Always the voice of reason, Kwik. But I need to inject ONE MORE bit for thought...

People tend to think of diesels as having 'low end power'. But that isn't really true. All engines, diesel or otherwise, have a range of RPMs in which the engine should be operated. It is different for different engine designs.

Because diesels rev lower than gassers, people tend to think you should be able to lug them down to just above idle because, after all, they are "low-end" engines. But turbo-diesels, as any engines, should be operated within a specific range - and just above idle is NOT part of that range.

Everyone on this forum has discussed the evils of over-revving an engine. There is no question that no engine should be submitted to that kind of punishment. The only question is, what constitutes overrevving on a Powerstroke? Me? I almost always keep it below 2600, and will NEVER stray above 3000, regardless of the 3200 rpm red line.

But there has been insufficient attention paid to lugging - revving too low with too high a load. This is a very damaging practice.

The perceived "loss of low end" takes place BELOW about 1500 rpms. I submit that a Powerstroke should be operated at this rpm only under light load (or low gears). Under heavy load, it would qualify as lugging - a decidedly damaging practice that brutalizes bearings in particular, but other components as well.

If the loss of power below 1500 is real, it should be irrelevant because it is below the high load operating range of the engine.

This is my opinion, based on many years of dealing with other engines, reading and research about diesels, and my experience with my Powerstroke. You don't have to agree with me - but I honestly believe if anyone likes to pull heavy loads with their PSD at sub-1500rpm engine speed, they do so to the possible detriment of their engines.

That is why I believe a loss of power below 1500rpms is a non-issue.

 

i agree with you. driving along with the TC locked, and if i slow to below 40 mph in OD, it will lug down to 1200 RPM or so. it just doesn't sound right. so i take it into D. also when towing, you can downshift to lower EGTs. it will add airflow and lower the EGT's. say pulling a hill at 1800RPM, you can lug it down and EGT's will shoot past 1250. take it out of OD, it can rev up and EGT's will slowly fall to around (about) 1000*. all at the case of fuel mileage.

 

Personally, I'm not afraid to run it up to redline. This is a quote from cookie in a different thread:
If these engines were designed by Navistar to run to 4400 RPM, the much lower 3200 RPM redline in our trucks shoud keep them safe. I don't hold it at redline, but if I'm on the throttle and it gets up that high, it doesn't make me nervous.

Sorry to be off topic.

 

I'd throw up if my Powerstroke went that high, JT. I wonder what it would sound like at 4400?

 

Arnineteyes, good post.

 

I don't know. You could ask mech though. He runs his that high when he's competiting in sled pulls. Custom programming lets him do that.

 

Back to the original question and along the lines of RPMs, when I posted my observations of my initial drives after my 5" install, I noted that the engine went to redline--3500 RPM so fast when I nailed it going up a hill that I was shocked. It never wound that quickly with the stock pipe and I was busy trying to take in all sorts of new sensory data. Seat of the pants, tach, and the road/traffic. Strangely, I noticed very little black smoke out the exhaust whereas it would have been billowing previously. I am at a loss to explain this. Perhaps the new muffler soaked it up? I just didn't see the customary smoke that I got with the OEM system which never revved that quickly or got that high. No, I wasn't concerned about the RPMs, everything was "singing". Anybody else notice this smoke decline?

 

I have the same thing. Stock, the thing could cover the highway with black smoke. With the 5" and the 6637, it doesn't smoke at all.

 

I like the sound of that, anybody else?

 

It's a well known trick in the big rig world, want to get rid of smoke, put on a bigger exhaust. No smoke is good, you can be assured that you are getting the maximum burn on the fuel that you are feeding the engine. Smoke is wasted fuel, unharnessed $$$ going out the tailpipe.

 

Ya hit me where I live, $$$$.

 

that is why Gale Banks has spent so much money on research and preaches the best airflow possible. if you have ever seen a truck with a complete Banks package on it, there is just the slightest hint of a haze behind the truck after the turbo is spooled. some trucks with fueling boxes such as the Edge Juice will roll the smoke constantly. like Banks says, "smoke is lost power you can see". trucks that roll smoke constantly is obnoxious. being able to smoke means your truck has power. yea, i like black smoke, but it's only for showing off. i drive conservative other times. if you can just roll the smoke all day long, you should consider some airflow upgrades.

 

The answer is really quite simple.

If you get a nearly complete burn from your diesel, there won't be any smoke. The black smoke is the result of having too much fuel, and not enough air to combine with the fuel. The excess fuel billows out the exhaust as unburned diesel fuel in the form of soot.

By putting in a freer breathing intake and exhaust, you are getting more air in to burn with the fuel, a more complete burn, much less smoke, more power, lower EGT, and better fuel economy.

Oh, and your emmissions are lower, too.

That is the purpose of the turbo-charger and the intercooler - the more air you get in, the more complete combustion. Ford isn't putting sequential turbo-chargers on the next PSD to get more power. They are doing it to get more air in and lower the emissions to make the EPA happy.

For us, the more air you get in, the fuel you can add to get more power. Besides, all that black smoke is just wasted fuel - I'd much rather have no smoke and put ALL that fuel into driving the wheels!

Edit - okay, sorry. Slow on the typing. Everyone already answered it before me!

 

Yeah, Banks is right about that. Even with a Tymar intake and 5-inch exhaust, my truck BILLOWED black smoke in the upper two settings with an Edge tuner. That is one of the biggest reasons I had to try something different.

Now, with same intake and exhaust, but stock turbo, stock compressor wheel, stock intercooler and a DP Tuner 6-position chip, my truck just kind of hazes in 80 hp mode, and only a bit more in 120hp mode.

After i put on the ATS housing (yes, yes, someday. It is here and ready, I just haven't had the time - after tax day, it will be THE priority) and my 6.0L PSD intercooler, I'm hoping to reduce the haze to barely noticeable, even in 120hp mode.

 

So with this in mind, replacing your compressor wheel with a wicked wheel (someone said they move less air) would be a bad thing?