2.0 Race Motor - Valve Size

[ber911]

I am in the process of changing the unknown cams in my 2.0 motor with 81mm JE 9.8:1 pistons to DC60/62 cams. Although the heads have been ported to 38mm, I have discovered that they have standard 2.0T valves in them. Would I be leaving enough on the table to justify the expense and hassle of putting in 45mm intake valves (if this is possible)? The plan is to run the motor to 7500rpm.

Rob

[Henry Schmidt]

Originally Posted by ber911

I am in the process of changing the unknown cams in my 2.0 motor with 81mm JE 9.8:1 pistons to DC60/62 cams. Although the heads have been ported to 38mm, I have discovered that they have standard 2.0T valves in them. Would I be leaving enough on the table to justify the expense and hassle of putting in 45mm intake valves (if this is possible)? The plan is to run the motor to 7500rpm.

Rob

The stock 2.0 heads had 39 X 35, 42X 38 and 45x 39mm (69S) valves. There is plenty of justification to use 69S heads if your goal is a performance 2.0.
Converting a 39mm head (earliest 2.0) to 45 x 39 would be possible but very costly.
Converting a 42mm head (42 I, 38 E) makes sense but requires a really competent machinist. I'm not sure changing the exhaust valve is necessary but 39 is the maximum.
45 X 39 is the maximum for these heads because the valve angle creates challenges (collision) with high duration cams.