6.2L (L9H) Owners - Get all your questions answered here

[SILVERADOSC540]

Hey buddy. No boost gauge, Callaway tells me about 7 pounds as well. As far as a tune, I'm told Justin at Black Bear Performance is the man for GM tunes. I'm told that these LS motors, in our case the L9H, have pretty good knock sensors and they will retard your timing if they sense detonation. That might ease your mind a bit. If you end up doing a boost gauge let me know how that works out, I may follow suit. You sound just like me, I get 540HP under my right foot and within a week I'm thinking "a little more"...

[PDYoung]

Edited July 16, 2012 by PDYoung

[PDYoung]

 

Finally i was able to post some pictures This is a video,click on picture to get video to play.

Edited July 17, 2012 by PDYoung

[PDYoung]

 

 

 

 

[Knowklew]

Go back and edit your original post...

[RyanbabZ71]

Trying to post photos is a train wreck

[MikeNH]

I use photobucket for photos. So much easier. Upload it and it even generates the correct code to post it on a forum like this.

[SILVERADOSC540]

Nice work PDYoung. You buy a truck, rip off the front end, re-wire it, and tear apart the motor, all in the pursuit of more power. You've got a giant set my friend. Keep the updates coming, If I ever get a day off I'll try to get some stuff together on mine as well.

[Knowklew]

How long did this install take for the Edelbrock Supercharger?

[200kss]

Just got back from a road trip while towing with my 2011 L9H 4WD non NHT. Had 4 people in the truck, pulling an alum. open car trailer and a 3500 lb. car. Love the 6 speed auto but would like 3.73's over the current 3.42's. Cruising at 75mph in 100 degree heat, the trans. stayed in 5th most of the time with downshifts into 4th on hills. MPG was 10-12 running between 89-91 octane, all had 10% ethonal. My only concern was the trans. temp. On the highway it would run 175-190 depending on hills, but in stop and go traffic it would go right up to 196 with a peak of 205. My 07 Vmax never got that hot even when pulling an enclosed trailer.

 

Did NHT trucks get a bigger trans. cooler?

[ChevyTech77]

That's not hot and appears to be changing (from highway to city) just like it should.

 

I'll assume your vmax had a 4L70 and 4.10 gears as well? That makes a huge difference.

 

As long as that trans fluid isn't 240+, I wouldn't sweat a thing.

 

P.S., I'd stop running lower than 91 octane as well cause you're just causing more issues with power and mileage because of it.

[200kss]

Thanks for the reply. I did some research today and see that my temp. wasn't as big a cause for concern as I first thought. This truck is still being broken in, turned over 4000 miles on the trip.

 

My previous Vmax had the 4L70 with 3.73's.

 

I was on the fence between 2500HD 6.0 w/3.73's or a 1500 w/6.2. Bought a leftover '11 and thought it was strange this truck had 3.42's as apparently all the others I had found were NHT's with 3.73's. Lesson learned.

[SILVERADOSC540]

Brian- Have you put on an aftermarket grille? My buddy put a billet style with the narrow bars/narrow openings between bars on his truck and his tranny temps went up as well. Did you use tow haul mode? That will usually keep it from downshifting quite as often. I'll bet that without that trailer behind you you're getting much better hwy mpg with the 3.42's. I guess there are pros and cons to both sets of gears.

[200kss]

No aftermarket grille. The truck is 100% stock down to the paper air filter, exhaust and factory chrome 20 inch wheels. Honestly fuel economy is unloaded is nearly identical to my 07 with the 4L70 and 3.73 gears.

 

Tow/Haul was used 95% of the time. On previous trucks I haven't liked t/h in city driving, felt like a large stall convertor and wouldn't upshift (especially in an 01 2500HD we had). Experimented a bit and didn't see any change as far as temps go with t/h on or off.

 

I realize LS engines make there power up in the rpm's but never have embraced the idea that 10 hours of 3000-4000 rpm pulling a load is ok. That's where I'll be running with the enclosed trailer hooked up. Trailer weighs 4400 empty and we put 4000 worth of stuff (car, canopy, cooler, etc.) in it. We only make 1 trip a year like that so a gas guzzling HD for the rest of the year didn't make much sense.

 

Now looking at the basics of modding, the replacement Magnaflow muffler, CAI kit and possibly a tune.

[Knowklew]

CAI is not worth it, just do an MIT tube and a BB tune. Should make a world of difference.