This was "pulled" from another thread that JetTech was "in".

Just some more info:

Here's a pic of the Coolant By-Pass Mod that I did to my truck. At your local auto parts store buy a package of 5/16" Rubber Caps and 1ft. of 5/16" rubber hose. And if your a little leery of the stock hose clamps that Nissan uses, like myself, you can also buy 2 small hose clamps like you see in my picture.

EDIT: One thing I forgot to write is you need to remove your intake shroud before doing this. Ok, now the instructions...

First place a towel or rag under the throttle body to catch what little fluid will leak out. Next loosen your coolant cap to release the pressure in the system. Remove the 2 small coolant lines going to the throttle body and install the 2 caps as shown in my pic. Then install the hose, of which you can cut down to length so it isn't flopping around or rubbing on anything. Your just re-routing the fluid back into the system and bypassing the throttle body.

Now I have no idea if this helps or not with power, I've seen several dyno sheets from Camaros where they were gaining 5 to 7hp by doing this. I can't tell a difference but it's a quick easy thing to do and it won't have a negative effect as to how your truck runs no matter what your climate is.

Theory of this mod is, that by removing the hot coolant that is circulating around the throttle body, you create a cooler denser air charge entering the intake, thus MO POWER!!! BUT....the part that I have a doubt about is the fact that the air has already been sampled by the MAFS upstream of the throttle body, so how does the ECU know to add more fuel due to this cooler and denser air??? Things that make you go hmmmm. Oh well, here it is. If the picture is too small the full size one is available on my pixagogo site.

http://www.pixagogo.com/S5jyPZI7SzD9CwJPPyeh1h7!QCDU-N5x1b7H16fG53RRspYtHLoUxUdGSk!1l09xzdOcLyhCsRmH9pm nPbfV!Dp2sU7FD2TTIfRj8!-cpZ!mg_/Coolant_Bypass_Mod.jpg

Thanks firecracker for moving this thread. I meant to do this many moons ago but it obviously slipped my mind... :oops:

Although this is not the time of year to think about this. What you have done is remove what we reciprocating engine flyers call carb heat. Yes, I do know that it is not very common, but that is due in the most part of the location of that valve (which it is). Most TB/Carbs are located on top of the engine, no need for external heat, this TB is in a partially unheated air stream (OK argue with me, IT is an educated threory). But, I will agree that removing the heat from the engine intake air will increase HP. A perfect example of this is, when a pilot aplies carb heat to a carburated engine (fuel injected piston engines do not have this feature) there is a very noticeable loss in available power.
Just food for thought, if you live in the northern states, you might want to reconnect during the cold season, or not do this mod at all. I might do it, but then I live in Florida and need to outrun hurricanes!
Yall have fun now,

Bert

So do you guys think there is any real threat of icing up the TB for those of us in cooler climates?? I've been thinking of doing this for some time, just haven't got around to it yet.

I did the throttle body - coolant bypass yesterday... Don't even have my CAI yet, but I just felt like getting under the hood and doing something....

So do you guys think there is any real threat of icing up the TB for those of us in cooler climates?? I've been thinking of doing this for some time, just haven't got around to it yet.

I doubt you'll have any problems rocky. I had this mod done on my first Titan, of which I took to Maine in Feb. 04. I don't remember the exact temps. that it was when I was there but it's safe to say anywhere from -25 to 20'F. It didn't hiccup once during that time so I believe you'll be fine if you live in a cold/cool climate.

any reason why you just can put caps on all the fittings, rather than put on the bypass hose??

also, the ecm probably makes adjustments from reading the 02 sensors measuring air/fuel ratio.

any reason why you just can put caps on all the fittings, rather than put on the bypass hose??

Good question......Give it a try and let us know...

also, the ecm probably makes adjustments from reading the 02 sensors measuring air/fuel ratio.

That's exactly right, good catch....

also, the ecm probably makes adjustments from reading the 02 sensors measuring air/fuel ratio.

That's exactly right, good catch....[/quote]


hey my brain acually did sumthin good, whoa! lol

well, i did just put on the bypass hose like everyone else because my mind started thinking,,

because i dont know how much pressure there may be going through the system, i figure those little caps just may not handle it

Going to do mine in a little while. I also bought the $26 spring mod kit. As long as the rain holds off/quits in a little while, I'll do the mods. I'll post more later!

Well...Mod complete! Easy mod with minor mess. For those who do this in the future. Be sure to TAKE CAP OFF to release pressure and go ahead and have your new hose ready. The more time that's spent w/o a hose...the more mess. I finished the mod and rinsed off the engine with the water hose real quick. I did go ahead and buy new clamps just for good measures. Thanks for the idea. Hope it helps in the NC heat!

:flamer:

So do you guys think there is any real threat of icing up the TB for those of us in cooler climates?? I've been thinking of doing this for some time, just haven't got around to it yet.

I doubt you'll have any problems rocky. I had this mod done on my first Titan, of which I took to Maine in Feb. 04. I don't remember the exact temps. that it was when I was there but it's safe to say anywhere from -25 to 20'F. It didn't hiccup once during that time so I believe you'll be fine if you live in a cold/cool climate.

Thanks, JT...it's officially on "the list"!

