Intake Ports On 16V 1100?

[mark m]

Hi All,

Does someone out there happen to have a 16V 1100 head with carbs off? I would like to know what the ID of the intake ports are where the head meets the intake manifolds (basically the ID of the hole in the aluminum). I would do it myself, but my bike is together and under a pile of junk after a house move, which is a bit inconvenient... :?

I'm just doing a bit of tinkering and need this for some flow area calcs.


Thanks,
Mark

[RacingJake]

I just check my 82 1100 16V head and at Horizontal I get 1.285 but at Vertical I was getting 1.300. Must be alittle egg shaped

This was right at the tip of the intake if I went in farther the hole is getting smaller.

[mark m]

I just check my 82 1100 16V head and at Horizontal I get 1.285 but at Vertical I was getting 1.300. Must be alittle egg shaped

This was right at the tip of the intake if I went in farther the hole is getting smaller.

Thanks for the info, Jake. 1.300" = 33mm, so that is pretty small by today's standards. Even for high velocity/impulse tuning uses. I have been doing some reading on current MotoGP engine design and simulation and they use pretty small ports given their output. By the parameters given in some tech papers, the intake area at the manifold should be 0.95 x valve area. For 27.5mm valves, this gives me a inlet diameter of 38mm, so the GS is quite a lot smaller than that. There isn't any room to change that, either, is there? Not 5mm worth of diameter anyways...


Mark

[mark m]

I just check my 82 1100 16V head and at Horizontal I get 1.285 but at Vertical I was getting 1.300. Must be alittle egg shaped

This was right at the tip of the intake if I went in farther the hole is getting smaller.

Thanks for the info, Jake. 1.300" = 33mm, so that is pretty small by today's standards. Even for high velocity/impulse tuning uses. I have been doing some reading on current MotoGP engine design and simulation and they use pretty small ports given their output. By the parameters given in some tech papers, the intake area at the manifold should be 0.95 x valve area. For 27.5mm valves, this gives me an inlet diameter of 38mm, so the GS is quite a lot smaller than that. There isn't any room to change that, either, is there? Not 5mm worth of diameter anyways...


Mark

[outofcontrol]

how do you do this math?

27.5mm diameter X 3.14 (PI) = 86.35sqmm
86.35sqmm x 2 (2 IN valves) = 172.7sqmm
172.7sqmm x .95 (motoGP ratio) = 164.07
164.07 / 3.14 = 52.25mm inlet diameter.

what? why am i so bad at this?

[pano]

27.5mm valve dia = 13.75 valve rad
valve area = r^2(pi) = 593.957
Then 2 valves = 1187.9
95% of the area is .95 (1187.9) = 1128.5

1128.5/pi = r^2 = 359.2
sq rt of 359.2 = 18.95 = r
dia = 2r = 38mm

[RacingJake]

I've seen some intake runners that were hogged out and looked to be paper thin too. I guess it all depends on what your trying to do and at what rpm too.

But if I owned a flow bench I'd be given it a good workout.

[outofcontrol]

Oh yea.
2r(pi) = circumference
r^2(pi) = area

Thanks Pano, I needed a little geometry review.

Don't those MotoGP motors spend all their time between 11-17k RPM?
Does that translate to a 30yr old hunk of iron with a 9k redline?
I'd love to know more about MotoGP bikes!

-Kevin

[spdjunkie]

Here's a really good idea if you're interested, markm. Check out http://www.bertaut.com/gsengine.html



Here's his explaination:

Pro Race Only Epoxy Filled Intake Port. Port retains the Pro "D" shape and is made smaller, flow remains near the same (over 130CFM at 10 inches of water) but the velocity goes to the moon! You then adjust camshaft timing to take advantage of this ram tuning by spreading the lobe centers apart more. 113-116 degrees! These engines get over 100% volumetric efficiency. The flat port floor gives the port short side radius more area and it thinks it is as long as the long side. Flow and velocity go straight up.

