DOHC 300 Head

[StrangeRanger]

4000 FPM average piston speed is the limting number I have always heard for reducing catastrophic failures.

For various Ford engines:

200 - 7678 RPM
240 - 7545 RPM
250 - 6138 RPM
300 - 6030 RPM

302 - 8000 RPM
351 - 6857 RPM
460 - 6234 RPM

4.6 - 6773 RPM
5.4 - 5762 RPM

 

[Stubby]

Long rods help reduce piston acceleration and decceleration at TDC and BDC effectively reducing inertial loading. It also helps to keep reciprocating mass to a minimum.

Piston speed is still the same but these two factors help tremendously.

The thing that blows my mind is the fact that @ 7000rpm the valves open and close 58.3 times per second and for over half of that second they are setting still When you think about it valve springs are pretty amazing, yet mostly taken for granted.

 

[Anonymous]

eh, for the supra guy. this is a 300 inch motor we speak of, its alot more than just 3.0 liters. if you could find a way of adapting DOHC and some fuel injection to one of these engines it would be a beast, but the engineering process is murder. not to mention the price. one day we will all hit the lottery and build a ford six that can rev to 8000 rpm and make 600 whp on pump gas. 8)

 

[MustangSix]

Four valve big engines have been around a long time. Witness the Rolls Royce Merlin. Something like 21-22 liters? IIRC with a four valve pent roof head.

 

[80broncoman]

During bike week in daytona in the early 90s. I saw a motorcycle with a V-twin It had two 4 valve heads cut from a merlin v-12 as far as I could tell.
I can still picture it in my mind. It had on the side of the seat "5000cc"
It also had a small looking 4-71 blower and a Q-jet card at about chin height.
Oh one more thing it had a No2 plate system under the carb.