Danko

Well that was simple enough but now I have to ask is the only difference the upper pulleys and is it that simple? Putting an L upper on a HD and changing"stock tune" gives the HD 40 more h.p.? Seems like there has to be a catch here somewhere......... "Stock tune" needs what to be changed? Yeah, I AM this ignorant!

bgstew6

Well you can take two identical motors with the same amount of boost. One has a tune with say 14 degrees of timing and fatter A/F ratios and the other has 16 degrees of timing and leaner A/F ratios. The latter of the two will produce more HP. (Hope I got that Right).

Then you can factor in the parasitc loss that keeps the Harley from efficiently putting the HP down to the ground. Two peice steel drive shaft, heavier wheels/tire combo each, different rear end gears and overall weight of the vehicle.

I think that the lightnings wheel/tire combo weighs as much as our 20 inch wheel alone. The lightning also has a one peice aluminum drive shaft, and over all is lighter than the harley.

One of the experts will chime in here I am sure and give you some mathmatical computation to determine the parasitic loss in relation to rotational mass. LOl

THat is about as good as I can break it down for you.

Danko

Damn! That is good! So what should an old fart consider doing to his nice two HD's, if anything, other than just drive them and trade them in on SuperDuties? If I could kick up the performance a bit with low effort and expense, maybe it would make sense? I have a 2005 regular cab F250 being built this week with the newly improved 362 h.p. V-10 with 457 ft.lbs. of torque, a 4.30 posi, steps, best radio, 6 speed, etc. and going out the door for $23K including 6% sales tax and $3K rebate on employee discount (thnx to a bro-in-law who had been with Ford but was not when I got the two HD's but is again).

bgstew6

6lb lower pulley with app belt runs bout 180.00
K@N Flat panel high flow filter bout 48.00
A LIVE (not mail order) Custom Dyno Tune from a reliable tuner = bout 350.00

SHould get ya up to the 365-375 RWHP range

Lightningforce

Here is what LFP offers.
LFP Quick Change upper pulley with choice of a 2.80" upper or a 2.93 upper. Hardened steel hub, CNC machined billet aluminum pulley ring and stainless steel Allen bolt hardware........$89.00

LFP Quick Change lower crank pulley in just about any size you can imagine........................................... ..........................$188.00
Kit includes LFP mounting Hub, LFP pulley ring ( in 5 sizes, based on a 2.93" Lightning upper the sizes add 2#,4#,6#,8#,10# of boost ), Proper sized Goodyear Gatorback belt, Allen bolt hardware, converter lockup tool, forged 14mm hex tool.

LFP also has a power package that includes our lower crank pulley kit, Predator tuner, NGK TR6 plugs, 160 stat.......$459.00
Custom tuned ExCal2 also available for this package.

Add an LFP 12" power stack CAI for as little as.............$119.00
with new pre-installed air charge sensor.

Mark/LFP
1-281-385-5339
www.lightningforceperformance.com
" Check IT Out "

BlairTruck

way to dig this one up mark

fordfan1

great thread here i had no idea about the pulleys putting out less boost in hd's

fordfan1

hey guys 1 more question id 6 is really 4, and 4 is really 2, then there is no point in putting on a 2lb'r is there since it wil put out 0?

tonysailor

Have you replaced the upper pulley?

I recommend using an L pulley. A used one is about ?? I can't recall ask around.

Do a search for the pulley boost formula. Then research pulley size because a 4lb pulley might be a different size from company to company.

best of luck,
T

Harley#356

not exactly, there is a ratio so its not an exact 2 lb less equation. a 2 lb will add some boost since its going to be a bigger diameter than the stock lower pulley since its the same size lower as a L's lower, but it wont add the same 2 lbs of boost it will on a L, but it has to add something since its a bigger pulley.

there was a chart somewhere's on here with the exact math figured out. ken800 on the boards years ago was great for doing the nitty gritty calculations for all that kind of stuff to find out the EXACT answers lol

DATS TTRAH!

would it be safe to put a blower pulley on with my 6lb that is on now or would it blow?