Hey guys, I am new to this site and I am sure that my question is like beating a dead horse. I want more torque out of my 5.8. I have a '93 F250 with a 5.8, 5speed and 4.10 gears. My goal is to get more torque so I can drop the rear end to 3.55 to get better highway milage with out haveing a dog for a truck.

I am looking at installing a comp cams 35-255-5 cam which is specifically ground for this engine. Does anyone have any experience with this cam and if so, what can I expect out of it? I would also like to add a set of headers since my exhaust is rusted out and needs replacing. Should I go with long tube or shorty headers and are there any known fitment issues with certain brands? I am looking at a set of hedmen elites long tube. Should I run a 2.25 or a 2.5 inch dual exhaust or a 2.25 or 2.5 inch into a single turbo muffler with a single 3" out? Does anyone know how loud a 70 series flowmaster is? I have a single thrush turbo on it now and am looking for a comparison. Is that cam and a tru duel exhaust going to **** off the computer?

Also, the truck has a slight mis at idle. I have tried the standard tune up but it really didn't help it any. It doesn't seem to affect it any and I only really notice it through the shifter. Is this normal? I am not really worried about it, it is just a little anoying since I noticed it.

Thanks in advance for your help,
Joe

 

well as for me i have never had much luck with installing non stock cams on fuel injected engines. they either flood alot or starve for fuel afterwards. but i bet if you post this same thread down in the engine building forrum below this one they will have lots of advice.

 

As for the exhaust, a turbo or chambered muffler isn't going to flow as well as a Magnaflow or similar style muffler. A single 3" should work. Your short tube headers + a Bassani Y-Pipe + a 3" Magnaflow should do.

Have you tried advancing the timing a couple degrees?

 

I am a big fan of the Bassani 3" y-pipe and full single 3" exhaust. I recently installed the same on my '92 F350 w/351W 4x4. I stayed with the factory manifolds instead of shorties due to $$ available at the time. I used Bassani's 58150B2 Y-pipe, a Magnaflow spun series metallic core converter, Magnaflow 3" center In/out muffler, then finished it off with a Maremont 3" mandrel bent tailpipe.

I have an E4OD trans., 3.55 factory gears and 31" tires. My in town mileage is averaging 10.5 MPG, All highway is 14 @65 MPH. My mileage before the exhaust swap was about 1-2 less than that overall.

I am not so sure dropping your ratio down to my 3.55 is going to gain you that much. If I had swapped in shorties, my gains may have been a little better. My truck is a 4x4, so fitting long tubes would have required a full custom exhaust with some overall potential loss due to exhaust routing issues. If your truck is 2WD, long tubes may net you a little more.

Before you start dumping money into gears and a cam. Start with a better flowing exhaust. As well as making sure your intake can flow as good as it can with a good quality fresh drop in air filter. If you are experiencing a miss, fix that first. Make sure the number 7 and 8 plug wires are separated. Very common problem that Ford released several TSBs.

So to answer your cam question, it may help a little but it is going to take a better breathing engine combination to take advantage of any potential for a torque/horsepower gain. Aftermarket cams can boost performance and be compatible with a Speed Density based computer such as ours as long as it keeps a reasonable LSA, duration and lift. The Comp Cams bumpstick you are looking at meets those requirements. Once you get beyond any mild performance upgrades the 351W intake become a huge bottleneck, then after that the E7 heads....

 

That Comp cam is a good fit for your goals and will keep the computer happy. Longtubes will maximize low rpm TQ so the extra effort to install a custom Y pipe or duals is worth it. If you install a cat with the 70 series you should have a reasonable sound level while still sounding sporty, the 50 series I have is still pretty loud even with a high flow cat in the system.