alot of you ppl fail to realize that are cars dont work on lift... do your homework ppl... cams dont do ____ for us NA...and even for turbo setups the gains are almost NIL.... you guys are comparing b/d series motors and american motors that work on lift and timing to a motor design to only use timing as a factor...

 

Lift is a toyota only term. It refers to the VVTL-i engine where at 6k rpm the valves lift higher suddenly causing a dramatic increase in power. A cam in a VVTL engine helps a lot since it moves the lift rpm down to a lower rpm so you hit your power sooner, and they change how far you lift. American engines dont run off lift most are SOHC or DoHC meanng that the valves are always lifted the same amount no matter the rpm since there is only one cam per valve series. Cams help because they make the valves lift higher thats way you have to get springs and retainers when you get cams. Cams dont help us much since our engines are small if you have a high hp turbo tC and put cams it would help a lot more over NA since they have so much more exhaust and air going into the engine, but a well made set of cams will give horsepower just not as much on a small or low hp engine.

 

tcpete can you give me some links on how the vvti valve train works im still not fully understanding how this setup doesnt need lift or duration.do the cams in our cars not determine how long the valve stays open? or the lift of the valve?

 

they do, all lift is, is a cam on some toyota engines that lift the valve higher at 6k rpm vs the other cam, and adds some hp. all engines run on the lifting of valves except rotary engines

 

if thats true then how can a cam with more lift and duration not help?

 

thats what im saying, i believe a cam will help some, but our engines are smaller and there is only so much it can help, on an NA tC we wont see much gain since you can open the valve all you want but if there is only so much to come in and out, if there isnt enough flow your going to loose power thats why huge cams arent always better its all about setting it up for your application

 

i get it now.......



Now with vvti all this does is change the duration of which the valves open. The system changes the cam timing so u can go from having alot of valve overlap or have zero overlap. This system is good for some power(example the 1999 1.8l corrolla was 120hp but on the 2000 model with the addition of vvti it gained 5hp). Another thing with vvti is that there is no need for an egr valve as the system controls the flow of exhaust gas from the combustion chamber leaving some behind to be used for the next cycle. The plus with this is no egr maintinance or replacement.

 

lol. funny thread. keep it coming, guys. this is great.

 

exactly, where in the VVTL-I is the same system as the VVT-i but when changing cams the secondary cam lifts the valves an extra bit adding power where our engine adds no valve lift

 

what confuses/amazes me, is the fact that i have a built 383-which is roughly a 6.27L engine....using some basic math, a 2.4L(yes this is slightly innacurate) is about 38% of the motor. MY 383(undynoed, but an expierenced engine builders opinion) will run between 450-500, with decent compression, mildly big cam, decent intake, 670 carb. and s/r torquer heads ( race version of the chevy stock head, not much improvment over stock, nothing like a race head).

Now, based on pure cubic inches/L measurements, a TC in the same shape would make 171 HP up to 190 hp.

Now, with this being a bunch of math out the door it doesnt make since to me why a fairly high compression TC(11:1, give or take depending on octaneo f gas), a full head(P&P, upgraded and lightened valves, bigger valves, etc), a upgraded intake manifold, a good header, and not to mention most importantly, EFI!!!!, even this small of a motor should make at least 220 is hp N/A.

yes i know there is a big difference between domestic and imports, I am/have worked on both, and understand that.




Now, onto the cams/VVT-I. increasing the lift (logically) should increase possible airflow into the combustion chamber, limited of course as any other engine would be. Small block chevy's do not see much increase in airflow after more then .600 lift, but the average stock cam is not even near .500 is the 300hp crate motors....


Now durations big hp gains come in the upper RPM's, where the overlap from valves matters less simply becuase there is less time for the valves to stay open. So adding duration at the upper RPMS increase hp to an extent(gives that nice little umph), and lower the duration at lower RPM's provides a nice smooth idle, even on a built motor with high CR.



So, in the end, a Cam with more life should increase hp, but duration should not be neccesary since it is DOHC, and the cam timing can be controlled to increase and or decrease duration. so with a decent lift cam, and a VVTI controller, HP gains should increase, and if we had a really good intake manifold design(which i dont think we do??) and a nice head/valve package(not just P&P, but an increase in size and or undercutting) there is no reason we couldn't see over 220ish HP

Phew......

 

wow... all of you are pretty much wrong in almost all of your posts... if this was jeopardy..trabec would be slicing his wrists by now.

 

 

ok if were all wrong why dont you correct us, since all you have said is cams wont work since we dont run off lift, which makes no sense since all piston engines run off the lift in some way and the lift feature is a toyota engine only feature, When you write something intelligent i'll listen but so far that hasnt been accomplished.

 

hey pete, we got 1 more cry baby on the forums.

 

idk how im being a cry baby, if i have false knowledge id like to have it corrected and be told whats right, not just told no your wrong with no explanation that helps no one.

 

damn straight...if im wrong, prove it

 

well ive'd google'd vvti and ive gotten mixed results as to how it exactly works,some sites say its alot like vtec,and others say its just intake cam timing( like a cam gear).if the cams in ours cars are like vtec or i-vtec they can for sure benifit from cams.and if its all a matter of vvti controling everything then wouldnt a camcon or similer controller make cams work?

