High Performance F-head Musings

Although not chasing big numbers, I discovered something by accident.
During an engine rebuild and due to a mis-labeled box, I installed a L-134 cam into a F-134 engine.
World of difference, that engine would out pull my old engine all day long.
Right up until the intake rocker arms started bending/breaking......
Apparently the intake lift on an L cam is higher than an F cam FYI.

 

There were two reasons that wouldn't have worked. I needed about 3x the flow that the pump (with a return) would have put out. I wanted to make sure I was on the rich end of a mixture so I wouldn't blow it apart. By pressurizing the tank, the volume I could squeeze through the injector was increased drastically, and tunable with the regulator. And secondly, that injector was pulled off my daily driver to use in the jeep. I couldn't exactly pull the fuel pump too.

 

The solution to the low end performance problems of a big carb is a progressive two barrel like the Holley Weber 5200 or a Weber DGV 32/26

The best header design for the 134L would be some sort of Tri Y combining #1 and #4 and then #2 and #3 use 1.5" OD 1.375" ID primarys about 1.75" D secondarys and then out to a 2.25" OD collector and tail pipe.

 

If my new to me motor works out well. Turbo and some combination of head and block milling is not out of the question. Controlling timing will be interesting.

I think these motors crave a small turbo. Keep that power band in place, just make the numbers larger.

 

One of my concerns with running a turbo would be where to tap into an oil supply line that would give enough oil pressure and volume to keep the turbo happy and healthy. A seperate dry-sump setup (maybe retro-fitted from a motorcycle engine?) with its own cooler has crossed my mind.

Am I overthinking this aspect?

 

I think so long as you’re post filter, it’d be ok.

 

But isn't the standard filter feed for these a "passive" line?
I.e, not all of the oil is going directly from the pump to the filter?
I might be wrong in remembering that... but if I'm right, I'd worry about how much oil (volume) is actually getting to the turbo.

 

I planned on using a water cooled turbo. The oil is just for lube in that case.

 

wow. typed into youtube turbo 134 Fhead motor....lots of videos on the subject.

 

Yup. The motor has a diesel type under-square coupled to mild cam. Adding some boost will increase the dynamic compression, which the motor desperately needs. Any cam or exhaust solution will simply move the curve, which on this platform is likely the opposite of what is desired. Small turbo I think is the best approach to making usable safe output. Low boost though. It wont take much to broaden the mid range of the motor and make it more all-purpose.

 

Thanks for the links Howard! That's sweet. I might have to hunt that guy down the next time I'm over that way. This made me smile:
(Forward to 3:39)

 

Def neat videos. Def a cool project and on a budget to boot.

The ideal would be a turbo mounted directly to the exhaust manifold, keeping the turbo close to the exhaust outlet from the block. My idea was to have a simple log manifold fabbed up. Turbos live off heat, so the U pipe he used along with the stock manifold was going to allow a decent amount of heat to escape, reducing the speed of spool (which we want to be very quick to keep the tractor feel).

Boost can make much of the breathing hassle of the engine design (exhaust side anyway) go away.

 

My buddy sent me this video yesterday. He took the old “Grundsow” out of storage and got it running for an upcoming anniversary race in September. Listen to that F-head idle. I love it.

 

Gotta up that idle lol

 

I meant to post this here awhile back. Just some eye candy. All custom made on a guy's Bridgeport. It has a 4 port intake, relocated intake valves, reshaped combustion chambers, titanium valves, Jesel rocker arms, fully water jacketed, and arias custom dome pistons.

 

That was my reaction too.

I really admire the skill and time that went into this, but at some point you should just use a better engine to start with. Must be for a f134 required swamp buggy class or something. This is how cheap racing classes requiring "stock" motors that don't nail down "stock" very well end up being expensive.