TRX cylinder head crankcase 3D

[Quan-Time]

Yamaha used 5v on their motogp engines for MANY years, and only in the past few years have they reverted back to 4v. From what ive heard via talking to certain people, the main reason for 4v being "better" is 2 things:
1: harmonics (air moving thru the inlet tract, etc)
2: load and wear.

The cam has to push 3 valve springs open instead of only 2, less load is the main goal here. Also 2 larger valves can get a more "direct shot" with the air mixture.

It was discovered long ago that 5v is great for torque, but ruins top end from what i understand of it. Perfect for a twin with low down punch. Probably what makes the TRX so punchy off the bottom end.

[arrivisto]

Yamaha ... reverted back to 4v ... for 2 things: 1: harmonics & 2: load and wear.
The cam has to push 3 valve springs open instead of only 2, less load is the main goal here. Also 2 larger valves can get a more "direct shot" with the air mixture.

I cannot see why three inlet valves of a five-valver should create a greater load than the two inlet valves of a four-valver (given that the 3 valves are smaller and the lift is less); but perhaps that is the case.

I recently learned from a website on multi-valve cylinder heads ( http://www.autozine.org/technical_schoo ... to-5-valve ) that the Ferrari F355 arranged the outer intake valves to open 10° earlier than the center valve, to promote swirl. I wonder if that worked!

[Mincehead]

Really?
That`s very interesting and I can see their idea working well too.By the way the rotary valve thing is far from new.
Think 1907 and you`ll be about right :

http://www.dself.dsl.pipex.com/MUSEUM/P ... alveIC.htm

[redkiwi]

I cannot see why three inlet valves of a five-valver should create a greater load than the two inlet valves of a four-valver (given that the 3 valves are smaller and the lift is less); but perhaps that is the case.

Maybe it's to do with pushing against three valve springs instead of two?

[haggisbash]

I always wondered what a supercharged two stroke gasoline powered motor would be like using a similar design to what they use in diesel prime movers. Inlet ports for the incoming air with pressure charging by a Rootes blower or similar, direct fuel injection and four exhaust valves. If nothing else I bet it would make a lovely noise

[Quan-Time]

Maybe it's to do with pushing against three valve springs instead of two?

Thats exactly what its about.
5v does provide "more" air, to some extent, bit the benefits it provides is only minimal.. YES its there, but its negated by extra load on the engine / cam. Its why most high performance engines run 4v nower days. Yes the ferarri had 5, but they all went back to 4 eventually.

I still prefer the sound of a 5v, its note is deeper and sounds "stronger" up top.

[dandywarhol]

I always wondered what a supercharged two stroke gasoline powered motor would be like using a similar design to what they use in diesel prime movers. Inlet ports for the incoming air with pressure charging by a Rootes blower or similar, direct fuel injection and four exhaust valves. If nothing else I bet it would make a lovely noise

Y'mean like this?
http://www.youtube.com/watch?v=19eQBQep ... re=related

[punica78]

@DrSlumper: Like everyone else here I must compliment you on your modelling. I've recently started working with solidworks myself but I have to go a long way to get where you are now. Gradually I'm working my way throught the tutorials

Now I was wondering if you would share your Solidworks-files of the TRX-parts. Just for me to see how the where made up.