Just wondering if anyone has done this on their IS? A buddy of mine did it on his 350 and said there was a big temp drop on the throttlebody. He said he was able to touch the TB after driving around without burning his hand where as before the mod, you could probably only touch it for a couple seconds or so. I live in southern California and the winter's here arn't cold enough that the TB would need to be thawed out by having coolant run through it so i'm thinking about doing the mod this weekend. Any thoughts or suggestion? Reasons not to do it? It's also easily reversable.

 

The first question is why?

 

I thought that you want to warm up the throttle body because the car will run better, until it warms up, will warm up faster giving you better performance and better gas mileage.

 

The thottlebody is where the intake system connects to. It contains the butterfly door which opens and closes depending on the position of the throttle. It has no effect of the actual engine temps. What it does effect is the temperature of the intake charge going into the motor. Cooler air is more dense than warm air. The cooler you can get the air the more of it can be drawn into the motor, creating more power. That is why

 

you're on the right track but its not' more air'...thats forced induction. the idea about more dense air is correct though, as cold air is more dense than hot air in the same space. gas + dense air + spark > gas + less dense air + spark. f/i essentially 'turbocharges' (sorry for the pun, hehe) the air to being EXTREMELY dense (if u have a fmic) and then to boot you have the fact the air is compressed into the combustion chamber (the "more air" part)

 

Maybe, just maybe Toyota/Lexus put the heated jacket in because in their extensive testing they encountered a problem with the engine running characteristics. It could be rough idle, stumbling, WOT,...who knows. I know one thing,...they would not have spent any unnecessary money on the engine if they did not have to.

 

All modern cars (or all i've looked at reciently) have coolant running through the throttle body. Its designed to keep the moving parts inside from seizing up in severe (cold) weather which I do not get any of in southern california. Its a very common "free" mod on a lot of cars. I've yet to hear of any negative side effects due to the mod on any other car, so I was just curious about the IS. I'll ask my buddy if he's had any negative effects before I do it on mine, he's had his done for nearly 2 months now.

 

people also did that mod when I had my G35. only minimal gains were obtained. lots of work for not a lot of results.

 

Yeah, thats about what I expect, minimal gains. I don't know how difficult it is on the G, but on the IS it takes just a few minutes. Obviously its a lot easier to do on a cool engine.

 

Could very well be a good mod,...sometimes I wish I were back living in CA too instead of ON

 

Intake icing, which the coolant line through the throttle body is for, is not there to prevent icing in cold temperatures, but to prevent it at moderate temperatures.
Any pilot of small planes will tell you that icing is mostly feared between 45 and 70 degrees.
It is caused by the rapid cooling of air due to venturi effect within the throttle body. Most common in carburetors, but can happen in the TB of injected cars as well. The air cools when accelerating, and the water in the air freezes.
Below 40 degrees, the air contains too little humidity for it to be a problem. Above 75 the cooling isn't enough to cause the water to freeze.
So I would recommend against removing that feature...

 

intake manifold gasket like what hondata offers is probably better, but they only make them for hondas

 

Even if you bypass that 1 hose you still hav coolant flowing threw the intake manifold and the engine. Once the engine warms up your not going to notice any difference in temp. This mod altho free is not making any more HP, so there for pointless even if its free. Might as well remove the floor mats in the car to make it lighter. That mod is also free and will help you just as much.

 

Thanks for the input guys... I will hold off on the mod.