Mods to improve efficiency and performance

Ditch the cat? That is illegal. What will you do at your next inspection?

 

For me, performance is just fine the way it is, and a couple MPG increase (presuming it was a given) would not entice me AT ALL to turn the car into a chimney.

If you want a polluting car with spunk, just buy a diesel. :blink:

 

Wouldn't it just be easier (and legal) to partially block the radiator and run a home-made air intake hose to just close to the cat? I did this on the Insight and it assisted bringing warmer air to the motor and warmed it up faster....

 

i dont think exhaust backpressure is as large of an issue compared to normal cars. i remember we were discussing the possibility of adding a turbo to a Prius, but someone concluded that there would not be enough exhaust to spool the turbo.

btw: 2hybrids, nice cylon. but i like boomer, myself

 

Maybe a supercharger could be used instead, but the engine would have to run more.

 

Why Thank you

 

Because of the small displacement, low revs and Atkinson cycle, the intake air requirements of the Prius engine are among the smallest on the road today.. Intake size/box modifications, K&N filters, etc will do *NOTHING* for engine performance.. A supercharger/turbocharger will work, but requires a lot of extra work to make the system function.. The only easy intake modification that may have some positive impact to performance is a warm-air intake, where the intake is routed to pull hot air from around the catalytic converter; this is counterproductive in the summer, but can improve MPG somewhat in the winter.

In terms of the cat itself, removing it in pretty much any car will improve performance somewhat due to reduced back pressure, but it's not legal to do so.. On the Classic Prius, with its dual cats, one possible mod might be to remove the first cat with the hydrocarbon adsorber and valve and leave the second cat in place. Since my car is no longer under warranty, if the cat valve ever rusts closed, rather than spending the $1000 or so for the Toyota replacement, I may just try this mod and replace the first cat with a section of stainless steel pipe.. If a single cat is good enough for the HSD Prius, it should be fine on the Classic as well..

 

ok before this gets out of hand.....if your goal is to increase hp then routing hotter (and therfore, less dense air) is going decrease performance, not increase it. Granted the 1NZ-FXE's Atkinson's cycle is designed for maximizing emissions and lean burn characteristics the engine ECU does try to make as much power within those constraints as possible. Introducing hotter air into the engine increase the possibility for low level detonation (something your ear is not going to hear but the KNK sensors are going to pick up) and the ECU will back of cam timing, ignition timing and increase injector duration to lower combustion temperatures in an attempt to quell the detonation. This means less power. The cooler the air the more dense it is, simple as that. Also what needs to be understood is the current generation catalytic converters are designed to operate best within certain temperatures. Also they are required to "light" now in a very short time. To achieve this the walls of the cat's matrix are very thin. This allows for more surface area, however the drawback is less ability to absorb excess heat. This has already become somewhat of an issue with current OBD II cars that spend a great deal of time at low to mid load, high RPM conditions. Anyone who owns a previous gen stick shift RAV4 (2AZ-FE) and drives in the hills will most likely attest to having there cat's replaced due to overheating and burning them out.

As far as this turbocharger debate goes.....volume and heat drive turbos. The 1NZ-FXE produces quite high EGT's in stock form. The Biltz turbo kit has been reasonably successful due to good EGT's, a small turbo and taking into account the specific RPM range the ECU tries to operate the engine in. Remember making power with a turbo is about how much air you actually move, not boost pressure. I remember seeing someone on hear say that the boost pressure levels were too low to matter. This arguement means nothing. Its all about how much air you actually pump in and pump out. A circa 1998 Toyota CART engine ran at only .7-.8 bar but pushed over 85lbs of air per minute, yet they made approx 850-900hp. Toyota's 503E which powered the dominate IMSA MKIII Eagles of the early 90's ran upwards of 3-3.5 bar to push 90-100lbs of air per minute to produce 900-1000hp. Two completly divergent ways to produce the same power...the constant...how much actual air is being pushed.

As for superchargers we end up getting into all kinds of funky physics. The simplest way to look at is to just follow what tuners have learned over the years and know that for some reason superchargers hate intake and exhaust valve overlap. There are other factors but it gets long and complicated.

Either way I have also seen the arguement made that the Prius's compression ratio is prohibitive. True it is a static 13.0:1 however when looking at actual cylinder pressures the compression ratio is actually closer to 9.0-9.5:1 depending on cam timing. 9.5:1 is a completely manageable ratio for .6-.7 bar. The previous generation TRD supercharged 5VZ-FE powered 4Runners/ Tacomas ran happily at 7psi with a 9.6:1 ratio.

In the end, lets not lose sight that an engine is a pump, to make more power you need to pump more air in, add fuel in the correct ratio (more air means you need more fuel),get a bigger "bang" and get the air out. There is no free lunch. Its kinda funny, anyone with a scantool can pretty much get a barometer for how much power they are producing. Just check out what the airflow meter is reading. Just about any 4 valve Toyota motor can be calculated to a fair degree of accuracy by seeing how many pound of air per minute is being processed and multiply by 10. Matrix XRS owners typically read a maximum of 18-18.5lbs per min. Matrix owners were seeing between 165-170whp. Taking into driveline loss that comes in at right around the advertised 180 crank hp. My roomates Supra turbo pushed 46.8lbs per minute en route to a 408hp dyno pull just recently. In the end it all comes down to how much air you can get in and out. But don't lose hope there is options for those of us hop up minded Prius owners....it just takes practical thought, work and some creativity.

 

Very nice post... I've been looking for more detailed info about the 1NZ-FXE for some modeling and simulation I've been doing with Matlab and a few other engine toolbox programs. I would imagine that the Atkinson cycle would preclude supercharger use due to valve overlap, but I don't have the cam specs to prove it via simulation. I'm currently developing a NOS wet kit to fog mixture just below the throttle body, but again I'm worried about blowback into the intake manifold and possible NOS explosion. If you have any good info on the 1NZ-FXE 1.5 please reply.
Bryan

 

Any mod to the cat causes the car to run open loop, causing the MIL to light and destroying performance, and efficiency.

 

If you were trying to alert any of the posters in this 12.5 year old thread, none have been around in over 3 years.

Thanks for sharing .

 

If you want more power, just ditch the heavy intake for a plastic one and swap out the water pump for an electric one.

 

Okay
To start thank you strong bad and op ….although this thread and forum touch lightly on where some always say NOT aka or bad idea ..
Myself and a curious minority like the what if?

So here goes my questions

Electric water pump (maybe Prius C) to replace OEM belt drive pump on Gen2

Metal aluminum air intake manifold switch out to plastic style/design

that was hinted to by deces post

I am sure some will be negative on the above

However
I have interest (based on efficient application towards economy)

I am already watching others PC members going with Gen2 cam swap
I am considering custom engine rebuild on my 1NZ Gen 2 even considering most of the engine lifecycle run time is below most other Toyota engines like Echo, Yaris, etc

Admittedly some modifications have marginal to no benefits whatsoever....really burn out on stupid listing on ebay for aftermarket cold air intakes, turbos, intercoolers, and so on that generally either jack or just further deviate from OEM original design benefit. Turbo are costly and OEM turbos ever more so on USA dollars. ANYwho