Gasser, what is meant by "slows the flame travel". A blown Top Fuel engine has the slowest flame travel of any piston driven engine on earth and makes 7000 horsepower.

Are you refering to a wedge type engine like the small block chevy where the spark plug is on one side of the chamber and can't light the air fuel mixture efficiently. The rotax engine has two plugs firing directly on top of the piston. I see no way to have flame front problems with this engine as the mixture is always being lit from the top.

The 14:1 will clear .425 lift cams with a single base gasket. I know of three bikes running that combo right now with no problems. If you run two base gaskets then the .433 should be no problem. The 14:1 is as advertised with two base gaskets.



MrHorsepower

 

Thanks MisterHP, What gains will I see going from the 11.5:1 to the 14:1 using Alky. I heard that alky likes the higher comp.

 

I have a picture in my head of what gasser is talking about. With the dome of the piston creating a (for lack of a better word in my vocab) blockage for the flame front. But like Forcefed said I think it could be fixed with ign timing. IMHO

Any thoughts about how it would affect the single plug (compared to the twin plugs) in the center of my head, Raptor remember [img]i/expressions/face-icon-small-wink.gif[/img] ?

 

If you use 1 gasket you will have a 16:1. Clay them up guys.

JMiller

 

I have only dynod my quad once - that was at 4SW. At that time it did not have the 14:1 Piston. I know the mobile dyno was controversial. It was primarily used for comparison purposes. My quad dynoed at 56 hp. There were several stage II quads with very close results. The modest numbers are that you should gain at least a 2hp gain with the 14:1 piston over the 11.5:1. However, torque is hugely increased as well (guys, you wont need the A1/A2 cams). Like I have said before, most motor mods put all the power on the high rpm range. However, if you have 425 lift cams, the 14:1 piston, and the Vortex, you WILL have switchable power wherever you want it. I followed this same concept with my 400EX recently and got great results.

As far as the crank goes - I have great confidence in my stock DS crank (running 14:1 piston) and my stock EX crank (running 13:1 piston).

 

does this mean that if you have the larger valves installed that the 14:1 will hit. As you all know, Woods installs the larger valves in their stage 3 heads. Will there be a problem. Can you still run the 425's or maybe only the 395???

 

OS valves here also....with no issues (and FYI alot of missed gears[img]i/expressions/face-icon-small-shocked.gif[/img])

Peak Dyno numbers were mid-60`s on gas, thats cool and all.....but you should see the torque curve!

Woa Nelly! [img]i/expressions/face-icon-small-happy.gif[/img]

 

The 14:1 is designed to clear 40mm intake and 34mm ex with .450 cams. But once again you should always check valve pocket clearance on any aftermarket piston-cam combo. Example: my friend put together three Warrior 350 motors with the exact same cams, pistons etc. The first two had plenty of clearance, on the third motor the valves hit the piston! Was it cam chain stretch, decked cylinder, cam gear degreed wrong? Who knows but this why you should check.

Bartlett, I have dynoed several 14:1 combo's. What are you wanting to know.
Yesterday I dynoed a 14:1, web 109/110 split, Lectron 46HV, Big Gun pipe that made 57.6 horsepower and 50 ft lbs of torque. The same motor with RW 11.5:1 made 52.3 horsepower and 45.6 ft lbs. This engine runs 110 octane is not ported and runs stock size valves. The dyno I use has repeated within 1 HP every time I use it.


MrHorsepower