What am I getting with a "Shredder" head?
TL:DR (the quick and dirty):
- +1 full point in compression at 16cc with no milling needed
- 25% increase in flow over stock heads verified on our flow bench
- Larger 28.5mm and 24mm x 5.5mm stem stainless steel valves compatible with aftermarket billet retainers and split keepers
- Heavy duty 1.2:1 ratio stamped steel rocker arms
- Stronger automotive style steel retainers and keepers
- 26lbs valve springs
- Intake flange accepts Mikuni, Nibbi, or other PZ style round slide carburetors
- Adapter is available for PWK D-slide spigot style carbs.
Below is a spreadsheet comparing commonly available GX200 clone head flow in corrected cubic feet per minute (CFM). These reading can be loosely compared to other flow benches, but they are most relevant to other heads flowed on our flow bench. All heads in this comparison were tested under identical conditions, one right after the other on the same night, of course on the same bench except for the DED, which came into the shop later. Higher numbers indicate higher flow, and although they are far from the only determiner of performance, they do give you a basic idea of how much valve lift is needed to get the best performance from a head. You can see that the Predator hemi gains nothing above .250" lift, so a 308 cam is useless for it, but the Shredder keeps gaining until over .300", so it can take advantage of a 308 or a 356 cam or use lower lift cams with ratio rockers to keep duration shorter while still getting over .300" lift at the valve. The Level II works even better at high lifts, so you'll most likely want higher ratio rockers, like the Gage 1.35:1 ratio, unless your engine is very small, like a 196cc that needs the longer duration of the bigger lift cams because it needs higher RPMs to use up all the air that the Level II flows.
| Cylinder Head Designation | .050" | .100" | .150" | .200" | .250" | .300" | .350" | .400" | .450" |
| Predator 212 hemi | 23.7 | 41 | 55.5 | 60.3 | 62.6 | 64.8 | 64.8 | 66.9 | 66.9 |
| Predator 212 non-hemi | 23.6 | 39.1 | 55.3 | 60.1 | 62.4 | 64.6 | 66.7 | 68.7 | 70.7 |
| Predator 224 non-hemi | 23.7 | 41.1 | 55.6 | 62.8 | 65 | 67.1 | 68.2 | 71.2 | 71.5 |
| Predator 212 Ghost Racing Engine | 23.7 | 41.1 | 58.1 | 65 | 66.1 | 66.1 | 66.1 | 67.1 | 68.2 |
| BBC Shredder Level I | 28.9 | 47.1 | 64.5 | 74.5 | 79.9 | 79.9 | 78.2 | 79.9 | 79.9 |
| BBC Shredder Level II | 28.9 | 47.2 | 64.7 | 80.1 | 91.4 | 97.3 | 100.2 | 100.2 | 100.9 |
| WC946-2 31mm/25mm | 37.3 | 57.7 | 68.7 | 72.7 | 74.5 | 76.4 | 78.2 | 78.2 | |
| Honda GX160 | 22.5 | 39.9 | 51.8 | 56.5 | 57.8 | 59 | 59.6 | 60.8 | 62 |
| DED Big Valve 34.29mm Intake Valve | 29.1 | 50.4 | 73.2 | 98.7 | 116 | 124 | 132.3 | 138.5 | 143.5 |
These Shredder heads can be bolted on with our intake adapter and a suitable boot and carburetor for a full top end build.
The details:
The Shredder head was a factory big valve sand casting designed just for the DTV Shredder's 208cc gasoline engine built by Lifan Corporation and designated the HP212e. Derived from the Honda GX200, it had a steel flywheel with charging coil and electric starter, oil pump with filter and cooler, high performance cylinder head casting with a 28.5mm intake valve and 1.2:1 ratio rocker arms, a forged steel connecting rod, and other high performance equipment to help it make power reliably. Its cylinder head was designed to work at all engine speeds below 6,000rpm with a small cam, so it works great as delivered with the popular .265 lift cams out there. If you know you are going to be removing the governor and going to "stage 2" long block, this head and intake are the ultimate "stage 2" upgrades, and with porting you can keep using this head LONG after you’ve made more power than a D port die casting can ever make. Here are the specifics of what makes power with this head:
+1 point in compression ratio - And that is with a 0.045” head gasket due to the smaller 16cc chamber.
25% more flow over a die cast stock D intake port clone head – The port floors in the Shredder head have more material in them and a gentler transition to the valve seat allowing more flow which means more horsepower. The bowl area and valve guide are also a HUGE improvement over the die cast heads. Port flow is not as much about perfectly smooth and shiny runners as it is about the overall shape of the runner and bowl area. Bowl, floor, short side radius, and transition to seat are all massively improved with this head.
