Myraceshop HBV and Header Tank Install

[Rigdotcom]

Currently reworking GTM #34. Finishing up some of the last steps before it goes for paint and I decide to stop changing things that I don't like.

I have the cooling system sorted, but when I got to the heater core portion of the install, I ran into a little roadblock. There is a short "Jumper" style hose going from the heater core to a module that I am not familiar with. It's part of the vintage air system and should be visible in the picture.

I have a 5/8 and a 3/4 hose running to the front of the car as shown in all of the pictures for installing the header tank and the bypass.Screenshot_20240909_225410_Gallery.jpg

[doug_porsche]

I believe that is the thermostat/head controller for your heater.
The vintage air way of regulating heat in the car.

[beeman]

It's the V.A. solenoid that blocks hot coolant flow to the heater core when you don't want heat. I believe people had issues with them, maybe drawing a lot of current? Get a manual shutoff and ditch it.

[VRaptor SpeedWorks, LLC]

Yes, that is just an electrically controlled shut-off. It blocks coolant from flowing thru the heater core in order to get max AC cooling. This can cause overheating issues in the GTM...as the t-stat requires circulation in those hoses for the T-stat to work properly..... which is why I don't use those VA solenoids. As beeman said, IMO it's more reliable to just install a manual shut-off valve inline to leave closed during the summer.....but if you do that, you also will want to create a "bypass" so that coolant can still circulate between the 3/4" and 5/8" heater hoses. I do this by simply installing some T fittings in those hoses that have a 3/8" center hose barb...and connect the 2 hoses with a short piece of 3/8" hose.

[beeman]

Good points, Shane. I did T in a coolant bypass as well.
There was something else 'weird' about that electric shutoff, I believe the solenoid drawing constant current in either the 'on' or 'off' position was a unit failure concern or electrical fire concern.

[Power Surge]

Yes, that is just an electrically controlled shut-off. It blocks coolant from flowing thru the heater core in order to get max AC cooling. This can cause overheating issues in the GTM...as the t-stat requires circulation in those hoses for the T-stat to work properly..... which is why I don't use those VA solenoids. As beeman said, IMO it's more reliable to just install a manual shut-off valve inline to leave closed during the summer.....but if you do that, you also will want to create a "bypass" so that coolant can still circulate between the 3/4" and 5/8" heater hoses. I do this by simply installing some T fittings in those hoses that have a 3/8" center hose barb...and connect the 2 hoses with a short piece of 3/8" hose.

This is interesting... I did not know this at all.

[VRaptor SpeedWorks, LLC]

Good points, Shane. I did T in a coolant bypass as well.
There was something else 'weird' about that electric shutoff, I believe the solenoid drawing constant current in either the 'on' or 'off' position was a unit failure concern or electrical fire concern.

The other problem with some of them is that they had a moulded-in arrow in the housing that was supposed to indicated coolant flow direction....and then a sticker that indicated flow in the opposite direction. I don't recall which was correct, but the first car I built, I installed it in the wrong direction and as the engine rpm increased, the flow of coolant in the heater hose would close the valve without any electrical power to the solenoid. So you'd end up having heat at idle or 1500 rpm, but by the time you got it out on the highway at 2000 rpm, you would not have any heat.

[crash]

So I was kind of holding off on commenting until one of my products actually came up in the conversation as opposed to just the title but...what Shane is talking about is specifically what the Heater Bypass Valve Kit is designed to address.

Unfortunately there have been a couple people that had issues with the MRS HBV kits leaking after install. I believe this is due to the fact that some GTM projects take so long to complete that the seals dry out in the valve and then end up leaking right out of the gate. I know Shane had one of the MRS valves leak and I think one or two others have also experienced this. If you have the MRS HBV kit and it has been sitting for a good amount of time, I would suggest replacing just the valve body with a fresh one right before you are ready to fill the system. Also get water/coolant into the system ASAP. These are standard off the shelf AC Delco bypass valves that are included in the kit and the box the kit is shipped in has the correct valve part number on it.

[rolfer]

I went with a Craig Davies electric water pump. when you use their control unit you completely remove the thermostat and the manifold they sell for the LS fits so much better then the factory water pump. I have the belt going around just the alternator so that simplifies things as well. no problems with overheating in stop and go traffic because the water pump is working fill time where when it is cold it just pulses. I got the idea from the GT40 forums.

[Rigdotcom]

So I was kind of holding off on commenting until one of my products actually came up in the conversation as opposed to just the title but...what Shane is talking about is specifically what the Heater Bypass Valve Kit is designed to address.

