5.3 to 6.2 intake swap

NEMESIS-A/T · May 8, 2019

Whats the HP/TQ benefits to doing this swap?

kennerz · May 8, 2019

gears increase torque multiplication. You don't get more actual hp or engine torque. You loose torque multiplication when you put on larger diameter tires that effectively changes the gear ratio. (lower numerical ratio happens from larger tires - how much? simple math calculation should be able to find online).

Higher gearing (higher numerical value compensates/offsets the reduction from the larger diameter tires & to some extent can add torque multiplication to help with the increased weight).

IMHO you really need gears with that much tire, the higher the better, if you could run 5.xx I would. I don't think the factory carrier can go over the 4.56.

I think a lot of folks just don't understand the pure physics of large, heavy tires. In the sports car/drag world 1~2 lbs a wheel is noticeable and 1 lb of additional rotational mass takes xxx more HP to turn (I've heard 7 hp). No different in a truck just not as noticeable. A factory tire is like 35 lbs.

A 35" tire is 75~ 90 lbs per tire, With a heavy aftermarket wheel you have way more weight than a factory cast aluminum. So you can easily see anywhere from to 25 to 50+ pounds more a wheel rotational mass , plus leverage of a larger tire. Serious increase in forces required just to turn the wheels. On a diesel with 800ft-lbs not that big of deal, on a gas truck it's a dramatic performance sucker.

I would gear, tune, and get a exhaust.

Bohanan23 · May 8, 2019

10 hours ago, kennerz said:

gears increase torque multiplication. You don't get more actual hp or engine torque. You loose torque multiplication when you put on larger diameter tires that effectively changes the gear ratio. (lower numerical ratio happens from larger tires - how much? simple math calculation should be able to find online).

Higher gearing (higher numerical value compensates/offsets the reduction from the larger diameter tires & to some extent can add torque multiplication to help with the increased weight).

IMHO you really need gears with that much tire, the higher the better, if you could run 5.xx I would. I don't think the factory carrier can go over the 4.56.

I think a lot of folks just don't understand the pure physics of large, heavy tires. In the sports car/drag world 1~2 lbs a wheel is noticeable and 1 lb of additional rotational mass takes xxx more HP to turn (I've heard 7 hp). No different in a truck just not as noticeable. A factory tire is like 35 lbs.

A 35" tire is 75~ 90 lbs per tire, With a heavy aftermarket wheel you have way more weight than a factory cast aluminum. So you can easily see anywhere from to 25 to 50+ pounds more a wheel rotational mass , plus leverage of a larger tire. Serious increase in forces required just to turn the wheels. On a diesel with 800ft-lbs not that big of deal, on a gas truck it's a dramatic performance sucker.

I would gear, tune, and get a exhaust.

Wrong thread. Lol

Bohanan23 · May 8, 2019

11 hours ago, NEMESIS-A/T said:

Whats the HP/TQ benefits to doing this swap?

Gwatney claims 9 rwhp/6rwtq on their dyno. Their ported intake made 17rwhp/9rwtq over the stock L83 intake. All while keeping the peak HP/TQ in the same RPM range as stock. But I have read it'll shift power a few hundred RPM's. For about $250 or cheaper it's not a bad upgrade at all. I'm sure the upgraded throttle body size is a bonus for throttle response also.

WS6FirebirdTA00 · May 8, 2019

I think their setup was H&C too, so may not be the same for a stock internal motor.

That being said, my MAF frequency is up 300 Hz (even in warmer weather) and my manifold vacuum was 94 kPa and is now 97 kPa. Definitely getting more air that it was needing.

Bohanan23 · May 8, 2019

I think so. But still should see some decent gains with bolt ons only. I have a local single cab to me that has full bolt ons including this upgrade and he's running mid 13's. Going to take mine to the track when weather cooperates. I currently have 1 7/8" long tubes, y pipe, 3.5" exhaust and tuned on e85. Going to see what it runs then go back after L86 manifold/throttle body/ CAI upgrade and see what results are to come. Aiming for 13's. Mine is a crew cab though.

L86 All Terrain · May 8, 2019

Would porting, or a larger throttle body see gains if the intake ports on the 5.3L heads are still OEM? I wouldn't expect the engines capabilities would increase much by allowing more air into the intake, but having it just as restricted as before when it enters the heads? I guess it can hold more volume in the intake, but can the engine make use of that? I fully understand why port and polishing the head to match the intake makes sense, just not so much this. It seems like bolting a T4 turbo on a T3 flange type of thing to me, but I am not a tuner so I don't know much. Might be buying a C6Z soon so time to learn more.

WS6FirebirdTA00 · May 8, 2019

I debated cutting off the PCV tube, it is right in the middle of the opening. I decided to leave it since it can easily be done on the truck.

i suspect porting will help anything, the question is how much. I would like to see a 3 pull average to feel good it was a repeatable change.

Edited May 8, 2019 by ws6firebirdta00

Bohanan23 · May 8, 2019

It would be cool to see a L83 intake ported and compared to a stock L86. For $100 you can get a genuine L86 manifold new so it wouldn't be too costly of a comparison. I just don't want to pay for dyno time. Lol

WS6FirebirdTA00 · May 8, 2019

On my WS6 I used to do mod for mod comparisons. There was a Mustang shop that would do all the work and I would just come by to tune or whenever they did GM vehicles. That was spaced out about the right time for me to get one more new mod. I was able to see what roller tip rockers did, a clutch change, rear change, header to header swap, etc.

kennerz · May 9, 2019

12 hours ago, Bohanan23 said:

Wrong thread. Lol

Was replying to the gear thread - don't know how that happened?

Epsilon Plus · August 31, 2020

On 2/28/2017 at 4:23 PM, 07Softail said:

I had a Airaid MIT... but be sure to get a 6.2 (it's a 4" silicone coupler). or order a MIT for a 6.2L

RT

Thread ressurection!

Concerning the middle intake tube needing to be the AIRAID 200-911 for 6.2L TB size (as referenced above), does anyone know if the air box lid end of this swap is the same?

The reason I ask is in my L86 swap thread searching I haven't seen anyone mention the air box lid size being different. According to some GM parts catalog views, it lists 5.3 and 6.2 being the same.

I'm in the midst of maybe upgrading my intake tract in my quest for more pulling power. I'm sold on the stock airbox being plenty big enough and it also surprisingly pulls pretty good IATs under way. I just put a drop in K&N filter in, the AIRAID middle intake tube looks like a nice part to get rid of that monstrous Hemholtz resonator intake tube. A relatively inexpensive L86 TB/Intake swap to round it out sounds like it would all make a nice custom intake for more breathing. Not to mention maybe letting go some trapped heat that the monster stock tube is likely trapping and heat soaking from the fans.

Anyway, just wondering if I need a 6.2L air lid or if the stocker is the same.

Thanks.

flyingfool · August 31, 2020

air boxes are the same.

anyone know if a stock GM 6.2 cam slides into the 5.3, and what are the different variations for GM cams in the 6.2?

Edited August 31, 2020 by flyingfool

lucas287 · August 31, 2020

2 hours ago, flyingfool said:

air boxes are the same.

anyone know if a stock GM 6.2 cam slides into the 5.3, and what are the different variations for GM cams in the 6.2?

Pretty sure the LT1 and L86 use the exact same cam, LT4 is different and the 2019 DFM motors might be different. But any LT1/L86 from 2014-2018 should have the same cam. Should slide right in no problems - same base circle.

This guy did it. He's got install videos too: