My 4.6 V8 left the factory with 220 breakable horsepower. However, by the time it gets to the rear wheels ... I'm lucky to have 175 horsepower.

Instead of adding more horsepower to my engnie .. I am determined to "free-up" some of the horsepower that has been absorbed by parasidic devices installed by the factory. Case in point:

The OEM air cleaner was obviously holding the engine back from breathing all the air it was capable of consuming. With the new cat-back exhaust system installed ... the engine seemed to come alive like a giant wieght had been lifted. It had been suffocating. I have no idea how much horsepower that released. But, just for the sake of this thread, let's say 25 H.P.

Another case in point: The mechanical fan uses approximately 15 H.P. on the average. This parasidic device can be replaced with an electric fan that will allow the engine to cool better ... while freeing up another 15 Horsepower. That is quite a savings!

Now, this is kind of hard for me to understand. At this point I don't have 220 + 25 + 15 = 260 Horsepower ... do I?!!! No, I don't. The engine was designed to produce 220 H.P. But, at the rear wheels, I may have 175 + 25 + 15 = 215 Horsepower!!!

You experts can jump in here any time if you like. I am not an expert on this subject ... but I am excited about freeing up horsepower vs. adding more horsepower.

Thanks for any input you have to offer.

BillVoyles
LowRedRyder

 

You forgot the ASP underdrive pulleys...an extra 12 HP!!!

Classic problem...FLYwheel HP and REARwheel HP!
If you have a auto, you loose more...
A stick, you loose less...

My guess, with mods. your looking for gains in both. If you average higher in both catagories, your mod. is worth the investment of time and money. Unfortunatelya, you will have to strap your truck to a Dyno to find out for sure!!!

 

BillVoyles,

Is there a reason that you care where the HP increase comes from ? If you got a dyno pull at stock, and added mods, the HP was increased.

If you Dyno your truck and it is dead on to the factory RWHP and all the mods you did added say 35 hp, I guess you really added HP, not freeing up HP.

You actually added HP by removing items that use HP to run something ( fan or pulleys ) or added HP by allowing the engine to breath and xhst better, when comparing it to the numbers Ford provided.

All comes down to semantics of the word add. If you use the word add as in the case of increase, then anything you do to the engine is adding HP.

Don't know why you really care where the additional RWHP comes from, anything over stock is adding HP to the RW, and that is what counts.

The modular mods list :
Intake
Xhst
Electric Fans
Pulleys
SuperChip.

Dollar to HP the Chip is the biggest increase if I recall my calculations correctly ( 25 HP for $225.00 or $9.00 per HP ). HP to dollar the Fans are the lowest ratio ( 15 HP for $400.00 or $26.66 per HP ).

I think I have the list in order of gains ( pulley to fan is a toss up I think on which gains more 15 vs 18 ?? ).

The additional mods beyond the list above are items like headders ( chip reburn ) and MAFS / fuel delivery upgrades ( chip reburn ) or true duals ( high dollar ) are the more exotic ones that can be done to the engine. There are also other ones in there with true duals and high flow cats.

 

HI!... Bill Voyles : Your truck has the 4.6 engine and FORD rates it at 220H.P at the FLYWHEEL. If you have the AUTO (4R70-W) tranny then you will have a 65H.P drivetrain loss. Making your 220H.P FLYWHEEL = 155RWH.P. Now your cat back is good for about 10-15H.P FLYWHEEL, not 25H.P. The electric fans have been documented on a 5.4 to give about 14-17RWH.P, or about 20H.P at the FLYWHEEL. The 4.6 would be a tad less. If these are the only two mods you have then I would say you are making about 250H.P at the FLYWHEEL or about 185RWH.P. You have to remember that the drivetrain loss is just that. Your going to lose power by turning all the tranny internals, the driveshaft, and the rearend internals to get the power to the actual rear wheels. You can run FULL synthetics like REDLINE in all of the above to cut down the friction a bit, but were talking like mabey 10H.P at the most.

 

You also have to remember, you won't have a gain in peak horsepower. Horsepower may improve at different points in the entire RPM range.

 

Thanks NEAL and SSCULLY and everyone for your input . ..

You asked why I am interested in whether I am "freeing up" HP or "adding" Horsepower. The answer is I get more gas mileage ... not less.

To me, the term "freeing-up" something is to remove a restriction. Here is an example;

Let's say you are carrying around 150 lbs of weights on your shoulders and you can't run very fast. But, if I remove the weights ... you will easily be able to run. Right? (But, you aren't any stronger than before.)

Now, if you work out, and gain a LOT of muscle, you might be able to run with 150 lbs. of weights on your shoulders. (Now you do have more power than before.) But, you discover that you are eating like a horse and can't pass up a Burger King.

