i have a 95 z28. my only mods are...
Perfomance mods..........
1. K&N cold air intake
2. Trick flow elbow.
3. Magnaflow catback, w/gutted cat...(went bad)
4. slp air foil booster (throttle body mod)
5. RPM Speed Strut Tower Brace (red)

now i want to spend some $$$ and i was thinking of some stuff. but i dont want to **** my money away...

some stuff i was going to buy...
1. march underdrive pullys (crank, alt.)
2. 1le a/c delete pully/braket
3. 52mm throttle body (summit $249)
4. throttle body bypass

so is it worth doing those mods??? also how short of belt do i need for the underdrive kit? is taking off the a/c compressor hard? what special tools are needed for all the pullies and compressor???[/align]

 

[&:] blu oval some of your intended mods may be worthwile while others will certainly be marginable at best. the underdrive pulleys and ac delete dont really make any more horsepower but simply reduce the parasitic hp draw of the items. remember if you do the pulleys the alternator may not keep up with a bumpin stereo or other draw during a long low speed cruise or idle situation. the ac delete well i guess if you dont mind not having ac ( even here in the northwest it comes in handy once in a while) the ac also helps to defog the windows. the hp draw is really minimal

as for the throttle body i dont think its money well spent, i forget the numbers but the stock one will flow just fine even with some mild mods and is really only beneficial if other mods like engine internals, headers, intake etc that will sufficiently change your motors breathing requirements. not money well spent. the throttle body bypass i think has yet to be dyno proven by a REPUTABLE source to provide much if any improvements and will most likely cause throttle body ice up in high humidity and cooler temps

march should be able to tell you what size belt you will need for thier kits. the sucky part of these new cars is HP no longer comes cheap. save the majority of your cash and start planning on mods that increase airflow thru the engine. to make HP gains that are really noticeable plan on spending literally thousands as a minimum. probably your best bet is a 50 to 100 nitrous shot for a good and relatively cheap HP increase,HOWEVER be prepared to tune this set up to avoid costly repairs. kurt

 

. march underdrive pullys (crank, alt.) ok as for these what t9ojetpilot said is incorrect i have a underdrive crank pully and it does the oppsite of because its smaller it spins faster so u have better power from the alt, it was one of the 1st things i did to my car and i never felt a back in ur seat feeling, i say wait on that,exp and no real hp gain, maybe at higher rpms a couple...
2. 1le a/c delete pully/braket I have done this as well but no real hp grain here either, again maybe higher rpms, the a/c seleate is nice for lossing weight but notthing noticeable....
3. 52mm throttle body (summit $249) on this i say wait tell u need it this well not show hp gains either really untill u get into ur motor and it well need more air then, safe ur money here till u need it....
4. throttle body bypass I dont have this but if ur car is a DD (daily driver) i wouldnt bother cause it isnt going to do much with what ya got right now anyways...

depending on how much u got it u want to c inprovement right after i would get headers and a y pipe, get a good tune up plugs,wire, opti, fuel fillter exc.and if u want more speed and u want to feel it u can change gears up from what ya got but if u do that get the insalation kit with it so u dont blow ur rear... thats what i would do now cause that will help the most with what u got now... I hope that helps

 

8485, the point of an underdrive pulley is to slow the spinning periferals and thus reduce the paracitic loss, if it spun them faster you would get a decrease in HP, which wouldn't make sense now would it?

Ovulator: The 52mm TB is a waste of money on an otherwise stock motor, you're going to need to get some internal mods such as heads and a new cam before you would get any power out of a new TB. That being said I wouldn't even screw with a 52mm, you'll want to get heads, cam and a 58mm TB. You'll have to port your intake to match the 58mm, but it's money better spent than a 52mm since you have to do internal work anyway to see any gains.

The throttle body coolant bypass is the most worthless mod you can do, it's not that cheap and it may get you 1 to 2 HP and decrease drivability if you live in an area that has cold climates.

The A/C system only draws power when it needs to, otherwise the clutch in the A/C compressor is disengaged, so as long as you're not running the A/C on the track (or the defroster) you're not losing any power, all it's going to get you is around 20-30 pounds of weight loss between the compressor and the condenser.

Instead of the mods that you have listed, why don't you consider saving up and getting a good set of Long Tube headers and a new Y-pipe. That's a mod that you can actually see some good gains. Check out Kooks or Dynatch headers.

 

i would get headers, but the bolts are all rusty and i know it will be a pait to put them on. i dont think i can handel it lol...

 

u got it backwards dude. lets say the stock pulley is 18 inches around. so with each revolution of the engine 18 inches of belt passes through. now the smaller pulley is 15 inches arround (again, arbitrary numbers). this means that when the motor turns once 15 inches of belt moves. now IF you were to match this with a smaller alternator pulley, you can counter act this effect using the same logic. IF the Alt pulley is 8 inches around, 8 inches of belt must pass over it in order to get one revolution. if you move to a smaller pulley, say, 5 inches around, only 5 inches of belt need pass over the pulley to get one revolution. the key is identifying the drive pulley and the driven pulley in any belt system.

Ovlh8ter,
i would definitly do exhaust. just suck it up man, your bolts should come out fine. best bang for the buck at the stage ur at. if you absolutely wont do headers, then look into a good off road 2.5" mandrel bent ypipe. i believe stock is like 2.25 or something right? a larger ypipe will get u a little better power, altho both slvr and I are huge supporters of LT's whenever possible

 

All those improvements should make make about 5 extra horsepower to go with those other power adders.

 

The stock Y pipe is 2.5", but it's compression bent and is horribly restrictive.

Ovulator: Suck it up for a weekend or two and go for the headers. The bolts will come out of the heads fine, aluminum heads don't rust, so providing your bolts are seized to the head you'll be fine (they probably aren't going to be, so don't worry about that). The only bolts you may have some trouble with are the bolts between the manifolds and the stock Y-Pipe. Mine were horribly rusted and I twisted off 3 of the 6 while trying to get them off, but it's not like it matters if you're doing headers since you're replacing the Y-Pipe and manfolds. The hardest part about doing headers is jacking up the engine a bit and fitting them in, other than that it's 8 bolts and some time. Make sure you give yourself plenty of time, get a friend to help, and get some beer.

 

mine were too.didnt u know that the sawzall is the magic tool for exhaust removals?

 

not trying to start a fight by anymeans here guys but, the smaller under drive pully means u need a smaller belt i know cause it took me 4 diff belts to find one that works, and the way i said yes i was kinda wrong. but this is a better way to say it is if the old pully had to spin around 8 times to turn the old bigger belt 22in long 1 complete circle and the new smaller pully only has to spin 6 times to turn the new smaller belt that is 18ins around once then the speed is the same but it well spin the alt more times in one min then the old one cause the belt has less to travel to complete one turn.. now this numbers r just exempeles but at this numbers at ideal it would be like this

old pully 8:1
new pully 6:1

rpm's at 1000 means
the old belt will spin 125 times
the new belt will spin 166 times

its all in the math "old pully"1000 devide by 8 =125 and the "new pully" 1000 devide by 6 =166
but it does have a benifit to the fact it is way lighter then the OEM pully and in that case think of it this way it takes less effort for the eng to spin a 1lb pully then a 5lb pully.. No i dont work for any co that sells them and u guys r right theres not much hp gain or is it worth the new cost of one for what it does do, but on that same token its not a really bad thing to help cause as we all know u can still lose a race on a track cause of 0.001 sec slower then the car next to u and that underdive pully just maybe that 0.001 gain u need, lets just say this if u can pick one up cheap its not a bad ideal and it wont hurt, BUT could help just that little u need.