TOM'S Linear Throttle System "L.T.S."
07-28-08, 12:40 PM
#17
Lexus Test Driver
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I read somewhere that the throttle in the IS350 doesn't necessary open up all the way when WOT, only like 70% until you reach around 4-5k RPM, then it opens up all the way. Is that what this corrects? Or am I wrong on both?
07-28-08, 02:25 PM
#21
In general, its not going to improve performance by itself. But this in combo with an intake, exhaust, & some good DA will improve the driving feel of our dulled out IS's. This car has been numbed badly compaired to the previous IS300.
07-28-08, 04:17 PM
#22
As Kurtz said above, these devices can't improve performance. They can only make the pedal look to the ECU like it's pushed further to the floor. If you want to make the throttle plate open more / faster, all you need to do is push the pedal more / faster.
07-28-08, 05:48 PM
#24
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What most of you guys don't understand is the throttleblade shouldn't open instantly. It should only open fast enough to maintain sufficient intake velocity so the engine doesn't bog.
If you've ever owned a motorcycle with manually controlled slides you'd know what I'm talking about. My ancient FJ1100 came from the factory with vacuum operated slides. You could whack open the throttle at will with nothing to worry about because the slides wouldn't lift until there was enough velocity to change the pressure ratio across them. So I ditched the OEM carbs for some Keihin CRs (the baddest carbs available at the time) in 37mm trim. They worked really well, except for one thing: if you hit WOT below 4000 rpm, the engine stumbled, coughed, and would eventually die if you didn't close the throttle. There were two reasons for this - first, the airspeed through the carburetors was too slow so the cylinders would not fill, and second since the airspeed was low the fuel would dribble out of the metering jets instead of making a mist. So the engine coughed and died instead of pulling the front wheel off the ground and clawing at the stars (which it did as long as rpm was over 4k in three gears.)
So, Toyota know they want good performance from 3.5 liters. To do this, the intake had to flow enough to make 306 hp with the throttle at WOT. Making the throttle big enough to do this means if you open it too quickly the engine will bog. So they took control of the throttleblade away from the user and gave it to the ECM so the ECM could ensure (under all foreseeable conditions) the throttleblade doesn't open too fast and cause bog. In their typical fashion, they designed the system with exceptionally conservative settings so the likelihood of warranty complaints is very small.
Toms came along and said there's room for improvement, so let's make a gizmo with more aggressive profiles to get a little more responsiveness out of this engine. Ultimate power does not change (WOT is WOT no matter what), but (possibly) area under the curve could change (a little more low-mid range power).
The same is true for the fuel system. Toyota's settings are extremely conservative at anything over 75% load because they know it's possible there could be a problem with an injector or a hose cracking or some other small issue that could cause a lean condition. So they set the fuel maps to provide a LOT more fuel than is necessary because if the engine is going to die quickly it will die quickly at >75% load if fuel goes lean. Hence the standard rich fuel maps from ALL the manufacturers.
There's power and responsiveness intentionally removed from your car. It's done this way to ensure you don't have an unnecessary warranty claim. If your goal is "best performance" as measured in hp, then you want something different. If your goal is "best performance" as measured by minimal warranty claims, then you do what Toyota (and all the other manufacturers) did.
If you've ever owned a motorcycle with manually controlled slides you'd know what I'm talking about. My ancient FJ1100 came from the factory with vacuum operated slides. You could whack open the throttle at will with nothing to worry about because the slides wouldn't lift until there was enough velocity to change the pressure ratio across them. So I ditched the OEM carbs for some Keihin CRs (the baddest carbs available at the time) in 37mm trim. They worked really well, except for one thing: if you hit WOT below 4000 rpm, the engine stumbled, coughed, and would eventually die if you didn't close the throttle. There were two reasons for this - first, the airspeed through the carburetors was too slow so the cylinders would not fill, and second since the airspeed was low the fuel would dribble out of the metering jets instead of making a mist. So the engine coughed and died instead of pulling the front wheel off the ground and clawing at the stars (which it did as long as rpm was over 4k in three gears.)
So, Toyota know they want good performance from 3.5 liters. To do this, the intake had to flow enough to make 306 hp with the throttle at WOT. Making the throttle big enough to do this means if you open it too quickly the engine will bog. So they took control of the throttleblade away from the user and gave it to the ECM so the ECM could ensure (under all foreseeable conditions) the throttleblade doesn't open too fast and cause bog. In their typical fashion, they designed the system with exceptionally conservative settings so the likelihood of warranty complaints is very small.
Toms came along and said there's room for improvement, so let's make a gizmo with more aggressive profiles to get a little more responsiveness out of this engine. Ultimate power does not change (WOT is WOT no matter what), but (possibly) area under the curve could change (a little more low-mid range power).
The same is true for the fuel system. Toyota's settings are extremely conservative at anything over 75% load because they know it's possible there could be a problem with an injector or a hose cracking or some other small issue that could cause a lean condition. So they set the fuel maps to provide a LOT more fuel than is necessary because if the engine is going to die quickly it will die quickly at >75% load if fuel goes lean. Hence the standard rich fuel maps from ALL the manufacturers.
There's power and responsiveness intentionally removed from your car. It's done this way to ensure you don't have an unnecessary warranty claim. If your goal is "best performance" as measured in hp, then you want something different. If your goal is "best performance" as measured by minimal warranty claims, then you do what Toyota (and all the other manufacturers) did.
07-28-08, 07:28 PM
#26
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The Power mode, normal mode, and Snow mode all work just the same way as the TOM's throttle system. I was in my car today. While I was parked in neutral, I revved up the engine to 2500 RPM. At the same throttle position, I then pushed the power button and it went to 3000-ish RPM. So, there's basically no point in TOM's throttle when we already have that feature on our cars.
07-28-08, 10:44 PM
#27
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07-29-08, 10:26 AM
#28
Lead Lap
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The signal is basically being amplified when it goes to the ECU. It's bypassing the part that says "open at this rate" and opening it a bit faster.
Hopefully Ryan can get a few 1/4 runs in w/ the unit so we can get an idea if it really helps at all. Again, it doesn't increase the power output, just the response of the throttle.
So Ryan... when are you picking it up??X!
Hopefully Ryan can get a few 1/4 runs in w/ the unit so we can get an idea if it really helps at all. Again, it doesn't increase the power output, just the response of the throttle.
So Ryan... when are you picking it up??X!
07-29-08, 11:48 AM
#29
Not if it goes between the pedal and the ECU.
All it's doing then is saying "The pedal is THIS far down" when it's not really quite that far down.
Which doesn't bypass anything and does the same thing that just pushing the pedal further down would do.
I think we can beat this dead horse a little bit more!!