Engine is out and HP parts ordered, what headers
 

Upgrading due to noisy lifters,

Decided to upgrade, cam, exhaust, converter, etc...

I've ordered the cam package from GPI Performance, LLT2 VVT cam, 2300 - 2600 converter, now need headers and cats to finish it out. Once I get it all together and back in the truck GPI will tune it.

What is everyone using for headers, prefer ceramic coated but SS may work also. I've looked at the OBX but cannot find any with the cats, the ones for the 6.2l are with resonators no cats, I'm going to call OBX and see if they have anything that will work with cats.

Neal

Some of the top ones I'd consider would be Kooks, Pacesetter, Texas Speed, Gibson, Stainless Works, OBX.... a number of top notch brands out there. OBX is on the lower end but still very good. I put their stainless ones on mine and am happy with them but the cats are as you said, really just resonators. Couple of important points..... do not waste money on shorty headers. Those provide for almost no performance benefit at all. Long tubes is the only way to go.

Ceramic coated will be much cooler under the hood for temps and potentially a little less valvetrain noise but there is a caveat to them. Headers very very often need some "massaging" with a hammer to get them installed. If so the coating will get chipped and they will rust through there and there is nothing you can do to repair the coating if it does get chipped short of totally sandblasting it all of and having them re-coated. They also cannot be welded on without removing all coating where welding is wanted to be done. Stainless on the other hand is also difficult to weld but doable if the same composition filler rod is used and the welder knows what they are doing. One thing many are not aware of with headers is you will hear some valvetrain noise that cast manifolds hide... its not really loud or objectionable but its worth noting.

I did go through your thread on your header install, its what got me looking at the OBX headers. Welding is no issue as I did it for 10 years with a lot of aluminum and SS material.

My concerns with the resonators is I don't really want to delete the 02 codes and don't want to be fighting the MIL due to the 02 sensors, was this an issue when you installed your headers?

I installed some Pacesetter ceramic coated headers on my sons 99 chevy short bed single cab 6.0L we built up and they worked great along with a true dual with X pipe system

No plans for shorties, to me they are a waste of time if your looking for performance,

I'll look and see if they offer anything for the H2,

Neal

Actually I was wrong - the specific OBX set I bought is catted.... That was why I went with that one. At least they say they are.

eBay

https://www.ebay.com/itm/OBX-Performance-Exhaust-Header-99-05-GM-Hummer-H2-GMC-Denali-Silverado-6-0L-/122272027820?_trksid=p2047675.m43663.l10137&nordt= true&rt=nc&orig_cvip=true

That being said - I have had a code popup a few times but it then goes back off on its own. I think it might be due to some leaks on the clamps which I know I have. I just have not had time to jack it up and re-tighten everything but I've also been thinking on getting some of the better high end clamps and also putting some exhaust sealer paste in the joints when I do. I've also been skeptical that the cats are doing much though regardless - if the H2 is running you pretty much cannot stand behind it - you will choke on the fumes. I do run premium and have a custom tune which is a little rich at idle though - those also add to the fumes.

Edit to add - with the engine your are going to have... you will need to run a custom tune as well. So really you can just tell them to remove the O2 codes out of the tune so you will not ever have a check engine light for that.

I seen those but nothing like that for the 6.2l from OBX

Doug Thorley offers some but then I would have to build the rest of the system, if I do it will be true duals out the back

Neal

I'll take a look at the Dynatech setup, thanks

I'm not certain about later models but one thing to look for...... a LOT of places will not list certain models simply due to the fact that they have not directly tested them on a certain model. That however does not mean that they will not fit. For example OBX lists the exact same long tube headers set for

2002 thru 2005 Cadillac Escalade 6.0L
1999 thru 2004 Chevrolet Silverado 2500 6.0L
2001 thru 2005 GMC Yukon Denali 6.0L
2003 thru 2005 Hummer H2 6.0L

And you for other brands that say they have one for a 2004 Silverado, for example, they will show the same ones fit some of the same vehicles that OBX shows that theirs will fit on. So there is a good possibility that many others that while they do not specifically state they will fit an H2, it is quite possible and even likely that they will actually fit just fine. What I've sort of determined is that pretty much any one brand of long tube headers for a full size GM truck will just about fit all full size GM trucks and SUV's. Where you might run into issues though would be if the kit includes more than just the headers like the OBX kit which also includes the crossover Y pipe, cats, etc. Now from the cats back, that will be a different story and is a bit more specific to certain vehicles due to the different lengths, frame setups, whether or not they have a transfer case, different trans supports, etc.

One last thing - OBX and a couple of other brands have one bend in the driver side header which I severely dislike. On these, instead of going down like the rest of the pipes and like on other brands, the #3 cylinder pipe first bends up then towards the back and then down behind the #5 pipe. This makes it so that you will need to buy a very short spark plug wire for #5 as it will be touching the header and will burn up. Plus I just think it looks goofy with the one single pipe going up while every other one goes down. Dont get me wrong though, they are a great value choice and if you spend time on many of the GM truck forums you will find that a lot of GM truck owners really do like them a lot for the fairly low price you can get them for.

