Max RPM for Stock Longblock???
01-29-2004, 12:26 AM
#16
For sure that 4V Head is the best Head to use, but there are considerations to take here. The cost has been stated is the biggest one for sure. Any changes here will cost lots. Adding larger Valves is very expensive. Not only the cost of the Valve, you have to consider the seat and also you will have to de shroud the Valves in the chamber to net the benifits of the bigger Valves. Most probably the Guides will need attention also. Springs, etc etc. Multiply all of this by 16 and your into big $. If you have it, that would the best way to go.
It is believed that the 2V Head has not yet reached its full potential, and this is a very good alternative. Bigger Valves, porting that works, and Camshaft design can make these heads flow enough air to produce a lot of HP. If total costs are your limiting factor, the 2V Head still offers good options. Camshaft design, lighter valve Train parts all can help in getting into the Torque curve quicker. This can give an overall performance gain. The gains to be had here are RPM, not displacement. For sure the longer stroke/bore combo's can help, but it is displacement not RPM's that kills VE. Friction is the enemy we live with when we run higher RPM's. Spend the $ to lower the friction, limit out the 2V head with porting etc, and Cam the engine to produce a broad flat torque curve. Then use the porting and bigger Valves to run higher RPM's while continuing to flow good CFM. This will net good performance with less spent compared to the same in a 4V head.
It is believed that the 2V Head has not yet reached its full potential, and this is a very good alternative. Bigger Valves, porting that works, and Camshaft design can make these heads flow enough air to produce a lot of HP. If total costs are your limiting factor, the 2V Head still offers good options. Camshaft design, lighter valve Train parts all can help in getting into the Torque curve quicker. This can give an overall performance gain. The gains to be had here are RPM, not displacement. For sure the longer stroke/bore combo's can help, but it is displacement not RPM's that kills VE. Friction is the enemy we live with when we run higher RPM's. Spend the $ to lower the friction, limit out the 2V head with porting etc, and Cam the engine to produce a broad flat torque curve. Then use the porting and bigger Valves to run higher RPM's while continuing to flow good CFM. This will net good performance with less spent compared to the same in a 4V head.
01-29-2004, 02:37 AM
#17
Three Wheelin'
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If you have it, that would the best way to go.
Right now I have a rebuilt head from PD with generous intake porting, and full radius valve seats along with backcut valves. I am hoping that PD will come out with the new cam design soon. If I add that to my current setup, I think I would have a good flowing head for the money. As far as bigger valves, this seems to be something that would get you into the major $$$ category. This will be the first car I have ever done serious engine work to, and I am a little unfamiliar with what some of these upgrades cost. I have no Idea how much a set of big valves and the required machining would cost. M42, care to enlighten me with a general figure? Or anyone?
