52 mm throttle body

ramthis9501 · Jan 18, 2012

Anyone know much on the fastman 52 mm throttle body for the 5.2? Wondering if it would be worth getting one for mine...

wermbang · Jan 18, 2012

I would probably go with a 50mm unless you have a bunch of internal engine mods. You will also need a custom tune with it to make it work right.

the codes · Jan 18, 2012

^^werm is right, for the 5.2 50mm is recommended by just about everyone unless you have a cam and heads. the 52 is for the 5.9. Fastman runs in the 200 range I believe. I found a guy on another forum who mods them as a side job, he charged me 100 to shave everything down smooth and bore it out, shipping included. Ill post pics this weekend when I go home and install it. pm me if you want his email

ramthis9501 · Jan 18, 2012

I'll keep that in mind.. Thanks

A 50mm is stock size on the 5.2 though. And a larger throttle body mainly means more air flow doesn't it? I know more fuel to but how much?

the codes · Jan 18, 2012

I think stock is 48mm? could be wrong though

the codes · Jan 18, 2012

sorry about that previous post, correction

stock is 50 mm at the top and tapers down to 47mm at the plates.

so the guy opens up the plates to 50 mm as well to make it a true 50 mm throttlebody, thus 3 extra mm of air flow.

wermbang · Jan 19, 2012

yeah stock they are tapered

ram15 · Jan 19, 2012

so if i wanted to upgrade my 360 would i get the 52mm. i dont have any internal mods, just a k&n and a homade intake

Hotroder383 · Jan 19, 2012

No 5.9 or 360 comes with 52MM the 318 or 5.2 comes with the 50MM and I'd look into other mods before messing with TB myself.

wermbang · Jan 19, 2012

ram15 said:
so if i wanted to upgrade my 360 would i get the 52mm. i dont have any internal mods, just a k&n and a homade intake

the 50mm will be great since you don't have the internals that call for a larger one.

The 5.2 and the 5.9 use the same throttle body.

the codes · Jan 19, 2012

if you want a 52mm, you would prob want to at least get the first 3 basic mods

CAI, free flowing muffler, tuner.

talon6 · Jan 19, 2012

no big advantage to a bigger tb with out supporting mods. and larger tb's move the power band up the rpms. the 52mm fastman was one of the first mods i did. not a big bang for the buck. but there was a small increase in power in the upper rpms. with a small loss in the lower rpms. would i buy it again? yep. got mods to support it now.

ramthis9501 · Jan 19, 2012

I got exhaust and CAI. I don't think a tuner would be necessary though. I just talked to someone who did this to a STOCK 5.2 and it worked perfect. I also did the plenum fix so I don't have to worry about oil seeping into the TB.

talon6 · Jan 19, 2012

harland sharp 1.7 roller rockers are a better bang for the buck. also a tuner is even better. fyi

Okiespaniel · Jan 19, 2012

Colton, buy it...I'll give you a few edxtra bucks for it and my ported and polished 50 mm tb to boot. That will work much better on your 5.2. I got a good mid range boost out of doing mine.

ramthis9501 · Jan 19, 2012

Okiespaniel said:
Colton, buy it...I'll give you a few edxtra bucks for it and my ported and polished 50 mm tb to boot. That will work much better on your 5.2. I got a good mid range boost out of doing mine.

So your saying get a 52 mm then trade it to you for a ported and polished 50 mm plus a little extra money for it?

Okiespaniel · Jan 19, 2012

ramthis9501 said:
So your saying get a 52 mm then trade it to you for a ported and polished 50 mm plus a little extra money for it?

If you can get it for what you stated elsewhere. yes...I'll even throw in the mounting gaskets and maybe we can do a mod gtg and swap 'em. Now remember mine is a factory tb. The air horns have been removed and the throats have been polished but not cut to a straight 50 mm. This mod is listed throughout truckdom. It really helped my truck.

One thing though before you buy, whether we work out a deal or not...make sure it is a fastman. There are hacked copies out there "like" fastmans, but are not as nice. Everything will be machined perfectly and there won't be any tool marks. I believe he stamps his as well.
The only reason I caution ya is the price you named is almost too good to be true for a fastman. Check out his website.

ramthis9501 · Jan 19, 2012

I'll start my search and let you know when I find one. Thanks alot Al

Okiespaniel · Jan 19, 2012

ramthis9501 said:
I'll start my search and let you know when I find one. Thanks alot Al

5.2L - 5.9L V8 Throttle Bodies - The Fastman

Oh I thought you had a line on one bro! My bad. I have a a back up t/b and maybe I'll full port it this spring.

ramthis9501 · Jan 19, 2012

Yeah if you do that let me know if I can't find a 52 mm. I'd definitely be interested in that to!

52 mm throttle body

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