Another one to potentially check out will be Borla's "closeouts". Borla is the OEM for much of the official GMPP (GM Performance Parts) exhaust. I've seen a number of Hummer stuff on their closeout page over the past couple of years. In fact I got my exhaust tips directly from Borla. They are the only ones with H2 actually stamped into them. I had them on for a while but I took them back off as I do go off road a good bit and did not want to trash them. So I might also be willing to sell those. I also lucked out and spotted a craigslist ad about an hour and a half from me for a still new and unused original GMPP all stainless cat back setup. Turns out the guy owns a Chevy dealership and he used to be a Hummer dealer. He let me have it for just a couple hundred bucks. Crazily cheap for a Borla all stainless cat back setup. :)

Actually just looked and they have some of the straight flat end tips on there now (mine are the slant cut ones - as far as I know both have a fully rolled lip as well).

https://www.borla.com/products/closeout_corner.html

Not local to GPI, about 6 hrs away from them, they seem to have the market on the VVT stuff with the 5th gen camaros, They also developed the cams they sale for the VVT LS engine along with the tuning of the ECM / TCM's. I looked over the BTR web site and it looked like they sold comp cams for this application and I didn't see where they tuned after the install.

Neal

Appreciate the info MixMan,

I sent OBX an email a few days back but they didn't respond, I'll give them a call Monday.

Neal

Going to see if OBX will build a set with cats and ceramic coat them if possible, if they don't already have them.

Neal

We discussed what I wanted out of the truck and what I was willing to put up with as far as how the truck drove and my intended use for the truck and they recommended the LLT2 cam. With the converter and the headers I could go with the LLT3 but we both felt the LLT2 was a better option for my needs.

Neal

Still surfing the net for headers and converters, came across Speed Engineering but don't see anything listed for the H2 but they have a lot of stuff for the Silverado so I dropped them an email. If I can get what I need to put it together myself from them then that may be the way I go as of now if I have to fab it myself I'll re-use the OEM CAT's. I really want the CAT's to reduce the odor. SE offers a true dual 3" CAT back set up with X pipe that looks pretty good also.

MixMan I've noticed through looking at all the pics on the net that the OBX system for the 6.2 does not have the #3 pipe going up and over like the system for the 6.0 so hopefully they have corrected this.

Neal

That is good to know. I've not had a need to look into the headers for the later 6.2 so I've never really paid attention to that. On thing I did research some time back is a crossover pipe. There are essentially two types each with somewhat different characteristics. The X pipe is the more popular option and tends to add more higher RPM power and a higher pitch to the sound. While an H pipe tends to add slightly more bottom end torque and a lower tone. So that is also one to consider... Plenty of articles have been written on it, just search for "x pipe vs h pipe" online. Personally I'm going with an H and will be welding two T's into mine later this summer with a short section (probably use a band clamp for serviceability) joining them somewhere.

Received my Dynatech headers and haven’t installed yet but everything looks high quality. How’s the build going?

I have all the parts from GPI, took the heads down and cleaned them, installed the new springs and new seals so they're back together and ready.

I tried to ordered a converter from Circle D but they wont deliver to a different address from my billing address (PO Box) so going to have to drive to Houston and pick it up once its built. Should be ready in a week or two but that wont hold me up. Kinda odd to not ship to other addresses this day and time but I understand fraud is everywhere. I could have ordered from somewhere else but I really wanted the Circle D converter.

I ordered the headers and true dual setup from Speed Engineering, it should be here Monday. Called Jet-Hot about sending them to have them ceramic coated but they suggest installing them for initial start up of the engine before sending them. A test fit is probably best before sending them for sure. I ordered the high flow CAT's and they should be here tomorrow.

Got to finish checking bearing clearances on the bottom end then get it back together if everything checks out good.

Been busy with work and other projects also but hopping to get on it full time shortly

Neal

Very good idea on the headers. Headers in many cases require some massaging with a percussive maintenance tool (aka a hammer) to get them fit just right. You dont want to risk chipping a ceramic coating so if you have to put a tiny dent in them somewhere for better clearance its best to do that before coating.

How much do they charge for the coating?

Starts around $300 and goes up from there with options,

I'm a big fan of the ceramic coatings,

Neal

The headers and exhaust came in and I'm happy with the quality of the system, the entire system is polished SS. I spoke with them about the truck system fitting the H2 as they indicated that they didn't offer a direct fit for the H2 but that the truck system should fit with one exception, the mounting hangers may be in different locations than the trucks. They included adjustable mounting hangers with the pipes so that should resolve the hanger issue.

One thing I did stumble across is the L92 block while not equipped with AFM/DOD the block is cast for it with the oiling towers in the valley area. The valley cover has 8 seals that are recessed into a boss cast into the cover to block the oiling towers. Mine were very brittle and had not sealed for quite some time based on the impression on the bosses. I had read on the net that these seals can cause low oil pressure due to internal leakage over time. While my truck didn't have low oil pressure it was a little lower then I would have expected on an LS with these miles (around 25 psi while hot and at idle). There are a couple options to deal with the towers, one is to plug the towers and the other is to replace the seals, I haven't decided what direction I'll go for now. I'll be pulling the BRG caps and plasti-gauging them to make sure everything is in good condition and doing a good inspection of the parts while its open.

