I got a 2003 4.2 and I'm lookin to put MAC Headers, MAC Intake, Flex-A-Lite Electric Fan, AirRaid Throtlle Body Spacer, and some new ignition components in. I was wondering what kinds of increase I should expect. Also, are there any other things I could get to help out my low end power?

 

What are you thinking for ingnition stuff? also post back when you have done this and let me know what happends, I'm thinking about upgradeing most of the stuff you are.

Have you heard anything about exhaust systems on a 4.2 w/ loss of low end and what not?

Brian =D

 

Look around the 4.2 threads. Plenty of opinons out there, pro and cons. I myself like it, but the sound could be a bit deeper.

 

right now I got a Flowmaster 40 Series Delta Flow single in dual out, sounds pretty good but I havent noticed any loss of anything. There's just no low end on these 4.2's and i need more.

 

The set upon your exhaust that you have is probably the best, the only other thing would be to chip it, or get a programmer to customize what you want for low end.The thing about the 4.2, it's not full of all kinds of crazy power. We use them for what they are designed for, a light duty truck that is somewhat resonable on fuel for a full size vehicle.

 

I've been trying to find chips/programmers and people have mentioned diablo but i can't find out where to get for the 99 4.2s; did you guys ever think about changein the gearing? I have stock 255/70/16s on the truck but I've tighted up the torsion bars a bit and seem to fit a lil bigger tire (not sure what though) but then i was thinking i'd have to change the gearin.... i dunno sorry to change the thought of this post =X

 

Do all the above with the exception of the TB Spacer. It's a waste of time and money. I've seen reports of a TB spacer making your truck loose power in the end.

All the bolt-ons are fine...nothing wrong there. Be careful about the fans you put on. Get dual 16" fans and a controller for the best performance. I can't remember exactly what cfm they need to be, but make sure it's really good.

Low end power = 4.10 gear and an LSD or locker. I had those installed on my old truck, and it made a HUGE difference in power and traction. The problems with this: speedometer will be off, fuel with be slightly worse unless you drive really easily (yea right lol). You can offset the speedo with a chip or tuner. I had a Diablo chip and it worked great. Anyways, there ya go.

 

OK, I give up, I have searched on google, ford.com, everywhere I can think of. I see all the comparisons between the 4.2 against the 4.9 and 4.6. I want to see a chart with the torque/hp range for the 4.2 engine from idle to redline. Anyone have ideas where I can get the info? Rather, we need the info cause we debate the engines everyday and maybe the debate will never end but I know ford made the 4.2 with the peak torque at the higher end for a reason and I'm guessing it was for the "family man" who does not need all that low end torque, rather he/she needs the power at the "passing gear". I don't know, but my 06 has plenty of torque at the low end and yes it will downshift when I'm pulling the double axle uhaul trailer full of my college kids apartment plus the whole 8-foot box loaded to the max up a hill, but it goes up the hills just fine at 1800 to 2200 rpm at a comfortable speed. When I take off at a light, I have to be careful not to push the gas to hard because the initial torque will cause the truck to lunge a little......my ranger with a 4-banger also had good torque taking off. I have not interest in increasing torque/hp outside of a k&n airfilter because in the long run I save money on airfilters and my mpg did increase 3mpg. That is worth the $48 dollars for the life of the truck. If I needed to pull a huge boat, rv, I would have got a diesel, now thats a pulling engine.

 

I dont know where the idea that the 4.2 has poor low end torque has came from, but it is not true. I have never printed off a dyno sheet, but we have a dyno where I work and I have put my truck on it three times. The torque curve jumps up to 220 just off idle and stays there flat as a bourd until about 5000 RPM. Like I said it is flat. I attribute this to the dual intake runners. Horsepower is a nice upward slope that has just leveled off at 185hp when the rev limiter kicks in in third gear. It would be higher in fourth but the road speed limiter shuts the truck down before you can get to the rev limiter in fourth. Ford says 205hp for this engine. but if you use the 20% driveline loss constant that means 222hp at the flywheel. Not bad for a stock v6. By the way one of my students had a 4.2 with exhaust,tb spacer, and cold air intake. These mods totally messed up the torque curve and it could only muster 160 at the rear wheels. I am not sure what conclusion to draw from that, maybe he has damaged it by driving it too hard, or possibly his bolt ons resulted in a net loss.

 

Thanks. 220lbs torque at idle is pretty darn good and makes sense. Perhaps others think the downshifting is a lack of power but one has to remember the 4.9L engine (mine) used a 3-speed tranny and my 06 has a 4-speed. :You would think getting a spec sheet for the 4.2 with a auto or manuel would be easy to get.

 

I have never been impressed with the low-end power of my 4.2L. The 300 I-6 I used to drive had way more low end, although it seems like the 4.2L really screams up high in the rpm band.

Tula, I am very suprised you got a 3mpg difference with the K&N. I would probably pay close to $500 bucks for such a filter. I just calced some numbers and a 3MPG increase would save me $622/year. Unfortunately I bought a k&n filter for a bit over $60 after I had my truck for 1 year and despite the claims I saw no difference in mpg or power. I average about 15mpg and 20,000 miles a year.

 

I was just as shocked with the mpg increase. As I said before, I do not attribute all the increase to the filter, rather, I believe the filter forced the computer to fix itself. I was getting 10mpg which was/is unacceptable. I no longer get 10-13mpg, I've stayed in the 15-16.5mpg range----mostly city driving

I put a kn filter in my ranger with no change in mpg.

 

Some bad math here. The rating Ford gives for the 4.2 is not at the rear wheels, and it does not have 222 or whatever horsepower at the flywheel. Ford rates it at 202-205 horses at the flynet, SAE net. Power at the rear wheels given given the "assumed" 20% loss at the flywheel is 164.

If your motor makes more than 164 at the rear wheels, it is a likely incorrect assumption that your motor has more power than its rating.
Drivetrain losses are just lower than 20%.

It is a very, very rare gas engine that truly makes more power than its SAE rating. I very much doubt the 4.2 is an exception.

 

I believe he said aprox. 220 lbs of torque on the low end, followed by a flat line until th rpms got inthe higher end, he was not speaking of 220 hp at the flywheel. I had stated I wanted to see a dyno sheet of the power band. I pulled a double axle uhaul along with a full load in my 8 foot box. I have no idea to the weight, it was my college kids apartment. But the 4.2 pulled it with ease from stop light to stop light, up the hills, on the highway, even backing up. No strain. I realize its not a 5.4, but I'm not pulling 9000 lbs or more either. My 16 foot alumn. boat with a 25 horse engine, with the trailor is all the boat I need.

 

Drivetrain losses are just lower than 20%.

I agree. I doubt that it is making 222 at the flywheel. The point that I wanted to get accross is that the torque curve is absolutely flat. this provides a lot of useable power at any engine speed. The old 20% constant driveline loss probably doesn't apply with the newer more efficient drivelines and manual transmission. I agree with tula771. the most I ever pull with my 4.2 is my boat which weighs about 4000 lbs. It will pull it with absolutely no problem. It doesn't even breathe hard. I have been very satisfied with the power output of my 4.2. It is a nice running engine.