I have a couple questions and a little theory. These questions come from the "Insulating" IM and TB gaskets on the market today (Outlaw-Engineering, Hondata, AN-R). I have installed one set of my vehicle and have some Topics of conversation.

If you don't want to cut to the chase, here's a summary of the question:
Would the coolant routing shown in the image by the blue hose (to replace the green hoses) create and complications, idle or otherwise, in a M/T vehicle?

T1) The gaskets have a lower coefficient of thermal conductivity than OEM paper gaskets and thus they will slow the absorption of heat into the IM from it's primary sources of heat. As the coeffiient CANNOT be 0.00, they do only SLOW the absorption and thus must rely on fresh air streaming through the IM and cooler radiant temps to cool the IM as well. This they are most effective when the vehicle is moving, or providing fresh air to cool the IM.

T2) There are still areas of "vulnerability" where heat is conducted to the IM and TB. These areas are:
(a) Thermostat Coolant port through Passenger side of IM,
(b) Coolant through IACV, and
(c) Coolant Through FITV (A/T) / or TB (M/T).
While I know of no way to insulate the manifold from (a), I am intrugued with eliminating absorption through the IACV and TB (FITV).

To the best of my knowledge, IM heat absorption can be further limited by <U>two Methods</U>:
M1) Create 2 more gaskets. One to "insulate" the Plenum from the IACV, and another to "insulate" the TB from the FITV (A/T only). In cases of M/T vehicles without a FITV, but with fluid passages through the TB. An alternate method adopted by Outlaw Engineering is to use a Phenolic TB gasket that prevent this heat from reaching the IM Plenum.

M2) Eliminate Coolant flow to the IACV and TB on M/T (or FITV for A/T) (green in Picture). This would be accomplised by bypassing the IACV and TB/FITV with a separate coolant hose (Blue in picture), and blocking off the existing passages to the IACV and FITV/TB. (Refer to picture).



Here are the questions about Method M2.
Q1) Is the functionality of the IACV compromised by eliminating the coolant flow to it?
<U>i.</U> I know that the IACV recieves voltage from the PGM-FI Main Relay, and is controlled via ground through the ECM.
<U>ii.</U> It would therefore seem that the IACV does not "send" any information to the ECM, but is only controlled by it.
<U>iii.</U> Is this true? Does it imply that the coolant line is only to ensure that the IACV does not "freeze", or does the IACV depend on the coolant line to function correctly? I have head of air bubbles causing problems with IACVs, but I suspect that is more of wives tales than anything else. (I reserve the right to be wrong on that one.

Q2) Is the functionality of the coolant passages through the TB on a M/T vehicle to keep the TB from "freezing"? If NOT, then what is the purpose of the coolant passage through the TB on a M/T vehicle? The FITV only exists on A/T vehicles, and it needs the coolant to "activate" it's wax-plunger-style valve mechanism.

Again to summarize: would the coolant routing shown in the image by the blue hose (with the green hoses plugged) create any complications, idle or otherwise, in a M/T vehicle?

Thanks





Modified by WOTTEG at 2:58 PM 8/19/2003

 

Forgot, just in case anyone is not familiar:
GLOSSARY:

FITV: Fast Idle Thermo Valve, equipped on Automatic Transmission Vehicles below the TB.

A/T: Automatic Transaxle

M/T: Manual Transaxle

IACV: Idle Air Control Valve: Valve that opens to maintain proper fast idle speed when the coolant temperature is llow. The Airflow through the IACV is controlled in a nearly linear graph by the ECM.

TB: Throttle Body

ECM: Engine Control Module

 

It's important the IAC valve doesn't freeze. Don't laugh just yet.

The IACV does all it's work at idle, & a good manifold vacuum is what? 20" of Hg? Adiabatic expansion from 110deg.F & atmospheric pressure, down to about 5psia, results in a final temperature of about 40 below zero F. The air flowing thru the IACV doesn't have enough heat capacity to make the valve cold, but ice can form if the air is humid to start with...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">It's important the IAC valve doesn't freeze.</TD></TR></TABLE>

I suspected that was Honda's motivation for the "coolant" lines on the TB and IACV.

If you could please elaborate further on the behavior you described. If I understand correctly, you are describing a temperature drop associated with an increase in vacuum? Did I miss the boat?

Thank You.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">(a) Thermostat Coolant port through Passenger side of IM,</TD></TR></TABLE>

You can bypass this one as well. Hondata sells a "race" version of their gasket which blocks the port on the IM from the head. I think they are officially discontinued but you can still get them, IM me if you need one. However if you do this bypass, you need to tee the feed line back into the system or the car will overheat. THe best way to to this is to tee it into the return heater hose from the heater core.

A 4th major source of heat absorbtion into the IM is through the studs and connecting hardware. Hondata supplies washers of the same material as the gasket, but OEM studs on an ITR motor are too short and need to be replaced with longer ones to use the washers. Take care of all 4 things and you will be surprised your IM is cool to the touch.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sackdz &raquo;</TD></TR><TR><TD CLASS="quote">
A 4th major source of heat absorbtion into the IM is through the studs and connecting hardware. Hondata supplies washers of the same material as the gasket, but OEM studs on an ITR motor are too short and need to be replaced with longer ones to use the washers.
</TD></TR></TABLE>

Outlaw Engineering supplies Phenolic washers, M8 washers and longer bolts/studs to "complete" the insulation of the IM. The washers supplied by Outlaw Engineering seem to "hold-up" better than the teflon ones supplied with the Hondata kit. . ..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WOTTEG &raquo;</TD></TR><TR><TD CLASS="quote">If you could please elaborate further on the behavior you described. If I understand correctly, you are describing a temperature drop associated with an increase in vacuum?</TD></TR></TABLE>
When a gas expands as it flows thru an almost-closed valve, it gets colder. That's how AC works. Refrigerants are better, but it happens with any gas. It gets hotter when it's compressed. That's why compressors get hot, and why turbos need intercoolers. Any 1st-semester thermodynamics textbook will have equations for this.

