2004 6.0 NV4500 Tahoe

Played with the tune and got it to sound more aggressive without making the engine run like it's missing cylinders. It still wants to drop to far after a high rev so I need to figure that out but it's very driveable and WOT safe now.

I went ahead and ordered a Magnaflow 12599 muffler and hopefully I'll have that in soonish.

Heres some questions I asked myself before I started this and the now found answers.

Question: Does the truck feel faster?

Answer: No not really. I do feel that it continues to pull harder after 5500 up to 6500 but I don't believe it is anymore than a 1/10sec or so faster in the 1/4 mile.


Q: Did it lose low end.

A: Feels no difference down low. It still puts you back in your in your seat in 1st and 2nd gear. However my gear ratios are similar to the NNBS 6 speed guys so 4l60 guys you would probably notice it sluggish off the line.

Q: Any other benefits?

A: The valve train is considerably quieter. Could have been a minor exhaust leak that is fixed or possibly dual valve springs and the CHE trunion upgrade make for less noise.

Q: What would I do different?

A: Given more time I would have gotten some custom heads or had these sent off for CNC porting. Also would have gotten custom head gasket to raise comp ratio closer to 11-1. It's at 10.4-1 now. Even with those upgrades I doubt it would pickup more than 10% power gains.

Since I like posting terrible videos heres another one where it pathetically dies after a rev

Figured out the my AFR problem was that the sensor must have died when the engine dumped coolant on it. Anyway replaced it and finally got to some actually air and fuel tuning instead of band-aiding it from acting weird by messing with the spark. There were some very odd spots where I suppose this new cam flows better and the tune was off enough to cause a noticable spike in the graph.

Thanks to videos from Goat Rope Garage on youtube I got it straightened out and it's running smooth and steady. Might tackle timing tuning tomorrow and see if I can pick up MOAR POWA!
Also I wasn't paying attention on one pull and hit the limiter at 6500, subsequently I nearly browned my trousers. Thinking about bumping it to 6800 so I can hit 60 before I have to shift because the 2-3 shift is slow and kills my 0-60 time.



Here's a link to Goat Rope, if you have HPtuners and don't watch his videos your wrong.

Alright heres some new exhaust videos. I replaced the Flopro 2500 with a Magnaflow 12599 and wow it is seriously loud now. Both mufflers are dual 3"in and dual 3"out and the case size is nearly the same, the Flopro is just a tad wider.

First video is just a startup idle and rev

Second video is getting on it from 1st-2-3

what kinda gas you got in that thing?

whats with the knock?

Ahh... That familiar NV whine!

Is it too loud for you inside?

randeez said:

what kinda gas you got in that thing?

whats with the knock?

Click to expand...

Pump 93 for life. I don't notice any knock myself maybe its the camera or your hearing the "Wonderful NV4500 noises".

However at that time I was still on MAF only. Spark table isn't showing it pulling timing anywhere but maybe I'm wrong. Im knee deep in SD tuning now then Ill start on the spark table.

iamdub said:

Ahh... That familiar NV whine!

Is it too loud for you inside?

Click to expand...

The trans really isn't as loud as the video made it seem, my phone was sitting inches from the shifter so I think it made it worse. But they do make noise lol. The exhaust is just really loud anytime above 2k even at say 25% throttle its just obnoxious. My GF hasn't complained yet but I'm sure she will if we have a road trip with a trailer. I'm gonna have to see if there is any room to add resonators or not and I'll just go from there. I do feel as though it picked up some power with the muffler swap. I know that sounds dumb but it feel like more of a gain with the muffler swap than the cam lol.

I have never touched the VE tables myself and I suppose the PO never did either because holy crap it was running rich on SD. Unless I'm reading this wrong.

that KR




def a little rich, you really need to turn off the maf, ltft, run it in open loop, etc to make sure there is nothing else adding to the fueling.

randeez said:

that KR

View attachment 258747

Click to expand...

Oh dang you are right. I wasn't even looking at any of that when I screen shot it. I think that was my second run when MAF tuning and the first time I had run it that high. It should be smoothed out now, I will have to log and see tomorrow now that I think I have it straightened out and back to running the MAF and MAP.

I really appreciate the help because I am far from being a pro at this lol.

setup an error histo for the maf also

nevermind just noticed it up on the corner, you can adjust the VE table with it that far off. i would just cut like 10% out of the entire table or something (multiply entire table by .90) it will swing pretty far with everything else effecting fueling