Hey guys, I'm new posting here but i've been a reader for a few years now. Anyway, I have a 2000 L with a K&N, and Flowmaster catback. I installed a Motoblue 4 lb. upper pulley today and ran a 93 octane performance tune with the Diablo Predator. My first WOT showed 10 lbs. on my autometer, which is exactly what it was before the pulley install. It feels a little stronger, maybe...i dunno...should it be a big noticable difference? Am i missing something? If anyone has any idea what i may have done wrong or if there's something stupid i missed please let me know. Thanks for any help.

 

you mean a 4-lb LOWER pulley, right???

Did you upgrade spark plugs?
MAF upgrade needed to 90mm??
Proper belt length used?? slippage??

I also did a 4-lb lower and predator on my '01 but had a dyno/tune to be safe. Sorry, not an expert here myself, hope the gurus chime in. Good place to ask also here: http://www.nloc.net/forum/forumdispl...s=&forumid=399

 

was it a 2.7 pulley?

 

I don't have a MAF upgrade as of yet but a 90mm should be here next week. I haven't changed the plugs either, should I? The pulley is supposed to be 2.75 and on the RPMOutlet website, one description says 3 lb. and one says 4lb. for the same pulley so i'm not exactly sure which it should be, but either way my boost gauge is reading the same as it did before the install. Thanks for any help guys.

 

I just became aware that stock lightnings run 8 lbs of boost. It was running 10 lbs. before the 2.75 upper pulley install. I looked at both pulleys when I got the truck from the first owner and neither looked tampered with. Is there anything else that could make it pull 10 lbs. besides a pulley? And even if, i should be pulling 13 or so now right?

 

My stock Lightning put out 10 lbs boost, and 12 lbs with a ported blower. Now, with the 4 lb lower it puts out 15.

 

most stock Ls with an intake kit, even drop-in K&N, will hit 10lbs boost. a 2.75 upper is not a 4lb pulley. 2.93 is supposed to be stock size but i've heard from a well known tuner that some stock uppers vary between yrs models lightly. ? Take everything you see/hear at RPMOutlet with a grain of salt. a 2.75 should be more like a 2lb pulley (some may say 3lb but I think 2lb), 2.80 is about 1.5lbs, a 4 lb is 2.60" and with the latter you have to grind your snout down to use that pulley. I should think at the top of 2nd gear, if all is running right and no belt slip, you should be right about 12 lbs. but with the heat i wouldn't be surprised to see only 11. take it out at night and try again, see what she gets up to at top of 2nd. you may be getting belt slip. use a good gatorback or gates belt that fits it tight enough but not too tight.

 

Thanks for the replies. Sammy, I suspected exactly what you said about that pulley. Where should i go to get an honest pulley? Also since it looks as if i'll need a new pulley anyway...what's the most boost I can safely run with my setup? Should I maybe go with a lower pulley now? I'll take it out tonite and see what happens but it doesn't look like the pulley I put on made any difference on the gauge. Thanks again.

 

there's nothing WRONG with your pulley of course. if you're never going to be changing the pullies out, go with a 4 or 6 lb lower. lowers are less prone to belt slip. what is the safest boost you can run? That is the million dollar question asked a thousand times so i'm not going to go into that topic any more you can research that topic for days on end.

i really like the Southern Florida Pulley Headquarters non-slip Dial UR boost upper pulley kit. that's what i would buy for the upper. lowers reduce some rotating mass though. if you are going to be towing much weight, you don't want to have over a 2 lb pulley and you should get a good towing tune with it.

since you already have a 2lber, you could get a 2lb interchangeable lower. that's pretty close to 4lb combo, and with the 4lb lower you'd be right about 6 lbs. plus changing back to a stock upper would net you ~2lb additional. ultimate combination there.

fyi, it takes me about 15 minutes to swap lower pulleys and belts on my LFP interchangeable setup. maybe 20 if i'm taking my time. takes a breaker bar, a pry bar, allen socket & rachet, and is very helpful to have someone bump the motor over twice while you're under the truck b/c the top bolts are hard to get to due to stock fan.

 

Lightning1225, you may have been reading these boards for a couple of years, but you still have lots of work to do. I would spend time reading the FAQs and searching the archives.

If you keep just spending money and slapping on parts without first doing the research, you will almost certainly get disappointing results -- followed by catastrophic engine failure. No insult intended, but judging from your questions, you are not nearly ready to be modding your engine. It's not that you are not smart enough (I'm sure that you are), but you plainly don't yet have enough information to be able to make the right decisions.

Example: There is no reason to do an upper pulley until your are out of lower pulley options. This is Lightning 101 stuff.

 

Sounds like belt slip to me. Take your finger and run it on the ribs of the pulley on the under side of the upper pulley where the belt isnt touching. If your finger turns black then you need to call tim @chickeneers and buy a metco idler kit.

 

there is an old school spreadsheet here that will help you try to figure out what you really have as far as pulley - Blower rpm boost etc

http://www.svtlightnings.com/svt/how-to/blowerrpm.htm

As Tim said you need to read some more. There are a TON of threads here with bad things to say about RPM outlet and lots more with bad things to say about upper pulleys .. Lower is the first choice for a number of reasons

Doug