Performance Chips

[jdonnelly]

Has any one tried any of the performance "chips". Most seem to advertise better MPG and 25 more HP. Any one who has tried one, what does your "butt" dyno tell you? Also any change in MPG?

Thanks

Jeff

[SOMEONE ELSE'S GOT MY NAME]

Has any one tried any of the performance "chips". Most seem to advertise better MPG and 25 more HP. Any one who has tried one, what does your "butt" dyno tell you? Also any change in MPG?

Thanks

Jeff

Never mind the fact that consumer advocates shoot these kinds of things down left and right. Think how cheep chips (or gas additives, for that matter) are. Logic dictates that if they made even a 2% difference, the manufacturers would be doing it.

[Gryphon]

I would have to disagree. In some cases, for some cars, there is a definite trade-off between performance and fuel economy--more power often comes at the expense of lower mileage. Emissions can also be affected of course.

Tom

[RXREY]

I agree. Of all cars this one is the one that you want to leave alone in that respect for Pete's sake. I had a PT Cruiser and tried everything to improve gas mileage and power...Chrysler would have done it themselves if I could do it for a few measely bucks...I was never able to get that silly car over 20MPG! As far as power,it would struggle past 80. No matter what Chrysler advertises, that car only gets about 17-19MPG! So at over 25 MPG and 270HP....I LOVE my Lexus 400h!!! The only thing on it American is the back hybrid logotype from a Ford and me in the driver's seat! Warmly, Rey

[DArustik]

I wouldn't try it on an expensive car like a Lexus. I think thats more aimed at the lower class cars.

[Gryphon]

I seriously doubt that there will ever be sufficient market for any sort of aftermarket chip for an RX400h, unless the Hylander Hybrid crowd is considerably more performance oriented. Even if there were a chip, I would be skeptical about plugging one into such a complex vehicle.

Tom

[gordonw]

Do they still make performance chips for cars? I remember the early '80s when a buddy of mine pop the chip from his Buick GN and plug in a new Hypertech chip, but that was in those pre OBD days. Aren't most mods done through software reprogramming these days?

[RX400h]

You are correct - post OBD-II vehicles generally respond to software changes, only.

[wwest]

You are correct - post OBD-II vehicles generally respond to software changes, only.

Well, "mechanically" one could convert the engine to the Atkinson Cycle by modifying the intake cam to delay the closing, or opening, of the intake valves like is done in the Prius engine. FE gain would be as much as 30%. Shortcoming is loss of HP/torque due to the resulting 3.5L engine derating and non-operability of the catalyst since due to increased engine fuel burn efficiency it can no longer be heated to the 800F level required.

But.

You could then mill the heads to get the compression ratio up to ~13:1 and thereby regain the HP/torque. The delayed intake valve closing keeps the "charge" down to 70% so the effective intake/compression cycle ratio is still ~10:1, and thereby regain the HP/torque values due to the power stroke/cycle still remaing at 13:1.

Enough HEAT in the exhaust for the catalyst....?

Remains to be seen.

The Atkinson cycle works well, assuming late intake valve closing, on the Prius 4 cylinder because there is always an opposite cyclinder beginning an intake stroke just as a specific cylinder is "exhausting" a portion of its A/F mixture charge BACK into the intake manifold. An 8 cyclinder would likely work well for the same reasons. But what might the intake manifold "flow" be like for a 6 cyclinder engine?

I have always assumed the RXh did not get the Atkinson engine technique because the Prius' unique catalyst arrangement could not be scaled up to the level needed for a 3.5L engine.

But was it because of the 6 cylinder engine instead...?

[RX400h]

WWest, you really should work at the Toyota R&D lab!

[RXREY]

WWEST...I loved that explanation...I didn't understand much beyond "Well, 'Mechanically'..." but I love when someone knows their stuff! Can you explain why I can't put metal in my microwave?...oh, never mind.....have a great day Lexus folk. Rey

[wwest]

WWEST...I loved that explanation...I didn't understand much beyond "Well, 'Mechanically'..." but I love when someone knows their stuff! Can you explain why I can't put metal in my microwave?...oh, never mind.....have a great day Lexus folk. Rey

Arcing inside the microwave's "cavity" or waveguide will be reflected back into the magnetron as a short in its output path, too much of that and you'll need a new one. Sort of like shorting the wires together going to one of your ML speakers, no instantaneous failure, but.....

