Thanks Mike.
I do intend on getting the head work done. By using the stock lower end I can get the head work for about half what a forged lower end would cost.
I really don't need that much more HP to make me smile. I would be very happy just to get rid of the flat spot I get from 3500 to 4500 RPM. I'm sure that is a flow problem in the stock non-PI heads so this is really ideal for me.
One more question if I may. Since I travel, there are times when 93 octane pump gas may not be available. Will this be able to be done on 91 octane with a good superchip tune?

 

grinomyte,

IMHO; If you look at a crank shaft the stroke is the distance the rod will travel up and down. It is also the distance the rod will travel side to side during its rotation. When the rod travel side to side is greater than the piston dia (BORE) there is a great deal of stress created. The longer the stroke the greater side to side stress. A rod is designed to take the bulk of its stress up and down, not side to side. The piston is designed to sit square in the bore and the increased stress from the rod going side to side at high rpm can cause it to cöck sideways in the bore that is not good.

JMC

 

Hi WLF,

Understood, & sounds perfectly reasonable, the stock bottom end can take about 450 hp & a 5800 rpm upshift point no problem, so doing the heads & running them on the stock 4.6 truck short block should be fine.

Yes, as long as the 91 octane is a good quality fuel (high energy content), sure, that can be accommodated, and I'd do all of that in the 2-program Superchip Flip Chip, that would actually be the cheapest way to get all the custom tuning that will be needed anyway with cylinder head and/or camshaft changes. Then we can do a dual octane type of setup, say, 91 & 93 octane tunes, would best do the job.

 

Hi JMC,

I'm sure the info from Dave Crower re: how much lift can be run with the non-PI shortblock & PI heads, etc. made you happy!

You've shown a lot of people just how much these stock truck 4.6 short blocks can take rpm-wise with your dune racing for all these years, and of course, that's affected by how much power is being made. The stress of say, ~275 HP or so is a lot less than it is at 400+ hp under those same conditions, of course. Where someone with 400+ hp would blow the motor at some point turning those rpms, at under 300 hp, both of your 4.6's have (and still are) taking it just fine. I think (if memory serves) you were among the first (or maybe the first) 4.6 F-150 owner we did a 6500 rpm rev limiter for, years ago with your last truck.

The distance that the piston travels up & down in the bore (swept) is the stroke, but the big end of the con rod does not displace horizontally by that same amount from the crankshaft centerline, as that would result in a catastrophic rod-stroke ratio & the piston ****ing (tilting) in the bore, etc. Typically, that amount will be roughly about 60%-75% of the stroke length in most motors. I.E., a good rod/stroke ratio being about 1.6-1.75, depending on wrist pin placement in the piston, piston skirt design, etc.

The stroke & bore are almost identical in the 4.6, as you pointed out, so the motor is basically "square," thus it can turn more rpms & abuse with lesser grade parts compared to say, a 5.4 with it's huge for it's size stroke & it's almost 7" long con rods!

 

One more thing that I forgot about the stroke. A longer stroke wil cause the piston to travel faster during one revolution as it will have a longer distance to travel The increased stress from the decelleration and acceleration will also cause problems in an un prepped engine. If the piston travles 90.0 mm as in the case of the 4.6 then the rod is attached 45 mm from the center line. At 6000 rpm the piston is moving at 18 meters per second and a 5.4 is traveling 21 meters per second. I may not seem very fast but it is accelerating from 0 to 18m/sec 6000 times per minute. That is a lot of stress.

JMC

 

Hi JMC,

You're *absolutely* right!

And one of the primary ways to compensate for longer stroke is to vary the wrist pin placement in the piston. That will slow down the rate of acceleration off of TDC & BDC in the bore to reduce those stresses somewhat.

Good point! (as usual from JMC)

 

isnt Neal shifting at 5800 with no headwork, cams or major intake work?

 

Hi BrotherDave,

Neal is a bit of a special case as he has highly customized tuning, however, his WOT upshift points in his automatic tranny program are a bit under that level.

Now he *does* tend to shift it manually sometimes, so he may well hit that kind of number say, in 1st gear if he moves that lever a split-second too late, sure, that is possible.

I don't place much faith in factory electronic tachometers under hard acceleration, especially in the lower gears, as they vary far too much.

In any automatic (and this is basic so you probably already know all about this), the *only* way to exceed the rpms at which the WOT upshift point is set is by manually forcing the transmission not to shift (manual shift lever control) & keeping your foot nailed to the floor on the gas pedal.

The highest factory WOT upshift point on the 5.4's is about 5250-5300 rpm (with the rev limiter higher, of course), and we don't take them above 5400 rpm unless it's a custom program where the vehicle owner has specifically requested a higher rev limiter and/or WOT upshift point.

I hope that clears that up a bit for you,

 

HI!... MIKE you should know by now that I *ALWAYS* shift manually. Very seldom do I let the tranny shift it'self. When racing I shift out of 1ST gear at 5800RPM. Just a split second hesitation on my part and I will slightly bounce off my 5900RPM rev limiter, which was done by MIKE T on my custom chip. 2ND gear I shift at about 5500RPM, and 3RD at about 5400RPM. Overdrive max's out at 4550RPM. Ask JMC about the 1ST gear revs on this truck. It pulls hard all the way up to 5800RPM in 1ST gear and when it hits 2ND gear , HOLD ON!!!!!!! , because usually the a$$end of my truck goes sideways.

