I was searching around last night and came upon a post that claims he's had 100's of 6.2L's and mods don't work-GM maximized it and the engine can't take in anymore air- IE J code intakes, bigger exhaust, modifying the air cleaner etc so before I mod mine, is worth it?

I have an EGR intake so if I can find a non egr intake, is it worth the effort. What about opening up the air cleaner-i would add another snorkel and run a K@N.

Looking at headers and running a single 3 inch system for ease of install and having tons of 3 inch pipe at work.

Does adjusting the pump-richening it?????????? make any difference? why do you do it and do you lose fuel economy?

Sorry for this but I can't seem to find any solid answers and I want to tow my 4000-5000 lb enclosed trailer this summer without stopping at every gas station and only going 40 mph on the highway.

Hey Turbo...I owned a 92 chevy ext/cab 4x4 with a 6.2 diesel a few years back. I know the feeling of not enough power!! I tried to turn the pump till the motor had more power. Helped a bit, but got real loud.
My advice is to first have a look at changing rear end gears. Whatever you have now may not be steep enough.

I gave up on trying to get that 6.2 to where I liked it. You know what I did?? I bought a 6.5 Turbo. Problem fixed!!

I did however buy a much larger 5th wheel, and now again find myself with not enough power. Stupid of me... I am looking into mods this spring.

Good luck with your van.

Thanks, I basically got this van for free, so I dont' mind spending some money on it. I am also going to put a raised roof on.

I have been driving it for about week and a half and these things are wicked on fuel, over 300 km's and still over half a tank. I haven't towed with it yet but its got nice power, I am really suprised, especially since I drive a 13 sec Minivan as my daily driver.

Anyhow, all I see is the same questions asked but no one has any real answers so might as well ask again.

Wicked on fuel is right!! My old truck would do 30mpg all day long on the highway. My 6.5 turbo will get 22mpg.

Mods will help. The factory air and exhaust system was a bit restrictive. Sure, you can do all kinds of calculations about cross sectional area and come to the conclusion that it flows plenty of air, but it doesn't take into account the different bends and turns in the intake and exhaust which restrict flow. Also, the fuel on the stock C-code wasn't turned up as far as it could be because of emissions regulations.

Another thing that usually doesn't get taken into account when figuring airflow through the intake is the EGR... We're dealing with 20+ year old trucks here and the EGR valve doesn't usually seal perfectly. Ordinarily, on a like-new truck, the EGR valve is only active at idle and doesn't affect performance at speeds above idle (except for a slight restriction to intake airflow due to the location of the valve, which does make some difference). With an older truck, the EGR may shut off above idle but it may leak, allowing exhaust gases into the intake. Regardless of whether or not it leaks, it does restrict the airflow through the intake a bit. It also makes a mess of the intake.

Turning up the pump is pretty simple. It shouldn't get louder when you do it. It might get louder if you advanced the injection timing by rotating the pump. To turn up the pump, you pull the pentagonal side cover on the driver's side of the pump (or the top cover, but the side cover is a bit more idiot-proof). It helps to have the intake off of the engine when you do this. Then you rotate the engine (by hand using a breaker bar) until a small adjustment screw appears in the window where the cover was. You turn the screw a little bit with a 5/32" allen head wrench to turn up the fuel.

Turning up the pump increases the fuel output of the pump at fuel throttle. Basically, this makes the engine run "richer". The engine produces peak power when it runs slightly rich. A little black smoke means more power. Increase the airflow a bit and the smoke goes away. Turn the pump up again until you get some smoke again. Repeat until you run out of ways to increase the airflow... Then you need a turbo to clean up the smoke. I would recommend getting rid of the stock air intake setup and turning the pump up a little (1/8 turn or so).

I was searching around last night and came upon a post that claims he's had 100's of 6.2L's and mods don't work-GM maximized it and the engine can't take in anymore air- IE J code intakes, bigger exhaust, modifying the air cleaner etc so before I mod mine, is worth it?


Does adjusting the pump-richening it?????????? make any difference? why do you do it and do you lose fuel economy?


