I think this is the best place to ask....

Whats the bore diameter of the throttle body of:

• Mk2 1.2 16v
• Mk1 1.2 16v
• 1.6 16v (Marea)

As my vernier calipers is bent cant measure the 1.2 tbs Thinking of boring out another tb of mine, a mk1 1.2 16v tb, but unsure how far to go...

Thanks in advance!

There is absolutely no point in having a larger throttle body unless you gas flow the head and fit high lift (Stage 3) cams or have a bigger engine.

The edges of the throttle valve can be chamfered along with the spindle and any step changes in the throat but have a spare handy in case you mess it up. This will improve the max flow capacity without (if done right) messing up the low speed gas flow.

But on a standard engine the benefits wont be seen as the TB is already big enough.

I have a 1.2 block and head stripped awaiting work. The block will be bored out to give a total cc of 1284, along with a balanced crank and lightened flywheel. The head is going for porting and i have cams already for the job. This is a long term project hence im starting with the very small stuff

How far can i bore out the mk1 1.2 16v tb?

m20b25 said:

I have a 1.2 block and head stripped awaiting work. The block will be bored out to give a total cc of 1284, along with a balanced crank and lightened flywheel. The head is going for porting and i have cams already for the job. This is a long term project hence im starting with the very small stuff

How far can i bore out the mk1 1.2 16v tb?

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mate iv just bored out my throttle on me mk2 1.2 8v tho...i bored it out to 48mm...and no matter what logic is or theory i tell you now with all honesty it has made a very noticeable difference

its pulls a lot better and accelerates n much faster....most power at midrange all way through to top end...from 3k revs onwards to 6750rpm

2nd and 3rd gears pull a lot better now XD

any body that doesnt belive i will be getting me car rolling road tested to proove it...i also have engine mods such as induction kit, bored inlet, 4-2-1 branch manifold, de-cat striaght through, straight through middle pipe, derestricted backbox.

Brin said:

mate iv just bored out my throttle on me mk2 1.2 8v tho...i bored it out to 48mm...and no matter what logic is or theory i tell you now with all honesty it has made a very noticeable difference

its pulls a lot better and accelerates n much faster....most power at midrange all way through to top end...from 3k revs onwards to 6750rpm

2nd and 3rd gears pull a lot better now XD

any body that doesnt belive i will be getting me car rolling road tested to proove it...i also have engine mods such as induction kit, bored inlet, 4-2-1 branch manifold, de-cat striaght through, straight through middle pipe, derestricted backbox.

Click to expand...

48mms, thank you Isn't the standard mk1 16v tb 40mm? I have to make sure I can work this tb first

m20b25 said:

48mms, thank you Isn't the standard mk1 16v tb 40mm? I have to make sure I can work this tb first

Click to expand...

no idea mate...i only know about the mk2's mate im sure it will be possible to bore yours out though