TB Hot water bypass

[edthefox5]

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?

[SyCo]

Good idea. I've done the same thing with my Honda which I only drive during summer.

Unfortunately I cannot do it with my Prius since winter in Quebec are always below 0c...a lot below
It is interesting to know that it has a positive effect on the Prius also.

[edthefox5]

Originally Posted by SyCo

Good idea. I've done the same thing with my Honda which I only drive during summer.

Unfortunately I cannot do it with my Prius since winter in Quebec are always below 0c...a lot below
It is interesting to know that it has a positive effect on the Prius also.

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.

[NoMoShocks]

I found this information very interresting. I assume it would also be OK to make this mod if the temperatures rarely go below freezing like maybe down to about 29 three of four times a year? Seems like having my Engine Block heater plugged in would transmit enough heat through the castings for my situation.

Would I want to reconnect the hoses if I took the car in to a dealer for warrantee work?

[edthefox5]

Originally Posted by NoMoShocks

I found this information very interresting. I assume it would also be OK to make this mod if the temperatures rarely go below freezing like maybe down to about 29 three of four times a year? Seems like having my Engine Block heater plugged in would transmit enough heat through the castings for my situation.

Would I want to reconnect the hoses if I took the car in to a dealer for warrantee work?

Hi,
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!

[statultra]

hey how did u bypass it, did you disconnect those two hoses from the throttle body, and connected them together with one of those brass fittings?

[donee]

Hi All,

You know, one might get a thermostatic valve, that senses the temp of the trottle body, and lets coolant flow through the TB whenever the TB is below say 50 F. Sounds like something you might be able to get at McMaster Carr, or on EBAY.

[Pinan]

edthefox5: Pictures?

[statultra]

im about to do this mod with a copper tubing, i live in southwest florida so i think this would benefit me greatly

[hobbit]

I find it astounding that anyone would even consider the
available surface area around the throttle throat nearly enough
to significantly warm the air passing through it. I got news
for ya: it ain't. The only difference you observed was the
placebo effect hard at work. There's generally *way* too much
air going through there to make a single, low-volume turn of
coolant do anything more than, as noted, de-ice the thing.
.
And I won't even get into the issue of introducing strange new
chemicals into your cooling system...
.
_H*