gonemuddin

what size is the Stock 5.4 throttle body? 75mm? and if so would going up a size say to 80 mm make much of a difference? thanks

PRNDL

I asked this same question on a post about two months ago with no answers. I don't think anyone knows. From what I understand even a 5mm increase is huge. However, there are two schools of thought over this.

1. An increase in throttle body size does nothing due to the engine getting all the air it needs. Without mods an increase in TB size is pointless.

2. It does give you more power. There are a few youtube videos of people in their new f150's claiming an increase in power.

I would think a larger TB would make more power.... To a point. Just like in my old carburetor days, too many CFM's killed your power. I had some dumb *** friend buy a 850 double pumper and put it on a stock 305 chevy. Then he bitched that his car ran like crap afterwards. I can see him getting rid of his tiny 2 barrel for a 450 4 barrel, but bigger is not always better.

The question is, did ford put the perfect sized TB out 5.4's? Or is the stock TB too small? Would a larger TB help or hurt. What we need is someone to dish out $450 and do this mod and advise.

Pity7700

i just read 75mm. i was looking at parts on Amazon and came across a new TB. it said 75mm but that was for the 4.6, i didnt see the 5.4 listed under it but im sure tis the same size.

PRNDL

It would not make sense for them to be the same size.

Pity7700

both the 4.6 and 5.4 are listed as a 75mm Throttle body.

PRNDL

Interesting. Maybe a bump up to 80mm might open things up a bit.

Pity7700

yea i just checked autopartswarehouse.com and they list the same BBK throttle body for both engines, same part number and same 75mm size. im kinda curious about this now too lol.

gonemuddin

I saw a BBK throttle body for a 5.4 that was 80mm. Is BBK a reputable brand?

fordfan77

Yes, BBK is. They have been making parts for the Mustang for a while. I had their cold air intake and throttle body on my old Mustang. With the air intake on already, I noticed a definite increase in throttle response after adding the throttle body.

PRNDL

I really think this may work. Ford took the cookie cutter approach and used the same TB on the 4.6 and 5.4. I have a feeling the 5.4 could reap the benefits of a larger TB.