It's the same with an engine. If you remove the restrictive devices it will seem like you have just added a bunch of horsepower ... when all you have done is remove restrictions. Sure, you can see it on a dynamometer.

On the other hand, if you put a chip and a blower on your engine ... you have actually added new horsepower, but you won't be able to pass a gas station!!

Case in point: I have added a MAX fresh air system and Magnaflow Cat-back Exhaust System. It made a big difference in performance ... in both power and gas mileage. My 220 HP engine may be putting out more horsepower,
but the difference is; it is giving me a lot more ... not less gas mileage!!!

I think it is difficult for most people understand the difference between freeing and adding horsepower. I get a lot better gas mileage by "freeing' my engine of restrictions. If I added a blower and a chip do you think I would get better gas mileage?

I hope I don't sound arguemenative ... just discussing the issue from both sides ....


BillVoyles
LowRedRyder

 

I might be wrong here, but if you're running an automatic, getting a good shift kit installed so that baby really locks up should reduce the losses through the tranny since it will reduce the slippage. Taking your A/C compressor off will also help (of course summer days stuck in traffic will suck).

Magnum

 

Here is the real scoop . . .

If you're interested in performance ... you will like a low 4.11 rearend ratio. It will really get with the program at the drags.

But, if you are interested in gas mileage ... you won't be happy with your rig until you stuff a 3.08 gears in the rearend. I get 26.78 miles per gallon straight down the freeway. And that ain't no bull!!

BillVoyles
LowRedRyder

 

BillVoyles ,

OK that makes more sense for the question then.

When I put on the electric Fans on last summer ( pre Chip and True Dual and FIPK modifications) I had check mpg before and after, albeit for a short amount of time.

The gain in mpg I got post Electric fan install, I did a calculation on the gas money saved ( additional 2 mpg ) , and I would have to drive it for 36,000 miles to break even at last years gas prices for teh cost of the electric fans alone. That was using cost of money at 0% straight line calculations. That is withou the cost of the FIPK and Cat back included in the mix.

A quick calculation of the cost of rear end gears, FIPK and cat back show that break even is 41,708 miles. This was 0% cost of money, estimate for the gears, FIPK and cat back at $1,010.00, and the mpg gain of 7 mpg ( your 26 vs the 19 I saw with electric fans, cat back and FIPK ).

A more detailed calculation with actual costs might show something else. Swag at costs : gears=560.00, FIPK=200.00, and nice Cat back =250.00 These might be off one way or another. The quick was $ 8.15 of savings per 20 gals of gas.

Maybe a more detailed look would show better numbers, but every time I look at the mod to save gas money, it does not pan out.

 

 

When you are freeing up HP your RWHP gets closer to your BHP. Stuff like electric fans and underdrive pulleys free up HP for the rear wheels but don't make the engine produce any more power.
Jes

 

26.78 mpg!!! 3:08 gear ratio..... Its not a Honda!!!

 

Give it a little gas Bill... Those minimum speed limits aren't posted on the highway for nothing!

 

I beg to differ. I've had the blower and chip for more than a year now. I did see a slight decrease in fuel mileage. I also have found it very difficult to resest getting into boost. I had a drop of about 1mpg city and highway driving has stayed about the same. 22mpg was my best. I average something like 18-19mpg.

I have recently increased boost which has decreased mileage a bit more. It's even more difficult to resist getting into boost.

I don't like to spend any more money than I have to, any more than any else does. The enjoyment I get driving this truck is well worth the expense!

 

Here is how I see it.

Ford rates their engines with all the accessories attached. So the 220 for the 4.6 includes power used to run the alternator, power steering pump, water pump and fan. If you remove the fan and install an electric fan you have freed up the power used to drive the fan. If you install under drive pullies you have reduced the power required by the engine to drive the accessories so you have freed up power.

If you Add a chip you have increased the power your engine produces. If you install a FIPK you have increased the power your engine produces. Headers, exhaust etc all accomplish the same thing: power increase of the engine.

If you install a Shift kit you;
a) reduce the slippage and that reduces the time it takes to shift gears so you have decreased the time the tranny is freewheeling and that makes your truck quicker. You did not increase power nor did you reduce the draw on the engine. You decreased the inefficiency of the drive train.

If you change the gears to a 4.10:1 ratio from a stock of 3.55:1 you are affecting the power to the rear wheels by multiplying the amount of torque available to the wheels. You decrease the HP but you increase the torque. That increased the acceleration of your truck but you did not change the engine. You decreased the inefficiency of the drive train.

JMC