PRC Forced Induction crankshaft mod

Flakey · Mar 16, 2009

Anyone else read about this in the new snowest mag? Sounds very interesting. Says they cut notches into the crank which forces the air/fuel mixture into the transfer ports in the engine. Says it'll gain 24% more horsepower! Wow!

It's in the Gear box section. Done by Parris Racing. I wonder how well this actually works and if it does will they start doing this from factory? Seems like a free 30-40hp on a big bore 2-stroke.

Snoclo · Mar 16, 2009

Not really a new idea, has been heavily bashed in another in another thread.
Can help low end power, probably over emphasized in horsepower developed. Time will tell if this a real development on an old idea.

johnsodo · Mar 16, 2009

i had it dune twice. the top end was a wash, mid OMG lots of power

Reeb · Mar 17, 2009

24% on the bottom-midrange power. On their best day on the strongest motor.

nmmiles · Mar 17, 2009

so any down side to doing this? More power low and mid, but what about top end? Does it just not effect top end, or does it bring it down?
Thanks,
Nolan

Flakey · Mar 17, 2009

I'd say the down side is $350 per cylinder. Thats $700 on a twin. Not to mention you gotta tear your entire engine down to do it. But I don't see why the factory wouldn't make use of this technology.

Still I find this to be very interesting. Pretty cool when you can figure out how to squeez out extra power out of a motor just by cutting some little notches in the crank.

mustang1 · Mar 17, 2009

did this on my 809 ,a little faster throttle responce due to height comming off the crank,but no improvment on overall .A lot of money for not much.Hear tell the improvement was at 10,000rpm and up.

GSXR1000 · Mar 23, 2009

you used the PRC mod? I am the designer of the mod in question,prior mods of this type were effective to a point but the designer didn't take it to the next step. I spent 5 years developing the angles and pitch of the veins being cut to optimize the charge being directed toward the transfer port and it does produce power increases across the entire RPM range,not just above 10,000. I would like the opportunity to see what my design can produce in your 809?

GSXR1000 · Mar 23, 2009

REEB that percentage was on a perfect day and on our best motor but the info was wrong it was an honest 17% not 24%. I am seeing an average of 15 to 17 percent increase.

spring snow hero · Mar 23, 2009

we tried it back in 1981....we had better luck with a pipe and good intake

POLARIS600cc · Mar 23, 2009

GSXR1000 said:
I spent 5 years developing the angles and pitch of the veins being cut to optimize the charge being directed toward the transfer port

Do you cut the veins the same on all crankshafts then? Or do you have a different design depending on the motor.

GSXR1000 · Mar 23, 2009

I have found that 1 set of geometry works the best for all models,I think that if somebody altered the shape of the upper cases i might have to change the angle slightly.

JROD · Mar 23, 2009

Steve, do you have any dyno sheets or statistical info on this mod? Videos? Customer reports? Just curious.

GSXR1000 · Mar 23, 2009

i have a website but have no venders membership here yet,it might get me in truoble

GSXR1000 · Mar 23, 2009

i have no venders membership yet so i don't think i can giveout the website on here.

GSXR1000 · Mar 23, 2009

you can find all the info in the march issue of SnoWest under the GearBox section

GSXR1000 · Mar 23, 2009

we have dyno charts on the dirtbikes and will have the sled dyno's soon.

nmmiles · Mar 23, 2009

How does this effect the strength of the crank? I have a 900 rmk soon to be going to a 975 and, as widely known, the 900's can have very weak cranks. Do you think that doing this would effect the longevity of the crank in any way? What is the turn around on getting this done? What are the downsides (other than cost)? At what elevation are you seeing the 17% increase?

Thanks, Nolan

GSXR1000 · Mar 23, 2009

the cuts in the weights is very slight and are spaced in a way that they are not cut in the area or the rod,The veins atomize the oil so well they mist the pistons/rods ans crank with a constant coat of oil,i have had riders report that they are seeing less harmonic vibration and less heatsoak.We have also seen longer engine life and slightly improved fuel economy,turnaround time with shipping is about 10 days.Our dyno tests were at 4800ft in Bozeman Montana. We also true the cranks free of charge before shipping them back.

GSXR1000 · Mar 23, 2009

not cut in the area of the rod. sorry fat fingers.

PRC Forced Induction crankshaft mod

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