TB Coolant Bypass Mod--With a Twist

RockyMtnTitan · 08-23-2005, 04:13 PM

I posted this over at CT...thought some of you here might be interested.

I was all set to do the JetTech Coolant Bypass mod the other day, when I had a thought.....why not just install a small ball valve instead so that you could heat the TB during cold weather if needed, and then close it for warmer weather to reduce intake temps.

The problem was trying to find a very small ball valve for the application. I went with a 1/4" brass-bodied valve I found in the air compressor accessories section at Lowes. Just install a couple of 1/4" npt X 5/16" barb adapters to each end. Other than that, all you need is about a foot of 5/16" id fuel/heater hose and 4 clamps. Install is straight forward, as you can hopefully see in the pics I've attached.

Intake Temperature Testing:

I did some bef/aft temp testing, measuring intake air temp rise across the TB to see how much this mod reduces the intake temp. I used a fairly accurate and fast acting Fluke 52, dual input digital thermocouple. Temps were taken directly upstream and downstream of TB. Here's a few numbers to digest. Let me know what you all think.

Before: (Motor at operating temp)

Ambient Temp= 85 deg F
Temp Rise across TB after idling for 5 min = 17 deg.
Temp Rise across TB cruising @ 70mph/3300rpm/3rd gr = 7 deg
Temp Rise across TB during 0-90 run @ WOT:
Start = 15 deg rise
60 mph = 2 deg rise
90 mph = 1 deg rise

After: (Motor at operating temp)

Ambient Temp= 87 deg F
Temp Rise across TB after idling for 5 min = 5 deg.
Temp Rise across TB cruising @ 70mph/3300rpm/3rd gr = 4 deg
Temp Rise across TB during 0-90 run @ WOT:
Start = 6 deg rise
60 mph = 1 deg rise
90 mph =.5 deg rise

As you can see, the biggest benefit of this mod is the reduction of intake temp at idle. The temp rise @ WOT was minimal both before and after mod, which makes sense. The air is moving too fast for much heat transfer to take place. But think about all that heat sitting inside the intake plenum at idle....seems like a real low-end torque killer to me. So by taking that 17 deg rise down to about 5 deg has gotta help.

Of special note, I found that the intake temp measured in the tube just before the TB inlet would reach temps as high as 134 deg! Keep in mind this is with an ambient of 85 deg, a Volant CAI, and with the TB coolant valve off. It appears that the plastic intake tube gets heat soaked from the radiator and a/c fan (if on) discharging a lot of heat across the tube, as it is directly in the flow path. This temp does not cool down instantly after opening the throttle (other than wot). It took several minutes of driving around to see the temp come down. I know thick-walled plastic is a pretty good insulator, but in the event it does get heat soaked, it takes a while to lose that heat. Aluminum, though, would probably heat up quicker (and more), but would dissapate quicker. I may try to insulate the tube, if I can find something that looks good....cuz that's important...lol!

Sorry for the long post...hopefully someone else finds this stuff as interesting as I do.

Titan4x4Aggie · 08-23-2005, 04:34 PM

So I'm guessing the value is so you can open it during cold (ambient air) periods and still have it operate as designed?

Seems smart. I like it, and maybe I will have to do this.

Parts list and price???

Finnattic · 08-23-2005, 04:52 PM

Quote:

Originally Posted by RockyMtnTitan

I posted this over at CT...thought some of you here might be interested.

I was all set to do the JetTech Coolant Bypass mod the other day, when I had a thought.....why not just install a small ball valve instead so that you could heat the TB during cold weather if needed, and then close it for warmer weather to reduce intake temps.

The problem was trying to find a very small ball valve for the application. I went with a 1/4" brass-bodied valve I found in the air compressor accessories section at Lowes. Just install a couple of 1/4" npt X 5/16" barb adapters to each end. Other than that, all you need is about a foot of 5/16" id fuel/heater hose and 4 clamps. Install is straight forward, as you can hopefully see in the pics I've attached.

Intake Temperature Testing:

I did some bef/aft temp testing, measuring intake air temp rise across the TB to see how much this mod reduces the intake temp. I used a fairly accurate and fast acting Fluke 52, dual input digital thermocouple. Temps were taken directly upstream and downstream of TB. Here's a few numbers to digest. Let me know what you all think.

Before: (Motor at operating temp)

Ambient Temp= 85 deg F
Temp Rise across TB after idling for 5 min = 17 deg.
Temp Rise across TB cruising @ 70mph/3300rpm/3rd gr = 7 deg
Temp Rise across TB during 0-90 run @ WOT:
Start = 15 deg rise
60 mph = 2 deg rise
90 mph = 1 deg rise

After: (Motor at operating temp)

Ambient Temp= 87 deg F
Temp Rise across TB after idling for 5 min = 5 deg.
Temp Rise across TB cruising @ 70mph/3300rpm/3rd gr = 4 deg
Temp Rise across TB during 0-90 run @ WOT:
Start = 6 deg rise
60 mph = 1 deg rise
90 mph =.5 deg rise

As you can see, the biggest benefit of this mod is the reduction of intake temp at idle. The temp rise @ WOT was minimal both before and after mod, which makes sense. The air is moving too fast for much heat transfer to take place. But think about all that heat sitting inside the intake plenum at idle....seems like a real low-end torque killer to me. So by taking that 17 deg rise down to about 5 deg has gotta help.

Of special note, I found that the intake temp measured in the tube just before the TB inlet would reach temps as high as 134 deg! Keep in mind this is with an ambient of 85 deg, a Volant CAI, and with the TB coolant valve off. It appears that the plastic intake tube gets heat soaked from the radiator and a/c fan (if on) discharging a lot of heat across the tube, as it is directly in the flow path. This temp does not cool down instantly after opening the throttle (other than wot). It took several minutes of driving around to see the temp come down. I know thick-walled plastic is a pretty good insulator, but in the event it does get heat soaked, it takes a while to lose that heat. Aluminum, though, would probably heat up quicker (and more), but would dissapate quicker. I may try to insulate the tube, if I can find something that looks good....cuz that's important...lol!

