Originally Posted by
javcrodgz In their defense, "minimal gains" are what modifying naturally aspirated motors are all about. There are no "large gains" when dealing with peak performance without LARGE money. Oversized valves can be just another 1 or 2 HP increase which can take your build above others! Do it!
Agreed
Originally Posted by
ashtonsser If done properly it will be more than 1-2 whp gain. Probably more like 5-7whp. But again like they said. Money can be better spent elsewhere. Your looking at 450.00 for the valves and then a massive amount of headwork to install them and have them work like they are supposed to. The seats are gonna have to be cut quite a bit and while your there you might as well have them deshoud the valves and port the inlet just before the valve seat to make it a nice smooth flow through that area of the port coming into the combustion chamber. There is more to it than just throwing larger valves in.
Probably the machine work to install them and do the deshrouding and smoothen out the port and valve opening will cost you another $500 or more in labor. They also have to make sure when doing the valve install that they use the correct install height so the top of the stem is at the proper height. This is done by measuring the valve height with the stock components in and then making sure the new ones come out the same. Its a very lengthy process.
Where I am machine work is not as overpriced as in the US.
This discussion raises good points and different schools of thought, which is always welcomed, but I think we're forgetting the original question, which is not whether if it's a worthwhile gain, but rather a matter of clearance.