6.0 5 speed manual advise

mdremus · March 2, 2019

I have an '02 2500HD X-Cab long bed 4wd that is a 6 liter with 5 speed manual trans. It has 4.10 gears and 245/16 tires. I pull a 32 ft bunkhouse camper and need more power. Thinking about going with 4.56 gears and maybe some computer programming. I can't find anything with internet searches for this particular truck, everything is automatic trans, or tall tires. Just wondering if anyone here has any experience with this or can give me some advise. This truck is completely stock with 117,00 miles. Pic of truck on my profile, Thanks, Mike.

NHUSA · March 2, 2019

I would start by talking with a tuner.

bubbanbrenda · March 3, 2019

Explain exactly what you want the truck to do to him, and he will get it done. Literally a mail order custom tune.

https://www.diablewtune.com/

mdremus · March 3, 2019

Sent an email to diablewtune, and he basically said with a manual trans a tune wouldn't do very much and changing gears would give the best results.

SierraHD17 · March 3, 2019

Very very few trucks have the NV 4500 in them so you will be hard pressed to find anything.

You have more or less the same ratio in overdrive as a 4L80e truck does so you already turn some rpm with 4.10s and 245s as one of my own trucks is equipped the same as well. If you don't care and it needs more torque it's just going to rev higher and give the truck more mechanical advantage. I have re-geared a couple of my own truck including my 2017 to 4.56 and would do it again... or go even deeper.

A tune on an LQ4 is a huge gain in power lol... they have next to no ignition timing stock. 5 speed or not that fact does not change. You need tuning anyway with the gears. I just wouldn't use Diablo in the first place and get a real tuner using real software like HP or efilive.

mdremus · March 3, 2019

I'm not too worried about turning the motor faster, or the fuel milage, as the manual trans is a huge jump in milage over an auto in my experience. Making it easier on the clutch in regards to backing up the camper or pulling away from stop lights is a main concern also. Will look into other tuners, also.

SierraHD17 · March 3, 2019

4.56s will rock with your tire size pulling. Even in my 6 speed auto truck it's a ratio GM should have offered factory for the jump in pulling power it gives over even 4.10s. Definitely will make your clutches life easier getting a load moving.

The tune will still fix a lot of what the old LQ4 has locked away for power. The advance curve is pathetic in them and if i remember the manuals still have power enrichment delay which is just running it lean when you have your foot in it. The difference in the power my LQ4 trucks make has little to do with the transmission and all about what the engines tune itself is missing.

If you do the gears you will want your speedometer corrected so you need a tune anyway for that. Even the tune I run in my 05 would work well in your truck haha. Be a whole new truck with some timing and some gear!

mdremus · March 3, 2019

Thank you, online forums is the only place to find info about this. My truck is very rare and nothing applies to it in online searches. Mike

SierraHD17 · March 3, 2019

Yeah like I said the 5 speed 6 liters are hard to come by and I would love to find a regular cab long box version of one. My buddy has a 5 speed 4.8 half ton we play with so it's not totally unfamiliar as yours is similar with even more restrictions on it than the half tons have.

mdremus · March 4, 2019

I live in Missouri, and we went to South Dakota to get this one in 2011. One owner trade-in with 52,000 miles. Will get 16-17 mpg on the highway unloaded, goes way down pulling a trailer, but I can live with it. I told my wife it might be the last truck I buy.

kstruckcountry · March 4, 2019

Regear, and tune for gearing change and performance. You will need to tune for and run 91 octane for the best results.

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SierraHD17 · March 4, 2019

Eh... it's an LQ4. Even with 28 degrees total advance at wide open throttle I have yet to get one to knock on 87 octane gas. They are low enough compression it makes them extremely tolerant of cheap swill. 91 is more an extreme situation insurance policy.

mdremus · March 5, 2019

So, I went to GM dealer today and had them print me off the build sheet and it was built with 4.10 gears. My next question is how accurate is the tach/speedometer? According to different gear charts I've looked at (don't know how accurate they are either) with 31 inch tires and 4.10 gears it should be running 28-2900 rpm at 65 mph. My tach reads about 2300 at 65, and 2500 at 75. I'm thinking I should pull the rear cover and count gear teeth.