Yesterday I attended the North American press introduction for Yamaha's 2006 R6 for my work (http://www.motorcycledaily.com).

Basically what happens at these intros is that they give a big powerpoint presentation about how awesome the new bike is and all the changes they made, then you get to the good part where they let you ride it on a track (Willow Springs in this case).

Usually I have to struggle to stay awake during these presentations, but I saw some interesting stuff in this one that I wanted to share with my everyone here. I hope you guys find this stuff as interesting as I did.

Remember that this is a production engine and it runs on 91 octane. 600cc displacement. Makes about 112 dynojet horsepower at the rear wheel.

(Note that when they refer to something as lighter, it is in comparison to the same part on the 2005 model which made about 104whp)

spec sheet (I highlighted the parts I thought were important)

 

BTW Yamaha now admits that the '06 R6 is rev limited at 16,000rpm, not 17,500rpm as they previously claimed.

Anyway not all of these ideas apply to car engines, bike engines have different design parameters since they make barely any torque/low end power compared to a car engine. The low mass of a bike doesn't require nearly as much torque to get it moving.

Still the valve angles and some of the other stuff is pretty interesting....

 

Do you know why the have a narrow valve angle? Started in 1968.
and with that bore/ stroke a B-series LS would need a 140mm bore.

 

How do they make it run on 91 octane at 12.8:1cr? That's amazing!

 

that crank with rods is so funny looking because of the short stroke.

i have a 04 R6 and if you have someone on your back, the lack of torque is a bitch around town. its easy to stay up in the rpms if you need to, but you can easily get caught with no low end torque trying to move 650 lbs.

 

I believe higher compression is capable due to the lesser weight of a sport bike. The lower weight creates less of a load on the engine thus allowing you to run higher compression...
Someone correct me if im wrong.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PyroProblem &raquo;</TD></TR><TR><TD CLASS="quote">I believe higher compression is capable due to the lesser weight of a sport bike. The lower weight creates less of a load on the engine thus allowing you to run higher compression...
Someone correct me if im wrong.</TD></TR></TABLE>

never thought of that, but it makes a lot of sense.

 

you can tell from looking at the pistons that the whole chamber is really flat...

Don I would love it if you could tell us why they have the narrow valve angle? I could offer a few guesses but I don't KNOW...

 

i would say that the high r/s is much more acceptable to a lower octane compared to a short r/s, and you'll increase more dynamic compression with the longer TDC dwell time by timing the valves to come very close to the valve face and for a longer duration.

that overlap is alot i would say compared a car engine but relative to it's rpm range. but of course a large percentage of the intake cylinder filling is due to exhaust scavenging. please correct me if i fucked up anywhere...

 

mee tooo don? randy? GOD?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by revolt_allmotor &raquo;</TD></TR><TR><TD CLASS="quote">BTW Yamaha now admits that the '06 R6 is rev limited at 16,000rpm, not 17,500rpm as they previously claimed.</TD></TR></TABLE>

Minor correction, the rev limiter is actually 16,200 The tach was produced to read at 17,500 when in actuality the computer is rev limited to 16,200. And now Yamaha is having to remove all those claims of the high red line

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mekanism &raquo;</TD></TR><TR><TD CLASS="quote">How do they make it run on 91 octane at 12.8:1cr? That's amazing!</TD></TR></TABLE>

Pull alot of timing is my guess

 

http://www.motorcycledaily.com...k.htm

 

Just realized the original poster works for motorcycledaily.com

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PyroProblem &raquo;</TD></TR><TR><TD CLASS="quote">I believe higher compression is capable due to the lesser weight of a sport bike. The lower weight creates less of a load on the engine thus allowing you to run higher compression...
Someone correct me if im wrong.</TD></TR></TABLE>

Actually, the answer to that question is answered by their literature which actually gives the valve timing points. In this case the intake closes 71 degrees ABDC.

This is cut from a previous post I made:

The higher the compression ratio you run the more duration you will need to run on the cam. This is because the static compression ratio is not the one the engine sees. There are three types of compression ratios. Static, effective, and dynamic.

Static compression ratio: chamber volume + swept volume / chamber volume.

Effective compression ratio (this is the important one): The compression ratio that is measure begining at the point when the intake valve closes. If you think about it you can't begin building compression in the cylinder until you close the intake valve, otherwise it will just blow back into the intake. On a modern 4-valve engine running 91-93 AKI (octane) fuel the effective compression ratio can be somewhere around 8 to 8.5:1. Two valve heads can run about 7.5-8:1.

Dynamic compression ratio: Effective compression ratio x volumetric efficiency. There is 1 point in the rpm band (<U>peak torque</U>) where volumetric efficiency is highest. At lower rpm the incoming air/fuel charge does not have enough inertia to overcome the force of the piston coming back up on the compression stroke and some is forced back out the intake valve, but as rpm builds and the velocity of the A/F charge increases it is able to resist this tendancy and can almost fill the cylinder to 100% capacity. On good engines it can exceed 100% VE.