 

ok im half plastered from drinking and partying last night from new years so im gonna tackle this on half a brain...and to shut you noobs up...

FIRST EXPLAINING VTEC:

video on vtec : http://videos.streetfire.net/video/3...E74118BB4A.htm

VTEC works with cams shafts that have 2 different profiles a soft profile and a harsher profile...for daily driving and fuel economy ur driving on the softer profile until you hit about 5k-5500k rpms (depending on which vtec motor in which the vtec solenoid locks the rockers to now slide over to the harsher side creating VTEC in which now the car uses more power created by the harsher cam that has a lumpier duration to create more lift in the valves intake and exhuast making more power. VTEC motors run on lift and timing because there is no science and no ecu controlling at which point it deems it necessary to cross over to produce the power.. it is a steady punch and 1 time in the rpm range.

If u think of it this way say u have a camaro with a 350 v8, it comes with a certain cam that is designed for everyday driving and fuel economy. Now put a big choppy cam in it which gives u an incredible top end increase but u have a rough idle and ur low end power is dead untill u reach the cam's operating rpm. Vtec combines the 2 cams maximizing the whole powerband and allowing u to have a smooth running fuel efficient 4 cylinder for everyday commuting but when u want to play you have the power on demand.


also TOYOTA HAS 2 VERSIONS OF VVT-I TECHNOLOGY DUMBASSES

vvti = variable valve timing inteligence
vvtl-i = variable valve timing lift inteligence


Now with vvti all this does is change the duration of which the valves open. VVTI adjusts the amount of valve overlap there is. Valve overlap when BOTH the intake and exhaust valve is open at the same time. This between the exhaust and intake stroke. For an engine to make more power and be more efficient you want to bring the most air in and out as fast as possible. This is possible by keeping the intake valve open longer and opening the exhaust valve earlier. During high RPM conditions more valve overlap is better. However too much valve overlap can cause the air to enter the wrong port, as you can imagine when you have both valve open at the same time. At high RPMs the intake velocity will not allow the exhaust to enter the intake port. But during low rpms less overlap is better because there is less intake velocity. It works by using hydraulic pressure to adjust either the cam gear or the gear driving the timing chain (im not sure which one) So to sum it up VVTI controls valve overlap to make it more efficient meaning more low end torque and more high end power.

VVTI DOES NOT KICK IN AT A CERTAIN POINT LIKE VTEC R AT 6K RPMS IF U THINK THAT UR AN IDIOT....it continuously modifies the timing throughtout the powerband to compensate for driving conditions!! yes at around 4k rpms the motor comes alive but thats because that rpm is no longer a normal driving fuel economy using period int he rpms range in which the ecu advances the TIMING on the cam shaft considerably to allow more power to be made..

VVTL-I the key feature is the L in which THAT means lift... a motor to work specifically on lift and timing... these are motors in toyotas higher power cars (lexus's) they work on a similar vvti pattern how ever work also on LIFT duration which is more similar now to hondas i-vtec...

VVTI- AND HONDAS IVTEC ARE NOT the same.... honda designs their motors to create power at 1 point (vtec) toyota cerated their motors to have continous timing changes to created power through out the power band....

VVTI only works on the intake cam also.. not on the exhuast.. anyone who has ever opened up the valve cover will see the exhuast side having no cam adjustment system and the intake side having a large disc which continuously controls the timing on the intake side...THIS IS NOT SIMILAR TO VTEC MOTORS in which both sides are affected by timing...I KNOW THIS CUZ IVE WORKED ON BOTH MOTORS....AND HAVE OWNED AND BUILT BOTH...

here is more supporting and correct information that will explain vvti- vtec and vvtli

http://www.billzilla.org/vvtvtec.htm

http://www.billzilla.org/vvtvtec3.htm

IF YOU WOULD LIKE ME TO GO INTO MORE DETAIL I'D BE HAPPY TO!
if you want more supporting links blah blah blah there are so many on scion life saying the same crap i just said it hurts my brain to think of it...

thanks and have a nice day fellas and a happy after new years first day.....

and if your dumb enough to compare japanese motors and american motors and how they work and are built you should just sit infront of your tv, have a beer and go watch nascar and leave posting on the internet to those with more brains...

 

no you will not benefit from a cam because LIFT is not a factor!!!! only timing... and essense if you can control timing that would be more beneficial to you then a "lumpy cam" vvti and vtec are different in 90% of its essence. a camcom is workable but camcoms suck... ive never heard or read anyone who has really had any good success with that product. your better off getting and EMS and tuning the a/f of vvti sloppy management of a/f mixtures in the powerband..

 

the l in the vvtl-i code does not mean lift is how the engine is run, the lift refers to a process where the valve is lifted higher causeing a sudden increase in power, in a vvtl-i engine lift kicks in a 6k rpm, all engines run off lift if you dont think they do take out your cams and allow the car to have no valve lift and see what happens