Modern day magnetrons are not as subject to this, are more robust, compared to the old Raytheon QK-707 magnetron "tube" that this "RADAR RANGE" market started with. With the old airborne RADAR the waveguides were often pressurized to prevent arcing within the waveguide itself.

Sorry, you opened the door so I couldn't resist showing off with a bit of absolutely USELESS info gained from my sixties time in the USAF.

Now ask me about the OX-4...

[wwest]

WWest, you really should work at the Toyota R&D lab!

Yeah, and get my head chopped off...!

Wrong culture, I'm not a "keep my head down" type of person.

[SexyLexy430NY]

WWEST...I loved that explanation...I didn't understand much beyond "Well, 'Mechanically'..." but I love when someone knows their stuff! Can you explain why I can't put metal in my microwave?...oh, never mind.....have a great day Lexus folk. Rey

ROFLLLLL..lolll

[wwest]

Has any one tried any of the performance "chips". Most seem to advertise better MPG and 25 more HP. Any one who has tried one, what does your "butt" dyno tell you? Also any change in MPG?

Thanks

Jeff

Well, hey, in for a penny, in for a pound... so why not go for the gold coin....

The idea behind most of these performance "chips" is to fool the engine ECU into "thinking" the intake airflow "mass" is more dense, ENRICH for more HP, than in reality. Or in the alternative, less dense, LEAN for improved FE. The most common method is to use an inexpensive, ~4 cent, 1/4 watt resistor in parallel or series, rich vs lean, with the IAT sensor.

If the actual intake air temperature is say, 75F, and you want a few extra HP then the theory is if you make the ECU "think" the intake air temperature is 60F it will enrich the EFI fuel flow to accomodate, compensate for, the lower temperature, higher density, intake airflow.

The problem is that engine ECUs haven't been that DUMB for many years now.

Nowadays you could even think of them as being smarter, OUT-SMARTING, the purveyors of these "chips".

During engine idle and/or at a relatively constant speed, light torque, cruising, the ECU relies EXCLUSIVELY in the "upstream" oxygen sensor for controlling the A/F mixture ratio. And all the while its doing "that" its also adjusting the calibration parameters for the MAF/IAT module. It's only when you ask the engine to produce a higher torque level, acceleration, uphill, pulling an extra heavy load, etc, when the engine MUST have an enriched mixture, that the system switches over to the MAF/IAT module signals in order to run an enriched A/F mixture, say 12:1 or even more, vs the standard ~14:1 demanded by the oxygen sensor.

If the purveyors really wanted these 'chips" to work all they need do is remove them from the circuit during the times the oxygen sensor signal is being used to control the mixture and then switch them into the circuit, say, any time the O/D lockup clutch is not engaged AND the TPS indicates an above idle throttle position.

[mimle]

hi wwest!

Do you have any ideas how to change MPG to km/h on lexus RX400h?

Thanks.

[mimle]

hi wwest!

Do you have any ideas how to change MPG to km/h on lexus RX400h? Or F to Celsius?

Thanks.

[Gryphon]

WWest got a swift kick outta here a year or so back. It is rumored that he landed in a mental hospital in Serbia.

Tom

[dcfish]

WWest got a swift kick outta here a year or so back. It is rumored that he landed in a mental hospital in Serbia.

Tom

[SOMEONE ELSE'S GOT MY NAME]

WWest got a swift kick outta here a year or so back. It is rumored that he landed in a mental hospital in Serbia.

Tom

It's over a year after the fact, but I never DID understand the reference to "converting the ICE to atkinson" .l.. so a few months ago I read up on what the heck that is. Seems the atkinson ICE differs from a traditional ICE in that they complete all 4 strokes (intake compression power exhaust) in one revolution of the crankshaft instead of two. Also, 2 of the strokes are different lengths, instead of all 4 being the same length. It's a completly different ICE ... so you can't simply convert from one to the other. You can replace 'em all together, but you can't convert 'em. Maybe that's what wwest actually meant. I only did the read in the atkinson because the 2010 RXhybrid is supposed to have one, and I wanted to understand the difference:

http://www.caradvice.com.au/24062/2009-lex...hybrid-at-mims/

And in its most basic design, here's an animated atkinson:

http://www.animatedengines.com/atkinson.shtml

You can be sure the Lexus won't be that simple :P