Oversized stainless steel valves – The 28.5mm intake and 24mm exhaust valves are not only larger than a stock die cast head, but they are stronger too. You don’t need to order a built head with stainless valves because this one already has them for you. These valves have the standard 5.5mm stems and are compatible with available aftermarket billet retainers and split keepers, so you can keep using them even if you go to dual valve springs.
Automotive style steel spring retainers and split keepers – Just like some of the newer engines, this head comes with automotive style steel retainers and split keepers. This system of valve control is far superior to the lawnmower style slide-in retainers for better valve control at elevated spring rates and engine speeds. It’s another thing included with this head that you don’t have to spend time and money buying elsewhere. You might need aluminum retainers if you intended to rev to 7500rpms with the 26lb springs this head comes with.
26lb valve springs – This head comes with 26lb valve springs installed from the factory. You won’t need to upgrade unless you are going beyond a .265” lift cam and/or 7500rpms. If you like, you can upgrade to billet aluminum retainers with no other changes and just a valve spring compressor tool, or throw in some dual springs and explode with rpms because the valves will work with them too.
Heavy Duty Stamped Steel Rocker Arms with a 1.2:1 Ratio - 0.095" thick stamped steel rocker arms with a 1.2:1 ratio were used in the original Lifan HP212e and we sell them on these heads too. They work really well with the standard sized steel lash caps, stock non-hemi length 5.200" long pushrods, and a .265" lift cam giving .318" lift at the valve.
Can it be ported?
Yes, most definitely! This casting weighs double what a diecast D port stock type head weighs, so it has a lot more material in the casting that can be cut away to form the proper aerodynamic shapes. This is also where this casting excels because it has more material between the port floor and valve seat on both intake and exhaust runners, which is the Achilles Heel of the older D port style die castings. We need to make clear here that ported D port style die castings cannot, and will never, flow mod for mod, as much as this sand cast Shredder head because of their flat port floors and their resulting short side angle (it’s sharp!), not radius, and a lack of enough material to fix it correctly. It doesn’t matter how large of a valve you put in the die castings, because of the lack of any effective short side radius they will never flow what the Shredder can with porting and big valves. Because this material is present in the Shredder head you can cut a properly broad short side radius that allows much less separation on the floor and balances the charge velocity between the floor and ceiling where it is critical in the bowl and seat area, greatly increasing flow by reducing turbulence.
Will this bolt right up to a non-hemi 212?
Yes, but you’ll need stepped 10mm - 11mm head dowel pins to get it centered correctly. The stock head dowel pin size for a non-hemi Predator is 11mm, but this head fits the hemi block style 10mm diameter dowel pins. The dowel pins are important because they prevent the head from moving before, during, and AFTER the head is torqued to the block. With 10mm diameter dowels in an 11mm block you can see as much as 0.040” movement per side, and that is HUGE. Here is a link to our stepped dowels that will allow you to bolt a Shredder head onto any clone block. Sold in pairs here:
Stepped Head Dowel Pin Set - 10mm to 11mm
This head will bolt up to any of the 70mm bore blocks with 10mm dowels such as 196, 212 hemi, 223, 224, or 225 engines out there.
Depending on your block's deck height the 5.200" pushrods should work fine.
Will this bolt onto a Predator 212 hemi?
It sure will, and it works perfectly! Going from the worst flowing clone head to the best flowing has got to be awesome, right? If you're using a stock rod you can use a 0.010" thin head gasket and if your piston is at zero deck you should use a 0.045" head gasket. Pushrods need to be 5.200" in length when using the Shredder's stamped steel 1.2:1 ratio rocker arms. If you are going to use a Gage or EC roller rocker arm then you'll need 5.380" length and we recommend 1/4" diameter chromoly.
What intake adapters do I need for this head?
We have intake adapters for both round (PZ and PE) and flat (PWK) Mikuni style carburetors available on our website that are specifically matched to the stock port diameter of the Shredder heads. PZ style adapters can have a carburetor bolted directly to them with the included studs and nuts, PE and PWK style carburetors can use the 33mm diameter red boots and clamps from Amazon, and our intake has retaining channels cut into it for a good, firm hold on the carburetor.
What size pushrods do I need for the Shredder head?
We have found the best geometry using stock length inline valve (non-hemi) head pushrods for whatever block you are using.
Predator 224 non-hemi block w/ Shredder: 5.200"
Non-Hemi Predator block w/ Shredder: 5.200”
Hemi Predator block w/ Shredder: 5.200”
Any 135mm to 136.5mm block with Shredder head and Gage or EC rocker arms: 5.380" x 1/4" diameter.