rx1jim
New member
What does trail porting on an SRX involve? Are the intake and exhaust ports enlarged along with making the surface of the ports smoother? How does the engine builder know how much material to remove and where? Is this done on a flow bench or by taking measurements while removing material to match a known good port job? Is the port timing changed at all? Just curious since I just bought a 2000 SRX which was ported by a reputable engine builder in NY who used to work for Bender Racing. Thanks!!!
It will depend on who does the porting and to what extent the mods have been made to, 1 shops trail porting is no where near anothers shop, some might be more radical or less radical. Most do them in stages, like trail porting, then lake race then race, they can also be anywhere in between. If we keep this topic in general lamen terms, anytime you raise the exh port in a 2 stroke they make more power, there are other things that come into play such as lower compression, higher rpm peak, but these are addressed/corrected to make power by the engine builder. This would apply to a weedwhip, to a lawnboy mower, to a sled, motorcycle. The specs used are derived from dyno testing/field testing to come up with a "package of specs" this would be the best exhaust timing, best transfer timing and the best overall head set up to keep everything correct. The port timing is changed , this is what makes the power differance, youll hear "port and polish", but polishing does very little to no increase, its just a "looks" gain.
There is also computer simulation and engine building software for 2 stroke engines, this is also how specs are derived then applied to the field/dyno testing for fine tuning, some specs may show good on a dyno and perform poorly in the field. Because the load is applied differntly from the smaller water brakes and such used commonly to dyno sleds. Youll also see big dyno numbers in ads but if you look at the specs its easy to spot little things that change the output of the power reading. Running a engine wicked lean(bsfc), super high air quality, ice cold coolant temps(flash pulls) will all show you big hp numbers. These all can and will effect the readings and basicly you want real information, but some places sell from the numbers. Then when you run it in the field, it performs poorly. This is a complete differnt discussion.
There is also computer simulation and engine building software for 2 stroke engines, this is also how specs are derived then applied to the field/dyno testing for fine tuning, some specs may show good on a dyno and perform poorly in the field. Because the load is applied differntly from the smaller water brakes and such used commonly to dyno sleds. Youll also see big dyno numbers in ads but if you look at the specs its easy to spot little things that change the output of the power reading. Running a engine wicked lean(bsfc), super high air quality, ice cold coolant temps(flash pulls) will all show you big hp numbers. These all can and will effect the readings and basicly you want real information, but some places sell from the numbers. Then when you run it in the field, it performs poorly. This is a complete differnt discussion.
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