Choosing A TB For A Magnum

[805moparkid]

so i broke down and bought the hughes/eddy intake for my 5.9L magnum, anyways im working on building this truck for mpg but to be able to tow (its not a diesel, and dont plan on buying one). My biggest stumble is the throttle body, what CFM is to much??

5.9L Magnum
Stock TB (for now)
Hughes/Eddy intake
Stock Injectors
Stock Long block
Stock Exh (plan is shorty headers, 2.5" head pipes into flowmaster Y pipe, cat delete, flowmaster super 50 delta)
Stock Cam (Crower Hyd Roller Coming soon CRO-34418)

 

[Abodybomber]

Check out 72 Dusted's truck thread. I did sell the cam,BTW...

 

[805moparkid]

Check out 72 Dusted's truck thread. I did sell the cam,BTW...

no worries, hope it helps you get that thing closer! i'll start looking.

 

[805moparkid]

Check out 72 Dusted's truck thread. I did sell the cam,BTW...

i had no luck using the search, you have a link?

 

[spikekid999]

you can order the throttle plates (although it has slipped my mind right now on where, I think ebay though) and you can hone out you factory throttle body to 52mm without issues.

 

[805moparkid]

you can order the throttle plates (although it has slipped my mind right now on where, I think ebay though) and you can hone out you factory throttle body to 52mm without issues.

yes you can, but one 50mm might flow more than anothers 52mm, no different than modded carbs or ports.

not shooting you down as i'll probably be getting one of the ebay ones, just need the CFM i need first.

 

[itate]

Over in the Dodge forum the 52mm is pretty popular even though some claim to lose a little low end grunt, especially with a single plane manifold.

 

[805moparkid]

Over in the Dodge forum the 52mm is pretty popular even though some claim to lose a little low end grunt, especially with a single plane manifold.

well its coming down to loss in velocity. I really wish it was a dual plane but its what he have!

 

[spikekid999]

on my truck I didn't punch em out to 52mm, but I did cut off the air silancers and opened up the upper half a bit. not sure what cfm it was, but I didn't notice no lose in power. but now I have a built 390 stroker in my truck with the hughes big gulp throttle body

 

[805moparkid]

on my truck I didn't punch em out to 52mm, but I did cut off the air silancers and opened up the upper half a bit. not sure what cfm it was, but I didn't notice no lose in power. but now I have a built 390 stroker in my truck with the hughes big gulp throttle body

i'll do the 426 kit if i ever get to it!

 

[805moparkid]

After some reading i think im going to go with a 50mm, looks like the best for Towing and MPG which is what im after.

http://dodgeforum.com/forum/2nd-gen-ram-tech/283360-what-size-tb-2.html

 

[67Dart273]

The size of the TB has little to do with it. You are not trynna produce vacuum signal as with a carb

Biggest thing I think with NA EFI is "ram length" IE manifold design, runner length, etc.

The old Holley TBI on my 318 is 950 CFM 4 bbl!!!

Too small and it will act like a choke at WOT

"Really" large and my perception is that you get into a control problem, IE you move the throttle a tiny bit (slow street driving in traffic) and "that great big throttle" opens by a large percentage for a small input

 

[Abodybomber]

67,different animal...totally.Considered, his intake modifications, he's close. This is a tight, non programmable setup OOTB ,67...went Carb,on my Maggie...

 

[805moparkid]

67,different animal...totally.Considered, his intake modifications, he's close. This is a tight, non programmable setup OOTB ,67...went Carb,on my Maggie...

but i will be getting an SCT tuner as soon as the new one comes out (end of the year. so i can get a bigger one and shelf it till then, but it looks like the 50mm is the best for mpg and low end.

 

[jos51700]

Not happy with your Kegger mods?

 

[805moparkid]

Not happy with your Kegger mods?

i just cant keep the plenum gasket sealed, i bought a peice of 1/4" aluminum plate to make a thicker plenum plate but i just dont want to have to worry about it.

 

[67Dart273]

I have a junker one of these, got it with some EFI parts. So I'm not that familiar. Can't you use steel, or maybe just tig it ?

 

[805moparkid]

I have a junker one of these, got it with some EFI parts. So I'm not that familiar. Can't you use steel, or maybe just tig it ?

i was thinking about welding it, its what i should do and sell it. but im more interested in trying to understand how to select a TB for your engine and application.

 

[805moparkid]

Got the hughes intake! this thing is great, nice port size, dual plane, everything needed for install.

Bit on the underdrive pulleys to