At what point do the HPR HR3 cams stop producing power and what can effect where they top out?I was talking about this with another forum member and i have seen some dyno information that looks like maybe 7500-8000 would be about as high as they could build power.I have a Vortex CDI and some of its programs go as high as 9300.Can port work allow more flow and add just a bit to the point where the cam cuts off or is a set limit just that and it can not be effected by porting or any other factors.Can a very light piston as compared to the norm allow more RPM on the top end?Just trying to learn here.

 

Thats Randals and Erics Voodoo on any HPR cams, without specs you cant get any ideal of what the power band is. Did you post this on the ODP forum?? you should also ask Bigdaddy, real nice guy and he has put a few HPR cams in.

 

Hi Mike.

I am a little short on time this evening but i will say this. Port work will allow more rpm and/or higher rpm power peak if the porting is such that it limits or bottlenecks the cams potential. In other words if the cam is not able to make power at its potential peak rpm, port restriction could be the culprit.

Assuming your port work, carb, intake, exhaust and valves allow sufficient flow, changing cams is the best way to raise or lower your power band. Where a lot of people go backward is to have some bottleneck in these other areas that don't allow the higher end cams to really come on-line, then they just have bigger cams without any more output.

Are you staying with HR3's or are you upgrading to HR4's? [img]i/expressions/face-icon-small-smile.gif[/img]

Ron

 

Ron i will keep my HR3 cams.I need the great broad range of power they produce for the dune riding that i do.I was just curious what the maximum RPM level was that the HR3 would stop producing power in the best case.

 

I would post the question over on On-Dunes so Eric or Randall will see it.

Do you have your bike bike back yet?

 

Short course in cam timing:

For every 10 degrees in increased duration - Peak hp curve goes up 500 rpm
For every .050 extra rise in cam lift - Peak hp curve goes up 500 rpm
For every 10 per cent increase in displacement - Peak hp curve goes down 500 rpm

Size of carb, valves. porting and exhaust all add alittle, but mostly they affect the shape of the curve.

Example: This is on a stock 652cc motor.
Stock cam - .390 lift and 242 degrees duration
A1/A2 cam - .433 lift and 267 degrees duration
OMR Wrote:
Stock peaks at 6300 rpm.
A1 is .043 more lift - 500 rpm
A1 has 25 degrees more duration - 1200 rpm
Total - A1 1700, so peaks around 8000 rpm.
Type of exhaust may slightly raise or lower the point of peak hp a few hundred rpm.

Thus for this example, the A1/A2 cams to fit my original 7500 peak hp, they would work best in a 730 motor.

Hpr3s would work best in a 652cc. Wood 9, Pami Sport cams, and Web 109 all fit this combination, but they have not had as broad a curve as the HPR3s.

OMR

Big Daddy Wrote:
I've had them all, installed them all, raced them all, trailed them all.

Here is a brief account.

RWR 110's
RWR 109's
RWR 110 intake and stock exhaust
RWR 109 Intake and 110 exhaust
A1/A2
HPR 3
HPR 4
HPR 5

I think that's it..... who knows!

The 110's are pretty much worthless for anything else but trail riding. No run-out, and not much different than stock. I think the money would be better spent somewhere else.


The 109's are better, but lack on the top end and were peaky. After the peak, they tended to fall off the side of the mountain.

The combo's that I tried from RWR work well for torque but not real well for racing/run-out. Pretty good for cramped desert cams.

The A1/A2 were nice and responded well to many different situations. I would consider those to be very close to the HPR3's and somewhat similar on the the HPR4 low end characteristics. Not as much bottom end grunt as the 3's but somewhere between both.

The 4's have been a very nice cam and have proven themselve to be very good on racing, hills drags and straight-out hauling A$$. Mine to be specific
After all the cams that I've run, these are currently in my bike.

I think if I were to be running hills and doing a lot of line-ups (and I was a regular sized human being), I'd probably go with the 5's from HPR. And the lighter the bike and rider, the better the 5's will be. Less power to be made on the bottom, but they make power at the top end like no other. All that said, head work will make those cams work even better. To put 5's on a stock top end... I think it would be a waste. The head will not flow what the cams have the potential to do. HPR guys might have a different take.

Knowing what type of riding you are going to be concentrating on is the key to your cam choice.

If someone out there has another cam variation that they would like me to try.... send them on... I'll do anything once!

Those are teh cams that are out there based on the specs of the A1 and the Webs you get an ideal of what lift and duration do, call Web they know there too, but like I wrote those HPRs are there there voodoo , they dont post specs

 

And I hope they never do. Then people will get the research for free, make their own cams and HPR won't get paid for all the testing to find the great grinds.

Keep complaining about it though.. lol [img]i/expressions/face-icon-small-smile.gif[/img]

 

Ron my DS is still at CG .I am hoping to get it back this week because i have all of next week off and i am anxious to see how much more performance i will have now.I just posted this question at On-Dunes so maybe i will get some responses there.ERBEDS650 thanks for the information that you posted that is helpful.

 

I don't believe that at all Mr Nut, WEB has been posting specs for years, Woods has been posting, Hot Cams, Ect
The specs are tools for in designing the type of a motor is all, Don't read more than that into this please.
If someone was that desperate to have the voodoo HPR cam grinds, they would have bought them and copied the specs and would be re-selling them under there own brand, I don't think people have the time or the care with so many available great cams out there to choose from.
I'm happy with my grind from WEB also.
[img]i/expressions/face-icon-small-wink.gif[/img]

 

It doesn't make sense to me but it is a beautiful thing. It seems like the people that would try to cheat to get their research also don't believe the cams are better. It is a match made in heaven[img]i/expressions/face-icon-small-wink.gif[/img]............hard to deny KOTH and 3.96 at Planet Sand, lol.........People without an agenda can recognize a superior part when they see one[img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img]

Have fun with this one tonight, guys! [img]i/expressions/face-icon-small-smile.gif[/img]

Later[img]i/expressions/face-icon-small-happy.gif[/img] lol