Well...Mod complete! Easy mod with minor mess. For those who do this in the future. Be sure to TAKE CAP OFF to release pressure and go ahead and have your new hose ready. The more time that's spent w/o a hose...the more mess. I finished the mod and rinsed off the engine with the water hose real quick. I did go ahead and buy new clamps just for good measures. Thanks for the idea. Hope it helps in the NC heat!

:flamer:

Thanks for the heads up!

It'd sure be nice to be able to take a bef/aft temp reading in the intake plenum to see how much it drops the temp. I haven't looked to see if there's anywhere to sneak in my little thermistor wire on my Fluke to check it before doing mine (JT, or anyone else know?)....I really don't want to drill my plenum.

I really don't know. But yeah, that's a great idea to get that reading. I'm very curious. I think this mod was the cheapest one yet. When/if you discover the gain (in form of degrees) let us know. Below is what I paid today for this. Thanks...

AutoZone:

5/16" Vacuum Caps-4 pk._____$1.59
1' 5/16" hose_______________$1.14
5/16" hose clamps-4 pk._____$1.97

There ya go...couch change! :money:

I really don't know. But yeah, that's a great idea to get that reading. I'm very curious. I think this mod was the cheapest one yet. When/if you discover the gain (in form of degrees) let us know. Below is what I paid today for this. Thanks...

AutoZone:

5/16" Vacuum Caps-4 pk._____$1.59
1' 5/16" hose_______________$1.14
5/16" hose clamps-4 pk._____$1.97

There ya go...couch change! :money:

Thanks for the parts list!

Well...Mod complete! Easy mod with minor mess. For those who do this in the future. Be sure to TAKE CAP OFF to release pressure and go ahead and have your new hose ready. The more time that's spent w/o a hose...the more mess. I finished the mod and rinsed off the engine with the water hose real quick. I did go ahead and buy new clamps just for good measures. Thanks for the idea. Hope it helps in the NC heat!

:flamer:

i moved down here to NC about a year and a half ago,

DAMMIT ITS HOT!!!! LOL

What if you could route something cold through the carb heater path? Something like freon from your A/C?
Or am I just in left field here..

What if you could route something cold through the carb heater path? Something like freon from your A/C?
Or am I just in left field here..

Sounds like it COULD work even better, huh? JT, what do you think?

It would certainly be nice to cool down the intake air, starting with the air coming into the air-box itself. Cooling the T/B down by itself would help, although I think using freon would freeze it up quickly. I dunno......it's ideas like this one that create more ideas down the road, so who really knows until someone gives it a try.... :D

It sounds good, but in my head that whole extreme HOT vs. extreme COLD could warp or maybe crack something. But that's only if you run it to the metal TB itself. If you could supplement a bypass hose from a line going into the cab, that would supply extra air to a hole in the air box, that would be most efficient i would think. Only thing is, you couldn't run it in the winter, b/c you want the heat on...same time though, would you need it b/c the cold air was already coming in?....Things that make you go hmmm.

I did this bypass today....well, sort of. Instead of re-routing the coolant hoses, I decided to just install a small in-line ball valve instead. This allows me to close it during warmer weather, while still giving you the option to open it in cold weather. I'll post a pic or two, if anyone wants me to.

Also, I did some bef/aft temperature differential testing to see how much temp rise there is across the TB at various rpms, wot, etc. Pretty interesting results...I'll try to post them tomorrow.

Yeah, post those pics and explanations please.

Yeah, post those pics and explanations please.


ditto

maybe put sum nitrous through there, hehe

yeah, with the whole freon through the TB dry nos kit came to mind lmao

you know what they say, great minds think alike.

i think nitrous would probably freeze it up too tho

Anybody having problems with their caps staying on after doing this mod?

Anybody having problems with their caps staying on after doing this mod?

The caps I installed almost a year ago are still hanging in there. I've got just the T/B itself capped so there is no pressure there. I just capped it to keep the elements out of there and give a cleaner look.

Anybody having problems with their caps staying on after doing this mod?

The caps I installed almost a year ago are still hanging in there. I've got just the T/B itself capped so there is no pressure there. I just capped it to keep the elements out of there and give a cleaner look.

Mine is done exactly like the picture at the start of this thread. I went and bought different caps yesterday and changed them out. We'll see if that works...

Thanks Dale..

The coolant going through the throttle body is to keep it from freezing.

Believe me, it can happen. Chrysler had a recall just for that not too many years ago.

Air going through the throttle plate at high speed creates humidity/condensation around the throttle body/plate. This will/can freeze. Keep in mind that your throttle plate is operated by a motor, not a cable any more.

Want to take a chance of your throttle sticking wide open? Id rather not.

As far as horsepower gains... I had an 87 iroc z camaro with the 5.7 litre. I did this mod and did a before and after on the dino... It ONLY made a slight difference when engine was cold... but.. when the engine was hot... it didn't make a difference at all...

Your IAT sensor is already going to tell the ECM what tempature the air is coming in at well before the air hits the throttle, and think about this... the air is moving at such speed/volume, it has no time to heat up cause a throttle body is heated.

In my book... not worth the risk...

You made some good points. I am keeping the mod, but am going to put that valve in like Rock, so when it get's cold, I'm covered.

What's the link to those pics Rock???

Here it is:

http://www.clubtitan.org/postlite6417-coolant.html+bypass

I'll see if Josh will move this to the DIY section to give those of us in cooler regions an option on this mod.

It's moved.

Thanks!

It's moved.

Thanks, Cracker!

Hahahahaha......Cracka!