what mods are NEEDED for freeride 66e?

[egbrig]

P.S. I really am looking for info on this and not an argument.

 

[ROTATION]

Twin pipes give a broader power peak and make jetting easier as cylinders are totally independent
Single pipes give better low-end, can't remember the reason off-hand but you can check with the snowmobile guys, think it has something to do with a more constant temperature
Single pipes are lighter, improving power/weight ratio of ski so they can be built with steeper angles than twin pipes to give close to the same peak hp.
TSR is excellent at predicting hp, I have seen figures quoted by ski builders for freestyle skis with non-pv that if they are true would mean a poor low-end and the rpms are high.
A big factor is whether pipe is a wet or dry, a drypipe gives more horsepower with the same exhaust area.

 

[superramjet]

tsr software is not a dyno

 

[WaveDemon]

I see the postings of HP but who, where and on what type of dyno are these numbers being derived. Not trying to bust on anyone but I'm getting sick of HP posts from guys who have never dyno'ed an engine. HP is a mathamatical derivative of torque or work done at a given rpm. The more work done in a given time the more hp until the volmetric efficientcy drops of i.e. Hp happens at higher rpm and peak torque happen in the lower band. Race engines make the most HP and I do know numbers for some of the factory efforts. I find it hard to belive that a stock 66e with single pipe makes almost as much as my ported twin pipe. If I'm wrong please post specific info so I can drop a single into my blaster.

I'm pretty sure these numbers are coming out of a computer model.

 

[WaveDemon]

I've got my motor mocked up in the hull. looks like it would benefit from a shorter mid shaft. still a work in progress...

 

[ROTATION]

All the best builders use tsr, make a few calls. Until you use it and understand it, you will have no concept of how good it is.

 

[egbrig]

Ok, I see where this is comming from. I have spent time in Canada with one of the premier pipe builders and he swears that twin pipes made correctly give better bottom end. I have seen for myself a Mel Miller mod hx 800 engine power curve get blown away on the bottom end by set of twins designed for the engine. Like I said real dyno time. TSR is target but dyno is reality.The given reason for single vs. twin pipe bottom end is the scavenging effect of the 180 phase difference, but a well made pipe per cylinder is better, I saw it happen first hand, and I made the dyno run. I'm still interested in info, not trying to disrespect. I'd still like more info on the 66e singles.

 

[FLY6584]

Twin pipes give a broader power peak and make jetting easier as cylinders are totally independent
Single pipes give better low-end, can't remember the reason off-hand but you can check with the snowmobile guys, think it has something to do with a more constant temperature
Single pipes are lighter, improving power/weight ratio of ski so they can be built with steeper angles than twin pipes to give close to the same peak hp.
TSR is excellent at predicting hp, I have seen figures quoted by ski builders for freestyle skis with non-pv that if they are true would mean a poor low-end and the rpms are high.
A big factor is whether pipe is a wet or dry, a drypipe gives more horsepower with the same exhaust area.

What single dry pipe for the 66e are you referring to? Who makes it and are they still available?

 

[ROTATION]

Riva used to make. I have made my own, with the oem 66e header.

 

[#ZERO]

Hey Tim here's the port timing duration specifications for the 66e GP800 cylinder.

90° Exhaust Port Opens Power Valves Closed
78° Exhaust Port Opens Power Valves Open
117.5° Transfer Ports Open
120.5° Boost Port Opens
181° Exhaust Duration Power Valves Closed
205° Exhaust Duration Power Valves Open
126.5° Transfer Duration
120° Boost Port Duration
27.5° Blowdown Time Power Valves Closed
39.5° Blowdown Time Power Valves Open

The 60T GP1300 P.V. cylinder should give some interesting specifications because all the ports are lower by about 1.5mm

I'll have the specifications for the 60T cylinder real soon.

 

[WaveDemon]

Hey Tim here's the port timing duration specifications for the 66e GP800 cylinder.

90° Exhaust Port Opens Power Valves Closed
78° Exhaust Port Opens Power Valves Open
117.5° Transfer Ports Open
120.5° Boost Port Opens
181° Exhaust Duration Power Valves Closed
205° Exhaust Duration Power Valves Open
126.5° Transfer Duration
120° Boost Port Duration
27.5° Blowdown Time Power Valves Closed
39.5° Blowdown Time Power Valves Open

The 60T GP1300 P.V. cylinder should give some interesting specifications because all the ports are lower by about 1.5mm

I'll have the specifications for the 60T cylinder real soon.

thanks chris :woot: