Opinions needed: Mod the 350tbi? or upgrade to 454?

[cool_as_crap]

Hi Everyone,

I have a 92 k2500 with a 350tbi and 5spd (unknown exactly which tranny). I use it to haul a truck bed camper (about 2000lbs dry) and a light utility trailer carrying a quad and two dirtbikes to the desert in so.cal twice a year for camping.

Mods: Airbags

After adding the airbags my truck has no issue towing this load, except for once I get to hwy 58 past Bakersfield, which includes a very steep grade for about 10 miles. While on this grade the truck struggles to maintain 40mph.

So for my question: Are there any upgrades or modifications I can make to the 350 to help me up the hills?
Or is my best solution to upgrade to a different truck with a 454?

I'm hesitant to get a different truck because I really enjoy the one I have and I'd rather not lose gas mileage for when I'm not towing.

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[someotherguy]

From the pic I see it's a 6 lug, making it a "light duty" 2500 - in other words, it's a 1500 with the upgrade of a 14 bolt 9.5" semifloating rear axle, a little bit more spring in the rear, slight upgrade to brakes thanks to larger drums on the rear, and very minor extra bracing in a few parts of the frame (spring mount brackets, etc.) The transmission will still be the light duty unit used in the 1500's - an NV3500 or whichever variant was used in a '92 model; there were several over the years known as HM290, Getrag, NV3500, 5LM60, yada yada. No low "granny" gear, just 5 speeds.

I'd start with being sure the engine is in top state of tune and that fuel pressure is good under load. It's easy for it to be within spec sitting in the driveway idling and revving up in neutral, but in your case you might consider making an extension hose so you can hang the gauge under the wiper arm and see how it's doing during this uphill climb. If it falls down to 10 psi or below you've got marginal fuel delivery. Could be pump, filter, or regulator. A big red flag here is if you're running lean under a load you could end up melting down some pistons.

Uncorking the exhaust could help but I see you're in SoCal so you may be very limited in what you can do.

Being a light duty K2500 I can almost bet you've got 3.73 gears (look for GT4 on your SPID label in the glovebox). 4.10's could do better for towing without hurting your MPG much, but being a 4x4 you're talking about a 2-end gear swap and that gets pricey.

Richard

 

[cool_as_crap]

How does the 350 do with 4.10s? Will that cause any issues on the freeway?
I have the GT4, will i need new cases or can i just change gears?

I have a granny low (L, 1, 2, 3, 4).
Maybe i'll just replace the fuel pump since its only $25 on amazon and testing sounds like a pain in the ass

 

[someotherguy]

$25 fuel pump isn't worth the box it's in. Testing isn't a pain in the ass, it's good procedure.

If you actually have the granny low then your truck was optioned with the NV4500 which is a great transmission. ONLY use the recommended lube indicated on the side covers, otherwise known as "GM Synthetic Transmission Lubricant"

You can find gear/RPM calculators all over the net that will tell you your RPM's at a given speed with a certain gearset.

If you have 3.73's it shouldn't be a problem putting 4.10's in the rear, not sure about the front as I'm not a 4x4 guy.

Richard

 

[chevy6.5]

Advances in 6.5l TD over the pAst 10yrs makes it a viable replacement for a light-medium duty fuel sipping tow-machine.

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[someotherguy]

And with all due respect, you're one of three people that believe that.

Richard

 

[RichLo]

You can really wake up a TBI 350 with some minor mods. I wouldn't trade it in for a different truck until you try a few proven mods and see how it reacts first.

Ultimate TBI mod with adjustable fuel pressure regulator
radiator E-fans
fresh tune up with fuel filter, plugs, wires, dist cap/rotor, air filter, fresh oil, etc
do whatever you can with the exhaust while still being California legal like long tubes into an H-pipe then into high flow cats and dumped before the rear axle, all mandrel bent 2.5" with mufflers of your choice.

Gearing would be my last resort since its the most expensive but it would be a very effective solution to your problem.

 

[RyanMerrick]

Advances in 6.5l TD over the pAst 10yrs makes it a viable replacement for a light-medium duty fuel sipping tow-machine.

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uuhhh...I disagree... strongly. The poorly designed 6.5 is simply not worth the trouble.

I echo some of the others: Gears and tune up

 

[chevy6.5]

uuhhh...I disagree... strongly. The poorly designed 6.5 is simply not worth the trouble.

I echo some of the others: Gears and tune up

Those poor designs were fixed in 2001 when AM General bought the engine designs from GM, plus a handful of other aftermarket solutions. You asked a question, I answered it. My 6.5 gets 22mpg and makes close to 300rwhp, 550ft lbs. Have fun gettin 10mpg loaded or not. But if you insist, just find a lq9 6.0. That'd be your best option.

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[someotherguy]

You may be in love with your 6.5 and that's fine; you're that "one guy" that talks about how great they are, and I'm sure you'll continue to, until it lets you down in a big way. Seems like there's always that "one guy" around and they make excuses for the 6.5 over and over, for a while. Then they fade away after their engine fails in multiple expensive ways or finally one big catastrophic way. History has taught most of the rest of us this lesson already. Enjoy.

Richard