P*v^k = constant
then for an ideal gas...
T*(1/P)^((k-1)/k) = constant
(remember you have to use absolute temperature & pressure)

Now a racing engine spends a large part of it's life at WOT, so this isn't as important. A street engine needs to behave itself at idle, too, without acting all flaky. Take off those hoses so your intake manifold stays a bit cooler, & maybe you'll notice 1/2hp or whatever you get. But if the idle gets flaky, this might be part of the reason.

 

Thank You Sir.

So back in reference to the phenolic insulating gaskets; it seems the best way to "completely" insulate the IM from conductive heat trasfer through the FITV and IACV would be to fabricate a phenolic IACV gasket in addition to the IM, TB, and Pheno Washers supplied in the Outlaw Enginneering kit.



Now if only there were a way to insulate the IM from the passenger side coolant passage. . .

 

I did the same routing on my car and it runs the same as stock. No codes no idle problems.

Keep in mind that cooling the intake manifold a few degrees with do nothing. At full throttle, the air traveling from your air filter to the intake valve is moving at several hundred miles per hour. There is no way it will have time to absorb any additional heat from the the walls of the intake. How much heat transference can take place between the manifold and the air if the air is only in there for .001 seconds before entering the engine? Cooling the intake manifold wont work like an intercooler, there is nowhere near the surface area.

 

One of the first sensors we decoded was the IAT, and it was the measurement of this sensor temperature that lead to the development of the Hondata gasket.

"There is no way it will have time to absorb any additional heat from the the walls of the intake."

That is what I thought, until I measured it. Even at wide open throttle with the Hondata intake gasket in place (but throttle body heating), I measured the intake temperature 15 degrees warmer than ambient. This is with the IAT halfway down the runner. Close to the intake valve the air temp would be hotter.

Close the throttle and at cruise, the air temps will rise 15-20 degrees.

 

Hondata:

Were there any initiatives to develop a teflon gasket for the IACV?

I'd like to hear about that. I have a few suspicions about why there are no IACV insulating gaskets. Varrying IACVs per manifold, varrying IM IACV port configurations, the "flaky" nature of IACVs after removal/installation, etc.

Thanks for the input.
Karl

 

I was able to connect a 5/16" metal barb between the two hoses that feed the psuedo-FITV (I say psuedo, because on my M/T, I don't think it is really anything but a coolant passage). Thus no coolant flowed to the TB, and since I havea nice 1/4" phenolic TB gasket, then intake arm now stays very cool.

I did not encounter any idle or drivability problems by bypassing the coolant flow to the FITV.

Next I will make an insulating gasket for the IACV. I purchased some glass-filled PTFE a while ago. I know it has high temperature durability, but I don't know anything of it's coefficient of thermal conductivity. . . .
Nonetheless, it is easily machinable and just might be what the doctor ordered.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WOTTEG &raquo;</TD></TR><TR><TD CLASS="quote">... I purchased some glass-filled PTFE a while ago. I know it has high temperature durability, but I don't know anything of it's coefficient of thermal conductivity. . . . </TD></TR></TABLE>Somewhere around 2 (BTU-in) / (hr-ft^2-F)

Glass-filled is about the same, but there's a wider variation. Probably due to glass-fiber volume fraction, size & orientation.

(Per http://www.matweb.com)

 

Isn't all of this pointless because the EGR places exhaust gas in (open) or near (closed) the intake manifold anyways?

With my prelude I can just remove the EGR tube, but with the newer B series heads that I'm sure you guys are talking about, doesn't the EG run through the head and back into the intake manifold anyway?

 

The B18's don't have an EGR valve.

 

Then what is this?



It seems to me, even if you blocked this off you will still have hot exhaust gases hitting the manifold.

 

ahh nm, this must be the coolant passage on this engine. How about just blocking this passage with a steel plate?

 

It is the coolant passage. I would not block it off.

 

Some people have offered the idea of having the line terminate into the heater recirc hose instead of the IM. I don;t know the coolant flow within the block well enough to comment on this, or on other possible places to route it.

I'm trying to look into this though (Coolant flow and the "necessity" of this conenction..

 

We have had no negative reports of bypassing the water flow to the IACV. Just block yours off and see how it goes.

As for the coolant bypass at the end of the intake, this is a little trickier.

Block it completely and there is no hot water flow to the back of the thermostat. Ergo, the thermostat does not open and the car overheats.

Here is an untried suggestion.

- Block the coolant bypass
- At the end of the head, there is a water take off point. Insert a T junction and connect the hose that previously connected to the manifold

 

Hondata:
Which of the following methods are you describing?

Method 1:

Method 2:


My guess is 2.
Each of these methods benefits the intake temperature in a number of ways:
a) The TB will be cooler, wish will effectively eliminate all conductive sources of heat to the intake arm.
b) The IM will no longer have coolant flowing through it by runner #4. Again this will benefit intake temps.

Each method depends on the Phenolic IM spacer blocking off the coolant passage by runner #4.

Another note:
The TB gasket will probably not benefit the system assuming that the Phenolic IM spacer blocks the coolant passage, that the thermostat housing is fed by either method 1 or 2 above, that there is an IACV phenolic spacer, and that the TB coolant passage is bypassed.


Modified by WOTTEG at 9:43 PM 9/6/2003

 

Ok you have sucseeded in making me feel like a NOOB!

 

those are some nice pictures

 

I am describing method 2. By the way, nice diagrams. I can see you have taken some time making them.

 

I just wanted to subscribe to this thread