diameter of stock exhaust on 14+ 6.2 trucks?

ommegang · August 16, 2015

6.2 on gasoline: 420 hp 460 lb-ft

5.3 on gasoline: 355 hp 383 lb-ft

5.3 on E85: 380hp 416 lb-ft

E85 get significantly less mpg and supposudly attracts water. I never though it would increase HP and torque. Why wouldnt all use E85 then?

Badass69 · August 16, 2015

E85 get significantly less mpg and supposudly attracts water. I never though it would increase HP and torque. Why wouldnt all use E85 then?

I think because it lowers the MPG significantly which is becoming more important now than before. You have less energy per unit of fuel with E85 then gasoline. Pure gas is around 124000 BTU/gallon and ethanol is only 84,500 BTU/gallon. Ethanol is an anhydrous product so it absorbs water which makes it rubbish to store. I know even the 94 octane fuel I burn ( 10% ethanol in 91) goes noticeably stale in a relatively short period of time. Stabilizers help over winter but still.

It has better pre ignition tolerance if the engine is set up for it. Being you run the proper AFR for it and not run it too lean. Stoich on pure gas is 14.7:1...... E85 is on 9.765:1.... lol. A lot richer than gasoline. But if you run it rich the octane is over 100 versus gasoline at 91 at the pump so it's great for guys with boosted stuff and or high static and particularily dynamic compression ratios. A lot say it's 110 octane but that seems to be debunked and it test closer to 100 as E85.

In a 6.2 it would do similar to a 5.3 and likely be close to or crest the 500 lb ft mark for torque.

I am going to say it's a mpg thing if nothing else lol.

Edited August 16, 2015 by 1994Vmax

robvas · August 16, 2015

Hahahaha funny thing is everyone going back and forth, I started the thread, well I went and checked out my 6.2 truck (2015 GMC) and the tip is 3" the piping is 3.5" after the Y and muffler and tapers down wtf?! I did specifically notice 6.2 trucks w/ wider slash cut stock (not polished) tips.

The exhaust is 3.5" until you get to the resonator - it's only 3" coming out of the resonator

A little bit of math before we get started:

3.0" diameter exhaust has a circumference of about 9.5", that's the measurement of the outside of the pipe with a tape measure

2.75" exhaust will have a circumference of 8.6"

3.5" exhaust will have a circumference of 11"

Here's my tailpipe, 2015 6.2. As you can see it's not 11", it's closer to 9.5

Here's the pipe coming out of my muffler and up over the axle. 11"

(I have a 3.5" Magnaflow muffler that I put in place of the factory muffer and resonator. The factory muffler was 3" in/out and the 3.5" factory pipe necks down to fit.)

Here's the factory resonator. You can easily tell the pipe going into it is bigger than coming out

Just for kicks here's the factory exhaust I still have from my 2014 5.3 truck

And the tail pipe

Clearly < 9", which means 2.75" exhaust

BlackZ71Silverado · August 16, 2015

Listen here smartass, I dont care what you think is "correct" terminology for exhaust manifolds. I call them headers. I am looking at buying "Long Tube Headers", not Long Tube Exhaust Manifolds". Also you are wrong because my stock exhaust tip AFTER the muffler was originally 3.5", as measured by the exhaust shop. I still have the stock muffler with pipe attached if you'd like me to go measure it and take a picture.

Well you are INCORRECT. Headers and exhaust manifolds are two different parts. You seem to still be confused about some things. I don't believe there is such a thing as long tube exhaust manifolds.

On your stock exhaust tip, did you have the polished GM tip? There are a lot of trucks that have those installed by the dealer to mark the price up a little.

You see the same thing with people calling wheels rims. Two different items, the rim is part of the wheel.

Edited August 16, 2015 by BlackZ71Silverado

Spurshot · August 17, 2015

This thread is spiraling toward a pud knocking contest. Pud knockers will get bounced. Play nice.

BlackZ71Silverado · August 17, 2015

If for some reason GM is mixing exhaust pipe sizes between models, you will just have to measure everything on your own before you order parts. Seems that's the only way to be sure with the 14-15 trucks.!?

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using Tapatalk

Bvonscott · August 17, 2015

Well you are INCORRECT. Headers and exhaust manifolds are two different parts. You seem to still be confused about some things. I don't believe there is such a thing as long tube exhaust manifolds.

On your stock exhaust tip, did you have the polished GM tip? There are a lot of trucks that have those installed by the dealer to mark the price up a little.

You see the same thing with people calling wheels rims. Two different items, the rim is part of the wheel.

Re-read what I said. Then look at the 2 parts next to each other. Tell me what is different.

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crushNchowda · August 17, 2015

I think because it lowers the MPG significantly which is becoming more important now than before. You have less energy per unit of fuel with E85 then gasoline. Pure gas is around 124000 BTU/gallon and ethanol is only 84,500 BTU/gallon. Ethanol is an anhydrous product so it absorbs water which makes it rubbish to store. I know even the 94 octane fuel I burn ( 10% ethanol in 91) goes noticeably stale in a relatively short period of time. Stabilizers help over winter but still.

It has better pre ignition tolerance if the engine is set up for it. Being you run the proper AFR for it and not run it too lean. Stoich on pure gas is 14.7:1...... E85 is on 9.765:1.... lol. A lot richer than gasoline. But if you run it rich the octane is over 100 versus gasoline at 91 at the pump so it's great for guys with boosted stuff and or high static and particularily dynamic compression ratios. A lot say it's 110 octane but that seems to be debunked and it test closer to 100 as E85.

In a 6.2 it would do similar to a 5.3 and likely be close to or crest the 500 lb ft mark for torque.

I am going to say it's a mpg thing if nothing else lol.

No I don't think mpg has anything to do w/ it as #1 car makers would still be able to advertise the higher mpg ratings on regular gas, #2 it's not a fossil fuel, it comes from corn and govt. subsidized farming- it doesn't carry the same environmental stigmas as fossil fuels do and rightfully so.

I think it has to do w/ the new focus on moving away from foreign dependance on oil and more abundant and readily available sources all across the US....the tracking industry is going to be needing the govt. subsidies now that oil is heading below $40/barrel!!!

Badass69 · August 17, 2015

Maybe... but they offer it on the biggest seller versus a niche engine that barely makes a dent in GM'S sales. I doubt the us government will subsidize fracking anytime soon more than they already do. I mean the public is driven by mostly idiots that think oil should go away not realizing about everything they touch daily comes from an oil product. So why not offer the supposed "green" joke of a fuel called E85 in everything? E85 needs to go away lol. Not that I care as its never been offered here nor ever will be.

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Edited August 17, 2015 by 1994Vmax

qwank · February 15, 2019

Does anyone know if the 6.2 muffler flows better than the 5.3 muffler? I'm kind of thinking of using the stock 6.2 exhaust with an electric cutout when I put on my catless long tubes.