TKOPerformance

Heat does play a role, because as noted it increases resistance. One thing I forgot to mention is that you should run at least a 4 gauge wire from the primary output on your alternator to the positive terminal on the battery. Stock this wire is like 10 gauge which is not enough. Also, the finer the strands in the wire the lower the resistance and therefore the less voltage drop. That's why high end stereo wire looks like hair made from copper.

If the alternator's heat soaking that's another problem. There are products that will dispel heat that you could paint the case with which might help. Though, aluminum already rejects heat pretty well. The bigger case units simply have more surface area. If that's the issue then you might also be able to adapt a heat sink or two to the case. Aluminum heat sinks are found in all kinds of electronics, one reason I scour old stuff before throwing it out, even when its broken. You need a good surface area to surface area connection, and adding some zinc oxide between the two surfaces gives an even better coupling (done all the time for processors, etc.). I've used heat sinks to reduce the temp on RC car batteries (I used to cook mine with the load imposed by my super hot motor), desktop computers (allowed overclocking the processor without issue), and many other uses.

The fan on the front may also not be moving enough air, and if you slow that down with an underdrive pulley it may get worse. It might be worth seeing if different alternators have different fans (blade count, etc.). Typically when you buy a reman unit you don't get the fan and pulley and have to reuse yours. If you throw the fan for a low amp unit on a high amp unit you may compromise cooling. The truck alternators usually have a pretty crazy fan (the one on my Blazer had sealed air passages and like 15 passages in it), I'm assuming ti cools well since I have never had an issue with it charging either.

bgood71

I installed the March 3 piece underdrive pulley set on my T/A about 5 years ago with no charging issues. The car has not been on the dyno and I don't think there have been any noticable hp gains, but the engine does seem to respond to throttle much quicker. I had an 87 T/A with a mildly built 400sbc(oe 350tpi), and this car with an otherwise stock engine aside from the pulley set, revs up much quicker. So in my experience, pulley sets won't pin you to your seat, but will increase throttle response.

TKOPerformance

There is absolutely a measurable power gain. If you had the car on a chassis dyno you may or may not see it depending on the dyno's correction factors and degree of accuracy. On an engine dyno the effect is well documented. Honestly you are looking at maybe 10HP though. Granted that's good enough to shave .1 seconds off your 1/4 mile ET, but to see that benefit you'd need a car that was extremely consistent and even then you'd have to look at corrected ETs because of the effect that weather conditions play, even during the same day or night of racing.

On a side note, the whole seat of your pants thing is no way to measure a power increase, especially not at this level. Do something radical like add a blower or a totally new engine with different heads, cam, etc. and yes it will be obvious that the car is much faster than it was. You have to figure that you are talking about 100+HP there. At this level you are adding 10 at the crank, so maybe 7 get to the rear wheels. On a car that makes only 200HP that's only a 3.5% increase. The more power you're making the lower that figure gets, as does the likelihood of noticing it. Also, when racing I've noticed that often my fastest runs felt the slowest, and my slowest runs often felt very fast. Slow is smooth and smooth is fast. Sounds weird, but its 100% true. Shifting by ear isn't the same as a tach with a shift light., footbraking isn't a transbrake, and the seat of your pants isn't a dyno. I'm not trying to tear anyone down, just stating some facts. In fact it took me quite a lot of racing to realize those things.

I don't think anyone is going to call underdrive pulleys the best thing they ever did to a car or truck. You will gain some power and efficiency back, and maybe a smidgen of fuel economy, but that's about it. It's more likely that we've added them to our rides because it was another project and we take pride in having done it ourselves. For gearheads its all about the next project (sadly this is often how we take on too many or bite off more than we can chew). It's a sickness and an addiction, but there are certainly worse ones out there. Now I have to go, I see an Olds Cutlass in the swapper that I in no way shape or form need, but it could be really sweet with a turbo'd 455 and a T56, better call before its gone. I'll be sure to put underdrive pulleys on it too though, in keeping with the theme.

crazynights

iTrader: (3)

I ran the March Under Drive Pulleys in two engines and in my experience both suffered charging and heating issues. Again, this is my experience. I noticed the lights would get really dim at stop lights and also the temp would be around 220..not bad, but just didn't sit well with me. I got a set of standard size pulleys and figured I'd try them for a while. I noticed the car at stop signs (idle) and slow driving (stop and go traffic) my Z liked the standard pulleys better so I kept them.
Again, I know many people who run them and love them with no difference in anything.....as the saying goes...each engine is different and responds to different things...and this was my experience.

UnderCover89TBI

iTrader: (25)

Yeah im going to be gettting rid of mine because I cant stand the tensioner chirping when I have the a/c on during the summer..makes the car sound like ****

TKOPerformance

One thought on the hot running issue is that these cars were set from the factory to turn the cooling fans on at 220 degrees. Consequently that may be entirely normal. If the fan is not electric, or there are other non-stock components in the cooling system this will obviously have an affect, but it's important to note things like that when responding.

I'm not saying that the pulleys didn't cause the condition, what I'm saying is that in order for information to be considered objective there need to be controls on the situation like in any experiment. It's like when a person runs their car down the track, gets ready to run again and changes tire pressure, decides to launch at a different RPM on the next pass, and adds 2 degrees of timing. The car slows down or speeds up but they can't really tell you what did it. I'm, not talking about a pro race team that has all the info needed to make multiple changes like that, I'm talking about Joe average weekend warrior. You need to build a database of info on the car to know how it will respond to changes, and that can only be done one variable at a time.

That's why it's important to observe the behavior of you car before adding aftermarket equipment. It could be a case where the equipment caused and issue, or it could be a case where it exacerbated and existing issue. It could also be a case that the car always did what you're just now noticing. I think it's important to be fair to all manufacturers, and we can't do that if we aren't 100% sure that the new part caused the issue.