NemesisC5

I'm familiar with headers on many applications and in general I like the throaty visceral exhaust note they make. It's the L9H with VVT that was said to make more "mechanical noises" that I am concerned with. Typical stock manifolds help isolate these sounds on any vehicle and headers make these sounds more noticeable on any vehicle. With the added complexity of VVT it seems plausible that extra valvetrain noise could be present and made more noticeable with long tube headers. I'm asking if anyone that owns an L9H with long tube headers can tell me if there truck has more mechanical noise than a non VVT truck?

Not an answer to my question, I'm asking about mechanical noises on the L9H being louder than other engines. If you can't help with contributing helpful information please refrain from "if God meant for men to fly he would have given us wings" type of answer.

I still have factory exhaust on 2011 Silverado 1500 with the 6.2. Been looking into headers and read a thread on Performance Trucks of an owner removing LT headers because of mechanical noise made more audible after installing headers. Several other members chimed in and agreed they have the same noise but most were not concerned. I have a C5 Corvette with headers and the they definitely bring out more noise from the internals but the previously mentioned thread on Performance Trucks indicates that the noise on our trucks is louder than other engines / apllications. Can anyone here comment on this?

I've read posts on other forums referencing when installing TB spacers on certain Ecotec intakes they will not work correctly unless you grind down a hump or rise just inside the TB flange. I cannot speak to accuracy just passing along.

The LS9 cam provides noteworthy gains in mid to upper RPMs but loses low end torque. You would do better to have a custom cam or proven shelf grind VVT cam for your truck. http://www.performancetrucks.net/forums/gmt-900-trucks-general-discussion-188/installed-ls9-cam-escalade-537183/ http://www.performancetrucks.net/forums/gmt-900-trucks-general-discussion-188/ls9-cam-results-dang-490303/

Since many different engine / exhaust configurations exist I'm focusing my comment solely on the GM 6.2L L9H V8, the engine / truck combo this thread is specific to: Smaller primaries on headers increase velocity thereby create a scavenging effect to empty the exhaust gases making more room for cylinder fill of fuel/air mixture. Backpressure (downsized tubing-smaller or more restrictive muffler) downstream inhibits scavenging of exhaust gases and decreases performance. A smaller tail pipe will not increase performance. As rpms increase you may notice the fall-off of performance on top end creating the illusion that bottom end has increased.

First, Happy Thanksgiving To Everyone! Reducing exhaust diameter post y-pipe merge will not usually result in gains especially on a 6.2L. Power gains generally come from reducing diameter upstream to increase velocity thus increasing scavenging effect to evacuate non combustible exhaust gases from the cylinders leaving volume for clean combustible fuel. The reduced exhaust diameter on the 2014 6.2L is more likely a result of controlling exhaust note with AFM (in 4 cyl mode along with butterfly valve in muffler) and possibly a cost saving measure going with 3" as opposed to 3.5" tubing. I will follow up this post later today if possible with some information I gathered on the subject. Right now I'm off to eat Turkey!

That would be my guess, primarily to work best with the muffler / butterfly valve enhancing exhaust note and controlling drone.

2011-2013 all 6.2's come with 3.5", not sure on earlier model 6.2's. 2010 may have the 3.5" as well. 6.0L Vortec Max comes with 3"

3.5" on my 2011

Pro-Flo #2510 3.5" factory replacement Pro-Flo #2507 4" factory replacement Both of the above same size, shape, offsets as factory muffler so they'll fit right in place.The #2507 is 4" tubing so you'd have to have your factory 3.5" flared or adapted. It is also a 3 chamber design which is louder than the #2510 4 chamber design. Both louder and flow better than factory however the #2507 which is somewhat new would be the louder and best flow.

I don't know of cross application fitment but here are two urethane motor mounts from Corvette vendor Hinson MotorSports. One tall, the other slightly shorter. Good luck in your search and hope this helps. http://forums.corvetteforum.com/c6-tech-performance/3476506-why-are-hinson-motorsports-urethane-mounts-better-heres-why.html

Trucks are heavy so usually larger rotors are incorporated into a higher performing brake system for their ability to generate extra brake torque. Baer makes two systems for our trucks but neither will accommodate 17" wheels, you will find there are not many if any manufacturers that do. The first is their 6s Extreme system with 6 piston calipers at all four corners around $3k per axle. The second is their Aluma Sport system with larger 14" rotors and two piston calipers at the corners. If you just need increased braking power you would be amazed at the difference a set of quality pads can make with no other changes. You may get into an issue with some of the high performance pads of higher dust but you may find a low dust compound available that will suit your needs. You could call KNS brakes and get some recommendations, they advertise on Corvette Forum and specialize in brake consumables so likely could sell you something that will meet your needs. On a 2002 C5 ZO6 I installed some top quality pads for road course driving and it blew my mind how much brake torque was generated with factory hardware and only different pads.

I didn't think of it that way, didn't consider viewing the Diablo tune as HPT file? I purchased the Diablosport inTune because I read and was told that the Diablosport tuners don't leave the footprints on the PCM like HPT or EFI. A GM Tech 2 can see that the tune was viewed but no footprints of a change in calibrations. Again, just what I've read and been told. Tonight going to Best Buy to purchase a laptop to start playing with HPT again. Thanks for the good advice.

Currently on Diablo custom tune that I added timing to. Three rpm ranges to change. I added 5*, 4*, then 3* in top rpm range. Sounds like I left some on the table with you adding more timing up top than low-middle like I did. So you added more timing upper rpms? If so sounds like I need to get my head on straight and take it up a little. I do own HP Tuners but have not used it in 3 years.

I bumped my timing 5* over a mail order tune as well and the difference was BIG. Much more responsive. If I understand you correctly I will notice a difference without changes to tune and filling up with E85? If that's correct I know where I'm going to fuel up after work!

I have a custom 93 tune but factory E85 tune. A new fuel station just opened last week with E85 and I am going to fill up soon. Do you think the factory E85 tune will perform as strong as the custom 93 tune? I know there are variables like how sharp the 93 tune is but I would only like your general opinion/guess on what you think. This is the first discussion I've had with anyone on E85 in my truck so I'm starting off with zero information/feedback. Thanks in advance.

Thanks for the great info. Do you always run E85 or do you run 93 octane more often? I assume the pcm recognizes the E85 and switches to your custom E85 tune and when you run 93 switches to your custom 93 tune?

I understand, sorry to get off topic.In my original post in this thread I was asking for E85 power numbers from the L9H and got sidetracked. Still hoping someone has the information and will post.

Power Numbers Released for Gen-V 5.3L EcoTec3 and 4.3L Truck Engines I couldn't find the official E85 numbers for L86 6.2

That's odd. The 2014's have published numbers from GM showing power numbers with both fuels. E85 results somewhere between 15-20+ higher both HP and TQ

I've read not quite half of the 48 pages and ran outta time so I'll just ask: What is factory HP /TQ rating of L9H running E85? I know 403 and 414 running premium 91 but could not find the E85 numbers. What power numbers have some put down with BB E85 tune on stock or bolt on truck with L9H?