I've done many of the calculations and own over 20 6.2s now. But, can't say I've had "100s." I have been working on them since they were new.
Maybe you saw one of my posts, maybe someone elses.
I've neve said anything close to "mods don't work." I've said that some do, and some don't. That is the simple reality.

Just about any stock engine - gas or diesel has a volumetric efficiency of around 70%. What that means is - it's able to draw about 3/4s of it's bore&stroke when a piston goes down on an intake stroke-cycle. So - a 6.2 - which is 379 cubic inches - and each cylinder pulls air - every other revolution - is not very hard to figure out. In regard to how calcuations fail to account for friction in bends and curves? I've alway figured with that factor added in - but guessed at conservatively.
I've also studied several flowcharts taken from actual testing.

In regard to turning up the fuel - there can be one big problem. When you turn up the fuel with a gas engine - it runs rich and can eventually foul up - but otherwise does little to no damage. But, when you turn up the fuel on a diesel - especially one without a turbo - it does NOT run rich. What happens is - unburned or partially unburned fuel builds up and raises exhaust-gas temperatures. That can easily crack the cylinder-heads in the 6.2. You can also gain some power this way - but you have to be careful. Some people prefer to rely on a pyrometer. For myself - I can smell it when the heads get too hot - there is no mistaking the high-temp odor once you're accustomed to it.

Ok, thanks guys. I bought some of those Hummber headers off Ebay, for $60, you can't go wrong.

I will try to dyno it bone stock before I start playing.

Jemaris, it could have been you, someone else, but the person I saw said he had fleets of 6.2's? either way, no attack at your or him, just want facts. Heresay is great for some people, I am NOT one of those people, otherwise i wouldn't have a 13 sec Dodge Caravan that I drive everyday, :D

Also, looks like I'll get a fluiddamper also, I don't want my crank breaking in 2, :(

Jemaris, it could have been you, someone else, but the person I saw said he had fleets of 6.2's?

Also, looks like I'll get a fluiddamper also, I don't want my crank breaking in 2, :(

One could say I've got a fleet. I have somewhere around forty 6.2 vehicles - but many are rust-bucket parts trucks. I've got around 15 that run, and never have more the four registered and driven at one time. I do swap during the year - I've got three 6.2 diesel plow trucks that only get used in the winter. And, any that I have that are rust free - NEVER get driven in the winter salt.

In regard to protecting yourself from a broken crank - good luck. Personally, I don't believe any damper or balancer in the world is going to prevent a badly cast crank from breaking. Most diesels have forged steel crankshafts and breaking is not a issue. The 6.2s and 6.5s use cast cranks. Some have broke to pieces at very low miles without being used hard. Others have been worked very hard for 500,000 miles and held up fine. I personally believe it is a quality-control issue.

Nothing wrong with taking all the insurance you can get. But. . I don't think you'll find verified test data anywhere that can proove any crank has lasted longer with an add-on.
#1 best insurance is - if you can - get the block and crank checked for stress cracks. Seems the stud-girdle kit is a good idea also. Certainly can't hurt and doesn't cost much.

Maybe true on the girdle but add up the engine re and re, then tear it down, then you might as well freshen it up, all of a sudden, its alot more than "its not that much" My van only has 60,000 miles on it, if the damper helps it live, its piece of mind, :D

When you turn up the fuel with a gas engine - it runs rich and can eventually foul up - but otherwise does little to no damage. But, when you turn up the fuel on a diesel - especially one without a turbo - it does NOT run rich. What happens is - unburned or partially unburned fuel builds up and raises exhaust-gas temperatures

Not to disagree with you, but I think "rich" is being interpreted more than one way. Just to clarify, when I say the engine runs "rich" I mean that there is more fuel being supplied than is required to use up all of the air in the cylinder. No, a diesel doesn't foul out or "flood" like a gasser does when it runs rich, but it is similar in principle. Like a gas engine, the diesel will produce peak power when there is slightly too much fuel for the air in the cylinder.

I agree, EGTs are definitely a concern any time the truck is blowing a lot of black smoke. It isn't really an issue if you don't stay on the throttle for very long, but it is something to be aware of.

