I know that an engine's rpm is based upon the crank. So let's say for example I am cruising at 3000 rpm's. Now divide that number by 60 and you get 500 rpm per second. Does this mean that the crank rotates 500 times a second that seems impossible or am I looking at it wrong?

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

3000 / 60 = 50

50rev per sec

 

Oh ok, maybe if I was such an idiot, but still isn't 50 per second extremely fast.

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

Yes it is. Gives you a new found respect for your engine doesn't it? It did me the first time I figured that out.

Take 6000RPM for instance. That's 100 revolutions per second. 10 every tenth of a second, and 1 rev. per 100th of a second. That IS VERY fast. Now figure out the Indy cars. Then the cars in F1.

Remember this also. The cam turns at half what the crank does. Which would you rather be, the cam or the crank?

AJ

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92 RS w/t-tops 305 TBI Auto.
170K miles and don't burn a drop o'oil
-K&N Truck filter #1500 w, open ele.
air cleaner
-Dynomax 2 1/2" cat-back
-B&M TransPak
-Jet Stage2 Chip
-180* T-Stat w/ 185* Fan Switch
-JVC CD--Alpine speakers & 4ch. amp
Rockford Punch 100. 1 - MTX 12" sub

 

Yep, but its dead on.
You could look at this as a lesson on why destroked engines turn more rpm than stroked engines. less weight/less travel=more rpm. More weight/travel=more force per rev this equals high tq.
SSC
FIXORED it up a bit

[This message has been edited by SSC (edited September 03, 2001).]

 

Not sure where you're coming from on the "weight" thing & stroke, but longer stroke = higher piston speed. Higher piston speed = higher piston acceleration, which is where piston MASS comes into play. You have to accelerate the mass more with a longer stroke, and since we know F=MA, more force is consumed accelerating the pistons in a longer stroke engine.

Another thing to help scramble your brain cells in all this: The crank is rotating 100 times per second at 6000 RPM, meaning each piston is STOPPING 200 times per second (stops at the top and bottom of each stroke on each revolution).

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker 2055 headers, 3" Catco cat & 3" cat-back, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

I have always been amazed by the stresses also. I suppose that is the big appeal of rotary engines, the fact that the piston(or whatever the hell they call those things in rotary engines) does not "stop", ofcoarse they are a lot of forces still acting on it but aleast you are not transforming linear motion into circular motion. I saw a really cool desing for an aircraft engine once, instead of linear valve train it used a very cool and hard to explain set of rotating valves(rotated like a cam) which in a sense totally stoped all wasted power in compressing all those springs that many times a second. The crazy thing to me is that a thin film of oil protects constant metal on metal meshing for over 2000+ hours of total life with some serious forces constantly acting on all the metals moving parts.

[This message has been edited by UVA3rdGen (edited September 03, 2001).]

 

back from the dead


and yeah those stupid rotory things... geez never undstand them

they are mostly rotational but do still have some motion as that of a piston.... just not much

 

OMG, I was like I don't remember posting this topic.

 

how could you remember it


I mean it is only a drop in the 8300 post bucket you have

 

lol.