Throttle Body Coolent Bypass

Hi,

Has anyone doen the Throttle Body Coolent BypassCoolant Bypass

Most Fuel Injected engines have a line with coolant going into and out of the throttle Body (TB) right by where the throttle plate is. The reason for this is to de-ice the TB and to preheat the air during start up. This is great for people in colder climates, but it actually robs us of power in every other climate. For every 10 degrees of temperature change in your air you will gain or lose 1% of your engines potential horse power. This coolant bypass will effectively lower your intake air charge temperature and thus increase your hp. We have had varying results from this cheap modification, and have heard reports of people gaining as much as 20 hp on their larger displacement engines (V8’s).

Doesn't the Jazz have a plastic intake manifold and throttle body? I thought that alone would ensure a cooler intake charge.

No, its a metal one, and Kimo is right, there is little use for the coolant in the TB when you're in a hotter area of the world with no freezing winters. So I'd prolly just bypass it.

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Originally Posted by strepto

No, its a metal one, and Kimo is right, there is little use for the coolant in the TB when you're in a hotter area of the world with no freezing winters. So I'd prolly just bypass it.

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Today it's 38c back here :D

So the throttle body is metal but the intake runners and plenum are plastic? It looks plastic.

http://asia.vtec.net/Series/FitJazz/...hoto/iDSI2.jpg

It looks as is the intake is coated metal, but its kinda hard to tell.

Its definetly plastic. Says so on the Honda website.

http://www.honda.com.au/jazz/vti/=te...tec+engine.htm

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Powertrain: 1.5-litre VTEC engine
Power: 81 kW @ 6,000 rpm | Torque: 143 Nm @ 4,800 rpm

Honda has developed a light, compact engine quipped with a roller coaxial VTEC system and aluminium rocker arms, and it shares technology with the Insight and i-DSI engines to achieve maximum fuel efficiency.

Honda engineers sought to develop a SOHC, 16-valve, 1.5-litre VTEC engine with the best balance of power output, fuel efficiency and ultra-low emissions.

The Jazz 1.5-litre engine has a peak power of 81kW @ 6000rpm and 143Nm @ 4800rpm, and achieves Low Emission Vehicle (LEV) status.

Numerous measures were taken to reduce friction, including an offset cylinder design, roller type rocker arms, low tension and ion plated piston rings, streaked main and connecting rod metal bearing and blade-type chain tensioner.

To minimise the engine's weight and dimensions, the engineers designed the 1.5-litre VTEC engine with a compact cylinder head, hollow camshaft, plastic intake manifold and stainless pipe exhaust manifold.

The air-conditioner compressor is mounted on the oil pan to make the best use of the compact engine bay. The 1.5-litre engine also has a front intake and rear exhaust layout to maximise space.

The cylinder block has uses an offset design, which means the crank pin axis and the piston pin axis are both offset from the cylinder's centre line so that the piston's side force is minimised at the piston position where the combustion reaches its peak. This allows a minimum of friction loss.

Another benefit of the offset design is lower fuel consumption - the piston speed is relatively slow in the first half of the expansion stroke, which improves thermal efficiency and, as a result, lower fuel consumption.

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Originally Posted by racinghonda

So the throttle body is metal but the intake runners and plenum are plastic? It looks plastic.

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intake is plastic

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Originally Posted by muli

intake is plastic

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So there is no use to do the bypass

On the oposite! Theres even MORE use for it!

wat abt in australia? cold most of the time yet summer is so hot.... plus how to do the byass???

Mate Australia is not cold most of the time....Alot of Europe is cold most of the time, but not Australia.

Unless you are living inland (or Tassie), you are lucky if the temps get any lower than 5 degrees. Even Melbourne is not really that cold in comparison.

So have you tried it with your car Kimo?

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Originally Posted by Jus-10

Mate Australia is not cold most of the time....Alot of Europe is cold most of the time, but not Australia.

Unless you are living inland (or Tassie), you are lucky if the temps get any lower than 5 degrees. Even Melbourne is not really that cold in comparison.

So have you tried it with your car Kimo?

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No I didn't maybe I should as where I live is damn hot it's like 37c today. :D

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Originally Posted by Jus-10

Mate Australia is not cold most of the time....Alot of Europe is cold most of the time, but not Australia.

Unless you are living inland (or Tassie), you are lucky if the temps get any lower than 5 degrees. Even Melbourne is not really that cold in comparison.

So have you tried it with your car Kimo?

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I didnt think further when i wrote that comment.... Melbourne, I mean is cold mnost of the time.....how long is the summer in Melbourne??? max like 4 months..... in these 4 months, how many % really really hot???? i would say less that 60%.... hot 3 days, cool down for 2 to 3 days....

anyway this is not important, all i wanna know is, useful 2 do the bypass????

