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Thread: pulley/boost/tuning question

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    pulley/boost/tuning question

    OK guys, help a newbie out without being to harsh! I'm looking at doing a pulley swap for some mild extra horse power. Not looking at getting into much at this point. I've read many times that you can add the lightning stock upper, and add 2# of boost, and not have to have a tune. My question is what kind of boost can you have on a stock tune? The lightning uppervmakes 8#. Can you go 10# or is that's much? Thanks in advance for the help!

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    Although I plan to get into self-tuning sooner than later at this time I can't speak intelligently on the safety margin for either a Lightning or the HD factory tunes or how they compare to one another. What I do know is that many guy have pullied up on their Lightnings by a couple pounds and they seem to do it with no ill-consequence. Personally I don't recommend doing this but if you do I would encourage you to at least take it to a dyno to have the AFR verified.

    To give you a better understanding of pulley combination, going small on the SC pulley achieves the same affect as going larger on with the crank pulley. I mention this because pulley ratio is the better yardstick to use when considering pulley combinations. Boost is essentially a measure of resistence and is effected by numerous variables such as ambient air temp, porting of the SC, heads, cam, exhaust, etc.

    Pulley ratio refers to the number of revolutions the SC pulley makes for every one revolution of the crank pulley. Pulley ratio is very simple to determine... just divide the diameter of the crank pulley (in inches) by the diameter of the SC pulley (in inches). This number is expressed as a ratio. For example, the factory HD pulleys measure 7.5" (crank) and 3.16" (SC)...

    7.5 / 3.16 = 2.37

    When expressed as a ratio it reads 2.37:1. This tells you that the SC pulley is making 2.37 revolutions for every 1 revolution of the crank pulley.

    I mention this to illustrate the point that if/when you decide to pulley-up you can either swap to the Lightning SC pulley (2.93" diameter), or you can retain the HD SC pulley and go with a 8.0" (2#) crank pulley and achieve the same result while minimizing the possibility of belt slip.

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    To start...Leave the upper pulley alone on the HD.
    I did a 6# lower pulley (semi conservative good for DD), NGK-TR6 (colder) plugs and (in my case) a Diablo Predator hand held tuner.
    This is Also Know As P.P.& T. Tons of info on Boost to pulley ratio on here. The search feature is your friend.
    Even with that, if you give it the goose make sure OD is off (light is on). This will hopefully avoid the two gear kick down (go boom).
    Then for that extra grin with the fun pedal, I'd do a Punisher Valve body.

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    I think the majority of owners go with replacing the lower pulley with a larger diameter one. Replacing the upper pulley isn't as popular because of the limited benefits you get whilst also having to add more mods like a MP bridge and larger idlers to obtain more belt wrap to prevent slippage.

    An OEM L will make 8# boost whilst an OEM HD only makes 6#. The L also comes with a bit more aggressive tune as wel as the smaller upper pulley. Even an OEM HD could benefit from a dyno tune with zero mods as the factory sends them out with a really rich and safe tune.... but equals lower performance.

    Just remember, you have to pay if you want to play. I agree with Merlin's post above. Do the pulley, plugs and tune and then a transmission valve body for a good wake up call. After that you can take your time to see what deals pop up and see what other mods interest you. Have fun and be safe!

    Here is a good read which explains a lot of things regarding the pulley's.

    http://www.nhtoc.com/vbforum/showthr...t=pulley+chart

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    Thanks for the info guys.. I already have the valve body job done..like I said, I'm just looking to add a few ponies with our breaking intov the piggy bank much, as I'm just starting a street/strip fox body, and can't not stop running derby cars! Me and the guys from the car club are going racing at the strip for fun, and I was hoping to add a little boost, a few ponies and maybe get a slight edge on them at the track. B that'd why I was wondering if going 4# over stock is to much without a tune and I should just go with a L upper and get 2# and maybe 20 horse.

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    Pulley
    It's best to leave the upper pulley alone and add diameter to the bottom.
    I like a 6 pounder. I'm conservative. Some folks go with 8lb lower.

    Plugs
    Many folks on here use the NGK-TR6 colder plug.
    It is also recommended that you clean the inter cooler.
    This is a good time to change the plugs. It makes it much easier.

    Tune
    Woodbine Motorsports sells the SCT X4 Power Flash Ford Programmer.
    I personally use the Diablo Predator. It does what I need it to do for me.
    You may be able to pick one up for about $100. It has a canned pulley tune.
    It is highly suggested that you get it dyno'ed for performance and safety.
    How to pick a hand held tuner? Choose the one you Dyno guy likes to use.

    If you're shopping (on a tight budget) you can do the PP&T for approx $250

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    Quote Originally Posted by #4424 View Post
    ... B that'd why I was wondering if going 4# over stock is to much without a tune and I should just go with a L upper and get 2# and maybe 20 horse.
    In agreeance with the others here, save the headache of dealing with the upper change, and just change the lower. If you only want to add 2 lbs, just install a 8" lower and leave your HD upper on there. You will gain a little boost. But I am afraid that without a tune and weight of the truck the difference will be negligible.

    But, if you're diligent and keep an eye on the for sale page on fb and the forums you can get a used tuner and a 6lb pulley on the cheap, then you are a $125ish email tune and plugs from really enjoying your truck. The 8" lower is really not going to add much seat of the pants fun for you.

    Sold my 2002 BLK #9638 to my wife's uncle, Sold my 2003 BLK #6682 to a nameless man local to me.

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    That's the info I was looking for. So I guess I'll keep my eye open for a used tuner and go from there! I already have plans on cleaning the IC, and doing a plug change next week as well. I have bought an oil separator already. I've heard that cleaning the IC alone, you will notice a throttle response difference just in that. Truck has 120k on it, with no seperator as of now, so I'm sure that it's not too pretty in there! Plus I've already bought new coils to do at the same time as well..thanks for the help guys and I'll jeep you updated with the progress and decisions!

    Also if anyone sees a used tuner on here or anywhere, let me know!

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