CWR 460cc or FST 446cc??

[jasonp]

This is the question. It's going to be one or the other. One looks to be a little more trail friendly of 11:1 compression where the CWR is 12:1 engine is going to make a lot of heat and most likely run race gas or back the timing way off.
Go with more stroke or more bore.. I wonder if the compression would off set this. I bet the FST engine makes more torque. mmm

 

[courchaine]

That's a really hard question Jason I think it pretty much depend on what you'll be doing with it as you said the FST 446 seems a little more trail friendly but there is nobody in there that have tried the CWR I don't even see nobody on the CWR shop talk forum that is running one so we don't have any reviews of it. But that thing must be a high rpms screamer. I would personaly go with the FST cause of the fact that we all know it's a good and reliable setup and it's putting some pretty impressive HP numbers. I gave you my opinion now the choice is yours whatever you do that thing will be insane

 

[griff]

What is the bore/stroke of each?

 

[dave76]

What is the bore/stroke of each?

Bore x Stroke
FST= 87mm x 75mm = 445.9 (446)

CWR=89mm x 74mm = 460.4 (460)

FST = 90mm x 77mm = 489.9 (500)

 

[missouritrailrider]

is the 500 even still available?

 

[paulie1959]

If you look at all the high performance atv's, there only using 63mm stroke engines and close to 12:1 compression for more high RPM HP, I have a spare 350 motor with a bad cylinder and broken crank, I have a new +4mm (68.5mm)stroker crank in a box and web cam .430 with HD springs in a box, and I think I'm going with the 400 CWR 89mm cylinder sleeve piston kit and bigger intake valve and put in it, this should make about 430cc and I should get some good power out of the old warrior

 

[jasonp]

No they don't offer it as a kit but I could make my own.. I'm just not sure if I want to buy $500 dollars is worth of parts just to get that little more out of her (for the 500cc)... something to think about.

 

[griff]

I'd go for he FST Jason, especially if its 11:1.

The stroke is a pinch longer, but the bore/stroke is a bit more square than the CWR. It may not have quite the displacement, but in general efficiency, its probably going to be better. It should be a bit smoother making power/torque, and make less heat overall.

 

[missouritrailrider]

so about how much money are you looking at to have one of these motors built? Also, what is the biggest kit you can get with no case bore or cracking cases?

 

[dave76]

so about how much money are you looking at to have one of these motors built? Also, what is the biggest kit you can get with no case bore or cracking cases?

366 or 85mm. Anything bigger requires a case bore which isn't much of a problem, or splitting the cases to install a stroker crank.

 

[dave76]

I'd go for he FST Jason, especially if its 11:1.

The stroke is a pinch longer, but the bore/stroke is a bit more square than the CWR. It may not have quite the displacement, but in general efficiency, its probably going to be better. It should be a bit smoother making power/torque, and make less heat overall.

Also Griff wouldn't the extra stroke and piston duration aid in cylinder filling, esp. since it's two valve motor.

 

[dave76]

Jay if you do go with the 446 you'll prob. make more power then me since you already have a way better port and flow job and a 1mm bigger intake valve.

 

[griff]

Also Griff wouldn't the extra stroke and piston duration aid in cylinder filling, esp. since it's two valve motor.

Not sure what you mean by 'piston duration'... but in any case...

"Cylinder filling" isnt really a function derived from stroke as measured by itself. Displacement is how you would measure that, i.e. how much volume can be moved. It is just a big pump after all. But in the grand scheme, the final word belongs to the cam. You could call it the 'deciding factor' since it controls the valves.

I think that answers your question?

 

[dave76]

When I said piston duration I ment the time at top and bottom dead center being longer due to the longer stroke.