I never really liked the idea of vtec. (than again i've never driven a car with it either)I would like it better if vtec was always on. so wouldn't it be possible if I took a non-vtec engine, like a LS, than put a very large cam in it and port the head. Wouldn't that be the same thing as running vtec all the time. Also how well would that work with a turbo.

 

no.
why dont you like vtec?
on a REAL b series motor, vtec 0wnz j00.
a big cam (if you mean a high lift, and duration) would not be good would with a turbo.
just leave the stock cams in and run the turbo. it will be better.

 

you low end would suck with that cam also I would port the head so it would allow that cam to work better

 

so explain why you don't like VTEC? how can you be objective about something which you've don't even have first hand experience with and obviously have no knowledge about??

large cam profiles are optimal at higher rpms which is why VTEC exists. a large cam profile at low rpms would, as fsarfino said, suck. therefore, VTEC is never "always on" as you would prefer, but rather engages at higher rpms.

-jeremy

 

You said large cams are optimal at high RPM. So of course they are going to help in the low end,right?Correct me if I'm wrong on that. Also I did mention I would port the head. But my point was every one always says how much power they get when the vtec lobe engages. If i had say... a 2000 civic Si I wouldn't want to have to wait for my car to hit the 5's in the rpm's for my vtec to engage. i would want it right from the begging. So wouldn't it make sense to think that if someone had a non-vtec head with a cam that had lift and duration egual or greater than that of a vtec lobe and would flow as much or more air than a vtec head it would actually be kind of like having vtec "on" all the time,right. I mean as far as making power goes thats all that really happens right. larger intake and exhaust ports(I think, i'm a little rusty) and a cam with higher lift and duration.

 

no.
if you had a big lift/duration cam it would KILL your low end.
having vtec "on" all the time would make the car run like complete ***
its set at 5000+ for a reason.

 

so why would anybody ever put a big cam in there car. why do all these pro racers out there have big cam's if they kill your low end. show me a dyno chart comparison of a stock one a a big one and point out where iT loses horsepower than i'll belive you!


[Modified by CAMAROCRUSHER, 8:24 PM 6/3/2002]


[Modified by CAMAROCRUSHER, 8:24 PM 6/3/2002]

 

Because they don't care about low rpms and driving on the streets to work. The big cam only works one end of the rpm band. So that's why big cam cars have a different idle, or "lope" cause that's what the engine sounds like, a bad idle because of a big cam=no power in low rpms but lots on the high end.

VTEC is just a way of making a practical car into a relatively high performance car. If you want VTEC right away, then dowshift into the appropriate gear and ride till redline and do it again in the next gear if you want. When ppl put big cams into a VTEC engine, then end up with a rough idle and lots of power when VTEC is engaged.

 

Whatever, I don't care anymore. I was just looking for a way to duplicate the power you get when vtec engages and try and set that up on a LS engine without actually putting a b16 head on it.

 

tsssss haahahahahahahah

 

GRRRR!!!!!!!!

 

hey...you still can do it...you just have to have a non vtec head with a non vtec cam, and your car will run like crap on the streets, but great on the track.

 

thats all I wanted to hear.

 

You were asking about why pro racers put big cams in their cars? Someone else posted before it was because they are not concerned with low end. That is true. Let me expand a bit on it. To put it simply they don't ever use their low rpm range. When you are racing 1/4 mile you are launching your car high in the rpm range (5000 & above). The idea is to stay in that upper rpm range aka the power band...so you obtain your quickest ET.(Hondas make power up high like motorcycle engines)
Once again though, you can still get a ported head and larger cams in your ls and gain hp and performance from it. Your car WILL idle like crap . One way to help that. Check out systems like hondata. The base systems start around $ 350
I think.


[Modified by allmotorgurl, 9:15 PM 6/4/2002]

 

How is that a thumbs up?

When the intake & exhaust valves open, close, and how much they lift determines how an engine breathes. With a non-variable cam-timing system, there is only one rpm point where the valves are timed exactly right - this determines your torque peak. At every other point, you're making less power. The farther from that torque peak, the more power you lose. Put cams on an engine that cause torque to peak at 7,000 rpms, and you're going to have serious problems by the time you reach idle. This is the reason for VTEC.

VTEC gives you two camshaft profiles, which allow you to have a torque curve that's essentially twice as wide. Good power & driveability down low, which carries over all the way to redline.