In my opinion after reading posts here for nearly six years - and after driving 100,000 miles with after market pulleys

FAR more blocks were ventilated running 6# or higher pulleys than 4#

running a smaller upper will result in more potential damage to the snout and more potential belt slippage since the pulley surface area is smaller

90mm is often pushed because tuners have more current tunes for the 90 mm than the 80mm - Unless you are going WAY up in HP you shouldn't need it UNLESS your tuner has limited access to decent modern tunes for the 80mm. Lots more 90 mm lightnings out there than 80..

the more boost you push through the blower the more heat you make and the more likely you might get detonation

All of the above is my opinion

EDIT - FOR BAD SPELLING

 

Personally I would make the move to the 90mm, either stock or the SCT piece, it just makes sense, otherwise every bolt on you make will have the "what if" footnote. They can be had used and are very reasonable.

 

Thanks for your input, I will agree that more motors seem to blow with the 6lb vs the 4lb pulley. However it would also appear that this happens in the states that have rapid changes in the climate. Would you not also agree that ther have been member who have driven thousands of miles on a 6lber without trouble. So I guess that it may also have a lot to do with driving styles, meaning a lot of WOT.

I agree also that more boost = more heat and more likely to cause detonation. So if someone is running an aditional 6lb's of boost he/she should make sure that their fuel filter, plugs age in good condition and they use the highest octane at the pump like 93.

Probably some or all of the guys with 6lbers could give us their opinion on this issue if it really made sence going from a 4lber to 6lber and the problems they have encountered.

These are only my opinions as well no pun intended

 

i think im going to go with the 4. what about the upper pulley though?

 

How? With what bolt ons are you talking about? Please spill all. I am over on SVTPerformance.com as well, and that kind of power is usally only made with a 6lb or more. Hell, 50% of the guys with the same set I got only just brake into the 400/500 club.

 

That is truly a lot of power from a 4lber. Hats off and thumbs up of to you

 

this is an important bit of info that you should consider in your quest to ventilate your stock block
by adding "just 2 more lbs"

If you add the 6lb get a larger heat exchanger and reservoir tank and get the oil off your intercooler..... and get a tune for the 6.

I run a 4lb pulley, port, Troyer e-mail tune and run consistant 12.3@111 and faster below 60 degrees.
I have a larger intercooler reservoir tank and a clean intercooler.
I still need to upgrade my heat exchanger.


If I went with a 6 I would also add a 95 mm Pro-M MAF , a custom tune for the pulley and upgraded heat exchanger.

 

I can speak for some of the guys in my area running more than a 4lb pulley. They enjoyed the increased power and also are currently enjoying engine rebuilds..........these trucks were 2002 models......I also know of 3 trucks in my area running 6lb pulleys for many years with no problems....these trucks are 99 models....... for what its worth. Maybe 99's push less HP compared to 01-UP with a 6 lb pulley or maybe a 99-2000's rods are stronger.

 

anyone ever have engine problems from a 4 lb pulley?

 

Thanks for your imput RED 92. May I ask if you are suggesting that anyone with a 01 and up L avoid a 6lb pulley? For the rest of the members on this board can we confirm if the 01 to 04 L had stronger rods. If so we may have to make sure the we all get a dyno tune if we are running a pulley larger than a 4lber.

I currently have a 4lber tuned by Troyer performance and I have absolutely no hint of detonation, and I am seriously considering going to a 6lber in fact I have already called them about it. If the consensus is dont go or you will blow I am all ears for other suggestions for improving power for a similar cost.

 

Fowl

I think it is important to keep in mind that when reading any post on this board that 90% is opinion (especially my BS ).

The rod debate has been speculation since I have joined (and well beyond) and I think we all want to feel like "my year is the strongest year".

I think it is fair to say that improvements to the L happened over the years of development, just like any performance model, but I am not aware of any statistical evidence that 100% proves one year over the other has stronger or weaker rods! I think most will attest to that fact.

Where are our lawyer brothers when we need them - Mennace and Tim?

I do think that we can all agree that the only safe tune is stock!

That the minute you alter your pulley dimension you are taking a risk!

And that your tune has the greatest impact!

I respect most opinion's especially if it is backed by their own "factual" experience, but remember that is based on one L - their own. Your's or mine could be a different story - especially when pushing the limits.

It is better to over build an engine then over perform it and most of us who take the risk of modding are unfortunately over performing!

Hell I ran my '03 at 16lbs boost, KB for 12k miles not one problem, but this time around I am not willing to take that risk and I am content with 13lbs boost and 100 less hp - but still - I am taking a risk - caluculated or not.

The debate will go on and on - I think you need to assess your "risk" factor and go from there - as proven over and over anything can happen. A good example how unique each L is - When I sold my '03 I gave all my mods to a friend with an '02 (we know of many '02's pushing big hp and torque holding together) - he had the same tuner (who is conservative) applied all my mods with 2lbs less boost and two months later on the hwy, boom - so who can tell?

Good Luck!


D-Dan



D-Day

 

that if you have long tubes and high flows, you will loose some boost, so running a 6 is like running a 4 or 5.

 

Very true. I guess it depends on the luck you have with the motor you got from the factory (as far as quality of components, tolerances, etc.) I've been running a 6 lb (400/530 SAE on 91 oct.) on my '99 for 60k out of the 98k miles it has. Stock tranny (FTVB). I don't baby it by any means. Haven't cleaned my intercooler; no added heat exchanger; has a ProM 80mm MAF; haven't even changed my plugs; just regular oil/fuel filter changes. I'm down maybe 5 hp indicated from my most recent timeslips. I would never trade it in on a new one. I do live in CA. Haven't done a thing more to it in 3 years. My bike is the new money pit, but the truck still brings a smile to my face (and a scream out of the girls )

BD

 

Right, It would appear that it depends on the truck. So you are still running the stock plugs? WOW you are really fortunate. I mentioned in a earlier post that if anyone is going to run a 6lber that it would be a wise idea to change the filters on a regular basis, it would appear that that helps.

Hopefully others running 6lbers will chime in and tell us their opinions. Another thought just came to mind, what about those guys running 4lber and ported blowers, arent they over 14lbs of boost? That should be more than a 6lb pulley. Are they safer than us who might consider a 6lber?

 

folks are asking a lot of questions that have been covered a bazillion times in many other threads (is the search feature broken or are we just lazy?). anyway, yes a 4lb with port is generally considered to be safer than a 6 lber alone. this is becuase the port allows a better disbursement of air across the intercooler, thus lowering air intake temps for a relatively same amount of boost-- 4lb w/port vs. 6lb only.