Unfortunately there have been a couple people that had issues with the MRS HBV kits leaking after install. I believe this is due to the fact that some GTM projects take so long to complete that the seals dry out in the valve and then end up leaking right out of the gate. I know Shane had one of the MRS valves leak and I think one or two others have also experienced this. If you have the MRS HBV kit and it has been sitting for a good amount of time, I would suggest replacing just the valve body with a fresh one right before you are ready to fill the system. Also get water/coolant into the system ASAP. These are standard off the shelf AC Delco bypass valves that are included in the kit and the box the kit is shipped in has the correct valve part number on it.

I am not sure how long this valve has been sitting around. I will probably need to get another.
imag024.jpg

Following this picture from the site and what I have surmised. The 3/4 line hits the bypass and goes to the heater core, the 5/8 hits the header tank, the bypass, and once I delete the electronic unit, goes to the heater core as well.

Does this address what Shane said, in reference to putting a crossover tube in place and a manual shutoff valve?

Picking this project up, At a stage where it was completed, sold a few times, and driven has not been what I expected. I have reworked so many of the systems, wiring, and questionable original designs. You all have been a Godsend with your abundance of knowledge and experience.

[beeman]

From my build thread...
Depending on your line size, you could also put a flow restrictor in the bypass line so the coolant preferentially goes to the heater core but will take the bypass circuit if you turn off flow to your heater core....

Screenshot_20240911_195445_Chrome.jpg

[Rigdotcom]

From my build thread...
Depending on your line size, you could also put a flow restrictor in the bypass line so the coolant preferentially goes to the heater core but will take the bypass circuit if you turn off flow to your heater core....

Screenshot_20240911_195445_Chrome.jpg

Heading to your build thread now.

[Rigdotcom]

I went with a Craig Davies electric water pump. when you use their control unit you completely remove the thermostat and the manifold they sell for the LS fits so much better then the factory water pump. I have the belt going around just the alternator so that simplifies things as well. no problems with overheating in stop and go traffic because the water pump is working fill time where when it is cold it just pulses. I got the idea from the GT40 forums.

I need more information on this. What kit did you buy? I have a motor that will go in this car very soon, that would be a viable option!

[crash]

Sorry, reply with quote not working for me...

Rigdotcom said...
"I am not sure how long this valve has been sitting around. I will probably need to get another.
Click image for larger version.

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Following this picture from the site and what I have surmised. The 3/4 line hits the bypass and goes to the heater core, the 5/8 hits the header tank, the bypass, and once I delete the electronic unit, goes to the heater core as well.

Does this address what Shane said, in reference to putting a crossover tube in place and a manual shutoff valve?

Picking this project up, At a stage where it was completed, sold a few times, and driven has not been what I expected. I have reworked so many of the systems, wiring, and questionable original designs. You all have been a Godsend with your abundance of knowledge and experience."

Yes this is exactly what the heater bypass valve kit addresses. It was designed with the use of an OEM bypass valve that is used in many GM vehicles as this issue is one that was addressed by GM when they built their vehicles with the use of this bypass valve. It sends water flow back to the thermostat when the heater is off, then cuts direct flow to the thermostat when the heater is on and directs flow to the heater core.

A two way manual valve will do the same thing but you will have to turn that valve manually. This route, in the long run, may be more reliable, but I designed the HBV kit to take the place of the Vintage Air electric valve and work seamlessly when you select your HVAC mode from the dash. The OEM valve, just like heater cores, have a service life and will eventually go bad and need replacing. That said, the Vintage Air valve will likely also go bad in time, as will the manual valve. They all may just have different intervals of service life.

[crash]

Addressing the electric water pump...

I know people that have successfully used this set up.

That said, I deemed it not viable for the race FFR GTM because of how much power this engine makes, the amount of time this engine is at wide open throttle and making a lot of heat, and the fact that our electrical system is already at a pretty high rate of amperage use.

Street GTM doing mostly tooling around roads and even sitting in stop and go traffic would likely be fine. If you plan a lot of track days in high ambient air temps, probably not.

I have used Meziere electric water pumps on other projects previously and they have worked well.

I know Davies has some new pumps available and I think I would also check those out if I was considering doing an electric water pump setup today.

I have also had to go the other way and step up to a Stewart Racing pullied water pump when horse power numbers were high and a standard LS OEM pump would not cut it.

I suggest looking at flow rates at given engine RPM as the electric pumps really do not come anywhere close to the flow rates of the pullied pumps even at 100% duty cycle and full amps.

The beauty of the pullied pumps is the increase in flow when the heat produced by the engine also increases. Of course you also have to have an adequately sized radiator to take advantage of that increase in flow rate. If you can't expel the heat in the radiator fast enough then increased flow really does little for you and can actually make cooling issues worse. This is one of the reasons why multi pass radiators exist, so that the fluid stays in the radiator longer to have more time to transfer heat.

[Rigdotcom]

Pulled all the old hoses out, it was a pain getting the VA solenoid out with everything in the way, but everything is hooked up wirh no leaks. Thank you to everyone. I have more questions as I progress through this build and pick things apart.