 

Neal, this is kinda a dorky question but here it goes.
Is manual shifting hard on your auto tranny? I'm reluctant to try it in any situation. Any advice?

 

HI!... NOPE!!! . I do it because all of my other vehicles have had manual valve bodies in them. It's just a force of habit manually shifting. I've got my best 1/4 mile times by manually shifting.

 

Hi mf150,

Neal has his manual shifting down to an art, I don't think I've ever seen anyone else spend as much time refining manual shift points & when you need to move the lever to have the tranny actually execute the upshift exactly when you want it in one of these trucks.

In Neal's case, manually shifting *his* built transmission isn't going to hurt it, but we generally don't advise manually shifting on a stock tranny on these trucks, as that changes certain things the PCM does, and in some situations can damage the transmission. Now I'm not talking about the occasional manual downshift, or turning the Overdrive on & off, etc., I'm talking about running it hard & playing with manual shifting for best acceleration, etc., these trannys in stock trim just aren't up to a whole lot of that kind of use. Besides, you'll usually get your best performance having the Superchip control those WOT upshift points automatically anyway.

There are some of us, like Neal & myself, that have usually used and are used to using manual valve bodies; once you'd had that, it's hard to go back if you're a hard-core motor head like Neal & myself & some others around here. What that means is, you *have* to shift each gear, you have complete manual control and the transmission, even though it is an "automatic," will *not* shift automatically in or out of any gear. If you leave it in "D" with the Overdrive turned off, for example, you start off in 3rd gear, no 1st or 2nd. Traditionally, these special manual valve bodies were used for several reasons, primarily allowing much more fluid volume flow and higher line pressure for much quicker & firmer shifts, along with full manual control. And in most manual valve bodies I've used or made, they have also had what's called a "free-wheeling" 1st gear (no compression braking under deceleration) for blitzkrieg street starts, kinda like having a stall speed converter.

Just FYI in general..............

 

OK guys I’ve got a question. I read in posts about parasitic loss of the drive train. Having the auto tranny that loss is calculated to be about 65 hp for my engine. What I don’t understand is that as horsepower is added thru modifications, shouldn’t the parasitic loss remain a constant. I have read 25% but how can the loss go up with the horsepower?
If I now have say 180 RW horsepower with my mods and I add 75 HP at the flywheel, shouldn’t that added horsepower go strait to the wheels? I am having trouble understanding how parasitic loss of the drive train can vary without adding some type of load.

 

Hi WLF,

It's torque loading (along with a bit of dyno variance, etc.), basically. As you put significantly the more torque thru one of these drivelines, the resistance goes up a little bit. You're absolutely right in that you *CANNOT* use any kind of straight percentage to calculate those driveline losses, or to calculate driveline losses in all vehicles and here's exactly why, using these F-150's as examples:

With the 4R70W automatic, yes, the drivelines losses total out at about 65 HP at stock power levels, that is correct. So on a '99 & up 260 HP 5.4 motor, that's a 25% loss. Behind a 231 HP 4.6, that same amount of HP lost equals 28.14%. Even with the 4.2L V-6 in front of the 4R70W, we're still going to lose a minimum of 65 HP at stock power levels, which equals a whopping 31%+ loss in those vehicles, using a stock rating of 205 HP (and that has varied on the 4.2 F-150's, some years it's 205, some it's 202, etc.).

Take an F-150 with the 4R100 tranny, and the losses run about 69-70 HP at stock power levels. So in a "regular" 5.4 that would be a 26.92% loss, but in a 380 HP Lightning (and in any stock Lightning we generally see about a 69-72 HP loss), it's an 18.42% loss.

Get's confusing, eh? This is why you can't use a straight percentage for *all* vehicles. Now you *can* use a percentage on *some* vehicles, but you can really only do that when you've done a significant number of drag-down tests on a good chassis dyno to see just what the losses of many examples of the same basic vehicles are, with each different transmission type. And preferably at both stock and much higher power levels.

If we take a Lightning making 600 HP at the motor, that'll generally show about 515-522 HP at the wheels, so the driveline loss increases from roughly about 70 HP at stock power levels to about 78-85 HP, for example.

I'm not a math major by any stretch of the imagination, so I couldn't begin to properly explain the physics to you in a technically correct manner. I can really only share with you the actual data we've seen from doing this many times over the years in these vehicles. Specializing in a platform really helps here, of course.

Now the manual transmission generally lose about half the amount of HP that the automatics, do, your typical 5 or 6-speed manual tranny based driveline chews up 32-35 HP at stock power levels.

This basic topic is also a good reason to use all synthetic fluids, to keep frictional losses to a minimum, especially at elevated power levels where it really starts showing up.

Now all of these numbers we've been using here for HP losses are with 2WD vehicles, with a 4x4 you'll have a few more HP lost to the transfer case, but not much, maybe 3-5 HP more at stock power levels.

I hope that info helps a little bit,

 

HI!... WLF : Don't feel bad. I have NEVER beleived in the theory of losing more H.P to the rear wheels, the more H.P you make at the flywheel. Once you figure out your drivetrain loss you simply can't increase the loss by adding more power. Some will ague that fact but it won't change my thinking of it.