Head

[cali yaris]

Sorry Loren, but your theory or whatever you are basing your opinions on here (it sure isn't first hand experience with a Yaris or 1NZ motor) aren't valid or correct. And the misinformation you are spreading is, frankly, counter-productive.

As has been mentioned, the limiting factor for making HP on the Yaris is RPM

This is simply untrue.

From simple bolt-on mods (10-20 hp) to fully built turbo motors (300+), the car makes more power without changing the rev limit. I've pushed the motor pretty far now, and at 310+ whp, it STILL doesn't make power over 6000 rpm. Raising the rev limit does not make more horsepower.

If you put engine management on it that will allow you to raise the rev limit and get control of the fuel and spark in the 5-8k range, then you can make more power (assuming the engine holds together)

Incorrect again, from first hand experience.

[Tamago]

Originally Posted by cali yaris

S
This is simply untrue.

From simple bolt-on mods (10-20 hp) to fully built turbo motors (300+), the car makes more power without changing the rev limit..

horsepower is a mathematical representation of torque and rpm.

horsepower = torque X RPM/5252.. if torque remains constant, as rpms rise, horsepower rises... this is how a hayabusa can make such great horsepower, because it revs well over 12,000rpm and is still able to breathe.

raising the rev limiter will allow you to make more power mathematically, because the engine is spinning faster. whether or not the stock 1nz can breathe efficiently enough at a higher rpms (and all obvious problems with high rpms on a stock head being ignored) is another story.

also remember, you can't use your boost as an example. boosted cars don't need to rev to all high hell to make power, because their torque curve can get flatter sooner.

hondas make high horsepower because they can breathe efficiently at high rpms without failure.

[Loren]

Originally Posted by cali yaris

Sorry Loren, but your theory or whatever you are basing your opinions on here (it sure isn't first hand experience with a Yaris or 1NZ motor) aren't valid or correct. And the misinformation you are spreading is, frankly, counter-productive.

Okay, let's not argue and present opinions. Let's share references.

http://www.popularhotrodding.com/tec...ing/index.html

[Maitre_Te_Te]

I know polish intake on old head with carburator is not a god idea because the carburator is not the best for to do a good air/essence mixture. This is for this the turbulance are good for th do a good mixture. But now, tje injector is directly on the intake valve an do a good spray, then polish do a good flow for best mixture intake in cylinder. But it's sure to porting intake for to do a bigger porting this is not good on N/A beacause you reduce the mixture speed/flow. (like a presure produce with the same water flow in different pipe)

This is not just matematical because if you see a dyno sheet, the hp on yaris is at her top at 5600 rpm and after, hp go down. If I unlock the rev limit, thne engine in matematical can go at 8000 rpm but in reality with physic, the engine can't. Honda can go at 8000 RPM because her engine have maybe 13:1 compression and her disign is the best for high RPM. Yaris it's design for the torque, not hp at 8000rpm. What I think, with a best compresion, I will go search more HP at more rev (maybe 6200) at the top of HP at rev limiter.

Sorry again for my english! this is hard to explain.