Alternator pulley needed for 6 lb metco lower????

I finally am getting around to installing a metco 6lb lower pulley to a basically stock cobra (03)
I am also getting a SCT flash tuner by a very reputable vendor set-up for my car which will have:

6 lb lower
2.95 upper
Sct Flash tune with custom program for my car set-up by vendor
No idlers or aux idler... yet...
K&N FIPK
Boral Stingers
Stock cat pipe.
Stock fuel system

My question is, should I install a 3.2 Dia alternator pulley... or can I stick with the stock pulley. From what I gather, I will be spinning the alternator faster by a ratio of 9.1/7.5 (6lb vs. stock lower).

Secondly, is the 2.95 and 6 lb pulley combo too much for the (h)eaton.

The vendor is telling me that I most likely will be fine with the stock size alternator pulley. The reason they are stating is the programming going into the SCT. I don't quite understand how a program in the tuner can help this problem. It seems to me that spinning the alternator faster is a function of the engine rpm, not a fuel curve or timing adjustment... Am I missing something?

Slightly confused????

Thanks

yes you will need a alt pulley

OK, thanks

I happen to have the pulley, is it difficult to install? anyone??? do you have to remove the alternator to get it on... on my old 5.0l's I used my electric impact wrench to pop it loose. It kinda hard to turn a nut if it keeps spinning...

Need an impact wrench to take the old sucka off.....takes about 35 minutes to take the alternator out of the car if you follow Black 03's instructions in the "How To" section of the Terminator Forum.

And that 2.95/6 lb combo will be alot of fun on the street, but with your unported Eaton, once you get above 5,000 rpm or so, your Iat2 temps are going to start to shy rocket pretty quickly and hurt your power production. You're probably going to get about 540 RWTQ from this combo. I'd definately port the blower if you want to maximize this combo.

But, there are still going to be some very respected folks that are going to tell you that the 2.95/6 lb combo is too much for the Eaton, whether it's ported or not.....

Actually, if you're changing the lower pulley, the alt pulley is pretty easy to get to. You have to unbolt the alt from the car, but since you are removing a bunch of crap from that area anyway to do the lower, it's not bad. I just unbolted my alt, rotated it so the pulley faced down, and took my impact and unscrewed the pulley...put the new one on and tightened it up. I didn't have to remove it from the car. You have to make good and sure about the spacer though...I can't remember if you use one with the new pulley or not. It will be easy to tell.

It looks like a 3.5" pulley is what you need.

Thanks for the info...
What is the code for the chart... Green = Good, yellow = marginal, pink = not good???

Oh, one more thing, anyone have any info concerning what the vendor is telling me????? I really don't want to mention the particular vendor, I don't want to start a sh_t storm here. Thanks,

Why not just discuss it with the vendor? Maybe there is some reason we aren't hearing. I personally can't see any reason why you would use the stock alternator pulley with a 6 lb. lower. You do need to install the 3.4" pulley.

OK, I did talk with the vendor today and he said he has never seen an alternator fail due to 2, 4, or 6 lb lower pulley being added with a stock alternator pulley.

This vendor is a very respected member of the terminator community.

These alternators fail all the time prematurely. Some have come to the conclusion that its location does not allow it to dissipate heat well. Common sense tells us that spinning something faster is going to create more heat so it's really more of an insurance policy. I can't really see how anyone could say that their pulley did or didn't specifically cause a failure but we know that there's no way it's good for the alt. I decided to run a 3.5 on mine and I'm also running a 6lb.

OK, thanks for all the input.

OnFire4C said:

OK, I did talk with the vendor today and he said he has never seen an alternator fail due to 2, 4, or 6 lb lower pulley being added with a stock alternator pulley.

This vendor is a very respected member of the terminator community.

Click to expand...

hrmmmm ok...

Run without one and IF your Alt dies.... have the very respected vendor pay for and install a new one. :beer:

I just read the HPbyHerman thread about the low voltage issue with the stock alternators and added electrical items that draw more current than stock. I plan to go ahead and install my 3.2 pulley that I got with my metco lower.

Thanks

I would go with a 3.7" to be safe man. I am keeping my 4" from my 8lb on when I switch to the 3.1/6lb if that helps you any.

alt. pulley chart

thanks for putting chart up, i have had this question needing to be answered before i put my new pa alt. on. i have lfp 4# lower which is 8.75", they are different in size compared to the others, so as for this chart i am going to go to a 3.7 alt. pulley with my 4#lfp lower. looks like its saying 16,000 rpm should be a safe limit to spin the alt. ? as for the 2.95/6#lower(9.1),this is a blower ratio of (9.1 divide by 2.95)=3.0847 (3.0847x 6500rpm=20,000rpm blower speed)on a stock eaton its efficiency is more than maxed out but the low end torque is wild,up top boost drop off is exaggerated with this pulley ratio,port that baby. merry christmas everybody !!!!!!!!

jmproductions said:

These alternators fail all the time prematurely. Some have come to the conclusion that its location does not allow it to dissipate heat well. Common sense tells us that spinning something faster is going to create more heat so it's really more of an insurance policy. I can't really see how anyone could say that their pulley did or didn't specifically cause a failure but we know that there's no way it's good for the alt. I decided to run a 3.5 on mine and I'm also running a 6lb.

Click to expand...

I agree 100%.

OnFire4C, definitely do not stay with the stock alternator pulley if you're going to use a 6 lb. lower. Do you really want to risk your new alternator?

That's a fairly large alt pulley. But as long as you don't have any low speed charging issues, (and I'll bet you don't) you should be fine.

dougwg said:

hrmmmm ok...

Run without one and IF your Alt dies.... have the very respected vendor pay for and install a new one. :beer:

Click to expand...

Where has it been proven that a 2lb, 4lb, or 6lb lower pulley will cause alternator failure when using the stock size alt pulley?

I'm still running the stock alternator, along with several others I know, and we have had zero issues. I change my boost level all the time with different pulley setups, (3.5, 3.2, 3.0 uppers, 4# and 6# lower rings) and notice no difference on my digital voltage gauge at WOT. IF/when my alternator fails I will try to determine the cause and post my findings.

If you choose to use the stock pulley, great. Larger pullies are made for a reason. Please read the other posts above and it is pretty obvious that an upgrade is in the best interest of the alternator. And this has been discussed at length in many other threads. But again, use what you like. I just don't think it is smart to swim against the current on this one. JMO.