Getting cheap power from your 6.2 diesel

[Sterling]

Its about time someone writes up about the cheap power mods to make your 6.2L GM Diesel get up out of its own way.

I will list from lowest to highest cost

1) Turning up the Injector Pump - FREE

There are many how to write ups on this, so I wont go too far into detail to save space. But essentially what you are doing is setting the MAX fuel output of your DB2 injector pump. So now when you slam your foot to the floor, you have more fuel going to the cylinders. In diesel engines, you really can't run too rich unlike gas engines. All you do is just waste diesel (black smoke) but it really doesn't effect preformance. That is why high power diesel trucks shoot thick black smoke when doing a 1/4 mile run, because they want to use every last bit of AIR in the engine. At this point, your only limiting factor is air, hence why many put turbos on their diesels, to shove more air into the engine. Just don't get too carried away with turning up this pump, your Exhaust Gas Temperature goes up when you do this, and if it gets too high (over 1200 F) you'll start melting things. Usually an 1/8th of a turn of the fuel set screw (allen screw) is safe.

2) Cold air intake - $10

What you want to do here is bring fresh cold dense air into your air cleaner housing. My truck came with an intake tube that went to a rain deflector on the passenger side of the grille, just above my coolant bottle. All I did was get expandable HVAC 3" ductwork (the metal kind) and a 3" to 4" HVAC adapter. The stock air deflector (keeps rain from entering your intake) has a 4" output. I decided to keep the stock deflector because it takes in fresh air from up front, and flow will increase as my speed increases, and it flows pretty well. I then used the adapter to bring that intake down to 3" so I can use 3" hose. Then I ran the 3" duct/hose to the air cleaner box which has a 3" oval input. All I did was sort of bend the metal hose into an oval shape, and connected it to the air box with a rubber sleeve that used to connect the air box to the stock air hose/air muffler.
Instantly I noticed about 15 HP increase, and a lot less black smoke at full throttle, which means more fuel is being burned due to more air entering engine. Get rid of that restrictive intake muffler, and run $10 of HVAC hose.

3) Fuel Filters - $10-$20
This is a general maintenance item. If your fuel filter(s) are clogged, you aren't getting good fuel flow.

4) Fuel LIFT pump - $20
The mechanical fuel pump on your engine. Yeah these wear out over time. And your injector pump pulls enough pressure to keep the engine running if this is bad. Get fuel flowing to the IP again with a new Lift pump if yours is bad. Easy way to check is to loosen the output line from the Lift pump and turn the engine over, if fuel comes out, its good, if not, better head to NAPA

5) Cotton "lifetime" air filter - $20-$50

We all know about K and N air filters. Well FRAM at one point made the "air hog" filter, which is pretty much an orange K&N filter. Rock Auto still has some of these on closeout (fram stopped making them) and you can get them for cheap. They are the same numbers as fram tough gaurd filters, but instead of CAXXXX its PRAXXXX. I found mine on ebay. And if you cannot find a fram one, use a $20 off order of $50 coupon code at Advance Auto and get a K and N. As I said before, you want as much air flow as possible with your 6.2


6) Intake Manifold - approx $60

Most of our 6.2L came with EGR equipped manifolds. If you open your air cleaner, and see this big round thing in the center of the manifold, you have EGR. EGR is a big restriction for our engines, and let me be honest, stops properly functioning within a few thousand miles of when your engine first ran, due to poor design and soot buildup. And it blocks air flow. Lucky for you, many 6.2L were used by the ARMY that came WITHOUT egr. Many army surplus intake manifolds are being sold for very cheap. The best flowing manifold you can get (more air = more fuel that can be burned = more power) is the 6.2L HMMWV hummer manifold. It is a single plane manifold. The only mods you need to do for this is make a 3-4" spacer, because this manifold sits lower then your old one and your air cleaner box will hit the injector pump. I made my spacer out of 6" diameter PVC pipe I got at Home Depot, and just cut to the height I needed. Works great and is cheap. Make sure when you buy a new intake manifold gasket, you get the NON egr gasket, this gasket has a metal plate in the center EGR hole to block EGR gas flow to the manifold. I believe though, All of the Fel Pro gaskets for our engines come with the block off plates. Ive bought 3 sets and they all had them if you needed them.


Have fun hot rodding! also for those who know about the HMMWV headers, I would have mentioned them, but unless you can weld, good luck getting them to not dump out into your firewall.

-Sterling

[78K20]

Good tips !

[D13]

Try this:
Don't turn up your pump.
Add manual override to the glows and put in 60G's.
Cold air yes.
Get an early J code intake with the divided plenum but no EGR. Better lower torque.
Disconnect EFE/EGR and wire the exhaust valve open.
Fresh injectors.
Replace Model 80 filter and mechanical fuel pump with Racor 30 micron, 6.5 electric pump and then 2nd stage Racor.
Burn 20% recycled motor oil (higher heat energy).
Never get the motor over 3000 rpm.
Get 23mpg with the AC on at 55mph.
Enjoy 200, 000 miles with nothing but belts, oil, and filters. And an occasional CDR.

[zaccaglin]

Hate to dig up a three year old thread with a different topic that the OP, but does anyone have any mods that can be used to Maximize millage? Ive already done the Air Intake hose Change out, clean my cotton filter regularly. As well as replacing Oil and fuel filters..