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Originally Posted by Zimp13

Melbourne, I mean is cold most of the time.....how long is the summer in Melbourne??? max like 4 months..... in these 4 months, how many % really really hot???? i would say less that 60%.... hot 3 days, cool down for 2 to 3 days....

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how long have u been in melbourne? :D
http://us.i1.yimg.com/us.yimg.com/i/...c_logo2_sm.gif

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Originally Posted by spoon fit

how long have u been in melbourne? :D
http://us.i1.yimg.com/us.yimg.com/i/...c_logo2_sm.gif

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u saying that i m wrong???? i live in melb and i dunno???? :rolleyes:

no, juz ask

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Originally Posted by spoon fit

no, juz ask

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hehehehe.... :D

Hi,

I have done it, and it works, the car feels better, and the responce is faster.

kimo, how did u actually bypass the thing?

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Originally Posted by crankshaft

kimo, how did u actually bypass the thing?

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I just took off the coolent hose that goes to the TB, and blocked it from inside with a screw nail and put it back, so it looks like before.

Check : http://www.2003corolla.org/diy.php?diy=16

did u take any pics during the process kimo? a write up would b good :)

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Originally Posted by STTICH

did u take any pics during the process kimo? a write up would b good :)

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No I didn't get any photo, will it's so simple, just take off the hose and block it from inside and return it again back to TB, so when you go to the dealer they wouldn't know.

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Originally Posted by kimo

No I didn't get any photo, will it's so simple, just take off the hose and block it from inside and return it again back to TB, so when you go to the dealer they wouldn't know.

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would it affect the coolant cycle when that hose is blocked? the hose connected to the TB, i assume that the coolant would travel to the TB and where does the coolant go from the TB?

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Originally Posted by Zimp13

would it affect the coolant cycle when that hose is blocked? the hose connected to the TB, i assume that the coolant would travel to the TB and where does the coolant go from the TB?

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To be honest I didn't think of that. I will check and see.

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Originally Posted by kimo

To be honest I didn't think of that. I will check and see.

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Kimo,i had a look at the TB just now... there are 2 hoses next to each other.... i believe that one hose is for the coolant to enter the TB and the other hose if for the coolant to exit the TB... wat i did was unplug these two hoses and joint them together.... so instead of circling into and out of the TB, this should bypass the TB and the circulation of the coolant is not affected.... also, i seal the two holes from the TB so that dirts or watever wont enter into those holes... as for the effect, i just took the car for a drive.... it feels lighter.... but dunno if drive long distance though... :thumbsup:

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Originally Posted by Zimp13

Kimo,i had a look at the TB just now... there are 2 hoses next to each other.... i believe that one hose is for the coolant to enter the TB and the other hose if for the coolant to exit the TB... wat i did was unplug these two hoses and joint them together.... so instead of circling into and out of the TB, this should bypass the TB and the circulation of the coolant is not affected.... also, i seal the two holes from the TB so that dirts or watever wont enter into those holes... as for the effect, i just took the car for a drive.... it feels lighter.... but dunno if drive long distance though... :thumbsup:

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Right I just came from my friend shop, and we did exactly what you did. But will put them back if I go to the dealer.
So what you think about I felt the car better but want to share other people experince. Is there any side effect on that.

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Originally Posted by kimo

Right I just came from my friend shop, and we did exactly what you did. But will put them back if I go to the dealer.
So what you think about I felt the car better but want to share other people experince. Is there any side effect on that.

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The throttle feels a lighter and more responsive but i just took it for a spin... probably next longer distance travelling so i would know for sure... plus its winter here.... u guys mentioned will b better if weather is hot rite?

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Originally Posted by Zimp13

It feels a bit lighter but i just took it for a spin... probably next longer distance travelling so i would know for sure... plus its winter here.... u guys mentioned will b better if weather is hot rite?

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Will it's hot here about 37c, will it effect in fuel consumption.

Ya now all my friends are doing it all kind of cars.

I did the coolant bypass in my aristo turbo too. The effect is a lot bigger on turbo cars.... I might do this on the Jazz too. ;)

i found the rpm becomes lower and sort of a bit unstable on my jazz....

what exactly do u mean by rpm became lower? please explain in more details.... :) thank you.

idles too low?

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Originally Posted by muli

idles too low?

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yeah idle lower... plus a little bit unstable....

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Originally Posted by MRFIT

what exactly do u mean by rpm became lower? please explain in more details.... :) thank you.

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u wan 2 try joey? may be works better in a manual jazz... i dunno.....