[mark m]

Here's a really good idea if you're interested, markm. Check out http://www.bertaut.com/gsengine.html

Thanks, I've seen his site and his work is art. I do understand the principles behind the high velocity idea. That was why I commented on the MotoGP ports, because they are quite small compared to current sportbike ports. An 05 GSXR1000 has 29mm intake valves, which corresponds to a 40mm inlet diameter, but they are using 44mm throttle bodies (I think it was) and a similar sized inlet port. This means that the inlet has about 20% too much area according to the MotoGP numbers. This for a 12,000rpm streetbike versus a 17,000rpm racebike, both 1000cc displacements. Makes you wonder why the OEM's don't use the MotoGP ports on their top end sportbikes... It's not like it costs any more to cast a good port shape than a bad one, either way there has to be a hole there.

My numbers come from two tech papers by Prof. Gordon Blair, who is a top level engine design consultant. He writes a lot about engine simulation software and race engine design (search on Blair on the SAE website and you will find a ton of stuff). The one paper details simulation work done on big-bang firing orders and their effect on output. That engine is an in-line 4 cylinder and uses 33.5mm intake valves and has an inlet port diameter of 43.5mm (note the GSXR1000 has 29mm valves and the same size inlet). If you work it out, that is an area ratio of only 0.84 for the inlet area to valve area. All for an engine that made 230+hp. This also correlates to Bob Bertaut's work (and others, especially in dragracing) and the Motoman site and his "revolutionary" high-velocity porting methods. But it does make the sportbikes look like they have went down the wrong path or at least a very inefficient one. Imagine a GSXR1000 or ZX-10 with GOOD porting!

Mark

[mark m]

An 05 GSXR1000 has 29mm intake valves, which corresponds to a 40mm inlet diameter, but they are using 44mm throttle bodies (I think it was) and a similar sized inlet port.

My mistake, the 05 1000 uses 30mm intake valves (the 03-04 1000 had 29's), which correspond to a 41.4mm inlet diameter and the throttle bodies are 52mm 8O , not the 44mm I thought. So they are grossly over the MotoGP design specs, with likely 40%+ more inlet area than recommended by a race engine design authority. That REALLY makes me wonder what a new liter bike would do with GP spec porting... And makes Motoman's ideas seem a lot less radical.

Now I feel like going out and modifying one just to see how it all works.


Mark

[outofcontrol]

Awesome stuff. -K

[Mysuzyq]

Good to see you still have the GS, Mark. Thought I saw it up for sale, not too long ago....


Tony.

[Dink]

An 05 GSXR1000 has 29mm intake valves, which corresponds to a 40mm inlet diameter, but they are using 44mm throttle bodies (I think it was) and a similar sized inlet port.

My mistake, the 05 1000 uses 30mm intake valves (the 03-04 1000 had 29's), which correspond to a 41.4mm inlet diameter and the throttle bodies are 52mm 8O , not the 44mm I thought. So they are grossly over the MotoGP design specs, with likely 40%+ more inlet area than recommended by a race engine design authority. That REALLY makes me wonder what a new liter bike would do with GP spec porting... And makes Motoman's ideas seem a lot less radical.

Now I feel like going out and modifying one just to see how it all works.


Mark

Mark please note you said throttle bodies!! NOT the port size, MotoGP bikes are running 65mm and larger throttle bodies.
Dink

[mark m]

Mark please note you said throttle bodies!! NOT the port size, MotoGP bikes are running 65mm and larger throttle bodies.

That is correct, Dink. The GSXR throttle bodies are indeed 44mm at the butterfly as I stated in the first post. There was some confusion in specs for that info. The 44mm is still 15% bigger than the MotoGP guideline, regardless. Don't forget that the areas are really what should match and the valve seat ID will actually be about 2mm less than the valve OD. Using a 28mm ID gives us a 39mm port diameter...

Good to see you still have the GS, Mark. Thought I saw it up for sale, not too long ago....

It is still for sale, but I have been through a house move, Christmas and a ton of consulting work in the mean time, so I haven't been working too hard at it. If anybody is interested, PM me for details. It is also listed in the For Sale forum, if you search on "Calgary" it should come up.


Mark