Running a 7M without the Coolant By-pass Tube

[Van]

Hi,

The 7M I'm building is going in a road race MA70. I'm not going to have the heating and AC, just vent fan and ducting. Will the engine need the coolant by-pass tube (from the back of the head to the water pump housing), to function properly?
My plan is to insert a threaded plug at the back of the head, where the large banjo bolt is inserted (for the coolant outlet to heater core), and the back of the water pump housing, cap-off the by-pass tube inlet with a sealed aluminum plate.
Edit: Also, the throttle body and ISC aren't getting coolant sent in through them either. Is that going to be problematic as well?

Thanks, Van

 

[gofastgeorge]

Should be no problem since when the heater control valve is close, there is no flow through there anyway.
In fact, if you come up with a plug with that metric thread, I would be interrested in one for my track car build.

 

[mkIIIman089]

Yep, when the temp is turned all the way down the flow valve closes completely - so it shouldn't be an issue I don't think.

You can run a bypass tube to eliminate the circuit through the ISC/TB without issue as well, but I don't think capping off the ports on the engine are a good idea for this one.

 

[Van]

Thanks to you both for responding to my post.
I too have my doubts about how well the engine will get cooled w/o there being a by-pass tube. I don't know why the engine cooling would benefit from it being connected. What are the benefits?
Looking at the TSRM coolant diagram isn't informative to me...
Thanks, Van

Yep, when the temp is turned all the way down the flow valve closes completely - so it shouldn't be an issue I don't think.

You can run a bypass tube to eliminate the circuit through the ISC/TB without issue as well, but I don't think capping off the ports on the engine are a good idea for this one.

 

[mkIIIman089]

Honestly I'm not sure. Pure speculation: It somehow improved emissions, or they found some benefit to keeping the TB/ISC at the same temp as the coolant (perhaps in extremely cold environments). Someone else may be able to give a more definitive answer.

Personally, I bypassed it when I was in a pinch and had a massive leak from one of the hoses while a long way from home. I noticed no difference in the way it ran then and 2-3 years later, I still have never had an issue with my ISC valve or throttle. I left the bypass on because I liked the simplification it provided...

 

[shaeff]

Here's a great post from jdub regarding this very issue:
http://www.supramania.com/forums/showpost.php?p=1120709&postcount=8

And to aid you in figuring out what you do/don't need, here's a good diagram of coolant flow:

 

[mkIIIman089]

Welp, there you go, you may want to leave it alone if you're worried about icing up.

 

[Van]

Good useful information from JDUB on TB icing. Thanks, Shaeff.
Van

Here's a great post from jdub regarding this very issue:
http://www.supramania.com/forums/showpost.php?p=1120709&postcount=8

And to aid you in figuring out what you do/don't need, here's a good diagram of coolant flow:

 

[DRIFTER WANNABE]

Excellent information I am also removing my Heating/AC for my race application....

 

[jdub]

Thanks guys
Look closely at the icing chart and you will see there has to be a specific combination of conditions for icing to form.

I would not plug the hole at the back of the head. If you look at the above diagram, the banjo bypasses coolant to the water pump when the heater is not used. The rear of the motor is the hottest coolant wise due to the coolant having to travel the length of the block...it's already hot when it gets to the #6 cylinder. Plugging that port will restrict coolant flow from the rear of the motor back to the pump making it worse.

Also, the heater control valve never completely closes...there is always a small flow through the heater core. If you remove those lines though, it will not really matter.

 

[DRIFTER WANNABE]

Very Interesting so thats why hot air will always come out of the vents even when you have it on cool on a hot summer day.............

So the best thing to do is leave the J tube and just run a hose were the heater core was and this will ensure that all the cylinders get there coolant flow right.......

 

[mk3ukr]

From looking at coolant flow diagram I understand that when heater running it is helpful for cooling of rear part of the head (more flow)
When heater not in use there is no difference if bypass pipe there or not. If we assume heater control valve leaks - small amount of hot water from the head returns straight to water pump suction line and enters cylinder block

 

[jdub]

Even if the heater control valve is fully closed (which it never is), the hot coolant has a less restrictive path back to the pump. It improves flow no matter how you look at it.

 

[IJ.]

The critical path is the line to>from the Turbo as this is the Bypass in use when the T Stat closes, without it you have cavitation.

There is a 30c degree difference in head Temp on an idling 7M front to rear so ANYTHING that helps reduce the rear of head temp can only be a good thing.

 

[Txsupra]

^^^
So what your saying here is that if your running an oil cooled only turbo you should run a line from where the coolant to turbo line was to where the return would be. Correct? I have them plugged at the moment.

I have removed my A/C and Heater cores and have rerouted the coolant from the heater core "feed" (big Banjo) to the heater "from" hard line on the drivers side just behind the head. I have also rerouted the TB coolant line from the block under the intake runners to the same hard line (smaller line that tee's into it) just behind the head on the drivers side. As far as I can tell this will be a good setup but I haven't had the chance to run the car and find out for myself. If anyone sees anything wrong with the way I have this please let me know. Thanks

 

[IJ.]

^^^
So what your saying here is that if your running an oil cooled only turbo you should run a line from where the coolant to turbo line was to where the return would be. Correct? I have them plugged at the moment.

I have removed my A/C and Heater cores and have rerouted the coolant from the heater core "feed" (big Banjo) to the heater "from" hard line on the drivers side just behind the head. I have also rerouted the TB coolant line from the block under the intake runners to the same hard line (smaller line that tee's into it) just behind the head on the drivers side. As far as I can tell this will be a good setup but I haven't had the chance to run the car and find out for myself. If anyone sees anything wrong with the way I have this please let me know. Thanks

Correct

 

[Van]

Hi Txsupra,
You and I have both routed the coolant in the same way. I've been using it that way for the past two years, and it works well. Van

^^^

I have removed my A/C and Heater cores and have rerouted the coolant from the heater core "feed" (big Banjo) to the heater "from" hard line on the drivers side just behind the head. I have also rerouted the TB coolant line from the block under the intake runners to the same hard line (smaller line that tee's into it) just behind the head on the drivers side.

 

[WillieLZG]

I bypassed my throttle body and ISC valve coolant lines because i figured adding heat to them was stupid idea since you want intake air as cold as possible and i simplifies things a little. Also did the same when i removed my heater and first thought to cap them but looped a hose from the inlet to outlet figured the flow would cool the rear more. Didn't ever think of icing ever happening on the throttle body but I live in El Paso tx and it's hot and hardly humid here so i figure it's fine.

 

[Txsupra]

Correct

Some how I knew you'd say that. However since my car will will only be going a quarter mile at a time and maybe a few times down the street and back, mile or so. Do you still think its necessary? Asking for the crowd as I now plan to put in a hose. Also why would it cause cavitation? Is is because of system design? Isn't it the same setup as an N/A but with those bosses tapped for the hoses? Trickle valve isn't enough to keep pump from building pressure? Makes since to me but I must know why in order for the info to stick

 

[figgie]

I bypassed my throttle body and ISC valve coolant lines because i figured adding heat to them was stupid idea since you want intake air as cold as possible and i simplifies things a little. Also did the same when i removed my heater and first thought to cap them but looped a hose from the inlet to outlet figured the flow would cool the rear more. Didn't ever think of icing ever happening on the throttle body but I live in El Paso tx and it's hot and hardly humid here so i figure it's fine.

DOes not work that way.

The velocity of the air through the TB will prevent it from picking up that much heat regardless of the TB temprature. What that means is minute to probably indistiguishable power differences.