I have a 52 on the stock 5.9 in my Ram, it's pretty hard to over TB these things, all it is air, it's not like a carb.

 

How much $$$ does the fastman cost?

 

http://www.thefastman.com/throttlebodies5x.php

 

was there something wrong with your stock TB?

The only gain with a bigger one is 'more air quicker', which can be remedied with the smaller one with more pressure on the skinny pedal.. wayWAY up top you get more air, but, honestly, how often are you guys above 5kRPM?

the 'throttle response' is simply because you're tossing more air quicker.. the stock TB narrows from 50mm above the butterflies to 46mm below to create a laminar flow- to smooth the turbulence out, so to speak.. it doesn't really matter with a kegger manifold because the 'plenum' or 'air-reservoir' is huge and basically without any flow enhancers, but I'd venture that it absolutely would on a M1 or Air-Gap.. a matter of fact, that laminar flow feeding a a-g or m1 would likely make up for the missing mm's in the orifice opening..

the keg has a massive air reserve in that plenum- much larger than most intakes have.. it doesn't struggle for air unless it's wide open- and even then, the flow characteristics change dramatically.. I'd opine THAT change is a limiting factor inherit to the kegger more so than the size of the tb intake..

now if you were feeding a heavily modded engine (internal) or bored/stroked/boosted, that extra flow capacity would be a good thing- and an even better thing if it was something like 55-60mm north of the flies, and still tapering to something like 52~54mm south of the flies.. that laminar creating function of the taper is pretty significant..

 

So what would be the difference between the fastman and the big gulp from hughes? Looking at getting one or the other. Will i gain a whole lot with the 900 cfm with the big gulp? All i have done to my motor is the kegger mod

 

what's the difference in distance you press your go foot? That's pretty much the difference you'd feel- instead of having to press it 1/4 way to reach 2200rpm, you'd only have to push it 1/8...

what you will LOSE, though, is the ability to minutely alter RPMs via go foot..

it's a floggin' waste of money unless you are feeding A LOT more air through the engine- supported with intake manifold, ported heads, bigger valves, bumpy cam, opened exhaust, ect.... and this os coming from someone who has a fastman 52..

 

^ agreed. I bought into the hype AND didn't return my core fast enough because of my motor swap. If ppl are looking into it I'd tell ya to put the money elsewhere for now, possibly the gas tank!

 

youve got that backwards... they openings are smaller ABOVE the butterfly plates which are 50mm... and honestly more flow through them can help a bit but depending on what other mods have been done the abundance of air can hurt or help... this is why places like fastman dont recomment a 52mm on a stock engine... it does hurt more than it helps in everyday driving in...that situation... I do believe there is enough evideance to prove that any 5.2 or 5.2 with a better air intake system and exhaust can benefit from a 50mm throttlebody. especially the 5.9... intake keg size is really not the only factor for air flow... if the tb doesnt flow enough the air pressure in the intake just becomes more of a negative and restricts the flow available anyway? what good is a better flowing air filter if restrictions like tb bore and turbulance causing air horns hinder it? you have to have a good balance... the one size fits all oem size has to hurt performance on all but stock engines and one could even argue stock 5.9's which should be able to pump more air..

 

I'm sorry but I believe this statment is just wrong.....
For the same reasons related to why the kegger mod and cutting down runner size kills hp and torque on the mid and lower rpm range.

 

No, I'm not wrong.. the taper from 50mm to 46mm is inside/under the flies.. . Now, I wonder if you've ever actually handled one at all..