Neal

Following up to see you ever got everything back together and your impressions?

No, got real busy at work, been working everyday

Hopefully soon I can get back at it

Neal

rolled the vette out of the shop and started working on the 6.2,

Pulled the pan and 4 rod caps, everything looks perfect, crank still has a highly polished finish and the bearings look new. Going to plasti-gauge them tomorrow, rotate and check the other 4, if all is good I'll clean the pan up and start on the cam swap.

Neal

All rod and main bearings looked good but the cam brgs were another story. After gauging them they were out of spec so the pistons came out for cam bearing replacement. Once I pulled the pistons I decided since it was down that far I would bring it to the machine shop and have it cleaned and all areas checked and have the cylinders honed for new rings. At this point I'm going to do a complete rebuild since I'm in the "While I'm at it" stage.

Neal

Lol - snowballing. I started doing a pretty major project on my GMC truck, redo the interior, replace stereo components, convert to electric fans. 2 years later it is still in parts.... lol. Have the bed off and just coated the frame in Chassis Saver. Have added what seems like a hundred "while I'm at it's".

https://cimg5.ibsrv.net/gimg/www.hum...ab8b035b1f.jpg
Speed Engineering axle dump SS mufflers and headers.

Testing how to upload pics

Neal

https://cimg0.ibsrv.net/gimg/www.hum...4a3babb75b.jpg
Crank all polished up and ready for install
https://cimg5.ibsrv.net/gimg/www.hum...695dc0a594.jpg
Block cleaned and cylinders honed for new rings
https://cimg8.ibsrv.net/gimg/www.hum...25e9083d86.jpg
Springs installed and height checked along along with valve seating checked.
https://cimg1.ibsrv.net/gimg/www.hum...8c40219846.jpg
New Dura-Bond cam bearings installed

Got to order new crank and rod bearings along with rings then should start putting it all back together

Neal

Wow - nice!!

Got the crank dry fit in the block and bearing clearances checked, all still within production limits. Pulled it out and lubricated it the did final install. Also test fit the cam to verify cam bearings were straight the pulled it, lubricated it and slid it back in for the final time. Next is fitting the rings and installing the pistons.

Had some scored rocker arms so I opted for a new set of arms with the bronze bushings. The research I've done indicates they'll handle more load with less wear without the concern of needle bearing failure.

https://cimg3.ibsrv.net/gimg/www.hum...7195b92f2a.jpg

mufflers an headers look amazing!

Thanks, they're polished SS, hate to ceramic coat them but I think the heat control from the coating will help a lot under the hood.

Neal

got those headers installed yet?

anxiously waiting to hear how they fit...

No, things on the H2 have slowed to a crawl,
Was working ever day but now down with shoulder surgery, once I get rid of this sling and pillow on my arm I should be able to start back on the engine and get it installed.
I'm ready to drive my H2

Neal

Little update;
Tried 2 sets of Hastings rings but they are under sized so ordered a set of OEM's. The Hastings have more clearance brand new then the used OEM's with 145,000 miles on them.

I've checked the bores and the piston skirts and all was good there but close to the service limit so with the clearance I have I've decided to coat the pistons with Dry Film Lube (Tech Line DFL-1) on the skits and Thermal barrier (CBC-1) on the tops. The pistons in the L92 have this coating from the factory on the skirts but has worn off to some extent, the new coating will add around .0005" to .001" after curing. The bore to piston clearance service limit with the coating worn off is .0028" and mine are at .0025" to .0027".

The OEM rings should show up in a few days so I can get them fitted and installed once the pistons are coated.

I'm still working with one arm so things are moving a little slow, hopefully in a few weeks I can get rid of this sling and pillow and things will speed up.

Neal

little rant with Alldatadiy,
they have incorrect service literature and there really is no way to contact them to let them know, I tried a while back to email them but no response at all.

also searching the net it seems that the info is copied and re-posted, you really have to watch some of this if not getting your info straight from GM.

rant off now

Mitchell may be a better option with the needed data at the OEM level,

Neal

Started prepping pistons;

https://cimg7.ibsrv.net/gimg/www.hum...2cfd97a637.jpg
Hand held blaster with Aluminum Oxide for the surface prep.
https://cimg9.ibsrv.net/gimg/www.hum...157c11dd0a.jpg
Some of the pistons cleaned, baked to off gas and ring lands tapped off ready for blasting.
https://cimg2.ibsrv.net/gimg/www.hum...e69c419d3c.jpg
The lower piston blasted and the top piston just prior, for comparison.

https://cimg6.ibsrv.net/gimg/www.hum...7944687539.jpg
I was able to spray the skirts with the dry film lubricant today, next will be to let them air dry for a few hours then cure them at 300* for an hour.
https://cimg0.ibsrv.net/gimg/www.hum...92237e004d.jpg
I coated the tops with the thermal coating (light grey) a few days back but had to wait for better weather to coat the skirts.

Very Nice.
How's the shoulder?