TB Hot water bypass

[donee]

Hi Hobbit,

Your probably (more than probably) right about the the throttle body effecting the intake air temp.

My unspoken thought was that a thermostatic valve would reduce heat loss from the coolant. Like you say there is way too much air going through that throttle body to heat up the air much. But conversely there is plenty of air to cool the throttle body, and the coolant flowing through. I would not put it past Toyota to actually have a bimetallic valve in the valve body itself.

[edthefox5]

[quote=Pinan;567101]edthefox5: Pictures?

Here you go:...I hope...having trouble loading pics...

[edthefox5]

Originally Posted by 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*

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.

[Pinan]

Originally Posted by edthefox5

Here you go:...I hope...having trouble loading pics...

Thanks for that.

[F8L]

We've tested this mod on the dyno and never seen any real quantifiable benefits to it other than reducing the likelyhood of having a gasket break and leak coolant into the TB and this is only on older cars. So far I don't know anyone that has shown and real evidence in either HP or in the 1/4mile to warrant doing this mod. Sure there is anecdotal evidence but generally the people making such claims do not understand the scientific method and rarely look at other variables in the "test" if they have even truely tried to perform one.

This is not a slam on the OP but after doing this mod on numerous cars and seeing dyno results for all sorts of "free mods" as we drag racers like to call them, I am not inclined to believe that there is any measurable gain from it. I will admit I have never seen a Prius dyno test this mod so I could be wrong but.....

[bruceha_2000]

Originally Posted by edthefox5

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.

Curious, I wonder if it is related to terrain. I would have expected my up and down hills driving (since you don't get as much back on the down hill as you used getting up the hill) to have a lower differential between 55 and high speed driving but I see mid 50s at 55 MPH and mid 40s at 65 MPH.

Now back to the topic. If this is TB bypass idea is good, why couldn't it be a built in bypass, with a thermostat so it is automatic based on temperature? Lots of people complain that they need more power (no matter what they drive) so this seems perfect since it is a little extra oomph with no loss in fuel efficiency.

[ken1784]

Originally Posted by F8L

We've tested this mod on the dyno and never seen any real quantifiable benefits to it other than reducing the likelyhood of having a gasket break and leak coolant into the TB and this is only on older cars.

I second to F8L's opinion.
I think we need some real numeric data.
Assuming Prius Atkinson cycle engine's intake volume is one liter, its breath volume is 1000 liters per minutes at 2000 rpm. It's huge!
How much temperature increase can we see at the 2000 rpm when the warm coolant path is connected to the TB?
The TB has no aggressive structure something like heat transfer fins.
I believe we can't see any intake air temperature difference whether the coolant path to the TB is cut or not.

Anyway, if anyone has some real numeric data, please let us know

Ken@Japan

[statultra]

considering IAT is based on ambient temp, i would think doing the water by pass it would lower the temp by 2-3 degrees. Ive seen my IAT peak at 110 at some point. Since i had my air intake hose thing pointing on top of the windshield washer fluid tank my intake air temp has stayed at ambient temperature consistently

[edthefox5]

Originally Posted by bruceha_2000

Curious, I wonder if it is related to terrain. I would have expected my up and down hills driving (since you don't get as much back on the down hill as you used getting up the hill) to have a lower differential between 55 and high speed driving but I see mid 50s at 55 MPH and mid 40s at 65 MPH.

Now back to the topic. If this is TB bypass idea is good, why couldn't it be a built in bypass, with a thermostat so it is automatic based on temperature? Lots of people complain that they need more power (no matter what they drive) so this seems perfect since it is a little extra oomph with no loss in fuel efficiency.

Hi,
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.

[edthefox5]

Originally Posted by statultra

considering IAT is based on ambient temp, i would think doing the water by pass it would lower the temp by 2-3 degrees. Ive seen my IAT peak at 110 at some point. Since i had my air intake hose thing pointing on top of the windshield washer fluid tank my intake air temp has stayed at ambient temperature consistently

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.