JOSH13

I know the stock throttle body bore is 48mm but what is the bore on the intake manifold ? I've seached and found a site saying 52mm and a site saying 54mm . I'm just curious and was considering a 52mm throttle body if that was the same size as the manifold .

ElkySS

iTrader: (6)

52mm will fit. but in most cases not necessary. what kinds of mods do you have done to need a 52?

Formula350

iTrader: (3)

Well, there wasn't a 54mm till someone ported a stocker to it, so most sites will probably say 52mm because that's the biggest aftermarket TB that'll fit on a stock intake. So I'm going to say that it's actually a 54mm opening on the intake itself. Otherwise, why even make a 54mm TB? Why not go between 52 and 58, and make a 55mm?

96capricemgr

iTrader: (1)

What folks fail to consider is there is something like 4-5 LTx manifolds from GM. I forget the casting numbers BUT I have MEASURED 52mm and 54mm on seperate manifolds.

FlamingChicken

iTrader: (2)

as&m used to sell a 54mm i believe. ive heard there were 54mm intakes but the only one ive actually measured was 52. wonder why they would make ones with larger bores?

Elliott's94Z

iTrader: (12)

Mine was 52

JOSH13

Thats wierd that there were 52 and 54 mm manifolds . I don't really "need" a larger throttle body I just thought it might help out a little being the same size as the bore on the manifold .

96capricemgr

iTrader: (1)

I am quite sure the 52 and 54mm openings were incidental and had nothing to do with the reasoning for a different casting, hell it might have just been a oops in machining for all I know.

JOSH13

Thats a pretty big margin of error lol . I'll probably just go with a 52mm tb. Probably the professional products one . I seen them for about 200 and I know its not necessary being lightly modded but it seems that if that would match up to the manifold pretty closely it might help out a little with air flow over the stock one .

96capricemgr

iTrader: (1)

I did not say the opening was an error, I said incidental.

For 52mm you would be better off getting a rebored stocker as all the aftermarket TBs have some nagging little hassles that the stocker wont.

Z-RATED94

iTrader: (6)

Iv'e read that a few times too, and is the reason I went with a ported stocker. Plus I'm not making all that much HP, and I figure the 52mm is plenty for my set-up.

96capricemgr

iTrader: (1)

I have a BBK and had to drill the IAC bypass, reset the throttle stop, it whistles. It is 58mm though, for a 52mm or even some guys can do a 54mm out of a stocker would be a lot less hassle.