Flathead vs. Predator

[anickode]

Time and money seem to be inversely proportionate.

An old co-worker of mine always said that for any hobby, you need time, money, and space, and you will only ever have two of those things.

 

[J.S.@SMS]

For a high performance build I'd take a predator over a briggs any day. But the one part tht could really make a predator do 50hp is a billet block and head. Think about it, billet head, block, crank, rod, flywheel, rockers, sidecover, and valve retainers. The only parts that wouldn't be billet are the valves and springs, the cam, the pushrods, the coil, the valve cover, and the bolts. And if you had a billet block and head, with larger head studs, you could run a turbo.

 

[Randy H]

For a high performance build I'd take a predator over a briggs any day. But the one part tht could really make a predator do 50hp is a billet block and head. Think about it, billet head, block, crank, rod, flywheel, rockers, sidecover, and valve retainers. The only parts that wouldn't be billet are the valves and springs, the cam, the pushrods, the coil, the valve cover, and the bolts. And if you had a billet block and head, with larger head studs, you could run a turbo.

Here's a head.
https://dedracing.com/collections/gx-clone-head/products/honda-gx-200-212-clone-billet-head

And another.
https://minidragracing.com/product/mdr-block-enstein/

A billet flathead for fun.
https://www.arcracing.com/6027-billet-cylinder-head-briggs-5hp-flathead-finned-open-small-valve/

 

[Flyinhillbilly]

For a high performance build I'd take a predator over a briggs any day. But the one part tht could really make a predator do 50hp is a billet block and head. Think about it, billet head, block, crank, rod, flywheel, rockers, sidecover, and valve retainers. The only parts that wouldn't be billet are the valves and springs, the cam, the pushrods, the coil, the valve cover, and the bolts. And if you had a billet block and head, with larger head studs, you could run a turbo.

There’s a guy looking into having a billet clone block manufactured. He’s looking at moving the cam and crank for more stroke and making it 3.25” bore capable. It all depends on the economics of it as to whether it happens or not, but a 360cc all billet clone/predator engine sounds appealing to me. There is already a billet animal available, which is basically the same thing.

 

[JTSpeedDemon]

One of the many big things that gravitates me towards flatheads, is I don't have to worry about dropping a valve. Something absolutely catastrophic would have to happen for that to occur.

 

[Flyinhillbilly]

One of the many big things that gravitates me towards flatheads, is I don't have to worry about dropping a valve. Something absolutely catastrophic would have to happen for that to occur.

I guess that’s true. Flatheads have more piston to valve clearance than any engine known to man, lol

 

[JTSpeedDemon]

Another things that's great is that there are SO MANY variations of Briggs flatheads, with stuff like electric start, carburetors, crankshaft bearings, bore materials, block materials, and even cylinder heads and valvetrain in a few cases!
But with a Predator, it's just Hemi or Non-Hemi, early or not. Boooring.
Discovering the insides of an engine is fun!

 

[Flyinhillbilly]

The predator or ohv in general has a more favorable angle when it comes to the ports, you can also get a lot more compression out of them, and ratio rockers are available as well.
The ohv’s have more power potential period.

 

[BigWes]

The predator or ohv in general has a more favorable angle when it comes to the ports, you can also get a lot more compression out of them, and ratio rockers are available as well.
The ohv’s have more power potential period.

The OHV done away with the flathead in the automotive industry due to this exact reason along with increased cooling capabilities of more water flow around the cylinder walls instead of porting exhaust gasses around them like the flatheads did. Compression could be almost doubled from what the flathead offered. The original flathead Ford V-8 came in at 5.5-1 compression. Back in the day with high octane fuel it wasn't unheard of for some engines to have 10-1 compression and sometimes higher on performance applications. Not to mention ease of maintenance in the ability to adjust the valve trane. To map the airflow path in a flathead versus an OHV the winner is clear.

And we end up with Nate's final statement yet again.

The ohv's have more power potential period.

Like it or not. Your engine is an air pump. The most efficient design will win...

 

[txluke]

I'm a little conflicted here, I was gonna start calling JTSpeedDemon "Boy Wonder"

Stolen from Facebook.

That is my meme. I guess this is what the kids call "going viral"! I love flatheads and I love OHV engines. The reason I made it was to poke fun of the people on Facebook groups telling everyone to put predators on every vintage mini bike someone posts up. I have predators on my newer bikes and flatheads on my vintage ones.

 

[JTSpeedDemon]

I guess it can kind of be summed up like this:
Flatheads have charm and a serious amount of hop up parts, but most are worn out or beat to pieces.
OHVs have a lot of power potential, the hop up market is established now and still growing, and they're pretty cheap for a brand new engine.
BUT, flatheads tend to be more compact(especially on minibikes), and think about it this way:
A Predator looks wacky on a vintage kart(I'm talking Rupp, Simplex, Clark, and all of the really exotic/rare/sought after brands), but a flathead doesn't really look wacky on a brand new frame or an old one. Of course, a vintage 2 stroke is ideal for the old OLD karts, but not everyone can afford/want an old 2 stroke. A little double standard there.

 

[Budget GoKart]

My 2003 yerfdog 3202 has a almost fully built 8 horse briggs straight pipe shaved brow milled head port polish briggs walbro carb all the goodies it could easily smoke my buddies go kart if mine ran the carb needs rebuilt and tuned a bit but it rips already 50+ might be a possibility.