Crankcase compression??

[powerabout]

I dont think there are any engines like v outboards so they come with unique issues and we also need low down torque.

[H2OPERF]

The CR cranks have hollow tin cans on the outside theres only like .050 gap crank cheek to the cases. Makes them a bitch to rebuild some say u cant but if u cut it apart thru the rod with good band saw with a bi metal blade u can then press the old pin pieces out an rebuild it. Problem with V outboards is cylinder spacing port runners are on top of each other why a 2.5 cant get much bigger before it doesnt pay off.

[Chaz]

Map is in front of the reeds... like chaz said u dont get something for nuthin..

Please don't apply logic before at least the 5th or 6th page ...

Your comment about s CR500 was good.
Look at a good, tight 2 stroke, then look at our junk ��

You either Mr. Gator, whatcha tryin to do .. kill off some great fictional readin ..

Chaz... can't have "
5 psi of vacuum", vacuum is negative pressure.

Euro, in some ways your right .. but you said more of a "double negative" ie. Jumbo-Shrimp .. by saying "negative pressure"
Smokey Unick said .. there is no such &^%%^&(&*$ thing here on earth. Ya gotta make it yourself. Love that guy ..
I won't use PSI to speak of the phenomena when determining the pressure differential between the evacuated volume and the surrounding atmosphere

.

If you would like we can instead speak of Torr , unit's in Pascals inch's of Mercury or the one I'm more use to ... inchs of water. However it will be up to you to convert each to PSI, so it's an easier term to understand.

No positive pressure is generated. Map sensor always reads less then 14.7psi.

18 ... I'm afraid ole H2O got ya there, your on the wrong side of the reeds.
I gotz a question, ifin we always workin in a depression of atmosphere, why do they sell 3 and 4 bar MAP sensors .. ???

if any is created it’s only from piston tdc to intake open.

Best I remember, the carb mouth or mouth of the throttle body is considered the "intake opening" . That being the case, how far down from TDC will the piston have to move to open the reeds ... ???

their is a fan effect and centrifugal mass acceleration.

If you don't own a Spintron machine ... all I can say is, Bless yur heart .. !!!!

I dont think there are any engines like v outboards so they come with unique issues and we also need low down torque.

Power ol chap, cut the bloody pipe off a third meter from the spigot flange, an tell me of the torque curve then ... mate

Chaz = thinkin, piston goes up crankcase pressure goes down, fills the little square block with fuel. Piston goes down, push's the fuel out thru the hose. A smart feller would measure that and say , yup, thats all she's got ...

PS .. (sorry I have toooo) Ifin yur real good, you'll fill the case to 110% capacity ...

[H2OPERF]

An engineer once told me pumps don't suck anything, magnetism and gravity are the only real sucking forces everything else moves from high pressure to low... 110% needn some pipes for that.

[Chaz]

An engineer once told me pumps don't suck anything, magnetism and gravity are the only real sucking forces everything else moves from high pressure to low... 110% needn some pipes for that.

We're only two pages deep ...

[H2OPERF]

good shot of the 500 case

[Instigator]

Wow.
Youd have to press that crank back together straight for it to even fit in there!

I could take a nap in the dead space in an V-6 OMC looper.

good shot of the 500 case

[powerabout]

the big difference is the intake charge doesnt have to cross the crankshaft centerline

[H2OPERF]

Wow.
Youd have to press that crank back together straight for it to even fit in there!

I could take a nap in the dead space in an V-6 OMC looper.

They are hard cranks to mess with, those cans on the ouside are hollow n dent easily so you cant tru it by pressing on the outside. Power you talkin about the mass excelerator?

[powerabout]

Just commenting on a single cyl bike crankcase versus an outboard and why there is a difference

[H2OPERF]

Are you talking about the distance reeds to runner? Air can move pretty fast thru a motor...Think it still mostly comes down to crankcase or primary CR and the result on port velocity. kick one of the cr motors over without the head and the ports will blow your hat off lol.

[powerabout]

Are you talking about the distance reeds to runner? Air can move pretty fast thru a motor...Think it still mostly comes down to crankcase or primary CR and the result on port velocity. kick one of the cr motors over without the head and the ports will blow your hat off lol.

The air inlet is on the piston side of the crank on a bike so the volume change is piston side of the crank only.
Outboard has the air inlet opposite side of crank from piston so all air has to travel across the crank so the reeds are already causing a poor crankcase shape.

[Motv18]

We installed one in the crankcase(should have mentioned that)

I guess it’s up to what you call boost. For me it’s anything over 14.7psi or 30” water.

as for the other statement it’s pretty simple. Compression ratio would be volume of crankcase reeds closed at piston tdc. And volume of crankcase with piston at the point of intake port open. It might take rocket since to figure the volumes. The principal is simple enough.

the pulse pump works without boost. Because 20-10” is a pressure change

if you as is the pressure higher in the crankcase while the piston moves down. The answer is yes. It’s just not boost.

oh and college science just says things backwards. Higher pressure flowing to low is low sucking just pompous stuffed shirt way of saying it.

[bullet20vee]

When I grow up, I want to be half as smart as Chaz on this stuff.

[powerabout]

Read the other thread, nosub knows his stuff...