tb bore size?

[rspro]

Hi guys, I have access to mill at work and wanted to bore out the tb, but do not know what size? And also where to accually bore it at? I have a idea where but just want some of your info be I start. Thanks in advance.

 

[SoilentGreen98]

I haven't done mine yet but I commonly hear that 55mm is good for the 420a but I've also heard 57mm, I'm sure someone here can clear that up for ya though.

 

[aliczander]

you dont want to go bigger then 57mm unless u plan on puttin a turbo on very very soon... 57 gives you maximum air flow, and still keeps your air velocity high
some people put 60mm on but like i said thats only good if u have a turbo.... bigger is not allways better

 

[dr1665]

I'm not 100% sure if it's 55mm or 57mm, but one of those is the limit you can bore the stock TB without breaking out. The neck is only so thick when you bore it out. Going to large and you will bore right through the side walls of the TB. Unless you can weld some more material to the sides to thicken the walls, but then it might just be easier to buy the Jeep 60mm and go that route.

 

[rspro]

Thanks guys, I'm going to go turbo at some point. I was thinking about 57mm, but I would have to do the same to the intake manifold where they mate together right? And what about the butterfly thingy, is that just some round peice of alluminum that I can make?

 

[GSGoinFast]

I'm not 100% sure if it's 55mm or 57mm, but one of those is the limit you can bore the stock TB without breaking out. The neck is only so thick when you bore it out. Going to large and you will bore right through the side walls of the TB. Unless you can weld some more material to the sides to thicken the walls, but then it might just be easier to buy the Jeep 60mm and go that route.

i think its 57mm, i saw some company(big name, maybe ARP?) that would bore out ours to 57mm. you have to buy 60mm ones.