Porting & Modifications

The bulk of these modifications should be made while the engine is fully disassembled. This will make it easier to fully clean up after any drilling or tapping that you do - metal chips are very bad for any engine!

I chose to not port my engine. There's plenty to do, and given that my model engine (John Slade's) has almost too MUCH power, I didn't think it was worth the risks to try to make more (I had this vision of not fully cleaning out any metal shavings/dust, and having my engine eat its bearings).

Porting is also less critical in our turbo setup than for naturally aspirated engines, particularly with the beast of a blower I used. Still, if you do want to porting work, it's fairly straightforward and fun.

You'll need a die grinder and some carbide bits, including straight and ball grinding bits. The process is simple:

1. Spray or brush layout fluid on an iron around the port area.
2. Place a template from Pineapple, Racing Beat, or any of a number of other vendors on the iron and position it with dowels.
3. Scribe the new port shape on the iron, then remove the template.
4. Grind away, but take it slow and make sure to ease all edges.
5. Clean up the iron - supposedly a great way to do this is to take it to the self car wash and have at it with the pressure hose.

There are a few risks to watch out for. First, porting will produce a large quantity of iron (or aluminum) shavings and dust. Even small specks of this working their way through your oil system could wipe out your rotor bearings and eccentric shaft. Make sure your irons are immaculate when you're done.

Second, porting can alter how well your engine runs - and not always for the better. Poorly shaped ports can cause it to run rough at various RPMs, and aggressive porting can even shorten side or apex seal life. The worst-case scenario is when a seal falls into one of the ports - the engine will basically eat itself. This is probably the second worst thing that could happen to a rotary after from a sudden loss of oil pressure.

Remove the oil metering pump, and make or purchase a cover to fit over its usual location.¹⁾ Then plug the injection holes with M10-1.0 plugs with Loctite Blue or Red (depending on whether you might some day change your mind).

Examine the eccentric shaft oil bypass valve. This is a spring-loaded piston installed in the end of the eccentric shaft with a bolt. It's designed to block the flow of oil until the engine reaches 158F, which helps meet emissions standards. But this device can fail for a variety of reasons, starving the rotor bearings of oil.

Blocking it is as simple as adding three 5/16” or 8mm lock washers to the shaft of the bolt, behind the head of the piston. This prevents the bypass valve from sliding back and opening (and is much easier to do than actually removing the valve.)

Unscrew the two oil jets from the eccentric shaft. Save the springs and ball bearings in case you ever want to reverse the change, and press a Weber 200 carb jet into the back of each port. There's no need to fasten it in any way - there's nowhere for it to go, and oil pressure will hold it in place. Reinstall the modified oil jets in the eccentric shaft.

You could alternatively save the cost of the Weber jets by filling the oil jet with silver solder, then drilling a 0.2” hole through it. I didn't have any silver solder, so between the cost of buying some plus the time involved, I chose to just buy the jets. Plus, it's easier to reverse the change if you go with the Weber option…

Note that this change will increase oil flow through the eccentric shaft. That's great, but it lowers overall oil system pressure, especially at low RPMs. You need to combine it with a higher-pressure regulator. For both 2nd-gen and 3rd-gen engines, you need to buy and install a higher pressure main regulator, or follow Pineapple Racing's video on how to modify the stock regulator for higher pressure. Click here to see a video on how to do this. For 2nd-gen only²⁾ you also need to modify the regulator in the front cover by installing two or three washers under the spring to increase its pressure.

Some builders need to modify the water pump to deal with cowl clearance issues. I didn't need to do this, so I'd refer you to John Slade's description for more details.

Open the water pump and find the thermostat. Remove it. You'll find a port that allows coolant to cross from one side of the pump to the other when the thermostat is open. Tap this for a 1/2” NPT plug, then plug the hole (use Loctite).

Some builders use AN fittings for their radiator hoses, but I stuck with traditional hoses. AN fittings are VERY hard to find in the sizes (1.5”, or AN-24) required for the 13B's radiator connectors. Other builders have responded by simply using smaller fittings, but I didn't like that solution.

What I did do was use high-quality silicone hoses and constant-torque clamps to ensure that the hoses can't “blow off” the fittings, as some have had happen. Note that there is a HUGE difference in quality between the hose manufacturers out there. I would stay far away from eBay for this stuff - you just never know what you're getting there. If you aren't spending at LEAST $60/foot for 1.5” ID hose, then you aren't spending enough!

My supplier is no longer available, so I haven't listed them here. When you research suppliers, make sure you check that the hose is compatible with coolant (some unlined hoses are not) and can handle high pressures!

Be aware that the lower radiator hose is under considerable suction at high RPMs. The stock hose uses a “spring form” to resist collapse. If you can squeeze the hose, it's too flimsy.

As described in Reassembly, the tension bolts are prone to breakage under certain conditions. To help damp the resonance that creates these conditions, when installing the tension bolts, apply Permatex Ultra Grey in a spiral pattern around the outside edge of each bolt before installing it. (Also, don't forget to dip the threads in anti-seize thread lubricant, or clean engine oil.) Allow 2-3 hours to set before adding coolant.