GROUP K 845cc SuperJet Freestyle Tech Info

SUPERJET-113

GASKETS FOR CHAMP BRAP!
Site Supporter
Today from GroupK PWCtoday:

Group K said:
We will be displaying in Performance Alley at the Finals. Among other things, we'll be displaying a new Rick Roy freestyle boat, with our 845cc motor installed (assembled by Mark Dobson). We'll also have plenty of big bore top ends on display (Yamaha 845cc, Kawasaki 849cc, GPR 1390, etc)

We'll be back in the shop full time on Tuesday the 14th.

Respectfully, Harry Klemm

Cool, Harry got himself a FS-1 Rick Roy hull! Sounds like he is serious about this engine platform. I'm gonna test ride it!
 
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GIL

Power In The Hands Of Few
Location
Cullman AL
I am glad they are trying to 'step up', but I am afraid it may be too little too late. People always have the mis-conception that big motors are bad expensive. There are people that do a turn key motor at 6mil bigbore w/EVERYTHING for 5600.00!!! Engine, fuel, ignition!!! That to me is a bargain.
 

SJBrit

Extraordinary Alien
Location
Bradenton, FL
Does piston weight come into play too? I would think that a stroker with the same capacity as stock stroke big bore would have much lighter pistons and therefore spin up faster (as well as making more torque). Or doesn't it make that much difference?
 

SuperJETT

So long and thanks for all the fish
Location
none
Does piston weight come into play too? I would think that a stroker with the same capacity as stock stroke big bore would have much lighter pistons and therefore spin up faster (as well as making more torque). Or doesn't it make that much difference?

A stroker with the same displacement as a non-stroker will have more torque and slightly lighter pistons, though the rods could be longer/heavier.
 

SJBrit

Extraordinary Alien
Location
Bradenton, FL
A stroker with the same displacement as a non-stroker will have more torque and slightly lighter pistons, though the rods could be longer/heavier.

I guess the increased moment of inertia of the stroker crank would also tend to offset the lighter pistons, although with the pistons actually changing direction every stroke they might be a bigger deal. It would be interesting to do the math to figure out which is optimal for rev up. I have a 15 flight to Korea this weekend so maybe I'll get bored enough to figure this out....
 

GIL

Power In The Hands Of Few
Location
Cullman AL
I guess the increased moment of inertia of the stroker crank would also tend to offset the lighter pistons, although with the pistons actually changing direction every stroke they might be a bigger deal. It would be interesting to do the math to figure out which is optimal for rev up. I have a 15 flight to Korea this weekend so maybe I'll get bored enough to figure this out....

Going back to the mother land? BAWAAAAAAAA JK
 

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
He said they "could" be longer.

Some strokers have standard length rods, some have longer rods.
 

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
In theory the longer rod keeps the piston parked at TDC for longer period of time,which produces more power it also puts less side load on the pistons which is an important factor on a stroker engine.Longer rod =longer piston life.
 
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