SELF Re bore 75mm TB to 80mm - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

NZ GT-P · 05-14-2004, 04:12

After market throttle bodies have qouted an increaese of 'up to 13kw, if used with additional cold air intake'. I am thinking of reboring my Gt TB to 80 mm this weekend. The OD of either end is 80mm +, so why can't the 'butterfly' area be 80mm? Aftermarket TB's are 80 mm and clain large kw output over standard. As the gap between TB air inlet and butterfly shaft bearing is approx 3 mm each side, meaning if I rebore inlet there is approx 0.5 - 1mm each side for inlet to bearing separation, am not sure if this is enough. Also will butterfly jam open, making 'fly by wire' throttle jam full on? I will make a new butterfly at 80mm d, and have calculated a taper of about 5 - 7 mm to compensation for the new diameter. Has anyone done this and are my taper calculations correct? If I am wrong, no prob, at least I tried to enhance the induction system over the standard spec...., and Ill just have to buy a new TB to make my oil burner standard again (over 1 l per 1000km).

Please only reply if you have tried and succeeded, or tried and failed.

bossxr8 · 05-18-2004, 02:54

The 80mm throttle bodies make nowhere near the power gains as quoted by their manufacturers. Seems that about 5kw is about as much as you will get. Boring your own TB seems risky, as it is all electronically controlled and its not something you should screw around with without knowing what might happen. There are more power productive mods than bigger TB's for minimal money.

GT-P · 05-18-2004, 10:30

We remanufactre the 75mm bodies into 80mm no problems and for 2/3 the cost.

However, you can not just bore it out full stop. The bearing cavity is too thin and will intrude into this area.

We devised a way of getting around this and have been working successfully.
If you need a throttle blade in 80mm let me know, we sell these seperately.

Barry.

GT-P · 05-18-2004, 10:33

Quote:

Originally Posted by bossxr8

The 80mm throttle bodies make nowhere near the power gains as quoted by their manufacturers. Seems that about 5kw is about as much as you will get. Boring your own TB seems risky, as it is all electronically controlled and its not something you should screw around with without knowing what might happen. There are more power productive mods than bigger TB's for minimal money.

We found this to be the case also.

They are realistically good for 3 to 5 rwkW's