TB Hot water bypass

Finally got around to doing a hot water bypass on my 07's throttle body. It didn't increase mpg's but has a noticeable increase in high rpm torque.
The Prius like most other cars produced in the last 15 years has coolant piped through the throttle body to warm it up and keep it warmed up. Its sole purpose is to prevent the tb from freezing in sub zero temps and sticking the butterfly closed or open. A bad byproduct to this is its warming up intake air. A bad thing for performance.
You just pull the coolant lines off the body...using a small metal tube of appropriate size ( 3/8 o.d.) you then connect both coming and going coolant lines together and pipe clamp the rubber hoses to the tube. Done. Very easy. The intake now delivers much cooler air and its post maf so there's no mass error in temps. The motor just likes cooler intake air.All motors do.
I live in Florida and never see freezing temps. I've done this common mod to every car ever owned down here and it really helps the performance without affecting emissions. The car runs perfect when cold but after warm up when your doing about 70 and crack open the throttle a little to pass you will notice much better pick up. Its really noticeable in the dead of summer when its 99-100 out. The car then runs awesome. I'm not recommending anyone do this as you have to have some mechanical skills and you can't do it in a freezing climate but down here its worth the trouble. And its free! Now where did I put my flame proof suit?

 

Thank you! I wish I could say it was my idea but its pretty common isn't it?
Yes don't do that in Quebec (beautiful city btw) as the tb will surely freeze up as you know. I can't wait till summer as I bet the Prius will run really good with cool intake. I would really like to get a CAI for it also but the way they've positioned the maf sensor rules out a simple install. Its mounted in the airbox itself almost in the throttle bore. It would take some wicked surgery to do it right for not alot of HP gain I'm afraid. Or a complete re-location of the maf further up the pipe away from the carb as most cars have. I suspect Toy ended up putting the maf sensor there as a space saving thing not a strategic airflow position.

 

Yes that should be no problem. Its the wicked freezing temps that freeze up the throttle body butterfly and exactly my thoughts with a EBH too.Its a great performance mod with no ill effects at all. The car runs great! Not one hiccup. Can't wait till summer! Its easily done if you have a needle nose pliers with extra long jaws to grab the release tabs on the factory hose clamps. Just squeeze them together and push them down the hose off the metal stems. Then the hose pulls right off the stem. I then pulled off the factory pressure clamps and used regular hose clamps and saved the originals for possible restoration. I happened to have a 3/8's o.d. stem to connect them together. You will have to find a metal 3/8's piece of pipe about 2 inches long.You will lose about a pint of coolant from it dripping out. I put a pint of Water Wetter back directly back in the radiator. Same color as factory coolant! Whole job takes 20 minutes.
I have an 07 and if every thing goes the way I hope this car will never see the inside of a dealer service area. If god forbid it needs dealer service I will put it back together.
Right now my MFD says 46 mpg's average and that includes daily 75-80 mph for 30 minutes commute. if I crawl at 55 to work back & forth I can get about 49. That has not changed with this mod but expect excellent performance in the dead of summer.Good luck!

 

Sir:
You are clearly one of the resident guru's on this site and I have always enjoyed all your posts but please allow me to reply respectfully:

Firstly I mean no harm. This tb bypass is something myself and just about any gearhead I know down here in Florida does to there cars. Hot water in the tb serves no purpose down here and really eats performance.On a mildly souped up import the difference is quite noticeable in extreme heat. I doubt you'll see much difference anywhere else but in an area where its 100 degree's everyday it really helps. You yourself did an excellent study on the negative effects of induced hot air. Thats not just a Prius effect. No car on the planet will run better with hot intake air.
Way to much air volume? On the contrary given the very small diameter of the tb throat and the heavy filtering and the angularity the Prius intake system looks to me like large air flow was not important to Toy engineers.This is a tiny motor. Or at least the smallest motor I've ever owned. I think where this mod will benefit is not only is the TB now cool but the entire intake is cooler. Whatever the air volume thats flowing here I can guarantee you the air charge is now cooler. And my car runs excellent. It has more high end snap than it did and has shown no negative effects to this $0 cost mod. I expect the car to run like a scalded cat come 110 degree July/August weather. It gets so hot down here you can't touch the hood to open it. I had hoped to get another benefit in that now the coolant was no longer heat sinked through the intake I would achieve warm up quicker but not sure how to test bed that. I have ordered a Scan Gauge and expect it to arrive tomorrow.
And strange chemicals? Not sure if your referring to Water Wetter. Thats been on the market a long time and is an excellent product. Its red just like the existing coolant! Been using that for years and so has just about everyone else I know. Best product out there as a rad additive.

 

Good to see a VT poster. I grew up in VT. Lived in Bennington,Arlington & Ludlow & Plymouth (by Woodstock/Killington) Would love to run my Prius up there! That would be a blast!
But as mentioned earlier automatic valve aside this mod would have a negative effect in the cold icy Vt winter. You would need that TB de-icing up there for sure but like I said before this is strictly a regional thing. Down here in Fla mid summer it really helps whatever the dyno says. Its a very common thing. If you don't believe me just Google "Hot water bypass". Its a must do for Ford Ranger trucks for instance to stop pinging. Not sure why there's such a negative response here. It's no big deal. At the very least I have taken alot of heat off the throttle body and the throttle body motor itself which has to extend there life.And the car seems to love it.

 

Oh its a lot lower than that. I measured 116 degree's with my laser thermom before the bypass at the TB throat itself. After the bypass I can hold my hand on the tb after a good highway run. I did not test the temp with my laser 'cause I had left it at home but will do a test tomorrow.Also I'd like to try the re-location of the intake like you did but my 07 intake tube does not disconnect anywhere. The intake tube comes out of the air cleaner housing...goes through a little accordion joint and then makes a sharp curve terminating in a little box with intake hole pointing at the WW fluid tank. I'm sure that whole box network is designed to quiet the intake noise also. Please elaborate.Thanks.