5.7 vortec mpg

[L31MaxExpress]

I'm really not 100% sure if it will or not, but if it fits on a 350 throttle body, I'm sure it will fit on a 454 throttle body. You can go through my write up on my truck thread, the 454 throttle body is just slightly wider in OD where the intake hat fits onto the throttle body, and the factory hat has to be "forcibly persuaded" onto it with light tapping from a wooden block or rubber mallet. Also I dont more reading after I performed the swap that some people have actually knocked the lip off of the 350 throttle blade, theoretically achieving the same result without having to buy another throttle body. But without a doubt, the final decision is yours rather you want to do it or not.

Also if you dont want to deal with tearing throttle bodies apart, and swapping them, I could perhaps put together plug and play throttle bodies if one were interested in this

And on the headers, in my opinion, I wouldnt go with shorties, but I would rather go with mid, or long tubes due to the gains throughout the powerband.
But shorties do have their place, especially if you already had an exhaust done, and want something bolt on, and shorties only seem to have an increase in low end torque, and I havent heard too many people claiming increased fuel economy with shorties, but mid or long tubes seem to have a consistent gain in fuel economy. But you'll have to have another custom exhaust put in once more

Pull the orange plastic lip seal off your stock hat and the 454 TB fits with a nice tight seal to it.

I too ran the 454 TB but on a Marine intake. The stock TB necks down from 75mm at the plate to 72mm to mate to the stock intake. The Marine TB opening is 75mm. I JB welded the rubber o-ring grooves and opened up a stock plastic plenum to 75mm and played with that once as well. The 454s used a gasket. If you pull the restrictor lip off a 350 TB you can actually port the stock 350 TB to 75mm all the way through and get the same effect as the 454 TB. The butterfly is 75mm on both

The Volant intake should fit a 454 TB especially if you grind the small lip off the top of the 454 TB

 

[df2x4]

@Hobie Did you get a tune after your cam swap/overhaul? If not that may be why you're disappointed with your acceleration. A good tune will make more difference than any of these TB mods/swaps.

 

[Hobie]

experience in my V6 truck was that it made my accelerator pedal feel like an on/off switch

I've heard a lot of people who swapped throttle bodies complain about this, and when it came down to it, they all didnt swap the throttle return spring to the stock spring. The 454s used a lot lighter spring, and would go from 0% to 100% throttle with a feather landing on the skinny pedal. But like I said in all of my posts, I'm not pushing for anyone to perform this swap, but sharing with my experience. And it comes down to the owner to decide rather they want to try it or not

 

[Hobie]

@Hobie Did you get a tune after your cam swap/overhaul? If not that may be why you're disappointed with your acceleration. A good tune will make more difference than any of these TB mods/swaps.

I had a quick tune flashed, but nothing major. The cam was well within the ECM limits, and I figured it was going to perform like it does due to being fairly close to the factory cam in the first place. I'm waiting on some extra funds to send my 411 to Lextech to do a 411 swap at some point. But I'm not too worried about the tuning as I'll have to tune it again once the swap is done.

 

[df2x4]

I've heard a lot of people who swapped throttle bodies complain about this, and when it came down to it, they all didnt swap the throttle return spring to the stock spring. The 454s used a lot lighter spring, and would go from 0% to 100% throttle with a feather landing on the skinny pedal. But like I said in all of my posts, I'm not pushing for anyone to perform this swap, but sharing with my experience. And it comes down to the owner to decide rather they want to try it or not

If anything I think that would've made my experience even worse... The pedal feel wasn't the problem, it was the amount of throttle applied with any small movement of said pedal.

 

[Hobie]

If anything I think that would've made my experience even worse... The pedal feel wasn't the problem, it was the amount of throttle applied with any small movement of said pedal.

That may just be how the 4.3s react to this kind of thing?

 

[df2x4]

That may just be how the 4.3s react to this kind of thing?

Could be. It seems like the part throttle effects that most people mention from shaving the blade on a V8 were just amplified exponentially on my V6.

 

[Awest623]

But it does make a difference, not much, but it does. I recently made two trips (410 miles round trip) to the same location, both trips set cruise at 75mph, and the trip with the 350 throttle body made 18.8 mpg. (96 K1500 Z71 3.42 locker, 32" tires, with me, two bags of tools, and the usual things in the truck.)
Second trip was with the 454 throttle body and it averaged 19.9 mpg. Yes there could be tons of other factors, as it's not a huge long term data pool, but one huge thing to notice, is how much throttle it took to keep the truck at 75, 25-30% for the 350, and 12-18% for the 454, and as less throttle input was needed, I noticed there were a lot less downshifts during hill climbs. And due to the design of the 350 throttle body, there is a night and day difference between throttle response between the two. Yes it may not make any more power at WOT but it definately is a huge improvement in part throttle applications.

I'm not gonna say anything about mileage because those numbers are too close to tell, but I can explain your perceived part throttle performance. All you're doing by putting a larger throttle body on is shifting your throttle input higher. It's letting in more air at low throttle conditions, but not increasing overall power. If you were to dyno it you'd see that the power and tq per rpm is exactly the same. The reason it's not allowing more air to flow at higher rpms is because the throttle body is not the main restriction. As I said earlier, the intake manifolds on these engines are the biggest restriction.

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[Hobie]

I'm not gonna say anything about mileage because those numbers are too close to tell, but I can explain your perceived part throttle performance. All you're doing by putting a larger throttle body on is shifting your throttle input higher. It's letting in more air at low throttle conditions, but not increasing overall power. If you were to dyno it you'd see that the power and tq per rpm is exactly the same. The reason it's not allowing more air to flow at higher rpms is because the throttle body is not the main restriction. As I said earlier, the intake manifolds on these engines are the biggest restriction.

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This is exactly what I was saying in my later posts. I doubt the power numbers will change a bit, and its technically not a "percieved" improvement, due to the fact it is indeed an improvement, especially in my case of driving these long trips, the less throttle input does mean less downshifts if needed, and that is a set setting in the ECM. So I would say indirectly it could improve fuel economy, but it's not because of the larger throttle body. But for manipulation of input signals to get the same results

 

[Supercharged111]

454 and 350 tbs use the same blade as mentioned before. Removing the lip and hogging out the taper at the base of the 350 TB will, for all intents and purposes, make them flow identical. 454 uses a progressive throttle arm whereas the 350 uses a linear arm. 350 had the flap, 454 does not. LS1 throttle body has a linear arm, at least the f bodies did, and it's bolt on and go for a 454. The throttle linkage all lines up the same. This info is buried in my dually build thread in the Feb 2018ish time frame.