http://www.nrhsperformance.com/pictures/raybarrioshp.gif

http://www.nrhsperformance.com/pictures/raybarriostq.gif


1996 XL883 Hugger

Red is as delivered:
SE exhaust
SE air cleaner
otherwise stock

Blue is after:
NRHS 1212 conversion
Stock XB heads
SE .536 cams
SE 6800rpm ignition module

Bit of a reversion from the pipes down low, otherwise a good running little bike. Customer is happy.

Nice numbers for stock heads Aaron.
What compression ratio?

That's some good HP from stock heads!!! Would have thought he'd have a bit more TQ with those Cams!!! I'm running stock 883 heads and .497 cams and I'm getting 71.3 TQ and 68.2 HP!! Might have to really look into the stock XB heads!! Anybody got a Set Cheap!!!! :D

Might have to really look into the stock XB heads!! Anybody got a Set Cheap!!!! :D
Yeah Mike,
I got some REALLY cheap ones. $400 off :D :D

Yeah Mike,
I got some REALLY cheap ones. $400 off :D :D

Screwed up on posting this hit edit instead of Quote!!! :frownthre

Anyway!! Those Heads were'nt Stock!!! :D

I'm looking for real cheap!!!! :laugh

BTW, they're at $710.00 right now with 19 hour to go!!! Should get interesting!!!! :D

BTW, they're at $710.00 right now with 19 hour to go!!! Should get interesting!!!! :D
I don't get it

Maybe they're not your old heads on ebay!!

That's them Mike. Thanks for the heads up.
If they go for that price i'll be topping myself

Cameron, I'm sure before it's over they'll go for at least $1200.00!!! :D

CR is 10.5:1.

The exhaust is really holding this motor back. I think it could get upper 80's with a better system.

Still, it's a good demonstration of those heads right out of the box. They perform comparably to a ported set of the 883 heads, and are competitive on cost.

I did have to put short pushrods in this motor, the stockers were too long. Total gasket thicknesses are .040 (head & base), that's what it took to get low .030's squish.

Torque is not a performance metric, y'know ;) Only the power figure says anything about the performance.

What kind of squish in the XB heads in this run? Flat or 15 degree?

Flat squish bands, the pistons have a very small dome to get 10.5:1

Aaron,

What do you mean by this "Torque is not a performance metric, y'know Only the power figure says anything about the performance."

Wouldn't high torque be an important metric for a street motor? Wouldn't there be an advantage building a street motor with an emphasis on low end torque over peak hp numbers?

My bike runs nice but the previous owner had worked to get alot of torque over peak power. It makes only 76hp but it has 91 ft-lbs of torque.

Chuck

Torque is how hard you're pushing. But by itself, it says nothing about how fast you're pushing.

Well, it's very easy to push hard if you don't have to push fast. Just gear it deeper. For example, I can take a battery powered handheld drill motor and make a million ft-lbs of torque with it, if I gear it deep enough. It'd sure be turning awfully slow though. It's not going to win any races.

So how hard you're pushing, without also considering how fast you're pushing, is totally meaningless for evaluating performance. How fast you're moving is a key part of performance.

Horsepower is literally torque times rpm, or in other words, the combination hard you're pushing (torque) and how fast you're pushing (rpm). So it fully describes performance. But torque by itself does not.

What the horsepower number doesn't tell you is the makeup of torque and rpm behind it. It might be really high torque with low rpm or really low torque with high rpm. But for performance, it doesn't really matter. No matter what mixture of torque and rpm we have, we can readily change it into the mixture we want at the rear wheel with our gearing.

So for example, a motor may have 80 ft-lbs at 5000 rpm (76hp), and we apply a total of 10:1 gear reduction through the primary/transmission/final drive, putting 800 ft-lbs at 500 rpm (still 76hp, just a different makeup of torque and rpm) to the rear wheel. Another motor may have 40 ft-lbs at 10,000 rpm (76hp) and 20:1 gear reduction through it's primary/transmission/final drive, and it'll also put 800 ft-lbs at 500rpm (76hp) to the rear wheel. In terms of accelerating the bike, it matters not, these two are the same.

The motor with the most horsepower will always put more torque to the rear wheel when geared for a given rear wheel speed. So horsepower is the meaningful number for evaluating performance. Torque is just a component of horsepower, one that's meaningless without also considering the other component, which is rpm.

When most folks talk about a motor with a lot of "torque", really what they're saying is they want a lot of power at low rpm. But it's not really an accurate way to say it. It's quite possible to build a motor with a lot of torque but all coming in at high rpm. For example:

http://www.nrhsperformance.com/images/drdannorlin82.gif

This bike makes a bunch of torque. But not until it gets to high rpm. It really runs kinda crappy at low rpm. We set it up that way intentionally, did several things to move that torque peak to the right of the chart, because horsepower is the meaningful number and horsepower is torque x rpm, i.e. how much of BOTH you can make at the same time. But trust me, as much torque as this bike makes, you do not want this kind of motor on the street.

Anyway, we know what people mean when they say they want a high torque motor. They're just saying it wrong. And we know how to do it, not a problem. Torque is cylinder pressure, and it comes from filling the cylinder. So you simply target the cylinder fill for a different rpm. Port and valve sizes, cam timing, and exhaust augmentation are the key components of that; all can be tailored for a given rpm. The happiest motors are those that get all of them on the same page.

In a nutshell, torque gets you off the line quicker, horsepower gives you speed.

Find the mix of the two you want for your desired result, off the line hard, top speed, or anywhere in between. It all comes with how much TQ/HP you have and where it sits on your powerband.

Another way to look at it are towing vehicles VS. purpose built race cars (IRL cars). Example: My 1 Ton Dodge Dually pulled large amounts of weight with ease because of the large amount of torque(250+) the engine had, but wouldn't go very fast because it's horsepower(140 or so) just wasn't there. IRL cars can't pull jack squat because they basically have no TQ (250 or so) compared to their HP (around 800) yet can zip around at 200 MPH all day long.

Deadhorse, the motor with the most horsepower always puts the most torque to the rear wheels, i.e. where it matters, when geared for the same ground speed. Always. It matters not what the torque & rpm makeup that the motor provides, if it has more horsepower, it puts more torque to the rear wheel(s) at a given speed.