[Edahall]

Originally Posted by zaccaglin

Hate to dig up a three year old thread with a different topic that the OP, but does anyone have any mods that can be used to Maximize millage? Ive already done the Air Intake hose Change out, clean my cotton filter regularly. As well as replacing Oil and fuel filters..

I see that your Suburban has a TH400, 4x4 and is 3/4 ton.

To maximize mileage, you've also got to get your RPM's down and use a transmission that has a lock up torque converter or go with a manual transmission. A good compromise is 1800 rpm's at cruising speed.

The next thing on the list is a free flowing exhaust system.

I've got a 1982 6.2 Suburban, C10, 700r4, 3.08 gears and it'll yield very high 20's on the freeway driving conservatively.

[Edahall]

Another thing is keep your speeds down for best mileage. These trucks are not very aerodynamic and once you start pushing over 60-65 mph, fuel economy goes down like a tank.

[crashz]

Good tips.

I'll add:
- Opening up the exhaust will help it breath a bit better and help with power and mileage. I beleive Stan's Header's are pretty popular, but haven't tried them. Gonna upgrade my duals to 2.5" in the dump truck.
- Rebuilt, balanced and pop-tested injectors will help with power, mileage and smoother running. If you have a lot of miles this could really help. Not exactly cheap, but all 8 are cheaper than 1 Dmax injector.
- Recommended engine oil used to be straight 30 weight back in the 80's. I remember putting Valvoline 30 weight in my first 6.2L with Fram filters. Lots of better choices (even back then!) now.
- Harmonic dampers should be replaced if stock. My looked great in the front. The back side was swollen and cracked. I've been told that the Fluid-damper helps to smooth them out even more and picks-up a little power. Not cheap though.
- Oil cooler lines leak and crack. I replaced the O rings on mine, but plan on seperating the coolers, so new lines will be made for those.
- New thermostat. My old one cracked open at 210 (on the stove). I think it was supposed to be a 195. Either way, a 180 was put in with a weep hole added.
- Fan clutch. These tend to wear out and not engage enough. I modified the temp spring to come on early, but I've been thniking about electric fans. Once its back on the road, I'll work on that. I think by seperating the oil cooler, transmission cooler and radiator, E-fans might work pretty good on all three.

[Edahall]

Originally Posted by crashz

Good tips.
I beleive Stan's Header's are pretty popular, but haven't tried them.

I've got a set of Stan Headers in my 82 Suburban. The difference in power is like night and day. So much so that you wonder why people spend money on a Banks Turbo. The difference is very minimal. The Banks turbo gives a little more power at high rpm's while the Stans headers has an edge on low rpm power and fuel economy. The headers also don't take up space under the hood. It keeps things clean and simple. Also, with the price of diesel these days, it doesn't take much time to pay for the cost of the headers.

[special-K]

My answer is the same for the new and old question. I get power and economy from my 6.2 by putting fuel in,starting it up,putting it in gear,and stepping on the pedal. It gets out of it's own way,gets great mileage,and has for 29 years.

I would like Stan's headers,though. Those won't hurt it. On my '91 6.2 Suburban I had custom 3" exhaust and that gave the same feeling as Edahall mentions headers gave. I felt a good increase of power and wondered why people bother with turbos. I've also had an '84 pickup with Banks Sidewinder,so that's where I'm coming from. These engines need to be left stock,but exhaust is after the engine and can help keep heads cooler.

[crashz]

Edahall, I've read your review on Stan's Headers, and you are my primary source on this. I think you have me convinced.

I've been searching for some cheap power from my current 6.2, because this one is the heaviest truck I've owned with a diesel. I haven't run it over the scales yet, but she must be around 7-8K lbs empty. Both of my 83's were 4x4 pickups, and much lighter, so the 6.2 was pretty comparable to driving a stock 350, and was very driveable while returning 22 mpgs.

[85mudder]

You guys doing these mods, I just sold my cummins, and I know that the 6.2 will never compete with that truck should this truck be capable of pulling a 4000# gooseneck with 3000# of horses, 7-8000 total without a turbo? It's All stock as far As I know, it pulled it, but 55 seemed like a chore on flat with no wind

[Chevy3+3]

Originally Posted by 85mudder

You guys doing these mods, I just sold my cummins, and I know that the 6.2 will never compete with that truck should this truck be capable of pulling a 4000# gooseneck with 3000# of horses, 7-8000 total without a turbo? It's All stock as far As I know, it pulled it, but 55 seemed like a chore on flat with no wind

I went backwards in power as well. Don't get discouraged. I've had Cummins and drive my father in laws tuned twin turbo powerstroke Ford (crazy pulling power!) and even my recent Mega cab Hemi powered truck had more power than my 88'454/th400 4x4 crew cab. I may not be able to achieve highway cruising speed as quickly as the newer trucks but once I get the 454 cranking over 2500 rpms there isn't anything that can slow it down, lol. I don't tow often thank goodness cuz 5-7 mpg sucks! Lol

I may not get there as fast or as easily pulling but I will get there eventually. I'm fine with that because I enjoy driven the older trucks more.

[85mudder]

I loved the dodge, I love this truck, but if am engine has to work that hard, it's not gonna last, just want to mAke sure it's not gonna kill it

[D13]

Understand these were designed to be the power equivalent of a 305. To get more than 220HP or so takes a lot of stuff and over that needs the aftermarket block.

These area all about fuel economy not power!

[Edahall]

Of course there is the option of transplanting a 6BT Cummins under the hood. There are a lot of them out there because the engine outlasted the Dodge truck.