How do MotoGP 800s make 200+ HP?

[mambomonster]

I know a little, and I mean just a little, about motors. Having said that I wonder what the MotoGP teams are doing with 800cc normally aspirated engines to get over 200 HP. They are 4-cylinder (some V-4 and some inline) engines with fuel injection. No turbos or superchargers. How on earth do they get 200+ HP? 32 to 1 compression? I know it's all top secret whatever, but it seems to defy the laws of physics.

[drewvir]

computer management,near perfect cylinder heads,variable cam timing,high compression(probably 12-13:1)BTW the Honda rc212v is a v-5.

remember the bmw s1000r and the zx-10r are making 190 hp in a street bike. an 800 with a unlimited budget 200+ isn't that far off

[mambomonster]

Yeah I guess it's reasonable with unlimited budgets and perfect parts as you say. FYI, the current factory 800cc Honda is a V4. You're thinking about the 990cc V5 they ran before the displacement rules were changed to 800cc a few years back. Next year they're going to 1000cc and apparently one of the main concerns is fuel consumption. The 2012 bikes are being tested but I don't know if they have divulged configurations yet.

[jrj]

High RPM's. Like, astronomical.

[honda ng gingsa]

perfect castings, ported and polished to mirror surfaces, superlight internal components that only need to last one or two races then it all gets chucked and rebuilt.

[bls69]

The motors are super efficient.

[drewvir]

Originally Posted by jrj

High RPM's. Like, astronomical.

not really max rpm is 17500.2011 zx-10 redline is 14500

[Stutz]

I hear that the 800's are racing at 230-240 hp.

Back when they went to 990's a honda guy said they could
make 300 hp but did not have enough fuel to race at that level.

The intake system is very efficient. It can actually fill the
cylinder 120% of its displacement.

5 hp per ci in a n/a motor has been around for a while.
30 years ago honda had a 4 stroke racing at 4.25 hp per cu in.

[LDH]

Originally Posted by honda ng gingsa

perfect castings, ported and polished to mirror surfaces, superlight internal components that only need to last one or two races then it all gets chucked and rebuilt.

MotoGP does not allow that. They only get 6 motors to use the entire season and if they go over that allotment then they are penalized. That is why the riders immediately run to the bikes now if they crash and either stand them up to get the oil pump working again or hit the kill switch to save the motor.

You will also notice that they no longer do burn-outs after a win etc as they are conserving the longevity of the engine.

[nd4spdbh]

like stated... rpms... these motors are high strung, make nothing untill way high in the rpms... that and unlimited budget on design and build of the motors can produce a motor thats VERY good at what it does. just look at F1 race cars... 2.4L v8 .. 800+ hp.

[mambomonster]

Originally Posted by Stutz

The intake system is very efficient. It can actually fill the cylinder 120% of its displacement.

Seems impossible - details please.

[Bryce919er]

Not impossible. The incoming air fuel charge can continue to fill the cylinder even after the piston begins moving upward due to the inertia of the incoming air. The air rushing in can't stop instantly & the intake valve remains open a fair amount after BDC. Near BDC & TDC also keep in mind the piston is moving very slow so it has little to overcome. The valves overlap at TDC between exhaust & intake--both intake & exhauist valves are open at the same time so the inertia of the exhaust rushing from the cylinder can pull in fresh air/fuel charge right up through the intake tract even before the piston reaches TDC--again because the piston is moving very slow here. SInce the intake flow is "on" before the intake strroke has even begun, little is wasted getting the air stream up to speed when the exhaust valve finally closes.

In addition to all of this tune your exhaust & airbox correctly & you can "pulse" more air fuel charge in also. Tune your exhaust to create a negative pressure pulse that reaches the combustion chamber at some desireable RPM just as the valves overlap as mentioned above---free supercharging.

[bocomomark]

It's possible to acheive over 100% volumetric efficiency if you can get the charge of air coming through the intake to actually push the air infront of it into the cylinder. Same sort of effect can be used to help the exhaust scavenge. This is why the smaller diameter intakes on the 919 give it more torque down low. The velocities in our intakes are higher *at low rpm's* (the smaller intakes also choke the engine off at higher rpms)

I suspect the biggest reason the Moto GP bikes can make so much HP is that it does not need to be "streetable" The entire air and fuel delivery system is designed/tuned to give maximum HP and it's part of the riders job to keep the system happy (operate it in the appropriate RPM range)

[nd4spdbh]

Originally Posted by Bryce919er

Not impossible. The incoming air fuel charge can continue to fill the cylinder even after the piston begins moving upward due to the inertia of the incoming air. The air rushing in can't stop instantly & the intake valve remains open a fair amount after BDC. Near BDC & TDC also keep in mind the piston is moving very slow so it has little to overcome. The valves overlap at TDC between exhaust & intake--both intake & exhauist valves are open at the same time so the inertia of the exhaust rushing from the cylinder can pull in fresh air/fuel charge right up through the intake tract even before the piston reaches TDC--again because the piston is moving very slow here. SInce the intake flow is "on" before the intake strroke has even begun, little is wasted getting the air stream up to speed when the exhaust valve finally closes.

In addition to all of this tune your exhaust & airbox correctly & you can "pulse" more air fuel charge in also. Tune your exhaust to create a negative pressure pulse that reaches the combustion chamber at some desireable RPM just as the valves overlap as mentioned above---free supercharging.

yup.... exactly like an expansion chamber on a two stroke. theres so much science behind making a motor super efficient, and damn they have the money to do it.

[mambomonster]

Interesting. What cooling tricks are used?