What and how much difference is there between a standard valve job and a competition valve job?
Is it really worth the extra $100 bucks?

 

the regular valve job is just the stock valve job. I dont know the details of the competition valve job...maybe texas-speed will chime in.

If it is worth 10 rwhp it is worth it. How many parts can you buy for a car that add 10 rwhp for 100 bucks?

from the numbers ive seen lately I would say the competition valve job is worth at least 10rwhp

I would go for it.

 

Standard is usually garbage. You get one cut on the valve and one on the seat... usually leaving a wide seat and sharp edges at each end.
Competition means multi-angle (at least 3) on the seat, and hopefully the valve as well, but you'll have to discuss that with the machinist.
The valve seat area is the biggest restriction in the system, so it is definately worth it to get a good valvejob.

 

Yes,its worth the extra money.

 

The valve seat has that much affect on flow? Is that because it is the last and smallest orafice in the intake tract? And how wide are the 'steps' in a valve job?

 

That's exactly why.

How wide is up to you and the machinist.
You find a compromise between best flow and durability.
Most machinists have a standard they like for street use, and endurance engines.
Narrow cuts normally flow better, but are less durable.
A 3-angle flows much more than a single angle.
A 5-angle often flows slightly better than a 3-angle.

A 3-angle that has been radiused is about as good as it gets.
Some machinists have radiused carbides for cutting seats.

 

Thanks guys