3V vs. 4V debate

[1FastS197]

okay, so me and my brother are in a debate about 3V's vs. 4V's... he says that the 4V flows more CFM's than a 3V... i say it depends on how big the vavles are! lol... so what do you guys think?

 

[US-1]

Which four valve head are we discussing?

 

[1FastS197]

sorry, particularly a 2003/2004 Mach 1 head vs. a 2005-2009 GT head...

 

[ShadowLands]

Really depends on who you ask as different shops flow cylinder heads differently. On the INTAKE side the 3V uses a slight larger set of valves and a better velocity port. CFM wise....the 3V wins that one.

The exhaust however.........4V due to two valves instead of one. Although the 3V exhaust port isn't bad at all.

 

[1FastS197]

Really depends on who you ask as different shops flow cylinder heads differently. On the INTAKE side the 3V uses a slight larger set of valves and a better velocity port. CFM wise....the 3V wins that one.

The exhaust however.........4V due to two valves instead of one. Although the 3V exhaust port isn't bad at all.

this is EXACTLY what we have been debating (or argueing, we are brothers)... he is saying that 2 exhaust valves are better than 1... and i do agree as long as the valves/ports are the same size/angle/etc... but they aren't in this situation... but i could also be wrong too! the 4V could flow more than the 3V...

 

[ShadowLands]

As an overall package the four valve heads are better from an airflow standpoint. The early "B" heads flow more than any other four valve head until you get to the current Ford GT/GT500 cylinder heads. Several 1200+ hp modulars are using the early "B" heads. John Mihovetz uses them (albeit heavily modified) on his 6-second/225 mph Pro car. That engine makes 9.2 hp per cubic inch on gasoline.

The three valve head has yet to be put to "serious" power production although several shops/racers are using them quite effectively. Vinny Barber has gone mid-8's along with Justin Burcham of JPC. Peter Del Pino has also been high 8's with his Florida-based car. We will be seeing what the new/improved ChevyKiller has for power shortly I'm sure.

Until someone steps up with a serious (as in Outlaw 10.5 or Super Street Outlaw) setup to prove the three valve engine....the four valve will be THE choice for ultra-high horsepower modular setups.

 

[3vs197]

the exhaust flow on the 4v is much greater. maybe thats y headers are a waste of time on 3v's and 4v's get 20+whp out of them. the 4v heads still flow better all around. the stock mach1 intake flow is like 250cfm on the intake and 220?cfm on the exhaust. a 3v is more like 225intake/180exhaust, although i hear at the same hp level the 3v head will make more torque.

 

[eng943]

Flow is one thing, and in that category the 4V head has a slight advantage. However, the port velocity is greater in the 3V head. Not to mention the 3V weighs less.

The bottom line really instead of trying to declare a "which is better" is the realization that either head with a decent porting will produce some very impressive power.

Both are very good heads, and a solid foundation for almost any build.