|
Rotary Engine Porting
J Port - Monster Port
The J ported engine (also known as monster port) is as big as conventional side-plate porting can go. It is the same as the bridge port in design, but the bridged port is now fatter and extends past the face of the rotor and into the housing’s water seal / O-ring requiring the need for the seal to be cut back and filled with a metal type sealant such as "Devcon", plus, depending on the side plate used, the water gallery requires blocking off and filling on the side plate and the rotor matching.
Cutting into the rotor housing is also needed for port matching. The main problem with this design of port is a short life-span as water does and will seep through the seals. The main field where a J-port is likely to be seen is on the track where restrictions don't allow peripheral porting, or a slightly wider power band is desired. Typically around 300hp can be expected.
J-Port - The second port on the J-Port are a lot larger then a
Bridge
Port
and cut very close to the water jacket. These engines have poor low end but great high end power. Idle is around 1800 rpm. Less low end power is again to be expected. One drawback of this design is that the secondary port is extremely close to the water jacket and has a very bad tendency to break through flooding the engine with coolant. People argue the J-port and monster port are the same or do get them confused, but when looked at are considerably different.
Monster
Port
- The Monster Port was designed to get around the banning of Peripheral Porting in racing and is the largest/most radical of the side ports. These engines can have a short life span due to the secondary port cutting through the water jackets. One piece apex seals are required on a
Monster
Port
engine or the seals won't be held in place as the rotor turns.
(I believe some of the earlier make engines use the 2 piece seal design, the 10A for certain i know does) These engines will put out similar power to a larger Peripheral Ported engine, but share the same life
expectancy and excessive fuel consumption.
Unless someone's a top notch TIG welder, die grinder and heat treater then steer clear of the
Monster
Port
if you're after engine longevity. most builders just fill the water jacket they've just cut into with some kind of automotive 'mastik' - and in always ends up leaking remember this porting method was brought about by rally teams not being allowed to run a PP because of class restrictions leaving them with the 'factory' induction design, but needing that magic 300hp mark - a good 30hp over a top notch Bridge port of the day. They also had a rally team budget and didn't mind rebuilding them every 5000klms.
If you do build a J Port, remember that you really should weld an alum panel in to seal the water jacket instead of using Filler. Then remember not to weld for too long at once as to warp the housing, die grind it nicely without leaving any burrs or nicks, then polish it to remove any potential fracture points. After all that, if you're paying someone else to do it, you could have just gone a PP for cheaper, or a big Bridge port with EFI. IMHO, J Ports are a dying breed in the ported rotor scene. The only reason to run one is if racing class restrictions don't allow a PP, and you're made of money...
PRO'S: Slightly better power than a bridge port (5 to 10%) without the expense of a PP
CON'S: Short life-span, 6-12 months / 5,000-10,000km, narrow power band, need for free-flowing/loud exhaust system, poor drivability
|
|
