I'm having my 4.10 gears put in my truck on Monday. I was wondering if after I did that I should get the truck dynoed? Or if that helps at all or not? And also what the price should be on that

 

Regearing won't add any horsepower. It'll just make it transfer to the ground faster/better. You'll notice increased throttle response, but it's not because of increased horsepower or torque. My vote: Save your money and skip the dyno.

 

Well yes, it is increased torque but it's a mechanical increase.
Example: If motor produces 275 lb/ft of torque at 3000 rpm with 3.55 rear gear and transmission in third, the 'total torque' mutiplication is 275 x 3.55 = 976.25 lb/ft.
With a 4.10 the total torque under the same conditions is 275 x 4.1= 1127.5 lb/ft.
Torque is what moves the truck, not horsepower.
Horsepower is a math derived figure based on torque and rpm to denote the rate of work done.
All the motor puts out is torque applied to the crankshaft converting to rotational force at varying RPM.
In the example above with the 3.55 gear, HP = 3000 x 275/ 5252 = 157 HP.
As you see, the rear gear has nothing to do with the 'motor HP'.

 

So I'm better off saving money and just getting a shift kit e fans and underdrive pulleys?

 

no dyno tune required after new gears. E fans, custom tunes from someone like Mike Troyer, VMP, or 5 star tuning, exhaust, intake, and the gears will make a huge difference in how the truck drives and feels. Plus all the added power.

 

An opinion only is that E fans and underdrive pullies are not a good combination.
Reason is the alternator is slowed down causing possible battery charge and system low voltage issues especially at night and during A/C uses at slow road speeds..
Efans must move as much air as the stock fan. This reqiures them to take a good amount of current to run them.
As such a controller is needed.
Bottom line is a lot of money is spent to get a small return in performance.
Save your money for a 2013 Mustang with 650 hp that will curl ya toes when ya step on his tail.
Good luck.

 

Efans and UDPs make a GREAT pair. I don't know what setup you're using, but the few I've seen says normal alternator output at idle speed. Even then, most efans don't draw too much current at full speed, mines about 10-15A, which is the same load all the lights on the truck use. And that's if they are on. I have to sit at a redlight in the middle of downtown rush hour traffic for a good 7-8 minutes before they click on, and if they do, its for about 45 seconds before the cycle repeats.

 

Well lets put it this way for perspective.
1. The alternator is turning slower at idle and cannot supply the current needed under the worst operating conditions with under drive pullies.
The factory sized the pulley ratios for reliable cooling under all conditions, by design with some safety margin. Under drive pulleys takes that safety margin away.
2. Your fans if sized proper will draw more than 15 amps. Your heater A/C fan draws nearly 20 amps on high. I realize you may never run a heater fan on high but that is part of the reasons the pulley ratio is what it is from Ford, cosidering A/C may be used on high speed fan, night time lights etc all at the same time.
Part of the lower draw you may see is the lower alternator rpm and lower output. When the alternator rpm increases the voltage increases and the current also increases.

3. In FLA, I don't believe you about setting 7-8 minutes before the fans come on then only 45 seconds cycle run times. The engine is already at about 195 +/- for temperature and your water pump is turning slow to, I presume. Maybe you have a wacky setup that's fooling you.
3. The battery has to supply more than it's normal current to keep the fans and systems running and can result in shorter battery life form the extra charging it takes when the road speeds gets higher.
This also increases wear on the alternator brushed and commutator , extra heat generated shortening the alternator life at some point.
It just does not add up. You can't have it both ways.
But good for you if your getting away with it and it does what you want.
Many don't for the reasons mentioned above.
They could experience slower crank times under certain conditions when the battery had not been fully recharged with a long enough run time at higher speed.
So that's where i'm coming from with known facts.
And there is more if you would like to hear about it.
Good luck.

 

Yeah sure. I need as much info as possible.

 

1.)Here is where I'm getting my facts from:

http://www.thunderracing.com/shop-by...lleys_251.html

And some examples:
ASP 25% Harmonic Dampner, 2001-2002 Ford F150 4.2L engine, full charge at 850
ASP Underdrive Pulley Set, 01-04 4.6L GT: 25% Harmonic Balancer, 26% Water Pump, 8% Alternator, Full charge @ 950 RPM
ASP Underdrive Pulley Set, 94-95 5.0L Mustang: 26% Crank, Full Charge @ 750 RPM, Nitride

2.) Size has nothing to do with draw. Its all about controllers. If you have a marginally decent controller with 2-step system, you can have a high and low setting. I know for a fact when my fans click on high, the engine doesnt even hesitate for a bit, no drop in idle. You just hear them spin up.

3.) I don't care if you believe me or not. I've ran that test several times. I sat in a parking lot last summer for 30 minutes and timed it every time they came on. 7 minutes was the average, with 45sec-60 sec run time. I'm pulling ~6,000CFMS @ full draw.

4.) Of the several people I know (4.2L and otherwise) with UDPs, NONE of them reported charging issues. One of them even has a pretty legit sound system in his Mustang (along with efans, etc etc). The only downside I'm hearing is the power steering pump may be overdrawn at idle and you have to tap to gas to turn the wheel (which you shouldn't anyways, dry walling is bad for tires).