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6.2L/L86 Intake and TB Install - with Elite E2 Info and air box mod

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I figured I would share some info about my install of the L86 intake and throttle body. I was trying to find some information, but it was hard to come by. 


Boredom got the best of me and I found out that the L86 was a direct swap for the 5.3L L83. What made it worse, was the fact that the mod was $250 (with factory, non-ported TB). I couldn't not do it :)


The main reason I was sold on this was seeing some low end results, looked liked some good torque gains. I also saw my MAP drop to 94 kPa WOT, making it clear there was restriction.


I have the Elite E2 catch can (see notes on it below) so I did not need to get the PCV tube (and you should not either IMO, put a catch can on it). Here is a list of what I ordered:


  • L86 intake 12639087 $105 
  • Throttle body gasket 12639086 $7
  • Intake port gaskets 12626357 $4 each (need 8)
  • Tony Mamo ported LT1 throttle body
  • 3 7/8 inch diameter and 3 inch long silicone coupler for Airaid tube 


I ordered it all on Amazon, except for the throttle body. I decided to go with a ported throttle body based on reviews I saw online and the fact that I wanted to do it all once and be done. Tony always does great work so I have confidence buying from him. The throttle body shipped super fast! I have a few pictures attached, but I was too anxious to install everything and didn't take as much as I was hoping. 


Now for the install. I will try to go off memory the best I can. 


There are 4 bolts holding the intake cover on and several pop-in wire ties. I have some plastic trim tools and popped them out pretty easily. There are 4 in the back of the manifold cover that aren't quite as easy. By this point, I already had the Airaid tube off. I disconnected the throttle body harness and removed it. I also removed the MAP sensor and one other part (evap purge maybe?) from the front of the manifold. I removed the Elite catch can line as well. I believe at this point everything was disconnected. I removed the 10 manifold bolts and removed the cover and manifold together. 


I took a few shots down the intake ports. I attached one. I had 7000 miles at the time of the swap. I did Seafoam right before this swap as well. I wish I had some before and after shots for Seafoam. 


I did a little work to clean up some edges on the intake ports of the new manifold. There were some good edges so I just worked them down. The PCV tube on the L86 manifold sticks down right behind the throttle body. I was tempted to cut and clean this up flush with the inner wall but I left it. You can kind of see it in some of the pictures. 


One note before putting the new manifold on, put the old intake cover on first. I was not paying attention and missed the back side that would prevent it from being installed with the manifold on the truck. FYI - the 5.3L cover does fit the 6.2L manifold.


For the install, manifold bolt torque is 44 in-lbs on the first pass and 89 in-lbs on the second pass. If you number the bolts front to back, driver side 1-5 and passenger side 6-10, the torque sequence is 3-8-9-4-2-7-10-5-6-1


The throttle body bolt torque is 89 in-lbs. The bolts threaded into plastic I just snugged up. I think the MAP sensor bolt is going into a threaded insert so I set that torque to 89 in-lbs as well since the bolt size was the same.


I also wanted to share some findings on the Elite E2 catch can. Several people ask about the effectiveness. After the first 100 miles or so I was putting the correct coupler on the throttle body and took a look inside. You can see the oil residue on the PCV tube inside the intake. The Elite E2 is catching about 15 mL/500 miles. Obviously it isn't catching everything, but I did not expect it to. I would be interested to run some tests on others, but I don't have money to blow on that :) I am happy with the mounting of the can and the performance so far, but I can smell some slight oil pull at idle. I just assume the vapors are just passing through and the catch can is pulling out most of the aerosols. It would be nice if they tested and published some efficiency numbers, if I had to put a number on it I would call it 95% for aerosols. 


At the same time I did some mods to the air box. The first one I fully cut the insert. The intake noise was horrible and was vibrating stuff in the cab. I trimmed it back and only cut out the bottom opening. Quick calculations the throttle body area was around 5950 square mm. The factory air box has around 7000 square mm of open area. The lower cutout is around 1750 square mm. Looking percentage wise, the lower opening increased the opening more than proportional to the throttle body area change. There is still more intake noise like this, but it is mostly under high load and under 2000 RPM. 


Now the results of all this. The new intake was able to raise my manifold absolute pressure at WOT in the same gear near 5000 RPM from 94 kPa to around 97 kPa. My MAF frequency was consistently around 8700 Hz. With the new setup, I am around 9000 Hz. I have seen the mass airflow go from 32.0 lb/min to 34.2 lb/min. In the past with a calibrated MAF I (and others) have associated lb/min approximately HP/10. That being said, I don't expect this was a 22 HP gain at all. My point is, lacking any dyno numbers, this was a good move in a positive direction for the truck - less restriction and more air.


