But there are two paths to undercharged situations.

1) Underpowered alternator/too much electrical pull.

2) Heat/resistance

Number 1 would be people with stock alternator and big stereos. Stock alternator for my '89 was 105 amps. Optional (Turbo Trans Am) was 140 amps. It's easy enough to replace a 105 amp with a same sized 140 amp model.

I tried that, but it didn't solve my problem of low voltage at idle situations. That's because I ran into trouble with number 2.

Number 2 is what I call the southern problem. Simply put, you've got both radiator fans running nearly all the time (since the A/C compressor is also running constantly). Add in headlights and sitting in traffic and you have some serious power sucking going on. Adjusting the min. idle RPM helps a bit. But you can run into shifting issues if you adjust it too much (clunking into gear when pulling the leaver from PARK to DRIVE).

But the intense heat (and depending on location, humidity) of the south underneath the hood is hard to deal with. The heat kills the output of the alternator. So a bigger alternator makes no difference (as I witnessed when I tried the 140 amp). In fact, a bigger alternator itself will create more heat. That's why the people with custom stereos will get rid of the smaller CS130 case size of our alternators and build some custom brackets to fit the larger (truck size) CS144 alternator case in there. It has larger vanes for cooling the alternator. Trucks never have charging issues because they have larger case size alternators as well as more room under the hood for cooling in general.

The larger cables (1/0 gauge) that I got from Innovative Wiring cured my idle charging issues. That's because any resistance that is minor enough to not be an issue during winter driving or highway driving is amplified during the summer A/C time (which is 10 months a year here).

All of this is with stock pulleys. My friends up in Canada who use under drive pulleys say they make great gains. My friends down here in TX say forget it.