625-HP Ford "BOSS 300" Inline Six

[BlueOvalFitter]

Where can I get one?

625-HP Ford ‘Boss 300’ Inline-Six Destroys V8s Without Forced Induction

 

[Jackson_Slugger]

Know nothing about it other than it came from one of Ford's best motors ever, the 4.9L inline six. Pity they started making F150's it wouldn't fit in...

 

[c502cid]

Interesting, but not surprising since the custom head is Boss 302/Cleveland big port based, that they used the same port tricks that I used on many 351-4V Cleveland motors I built in the 80's and 90's. It's a pretty common mod to increase flow in a very large port.

 

[BlueOvalFitter]

Interesting, but not surprising since the custom head is Boss 302/Cleveland big port based, that they used the same port tricks that I used on many 351-4V Cleveland motors I built in the 80's and 90's. It's a pretty common mod to increase flow in a very large port.

c502, is it true that the Cleavland 2V heads flow better than the 4V heads stock from the factory?

 

[UncleDave]

sweet.

Standard hot rod tricks executed well work every time.

 

[c502cid]

c502, is it true that the Cleavland 2V heads flow better than the 4V heads stock from the factory?

At low RPM's definitely. The Cleveland hot tip was the Australian head. 2V ports with the 4V closed chamber. I used to import them by the pallet!

 

[oldhp]

Is this it? Go to Ellison's Machine Shop on FB.

 

[demarpaint]

@Trav - Hey Paul, can we build one for my van?

 

[sunruh]

how do you weld the extra 2 chambers onto the 4 and get it to seal (and flow water) correctly?

1971 BOSS 351 owner

Steve "R"

 

[wpod]

how do you weld the extra 2 chambers onto the 4 and get it to seal (and flow water) correctly?

1971 BOSS 351 owner

Steve "R"

Carefully

 

[UncleDave]

how do you weld the extra 2 chambers onto the 4 and get it to seal (and flow water) correctly?

1971 BOSS 351 owner

Steve "R"

Its 3 sections of 2 apparently - so you've got to wreck three heads to build it.

 

[Jake_J]

A cool engine for sure but given it was always a slow revving engine that never made much power (even the most modern ones made 150hp), a ton of money & time must of been spent to get one to 625hp.

 

[Cujet]

I'm not entirely sure I believe the HP number. A 310 cubic inch 6 cylinder, at 100% volumetric efficiency, stupidly high compression ratio and absurd piston speeds well beyond what Ferrari and the honda S2000 achieve, still requires one stress the 4.1 inch bore and 4 inch stroke, limiting RPM to about 8800 or so. Meaning a real world number of just over 500HP is what can be achieved. Calculate it out yourself. It makes little sense. 625HP might be possible at a very unrealistic 10,000 RPM. Note: 10K requires a 3.6 inch stroke and a mean piston speed well into the pro-stock range. Doing this on a 4 inch stroke is a pipe dream.

 

[UncleDave]

Whats unsaid is that at 13:1 you are going to need to run race gas.

Loads of expensive components.
2.25/ 1.71 int/exh, titanium valves, triple springs,
near straight shot in- out.

 

[A_Harman]

Cutting up two Cleveland 4V heads and furnace brazing them back together was done by a racer in Comp Eliminator back in the 70's.
2 HP/cube is a pretty common output to get from naturally aspirated 2vpc engines in the modern era.
But I always have a place in my heart for people that make weird stuff run.