Pedro Jesus

Thanks Rody
I thought I could have more evolution move to a 9 ports.
But I'm not an engineer.

Off-Topic: I still have a RB Products S7 MSC 2006.

Roelof

So it is all about the inertia giving a better push when going to the seccond gear.
Or is it just that we are already low on weight with the clutch (lightened flywheel and aluminium clutchbell) that some rotating weight is needed again to get a more stable running engine?

ralphierace13

iTrader: (5)

so roelof
what about these motors with the longer stroke they say its for more torque if so how?

also wouldn't u want more torque when u have like a heavier car to pull like an rc truck or like when u stuck in the mud? with the power to weight ratio from todays motors y do we even need more torque ? I rather have the faster acceleration no?

ralphierace13

iTrader: (5)

rody how do u feel about 7 ports vs 9 where do u see the main difference ?

thanks

VS_Rody

We tried many times 9-ports in several configurations but no real advantage over the 7-port.

ralphierace13

iTrader: (5)

sorry forgot to ask does it use more fuel?

VS_Rody

Yes, correct for the inertia.
Since the clutches are getting lighter the inertia is less. Indeed a heavier flywheel could be a solution but it will take more time for the engine to spin down in rpm when you close the carburetor. For sure a little(I mean just a little) heavier flywheel would not hurt.
BTW this is what they start to do in Off-Road sometimes.

VS_Rody

I personally never found a better engine with 9-ports and also no advantage in fuelconsumption either.

Roelof

How further the crankpin is located from the center the more force you can create on the output w/o needing more combustion power. I also believe the larger movement of the piston will make the pump to suck up the mixture a little bit better.

More torque is not only about the stroke, it is more about the height and width of the exhaust port together with how much fuel you can burn. The longer the combustion stroke is before the exhaust opens the more power it has. The same is with the barrel of a gun.

Looking at F1, more power comes from more combustions per seccond, to reach that a short stroke engine is needed due the physical speed limitations of the pistons and lubrication.

As Picco has succes with their extra long stroke engines Novarossi did not do well with their xtra long stroke Keep-on and Mito models as their current topmodel is the normal long stroke 35WC.

Longer strokes do not have to be better als also with the amount of ports. It is more about timings, dimensions and materials to make a good engine.

ralphierace13

iTrader: (5)

So adding a set screw to one if the holes in each fly weight would be a good idea?

VS_Rody

No, I strongly not suggest this kind of solution, the flywheel has to be 1 piece only otherwise too dangerous. Also this solution can create unbalance with even more worse results.

BigC2007

iTrader: (9)

I was under the assumption that 9 ports produced a little more RPM's then a 7 port. Looking at Novarossi's legend 9ON and legend 7ON the 9 port is putting out 400 more RPM's which is not much but could come into play.

So if there is no real advantage why even make a 9 port motor ?

VS_Rody

As said before this is my personal experience.
I have not experienced better power with 9 port engines, the same goes for ceramic bearings.

It could be that a 9-port engine produces a little more rpm but this is not all you need to win races.

BigC2007

iTrader: (9)

Thanks and I myself have very little personal experience when it comes to the science of these motor's and you are very correct on rpm's and winning races.

Roelof

First of all, do not rely on the written specs, mostly they are made out of nothing. And because Novarossi is producing several engines from cheap up to expensive they would never alow a cheaper motor running faster (in real and on specs). As I have mentioned several times that I have made 5 port engines run as fast as many top range models by just changing some timings. Timings is making the engine, not the amount of ports.