I've been thinking about this and i dont really understand why people with LS motors put a GSR head on it just to get vtec. Would it not be cheaper to simply put bigger cams in it? Is the reasoning to maintain fuel economy and idle during normal driving (and if that's the case, i'd take those as a necessary evil to gain more HP).
I know i'm probably going to get flamed for dissing TEH ALMITAH VETAK but i'm just asking a simple question i've been curious about. I suppose the same could apply to mini me's as well.
Basically: vtec vs larger cam(s)

 

ls/vtec > ls with bigger cams

if the ls/vtec is built right.

 

Well i suppose that makes sense...if the ls/vtec is built right But if they're built the same, what's the difference.
I know people swear by it, i'm just trying to figure out why.

 

don't know

 

When you ride in an LS and LS/VTEC that is built right, you'll understand why they do it..... As far as the mini-me's, look at BauleyCivic's thread about mini-me swaps. He gained quite a few seconds on his 1/4 mile after his swap. It doesn't seem like it would do much, but it does.

 

basically to have best of both worlds. get good torque from ls block, but then you have high reving off of vtec head.

 

can't rev too high if you don't have the correct valve train.

 

For one, the LS block can turn in excess of 9k w/destrying itself. Same with a B20, to a lesser extent obviously. The guy who did my swap beats his CR-VTEC all the time, shifts at 9k. The problem is in the head - not very hard to float an LS valve at 8k, let alone 9k. VTEC heads can rev much higher w/o floating valves - the springs they have were put there with that in mind. There's also the dual cam profile that gives both better low-end torque and top-end power.

If you've ever driven b16 & LS powered cars, and/or been in a race beteen them, you'll understand the swap better. B16's aren't very fun daily drivers (unless you redline it all the time and pop the clutch endlessly), whereas LS motors have the torque to make you smile w/o having to push it very hard. When you run both to redline, you'll appreciate the VTEC moreso than the 'daily-driver' cam profile of the LS.

 

my thoughts exactly. vtec is much more than just bigger lobes. on an ls, you can throw in those bigger lobes, but that power isn't gonna last up into the 8000 rpms unless you get some wicked cams not meant for the streets. my buddy has some pretty big cams in his ls and those things start falling off well before 8000. lsvtec gives you that low end fun to drive torque, and the power band that keeps going untill 8000 rpms... you just gotta build it right.

 

dont listen to them. it all boils down to this:

b18b heads intake valve is 31mm ( I THINK. i know its either 30 or 31)

P72 (gsr) and p30 (b16a) heads have 33mm intake valves.

the heads themsleves flow better.


put a P8R head ( rare non-vtec head with 33mm intake valves) on a built LS bottom end, and you will see almost the same high end.

put a vtec head on the same build LS bottom end, and you will see more low/mid, due to the smaller lobes, but around the same top end.

 

Thanks SkRiBLaH, that's more like what i was looking for.

 

What did the p8r head come on? I have not heard of that before hence the term
RARE, but i'm building an LS motor and that sounds pretty interesting.