High RPM?

[cdx2k1]

Hey guys.I figured what better a place to ask this..

How is it that certain cars have such a high redline (like the hondas of 8k+), while others have a lower one (like 7k on some other cars)..what's the ingredients to a high revving engine?

[5onDfloor]

VTEC..lol!

[spliffington]

vtec gotta love it..
gives valves more lift and duration...

[flatline]

^brrrrr? lol

Strenghtened rods and bore:stroke ratio, counterbalanced crankshaft, stiff valve springs and retainers.

[redsupra101]

^brrrrr? lol

Strenghtened rods and bore:stroke ratio, counterbalanced crankshaft, stiff valve springs and retainers.

and a good flowing head with a cam that can make power at the said RPM

[cdx2k1]

Finally 2 sensible answers Does compression ratio have anythinjg to do with it?

[ingalook]

Finally 2 sensible answers Does compression ratio have anythinjg to do with it?

yeah it does... but not with the redline... CR has more to do with where the power is made... you could still make an engine that reved high but made no power high up there.

There is something to do with the upward force on the piston being higher than the downward force at about 6500rpm... above this your engine would blow... vetec compensates for this by increasing the downward force after it kicks in, allowing higer reving

As mentioned above, other parts of the engine also have to be specialized to handle revs

[stephanweaver]

you need a good rod to stroke ratio
good rods and rod bolts
upgraded valve train.
cam profile for high rpm
good intake, header and exhaust.

[ingalook]

No stephan... he asking why hondas do it and other maufactures can't

[stephanweaver]

cuz hondas have a very good rod to stroke ratio.
its a very good balanced engine from factory thats why

[ingalook]

That is not the reason the spoon guy give... he give the reason I give above....

Yes thats true... but without vtec the engine would still tear itself apart at 8000rpm.... sabotage yuh vtec and rev to 8000rpm and see how long it lasts

do it in the name of science

[stephanweaver]

if i had no vtec i could still spin to 8000 rpm.
mechanically nothing will happen as long as i have the correct tune. a/f and timing.
because i still have a 81mm*77.4 stroke.

vtec design is for power and different cam profiles. not necessarily for revving high.
like a profile for soft or normal driving, and vtec for hard driving.

i could drop my cr to 9:1 and still have as much power as 10.4 which i am currently at.

i may loose about 1-5 whp.
thats all.

compression is not necassrily a factor for revving high.

if depends on how your motor is built.
of course spoon motors have high compression, they need to have the motor properly built to match the parts.

"There is something to do with the upward force on the piston being higher than the downward force at about 6500rpm... above this your engine would blow... vetec compensates for this by increasing the downward force after it kicks in, allowing higer reving "


i think u mixing up vtec with detonation

[cdx2k1]

No stephan... he asking why hondas do it and other maufactures can't

Nooo..lol..i wasn't asking that..i was just asking what is the mechanics behind it.This is not a v-tec discussion I don't mind getting a good N/A discussion going on here

[enigma]

No stephan... he asking why hondas do it and other maufactures can't

cause its a HONDA.

[ingalook]

I know dat flickin chiney man from spoon (Tatsuru Ichishima) was full ah BS!

I'll never trust him again

Thanks for opening my eyes

[SR]

mines works fine from him

[ingalook]

An oh yeah... you could never have the correct AF to run at that RPM without vtec... if you build an engine with that type of tune it would not be able to idle !

Any engine that crosses 6500rpm needs some sort of variable lift tech, like VTEC, VVT-i etc to give it the ability to idle and rev when needed... and that's why Audi can build a production V8 with a 8200rpm redline

[ingalook]

mines works fine from him

boy throw away yuh shitty spoon engine and buy ah stephanweaver special nah

[Zim]

waaays, chill guys

[Zh@ne]

...spoon or stephan special engine...hmmm... i would take the spoon... throw it by me

[stephanweaver]

An oh yeah... you could never have the correct AF to run at that RPM without vtec... if you build an engine with that type of tune it would not be able to idle !

stop feeding people MISinformation
i think u taking things out of context.
first off, cams or vtec dosent determine af!
your ecu does!

do u even know what vtec is? please explain to us, because i dont think u know, dont paste from a website, tell us in your own words what vtec is.
vtec stands for Varible Timing and Electronic lift Control.
so in other words, VARIBLE TIMING, u can have one profile for normal driving, and also have an Agressing cam profile for racing - VTEC.
what the hell does vtec have to do with af?



it have ANY engine sping high rpms and be RELIABLE, it is NECESSARY to have a good Rod To Stroke Ratio!

i could build a HIGH revving STOCK b20 block with b16a vtec head, rev the sheit out of it,
it WILL break at 9000rpm soon enuff! even tuned unbuilt it will break soon.
why? it has vtec dosent it? but why does it break?

because its a LARGE 84mm bore, THIN 1 piece sleeve, and a long rod to stroke ratio 89mm. vs the ideal bullerproof b16 77.4 stroke.

Any engine that crosses 6500rpm needs some sort of variable lift tech, <---- what varible lift tech u speak about?
like VTEC, VVT-i etc to give it the ability to idle and rev when needed... and that's why Audi can build a production V8 with a 8200rpm redline

dont start to talk about audi, afaik audis have 5 valves per cylinder!

ent it have motorbikes spinning till 11k? do they have vtec or vvt-i or vvl ect? no. sheit it have no vtec, its gonna bLOW
WRONG AF ratio. omg. go tell suzuki to put vtec and save some engines!

