Anyone have experience with underdrive crank pulleys? Looking to take some load off the engine, so the 4" crank pulley from LC is on order and an electric fan to follow. Basically just to get a bit better mileage really. I am wondering if someone has experience driving around town with one.
what is the intended purpose of this truck? I was under the impression that performance gain is only during acceleration when you have to overcome the rotational inertia of the pulley. Even then all I've heard is HP gain, not MPG. I'd like to hear how it goes, though! I'd love to improve MPG, just don't want water pump or alternator issues (I don't have power steering or AC, which are also powered by that pulley).
TBH, I've never tried one. I read too many posts from people who recommend against it (which is why I've never tried one). Generally, aftermarket crank pulleys don't have harmonic balancers so they can create other catastrophic problems (I dont remember what they are, off hand). Those people recomend you go with larger accessory pulleys if you want to reduce drag.
I have one , have the complete stage one 22RE Pro Street EFI LC engine with all the extras they recommended. Have been running it since 2007. In my 88 show truck, drive around 5,000 miles to shows every summer ( not this one)! Way more power, cruse at 75 most of the time, at that speed she gets 23 MPG, if I stay at 65 she will get 28 to 31MPG Manual W58 5 speed & a 9.5 lb flywheel.
TA, you running the 6" or 7" WP pulley? What temps do you experience in town? I would like to run with the stock crank pulley/balancer, but I've not found a set for them. What would really be nice is a serpentine conversion! As for catastrophic failure issues without a balancer, I've run solid pulleys on so many engines without any issues. One thing you need to understand about destructive harmonics are they occur in certain RPM ranges. Each engine is different and mods change that range. Typically avoid tuning a powertrain to run in that range. Not something that auto builder/tuners take into account when modding their car/truck. If you get a chance, look at a small aircraft engine tach, usually shows an RPM range NOT to operate in. It's where the harmonics are a danger. I have a 4" LC crank pulley on order, along with a 12lb flywheel, headers and cat back. not sure if the exhaust mods would be good for mileage, but I have hills to climb EVERYWHERE I go. I do plan to run this pulley awhile before I make any other changes. Currently I get 26-27mpg with highway miles being about 95% of the driving done. Would really like to better 30mpg though. Makes a difference when driving 200 miles a day for sure. Last job was a 112 mile commute, one way. Had to top the tank every day to get the same price gas (town the job was in was nearly a buck less on gas prices than home), otherwise I would have had to fill every other day in 2 different towns.
Exhaust mod is the only significant measurable improvement in gas mileage across the board that I have done to my truck.
4'' crank pulley & 6'' water [pump pulley I have a Spal 16'' electric fan & a aluminum radiator, runs at 185. I have a Centech fan controller set to come on at 185, & a manual over ride switch which I turn on once off the highway
