Originally Posted by
CarCrazy
I'm not going to argue with your advise, as I've only been modifying my own motors for about 3 years. I'm sure you know whats up more than I. However I'd like to run something by you guys on the porting.
Its my understanding that when a sleeve is ported, tapered, smoothed and such.. that this increases flow at higher RMP. Also when the fuel charge is thrown from the crank upwards onto the sleeve, that their is a certain amount deflection off the bottom of an un-tapered sleeve. That being said, doesn't the deflection cause an inefficiency? If that deflection of fuel-air was reduced and the ports had a smooth clear path up into the sleeve, wouldn't that increase efficiency?! If you remove the inefficiency's of the motor however minor, you should be able to slightly lean the motor and keep the same performance, thus increasing fuel mileage. Fuel efficiency is the only reason to port a motor in my opinion, as power really isn't increased much at all. Is that an urban legend? Also I get 9-10 minute runs on my RB's at 230 after my mods. Before the mods its 8-9min I've proven this over and over and over again.
One more thing... how does a lighter crank = less power? In every kind of racing, drag racing through motocross, kart, F1, Nascar...ect etc... a lighter crank increases throttle response and efficiency, as it takes less fuel to turn a lighter crank. I do know from my own experience that too light of a crank can effect how an engine idles. Not enough mass to keep it turning... Timing, I rarely mess with except on the WS73 as it needs a bit of a closing side increase because the duration is a bit off on those motors and graet power increases can be made.
I don't know... could all this be BS... maybe
Anyways, this GRP will probably be done as do my others, and I guarantee I'll smoke the stock guys out their.
Peace...
Same thing here. I know from actual engine building, the weight of crank changes how fast it revs or makes power, but almost does nothing on the dyno as far as HP rating. Balancing is another aspect of the engine as it will climb RPM faster since it spends less effort wasted in drag or centrifical force to climb the power band. What you will see on a dyno is the power band smooth out compared to a jagged power band from a not so balanced engine that has certain orders of vibrations aligning at certain RPM's. Plus the throttle response feels more accurate when it balanced better. Add better fuel economy also. Right now, I know driver's who are after fuel economy, smooth power and accuracy. The engines are making enough power now, we just need to make use of it efficiently. Then again, we mostly run blue groove, dusty or loamy.