[stephanweaver]

all vtec does is gives you the ability to alter cam profiles.
thats ALL.

it has nothing to do with revving high, but honda took advantage of VTEC [altering cam profiles].
by allowing a small displacement motor to make hp by revving AND gearing.

[stephanweaver]

cdx2k1

You can have a SR20 NON VTEC or NON VVL. REV HIGH
or u can listen to ingalook and say wtf i am saying i dont know sheit. it have no vvl. cant rev high

OR listen to me, any engine With a better/good/ideal rod stroke ratio, u can pull high rpms safely.
provided that u have a good valve train to support the high lift cams, and stong rods and rod bolts so they dont streatch out on you or break.

[X2]

*walks in.....leaves*

[havokkk]

stephanweaver is right... high reving mills always start with bottom end configuration. rod-ratio determines the engine spds a motor can be accelerated to safely. this certainly seems 'ass-wise', but piston side-loads, as well as piston spds increase with low rod-ratios... the higher the short-rod engine spd then, the more likely the she'll come apart. valve train components can now be chosen to complement spds attainable by the reciprocating bits below...

[havokkk]

^^^that said... short-rod motors are not lumps! pistons are accelerated more quickly in mills with low rod-ratios, than in motors with similar stroke lengths with higher rod-ratios. the result - higher port velocities at low engine spds, this being the secret to the higher, low-spd torque outputs for these mills

[pornstar4777]

stephan special......please elaborate!

[kes_vtec]

its all about torque vs horsepower, pistons speed and gearing
The perfect ratio is 1.75. If the ratio is off, it means that the rod is not using 100% of it’s momentum to compress the air and gas mixture. It’s using more energy to push against the sides of the cylinder walls than to compress the fuel mixture. This is normally not too bad because things are very well lubricated in your engine. But when you change certain aspects of the engine, in particular increasing the ECU fuel cutoff point or going forced induction, the imperfect R/S ratio will cause more stress on the engine block and could eventually destroy it. A good R/S ratio also ensures long engine life.

the b16 have near perfect RS and the gearing to go with it. torque to pull the car, but lots more power to speed things along
b20 RS is about 1.52, can't handle high RPM, because of it RS but it has alots of torque.

cams just let the motor breathe at higher RPMs
Higher CR adds torque.

i could build a HIGH revving STOCK b20 block with b16a vtec head, rev the sheit out of it,
it WILL break at 9000rpm soon enuff! even tuned unbuilt it will break soon.
why? it has vtec dosent it? but why does it break?

because its a LARGE 84mm bore, THIN 1 piece sleeve, and a long rod to stroke ratio 89mm. vs the ideal bullerproof b16 77.4 stroke.

but if u sleeve it, and get a b16 crank in there...
hmmmmmmmmmm

[stephanweaver]

"but if u sleeve it, and get a b16 crank in there... "

word. *runs out FAST*

[stephanweaver]

its all about torque vs horsepower, pistons speed and gearing

What does gearing have to do with engine dynamics?

The perfect ratio is 1.75. If the ratio is off, it means that the rod is not using 100% of it’s momentum to compress the air and gas mixture. It’s using more energy to push against the sides of the cylinder walls than to compress the fuel mixture. This is normally not too bad because things are very well lubricated in your engine. But when you change certain aspects of the engine, in particular increasing the ECU fuel cutoff point or going forced induction, the imperfect R/S ratio will cause more stress on the engine block and could eventually destroy it. A good R/S ratio also ensures long engine life.

So you say LS blocks that dont have a good RS dont last long?
all rightey then

the b16 have near perfect RS and the gearing to go with it. torque to pull the car, but lots more power to speed things along

b16 has torque? WHERE? b16 and d16 almost have the same amount of TQ.

b20 RS is about 1.52, can't handle high RPM, because of it RS but it has alots of torque.

It cant handle the high rpms becuz the ROD BOLTS stretch out, Cracking the Cylinder/Sleeve.
Yes they have a 1piece sleeve, yes its weak, but thats not the FAULT.
ITS the Rod bolts are the weak point.

cams just let the motor breathe at higher RPMs
Higher CR adds torque.

Is this why a CRVTEC with low compression arrounnd 9:1, has LOADS more TORQUE than a ls/vtec b18 with like 11:1 CR?
Keep misleading please.

i could build a HIGH revving STOCK b20 block with b16a vtec head, rev the sheit out of it,
it WILL break at 9000rpm soon enuff! even tuned unbuilt it will break soon.
why? it has vtec dosent it? but why does it break?

because its a LARGE 84mm bore, THIN 1 piece sleeve, and a long rod to stroke ratio 89mm. vs the ideal bullerproof b16 77.4 stroke.

but if u sleeve it, and get a b16 crank in there...
hmmmmmmmmmm[/quote]

Whats the point of having a Crvtec with a b16 Crank? Explain this ingenious idea to us and the world, because putting a 77.4 Crank will just Destroke the 2.0L back to a 1.6?



*Stay tuned to the next episode*