According to my research, Ford squeezed some more horses out of the 5.4L motor in 1999, and they identified it as being "performance improved (PI)." As near as I can tell, there was some improvements made to the cylinder heads, among other things. This brings up two questions:

1. How do you know which version you have - the 235HP or the 260HP? My owners manual (1999 Expedition XLT) claims the 5.4L puts out 235HP, and the Ford customer assistance hotline also claims my motor is the 235HP model. However, the information I have found on the internet says that all 1999 models are the "performance improved" design, and I talked to an engineer at Ford and he also told me that all 1999 models have the 260HP design. I have a friend with a 2000 or 2001 Expy, and his motor looks different than mine (looks like he has a plastic intake, for one thing). His truck is also noticeably quicker than mine. I have talked to the parts department at two separate Ford dealerships, and they tell me that there was indeed two different motors put in the 1999 f-series vehicles, but they can't seem to figure out how to tell which one I've got. Does anybody know how to look at the engine and tell easily which one I've got?

2. Regardless of which motor I own, can anyone tell me what the changes were that got an extra 25HP out of the 5.4L engine?? I would assume the changes Ford made would have addressed the major performance "bottlenecks" that they identified in their 235HP design. If all they did was clean up the heads, I think this would suggest you could really get some good gains out of some head work.

Thanks in advance!
Jerm

 

Navigators and Expy's use a DOHC set up, whereas the F-Series use a SOHC. This Is why when you check out the hp ratings on a 1999 F-150 with the 5.4L Triton, it is 260 hp, and the Lightning was 360, having added 100 hp with the supercharger and other mods. The Expy and Nav both have a rating of 235. I believe this is all correct, if anyone else can, please correct me if I'm wrong.

Ryan

 

Actually the Navigator is the only vehicle to get the DOHC setup (besides the upcoming Blackwood pickup) Expys come with the SOHC setup. The first year the Navigator came out the DOHC motor was making 300hp and 300ft lbs of torque, while the SOHC motor was making 235hp and 330ft lbs of torque in the Expys. Now the DOHC 5.4 in the Navigator is making 300hp and 355ft lbs of torque and the SOHC in the Expys is making 260hp and 350ft lbs of torque.

1979 F150 CUSTOM 2WD 302 BORED .040 OVER EDELBROCK CAM, CARB AND INTAKE. C4 TRANNY AND A 9 INCH REAR END

 

right, but as for the F-series, I believe, not sure though, that when they started using the Triton 4.6L in 1997, it was making 235hp, the 4.2L 6 cyl was putting out 205, and the 5.4L was crankin 260 hp. Like I said, not positive though.

Ryan

 

I own a 2000 F150 Extended cab 4x4 Sport truck and the rated horse power is 260 hp at the fly wheel and like 180 hp at the rear wheels...

 

I got some new info-

Apparently, the 1999 f-150s all got the 260 HP version from the factory. There is some conflicting info about the expeditions, but it appears like the older 1999 Expy's may have been used to deplete the older 235HP motor parts. The biggest change in the motors was in the cylinder heads, which were called 5.4PI (performance improved). The motor also got a redesigned intake manifold, which I believe has some sort of "power valve" that helps out low end torque.

I also know that Ford began using plastic intake manifolds somewhere around 1999. I don't know whether the plastic manifold correlates with the improved intake, but it would make sense. I have the older style cast manifold, which probably isn't a good sign.

So here are some new questions:
1. Does anybody know for sure if I have correct information??
2. If Ford used the Expeditions to use up old 235HP parts, what is the likelihood that some trucks could have PI heads and a non-PI intake manifold or vice-versa??
3. I would assume that the new power valve in the PI intake would require a different computer code, so is there any way to check the motor type by the software revision of the computer?

Jerm

 

My 1999 F-150 4x4 5.4 was 260 hp stock, 180hp @ the rear wheels.
K&N installed their SS exhaust system and the complete air intake system and the HP went to 216 on their dyno on regular gas, no chip.
This is 4x4 numbers and the large HP loss is from the transmission and transfer case.
My truck runs very strong.
It's problem is that it wants to shift down(out of overdrive ) at 75 when any hill is encountered. It would be real nice to have it lock in overdrive and use the torque to climb the easy hills.

 

[font size="1" color="#FF0000"]LAST EDITED ON 01-Nov-01 AT 10:59 PM (EST)[/font][p]With that sort of power, it will stay in overdrive with a chip. The performance improvement in the tranny is worth the price of the chip.

Mine stays in overdrive alot better with the chip.

Pantera: Are you saying you gained almost 40 rear wheel horses from their exhaust system and filter pack? That is impressive. Could you provide more details about your exhaust system? How loud is it? etc.

98 F250LD 4X4

 

[font size="1" color="#FF0000"]LAST EDITED ON 02-Nov-01 AT 10:05 AM (EST)[/font][p]I bought a system at a mail order store and installed it. And it did not fit! I put the stock system back in and drove to Riverside early one morning. After some discussion I drove my truck onto the dyno, we tested it-180hp. We went to the fab shop and they took everything out and started from scratch. 3" stainless from the y connector, all welded into place.
They installed the FPIK on the intake. Now back to the dyno. I was not impressed with only 216hp like they were. BUT it runs very strong.
Loud, YES, because they put the round stainless muffler on. I would rather have the OVAL muffler that they put on Navigators.
It was just under the California Db limit. I think it was 86 Db's.
I have 35,000 miles on the truck now and it it as solid today as it was new in 1999.
OK I'll chip it, now with which one?

Larry

 

I use the Superchip and like it alot. That one and the Diablo are available through this site. You might benefit from a programable chip where you can alter it's performance. Talk to Danny at SuperChips and see what he recommends.

98 F250LD 4X4

 

Hey chipped guys, how do you like filling up with premium each time? That is the only thing that is holding me back from chipping my 99 4.6. 30 gallons of premuim at equates to an extra 6+ bux on each fill. With that, I am leaning toward an MAS and perhaps one of the TBI spacers. A bit more expensive but cheaper in the long run.

 

Pantera,

The thing you have to consider is that the engine is rated at 260HP...not the vehicle. The engine by itself was dynoed at 260HP, minus things like air intake system, exhaust, fan, alternator, power steering, etc, etc. But after installing a more free flowing exhaust and a cold air intake, you are just approaching (but still far from) the actual testing conditions when Ford got 260HP out of the engine.

 

Brandon, I believe Pantera was talking about rwhp, which those numbers are quite impressive. Not flywheel hp, which is what motor vehicle companies use to rate their vehicles. 260 hp is not the rear wheel hp, it is the flywheel. It is not the engine alone, it is done using a test vehicle in closed environment conditions, on the dyno scale, measuring peak hp from the flywheel at optimum rpm's.

Ryan

 

I was talking about rwhp.
After my 1998 Lincoln Mark 8 was smoked at the drags by a 2001 Lighting, I am looking for a 5.4 Lightning engine and transmission for my 1999 F-150 4x4. I sure like to see the look on the ricer type when I turn 13 second 1/4 mile ET's.

 

That's what I figured. Those numbers are very nice. Good luck with the Lightning engine/tranny set up. It should be quite a truck. Careful, though...you may need other stuff, like F-250 SD brake conversion, beefier sway bars, maybe rear end? Make sure you got all your information, and keep us posted