Official Richard Holdener who wants to buy an intake manifold list

[richardholdener]

I probably shot myself in the foot for offering the mid-range manifold, but the comparison does deserve a little insight. Actually, it is possible to significantly increase the torque production at lower engine speeds using the proper intake design. The problem associated with this is that there is almost always a trade off in power at higher engine speeds. The intake is literally tuned to maximize torque production at a given engine speed. It may be possible to give big gains at 3000 rpm but it may also cost power at 5000-6000 rpm(menaing it may make less power than the stock intake). I doubt this is acceptable. I will run a few more tests on the mid-range version and see if there is a happy medium that is better than my previous results. Also I saw posts on difference between Hp & Tq, but in reality to the are mathematically related and any given torque value will have a corresponding HP value at a given engine speed. Tq is simply work or force and HP is that work or force applied over time. In a drag race scenario (or simple acceleration) the intake that will provide the best acceleration time is the one that offers the most average power over the rpm spread required. In the case of the Yaris, this means WOT at 4000 rpm to 6000+ rpm-except in 1st gear.

Originally Posted by eTiMaGo

Well, if I may share my 2 cents, I've had a lot of time to think about this conundrum...

As much as we want, we cannot expect any sensible improvement of low to mid-range torque with just bolt-on NA mods. You must realize that a 1.5L engine can only do so much. Sure, you could get higher compression pistons, a stroker kit and maybe some new cams, but AFAIK those also really come into their own at high RPMs.

The reason is, sadly, there is no replacement for displacement. You cannot expect the torque of a bigger engine, it's just not gonna happen. You won't see Pee-Wee Herman bench pressing 300lb, you won't see a 1NZ with V8 torque...

So, one must realize this intake manifold is not some magical end-all solution to more power. If the best results are a pretty sizeable increase of torque from 2500RPM onward, then I think it is correct for the manufacturer to maximize on this.

This means that yes, on the street, if you drive in a calm and "normal" manner, you'd never really see an advantage. This intake manifold will really come into its own where it is designed to, at high RPMs, so it will be of most use to those who really race their cars, be it on a track or autocross.
It was said in a previous post, or one that was lost with the hack, but this manifold could be compared to a "bolt-on VTEC", as it gives the engine the ability to keep revving far better than stock. And, as with VTEC, the love-hate relationship is that you have to keep the engine at high RPMs to get good power output from it.

If you really want more low-end torque, the most effective solution is more displacement. This is where forced induction comes in, as it can be considered "virtual displacement" (think about this... normal atmospheric pressure is what, 14psi? a turbo running at 7psi is thus forcing in 50% more of atmospheric pressure, thus giving your engine characteristics of one that is 50% larger, or 2.2L. Of course, this is a very rough generalization, kinda like giving steroids to Pee-Wee!). This is why superchargers excel in this area, they start shoving in more air as soon as the engine is moving, same thing with small, responsive turbos that may not create massive boost, but can start to supply it quite early.

There you have it... If you seriously want more low end torque, go for a small turbo or supercharger. Of course, it's $3000 vs $700, I think that's also an important reason why many are wishing for a "low RPM" version of the intake.

I'm in no way an engine expert, so feel free to pick apart what I've just written