[ruffas]

Hi
Can anyone tell me what the bore size is on a G16B and a G13B is. I have fitted a G16B to my '97 Sierra and am trying to work out if I need to get a certificate of inspection. According to the DoT in Perth if the RAC horsepower has not changed all I need to do is fill in the form. From what I can find out the G13B was 74mm and the G16B is 75mm but everyone is telling me this is not necessarily accurate. Where can I find the correct measurements?

cheers
blackjak

[Ben_Sierra]

The G13 has a 74.0 mm bore.

But since the horsepower will most certainly have changed from a G13B to a G16B, I guess you will need to do more than just fill in a form...

[jonno_racing]

dude u would have near doubbled your power... u will need the cert

[ruffas]

That's what I thought but aparently the 'new' form is only concerned with the RAC horsepower calculation which from what I can see and read has no bearing on the actual power. Technically if the bore remains the same and the stroke is longer although you have an increase in power all you have to do is fill in the form. That's why I am really interested in the actual size. If I do not have to put the vehicle over the pits then all the better as I do not have to pay or worry about what else they will find.

[Fatzook]

ruffas wrote:

That's what I thought but aparently the 'new' form is only concerned with the RAC horsepower calculation which from what I can see and read has no bearing on the actual power. Technically if the bore remains the same and the stroke is longer although you have an increase in power all you have to do is fill in the form. That's why I am really interested in the actual size. If I do not have to put the vehicle over the pits then all the better as I do not have to pay or worry about what else they will find.

This sounds very unlikely.

[ruffas]

I am unable to attach the form and as unlikely as it sounds, and I agree, the form says that

Note: If the configuration of the engine has altered to the extent that the number of cylinders, RAC horse power rating or fuel type has altered, then the vehicle must be presented for examination and a CERTIFICATE OF INSPECTION COMPLETED.

The RAC horsepower rating is calculater as follows h.p. = (D2 x n)/2.5 where D = the diameter of the cylinder in inches [1" = 25.4mm], and n = the number of cylindersit has nothing to do with the stroke so therefore the diamention of bore is critical.

[Damo]

Bore sizes are 74mm and 75mm for g13 and g16 respectively.

What changes the capacity the most is the increase in stroke. There are 2 versions of the g13, a 1324cc (77mm stroke) and a 1298cc (75.5mm stroke). g16 has a 90mm stroke.