I was told awhile ago an EGT guage wasn't necessary for an N/A engine but looking at these posts, it seems it is. Does it matter which bank you put it in or ?????????

Not to disagree with you, but I think "rich" is being interpreted more than one way. Just to clarify, when I say the engine runs "rich" I mean that there is more fuel being supplied than is required to use up all of the air in the cylinder. No, a diesel doesn't foul out or "flood" like a gasser does when it runs rich, but it is similar in principle. Like a gas engine, the diesel will produce peak power when there is slightly too much fuel for the air in the cylinder.

I agree, EGTs are definitely a concern any time the truck is blowing a lot of black smoke. It isn't really an issue if you don't stay on the throttle for very long, but it is something to be aware of.

Yeah, "rich" can often denote an inbalance in the air-fuel ratio - but certainly mean other things depending on context. I'm not trying to play semantics here. But, the affects of too-much fuel, or too-little fuel - differ a bit between the gas and diesel. A gas engine - if run too lean - gets too hot in the combustion chamber area - to the point that things can melt. If a gas engine is too rich (more than 14-1 ratio), usually no damage is done - things just get fouled up.
With a diesel - it is designed to run lean (using the air-fuel ratio meaning) with a wide-open air-intake all the time. If you turn the fuel down, the power gets lower - but otherwise no bad effects. But, if you turn it up too far - the internal temps rise - converse to what a gas engine does.

Yeah, "rich" can often denote an inbalance in the air-fuel ratio - but certainly mean other things depending on context. I'm not trying to play semantics here. But, the affects of too-much fuel, or too-little fuel - differ a bit between the gas and diesel. A gas engine - if run too lean - gets too hot in the combustion chamber area - to the point that things can melt. If a gas engine is too rich (more than 14-1 ratio), usually no damage is done - things just get fouled up.
With a diesel - it is designed to run lean (using the air-fuel ratio meaning) with a wide-open air-intake all the time.


:exactly:

I was told awhile ago an EGT guage wasn't necessary for an N/A engine but looking at these posts, it seems it is. Does it matter which bank you put it in or ?????????


No, I don't think it is necessary. You've got a built-in EGT gauge... Just take a look at the exhaust and see how much smoke it puts out. A properly tuned engine that is getting plenty of air will show just a slight haze of black smoke from the pipes at full throttle and that is fairly safe. You really only need to worry when you've got smoke pouring from the pipes for an extended period of time. A lot of black smoke is all right for a short period of time and a little smoke is all right for a longer period of time.

Another thought... There really is no established "limit" for EGTs on a non turbo engine. To find the limit you would have to break it... :eek:

Bottom line... Make sure it is getting plenty of air. The more fuel you can push through the engine the more power you will get, but you need to increase the airflow to match. You can overfuel the engine and push out a lot of smoke and some more power, but it is a little risky.

I was told awhile ago an EGT guage wasn't necessary for an N/A engine but looking at these posts, it seems it is. Does it matter which bank you put it in or ?????????

I can't judge what is necessary for someone else. For myself, I can smell the heads when they get too hot. I notice that with any of my 6.2s, the heads can get hot to a point where there is an unmistakeable smell that is similar to burning-paint. If often happens with a 6.2 that's been turned up, and is climbing a long hill - perhaps with a trailer behind. It must work for me - because I've never cracked a head nor have I ever blown a head-gasket.

But . . . my son recently took my 87 Suburban home to Colorado with him. He turned the fuel up a bit and advanced the initial timing a little. On his first "outing", basically beating the heck out of it on a hunting trip in the Wyoming mountains - with tire-chains on all four wheels - he cracked both heads and blew a head gasket to boot. And, my son is no dummy by any means. Just tends to drive harder then me - and perhaps expects a 6.2 to be as durable as a big-rig. I'm not that trusting. So, I think - at a time when I would of backed off - he did the opposite. In his case - a pyro-gauge would of been useful. But, he's having fun - and getting to see the inside of his engine for the first time. He's putting on brand new, heavy-casting, "made in China" 6.5 heads.

All interesting info. Hmmmmmmmm.