As far as the throttle body, tip in throttle response is much smoother and accurate for my pedal input. I felt the truck was pretty responsive before with the tune, but there was always this weird spot at low throttle. It wasn't in the driver demand tables, I think it had to do with the odd lips in the throttle body. I don't have a before and after comparison of the same throttle body, but I am definitely glad I went ported after looking at crazy lips of the stock one. Rather than port it myself like I did for my LS1 (which didn't turn out too bad) I figured I would leave it to a pro this time :) 


With the electronic throttle control and torque based control of the ECM, it makes it hard to draw conclusions. On a cable driven throttle body, 10% before and after would make the truck feel faster after. That was simply because of the increase in throttle area and getting more airflow for a given input. Seeing these computers are looking for a torque to meet the driver demand, it isn't as noticeable, so I feel the low end gains are more real from a SOTP feel. WOT is hard to tell because the intake noise really threw me off. It sounded like a 100 HP gain after cutting the air box haha I am still running around to see if it did anything to fuel economy, but I keep getting messed up with weather or short drives to do a good comparison back and forth to work. I did average 19.8 MPG on back roads over 20 miles, that was also with the full air box cutout. The best I could do on drives to work had been 21.8 MPG for the last 25 miles and right at 19.0 MPG on a half tank. The 19 is pump verified, I think my calibration for the DIC is off on MPG for the 21.8 number. I suspect it will be closer to 21.5 actual. I have not confirmed the unit updates to that calibration at that high of a fuel economy. 


As for the tune, all this was post MAF and I had it calibrated already. I saw no change in the MAF, but I still need to go back with a WB for a final pass. I updated the throttle area to 4118 square mm (from a 6.2L tune) and intake manifold volume to 15,010 cubic centimeters (also from a 6.2L tune). I increased the airflow correlation for P0068 tests as well as lowered the power enrich TPS since a lower throttle position will result in a higher load with the increased area (less throttle input for same airflow).






Edited by ws6firebirdta00
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you did it right on the tune, It was the first thing I thought of when I read the topic. There is a re-calibration that helps the tables. I still haven't done mine yet. I have the 6.2L TB ported by Katech. I want to do injectors lines and HPFP at the same.I don't expect much gain with mine turbocharged. The TB helps as it is the first size reduction from the turbo pipe. 

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7300 miles, catch can was installed at 6800 miles


I saw some other pictures on here of trucks around 10k and their intake ports looked worse, but that valve doesn’t look great. I did not see other valve pictures. I should have put the catch can on sooner.


I will likely run the newer Seafoam cleaner (foaming) in the future. That was cylinder #1 FWIW.

Edited by ws6firebirdta00
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I'd be interested to see the gains from this swap, I've found that changing efficiency has had a positive affect on every vehicle I've owned and I've been able to get better mileage with simple mods like this.

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So far my best 25 mile MPG went from 21.8 to 23.0 and by best 50 mile MPG went from 20.3 to 22.1 MPG. The 50 best may have been a big jump because I never strung two trips together to watch it. I have tried to intentionally beat my best 25 mile when i hit the 21.8.


I would say the weather was comparable to my last best and it happened on the same path coming hime from work.


I am at 19.0 MPG right now with 34 of the 155 miles averaging 15.3 MPG with a lot of short (<5 mile) trips running errands.


So as far as MPG improvements, I would say from what I am seeing 0.5 MPG is solid (based on where I sit right now for the tank vs my previous best). As I get more miles I will post if it changes.

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I think the TB from Mamo was right at $390 or so. It is on his site. So it was around $250 for porting and shipping on top of the cheapest price I saw a new TB at.


I am satisfied with the mod, but there is definitely more intake noise with the Airaid. I put a stock air box part in and could still hear it, mainly under 2500 RPM. Just something to consider. I could not take the noise with the full cutout of the air box mod shown above.

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  • 5 months later...

Any more updates on the swap? I'm for sure doing it soon, just can't decide if I want to have the throttle body and/or intake ported. The gain from porting the intake is nice, but I'm in preparation for boost next year so I'm not sure if the extra porting on the intake is worth it.

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  • 2 weeks later...
13 hours ago, ws6firebirdta00 said:

I wonder if the box/tube design help reduce noise? Mine was past annoying.

i doubt that reduced noise, 

if you look at the oem factory intake tube , you will see a device tuned for resonance hanging off the intake, this is called the Helmholtz device.. it canceles out the drone or intake howl.. older truck have a big bubble like resonator, our K2 is more stream lined and rectangular where the valve breathers connect too, but serves the capacity to resonate out the noise, 




Edited by flyingfool
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