The fact that this engines cam has so much duration (298 degrees on the intake, ) is why it can rev so high and run on 93 AKI fuel.

I didn't do the math so I am not sure exactly what it's effective compression ratio is on this bike, but it should be in the range I mentioned.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ChaseIntegra &raquo;</TD></TR><TR><TD CLASS="quote">Minor correction, the rev limiter is actually 16,200 The tach was produced to read at 17,500 when in actuality the computer is rev limited to 16,200. And now Yamaha is having to remove all those claims of the high red line</TD></TR></TABLE>

lol well maybe you should call Yamaha then, because according to the Vice President of Yamaha North America it is 16k rpm

http://www.motorcycledaily.com...e.htm

and

http://www.motorcycledaily.com...k.htm

both written by me (Alex Edge)

seeing as how we were the first media outlet in the world to report on this, I think I know what's going on

funny story, today the marketing rep from American Honda called and said that some of the execs in Japan read that article and were impressed....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Scott_Tucker &raquo;</TD></TR><TR><TD CLASS="quote">Actually, the answer to that question is answered by their literature which actually gives the valve timing points. In this case the intake closes 71 degrees ABDC.
</TD></TR></TABLE>

very informative post thank you!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NJIN BUILDR &raquo;</TD></TR><TR><TD CLASS="quote">Just realized the original poster works for motorcycledaily.com</TD></TR></TABLE>

yeah thats my day job, it pays for the race car lol not really

by the way your motors look SICK I looked at your site a while ago. would love to ride a 160hp chopper

 

Thank you.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Scott_Tucker &raquo;</TD></TR><TR><TD CLASS="quote">

The fact that this engines cam has so much duration (298 degrees on the intake, ) is why it can rev so high and run on 93 AKI fuel.

</TD></TR></TABLE>

that and the small bores, the combustion event has less distance to go in a smaller chamber. thus a faster combustion event is allowed at higher rpms were the time between strokes gets real small.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JCushing &raquo;</TD></TR><TR><TD CLASS="quote">that and the small bores, the combustion event has less distance to go in a smaller chamber. thus a faster combustion event is allowed at higher rpms were the time between strokes gets real small.</TD></TR></TABLE>

yeah that is also a factor...

you should read this article ('An Analysis of MotoGP Engine Configurations'):
http://www.motorcycledaily.com...s.htm

Basically one of the things I talked about was that it's easier to avoid detonation with smaller-bore engines.....

 

I would think that modern sportbikes can have such high compression ratios on pump gas has NOTHING to do with pulling timing--if you are going to pull timing why have such high compression on a production bike to begin with? I think the low weight of the bike helps, but also since the cylinder is so (comparitively) small --there doesn't need to be as much advance to begin with since the spark doesn't have to travel very far. The very shallow valve-angle seems optimal because 1) you do not need a large dome with a shallow valve angle which will require less timing all things considered 2) there is less area in the cylinder head part of the cc-so less heat is lost to the head and more can be transferred to the piston improving power. Also, because of packaging a shallower included angle will give a straighter shot into the head on a small sportbike. What I find interesting is the use of aluminum retainers with not durability problems. How would those retainers carry over to automobiles?

 

Narrow valve angle, lets see, think valve to valve promlems in a B motor with big valves and bib cam. Think small chamber and flat top piston with high compression. Think straighter intake port, like the one in the drawing on the engine above.

 

Right--I forgot about valve to valve interference which would be pretty much eliminated with a shallow angle like in the diagrams above. I hope I am using the term "shallow" and "narrow" correctly--I am referring to a CC like on the bike mentioned above--as opposed to the wide angle on an old 426 street hemi.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote">Narrow valve angle, lets see, think valve to valve promlems in a B motor with big valves and bib cam. Think small chamber and flat top piston with high compression. Think straighter intake port, like the one in the drawing on the engine above.</TD></TR></TABLE>

yeah that makes sense, I thought about the flat top/high compression thing but I didn't think about valve to valve - which would be a big problem with so much duration.

With a flatter piston wouldn't it transfer the force of combustion more efficiently since the pressure would be concentrated more in the center of the piston? That seems like a big benefit of the narrow included angle/'flatter' chamber?

also no one has mentioned the secondary "shower" style injectors. I have to find the chart they gave me which shows the relationship between the injectors - as in how much each injector is used at x rpm. It's interesting because I would have thought that the secondaries would be used almost exclusively at high rpm, but instead what they're doing is the secondaries are most active (and the primaries are least active) at the torque peak, and then the primaries start to take back over as RPM rises past the torque peak.....

I will try to post the chart today....