Sorry for the long post...hopefully someone else finds this stuff as interesting as I do.

Not a professor what!?!! See I told you. Awesome work bro!

RockyMtnTitan · 08-23-2005, 04:54 PM

Quote:

Originally Posted by Titan4x4Aggie

So I'm guessing the value is so you can open it during cold (ambient air) periods and still have it operate as designed?

Seems smart. I like it, and maybe I will have to do this.

Parts list and price???

Most likely, even those of us in colder climates wouldn't have an issue with the TB freezing, but I read on a vette forum that sometimes during really cold weather, the coolant bypass would cause rough idle. With the valve, it's just a summer/winter changeover deal....so no worries.

I don't recall all the prices, but it's safe to say all materials cost me less than $15.

(1) 1/4" npt male by fem brass ball valve. (Lowes...air compr accessory section)
(1) 1/4" fpt X 5/16" barbed brass adapter
(1) 1/4" mpt X 5/16" barbed brass adapter
(4) small adj hose clamps
(1') 5/16" i.d. fuel/heater hose

If you could find an even smaller ball valve that is 5/16" (or even 1/4") barbed, you could just pinch off the hose and splice the valve into the existing line w/o having to run a longer section of hose like I did. Less of a mess, too.

RockyMtnTitan · 08-23-2005, 04:55 PM

Quote:

Originally Posted by Finnattic

Not a professor what!?!! See I told you. Awesome work bro!

Hardly...if you saw my Math grades....you'd laugh!

bestatchess · 08-23-2005, 05:41 PM

Impressive post, good work!

PHOEBISIS · 08-23-2005, 08:36 PM

Hey,really interesting stuff.If I remember right absolute zero is about -450 degrees,so a one degree change would mean 1/535 change in density(450+85)-5 degrees would be a ~1% change.This should increase the power by 1%.
I always thought it would be interesting to cool the incoming air in a "normal" motor to increase the density.I think N20 does this a little.Spraying in alcohol would do it also.Gasoline does it,and that is part of the reason cars run a little stronger with a "too rich" mixture.
Doesn't Ford have some new gimmick on one of their hot rod trucks where they somehow run the incoming air thru the AC-or maybe run the evaporating Freon thru the manifold??
Pretty clever idea RockyMtn Titan.Thanks.Charlie

mod507 · 08-23-2005, 10:40 PM

are there any noticable gains with this? if there are i might do it also.

**gr8titan** · 08-24-2005, 03:02 AM

Very impressive. I've read about the "bypass" trick before but your "twist" added to it makes a LOT OF SENSE!! The before and after #s also supports the trick better than ever. Awesome!!!

Egan · 08-24-2005, 05:49 AM

Correct me if I'm wrong, but it looks like you have eliminated the coolant loop by installing the valve and shutting it. The bypass mod kept the loop by connecting the supply and return lines. I don't know if there could be any trouble caused by eliminating circulation for this particular section of the overall engine coolant loop.

the head · 08-24-2005, 06:17 AM

It's only a loop for the throttle body. I ran a hose bypassing it all together and haven't had any problems in over a year. Living in Houston it just doesn't get that cold here.

Egan · 08-24-2005, 07:40 AM

Quote:

Originally Posted by the head

It's only a loop for the throttle body. I ran a hose bypassing it all together and haven't had any problems in over a year. Living in Houston it just doesn't get that cold here.

I'm not talking about the cold issue. I'm talking about the fact that the coolant loops out of the main coolant loop into the throttle body and then back out to the main coolant loop. By doing the normal bypass mod, you still maintain that loop. By putting a valve in the supply side and shutting it off, you're creating a dead leg in that portion of the loop. It's a short dead leg so it may not be an issue at all, but I thought I would point out the difference between the two mods.

Ideally, to maintain a loop and have a shutoff, you would want to put a 3 way valve in the supply side and a 3 way valve in the return side and a piece of hose between the two. That way, even with the valves shut and the throttle body isolated, you still maintain the loop.

Titan4x4Aggie · 08-24-2005, 08:00 AM

It all seems the same to me, since the TB coolant loop is just a paralell loop to that of the main coolant loop(s).

Whichever way you do it, nothing is flowing through the TB. In the true bypass loop, you just get an extra coolant loop that does nothing.

RockyMtnTitan · 08-24-2005, 08:04 AM

Quote:

Originally Posted by Egan

I'm not talking about the cold issue. I'm talking about the fact that the coolant loops out of the main coolant loop into the throttle body and then back out to the main coolant loop. By doing the normal bypass mod, you still maintain that loop. By putting a valve in the supply side and shutting it off, you're creating a dead leg in that portion of the loop. It's a short dead leg so it may not be an issue at all, but I thought I would point out the difference between the two mods.

Ideally, to maintain a loop and have a shutoff, you would want to put a 3 way valve in the supply side and a 3 way valve in the return side and a piece of hose between the two. That way, even with the valves shut and the throttle body isolated, you still maintain the loop.

I did think about this before installing a shut-off here. This is such a small loop (TB and lines together hold maybe 1/2 pint of fluid), and it affects nothing else that I can see, i.e., motor cooling, heating coil loop, pumping capacity or pressure, etc. A 3-way valve, to me, would be a bit overkill (and more expensive) for this mod, but is an option if one was worried about it....I'm not. Thanks for the input...

RockyMtnTitan · 08-24-2005, 08:05 AM

Nice drawing, Aggie!