The beast is born

The cooling system has been a real issue on the GTMs
Most of the problems resulted from trapped air in the heads.
Seeing as the coolant hoses run down from the water pump, & then back up to the radiator, you can visualize the problem. There was (& still is) a lot of discussion about bleeding/solving this problem.
The other issue on the GTM was the corvette expansion tank being mounted in the front, right behind the radiator.
This is problematic, as it is not he highest component in the cooling system, as it needs to be, to effectively bleed air from the complete system.
Current solution is to mount a different coolant tank above the engine & run bleed lines from engine/radiator to repositioned tank. you can also just put a petcock on the top of the radiator, & manually bleed it.
We had success on the GTM-R race car with the standard system, but had to bleed system 2-3 times after running the car on the track to purge system completely. We now run the rear coolant tank, with few issues.

I have thought about the factory heater system on the LS engines. The water pump has a 2 stage function that allows coolant to bypass the thermostat & circulate coolant through the engine as it warms up. When the thermostat opens, it closed this port & all coolant circulates through the radiator & heater core.
I believe that installing a heater "bypass valve" into our aftermarket systems is a bad deal. With the heater valve closed & in bypass mode, all you are doing is circulating hot coolant out of the engine, through the valve & right back into the inlet of the water pump un-cooled.
As with any fluid, the coolant will take the path of least resistance, & flow through the heater hoses, instead of the radiator, & you may loose 20-30% of your cooling ability.
On the Corvette this water is running through the heater core (small radiator) continuously & at least you are dissipating some heat. Plus the system was designed for this feature.
 
Specific to the heater plumbing routing, my recollection is that if you removed the valve in the heater plumbing and just allowed continuous flow, that solved the problem. However, it eliminated the capability to bypass heater flow when the AC was set to max cool, which is what the valve did. . . I think.
 
Hi Ted,

Thanks for the comments. It's good to hear from the GTM crowd over here. I hope you'll find us to be pretty civil. We all have things we can learn from each other, which is why I surf over there frequently.


The cooling system has been a real issue on the GTMs
Most of the problems resulted from trapped air in the heads.
Seeing as the coolant hoses run down from the water pump, & then back up to the radiator, you can visualize the problem. There was (& still is) a lot of discussion about bleeding/solving this problem.
All water-cooled engines suffer if air is introduced to the cooling circuit. Proper purging and correct cooling system design is generally all that is needed, regardless of the source of the introduced air. The SLC comes standard with 2 petcocks on each side of the radiator at the top. One of these should be retained for use as a petcock, the other should be replaced with a line running back to a high-mounted overflow tank. This generally solves the problem of trapped air in the cooling lines and radiator.


The other issue on the GTM was the corvette expansion tank being mounted in the front, right behind the radiator.
This is problematic, as it is not he highest component in the cooling system, as it needs to be, to effectively bleed air from the complete system.
Current solution is to mount a different coolant tank above the engine & run bleed lines from engine/radiator to repositioned tank. you can also just put a petcock on the top of the radiator, & manually bleed it.
As noted above, the SLC already has such a petcock at the top of the supplied radiator to assist in manual bleeding, as well as another port (supplied with a petcock) that can be used to run the bleed line back to the expansion tank.

The donor approach of the GTM has sometimes led to design compromises, like the reuse of the Corvette expansion tank in a place where it isn't optimal. In a clean-sheet design as in the SLC, this isn't a problem- there is plenty of room for a number of possible solutions, one of which has been proven in production, and room for a couple of novel designs (as in Rob's car that has a cool custom expansion tank shaped to follow the cabin roofline).

The LS engines have steam vents as well, which should be used correctly. There are actually 4 ports that can be used, though many people have had success using just two. The use of only two works best when the engine is on a slight angle (the lines should be plumbed to the higher two, in that case). There are systems (as from Keith Urban Racing) that tie all 4 vents to a common manifold, then run a single line to the expansion tank. This is possibly a belt and suspenders approach. :) Managing the steam vents somehow is necessary to deal with the other source of introduced air in the cooling circuit, from localized boiling.


We had success on the GTM-R race car with the standard system, but had to bleed system 2-3 times after running the car on the track to purge system completely. We now run the rear coolant tank, with few issues.
The 01 car also has a high-mounted expansion tank, as do most of the SLCs I've seen. I think it is pretty clear that that is what is needed- and one of the reasons why there is such a difference in some cars that seem to be plagued with cooling problems compared to others that don't seem to have those issues.

I have thought about the factory heater system on the LS engines. The water pump has a 2 stage function that allows coolant to bypass the thermostat & circulate coolant through the engine as it warms up. When the thermostat opens, it closed this port & all coolant circulates through the radiator & heater core.
I believe that installing a heater "bypass valve" into our aftermarket systems is a bad deal. With the heater valve closed & in bypass mode, all you are doing is circulating hot coolant out of the engine, through the valve & right back into the inlet of the water pump un-cooled.
As with any fluid, the coolant will take the path of least resistance, & flow through the heater hoses, instead of the radiator, & you may loose 20-30% of your cooling ability.
On the Corvette this water is running through the heater core (small radiator) continuously & at least you are dissipating some heat. Plus the system was designed for this feature.
Ironically, the use of a bypass valve is intended to make the engine see exactly what it sees in the OEM installation, which is a coolant flow from one side of the heater outlet on the engine to the other. That's why a simple loop - as the 01 car has, and I suspect the GTM-R you run has?- works just fine if you don't have a heater, and why just capping off the outlets is a bad idea.

If I understand your point, it is that not enough heat is dissipated from just a loop to a bypass valve, compared to running it through the heater coil. If so, I think you might be overestimating both the amount of heat rejection the heater coil provides in the warmup cycle, and the amount the engine needs during the warmup cycle- both of which are very small, as the idea is that the engine needs to warm up as quickly as possible for emission and economy purposes.

In the real world, this is a working solution, and likely the best possible one for evaporators that don't have blend doors. If we could fit larger evaporators like the Corvette OEM one, this discussion might be moot. But as long as we are stuck using small evaps without the ability to run coolant through the heater core at all times, this is the best solution I've seen.

If there is a better solution, we'd all like to hear it! :)
 
Will is wealth of information. He is the SLC wizard. Full of cool ideas, stories, and insights. I have his # on speed dial and programmed into my bluetooth. He is probably sick of me calling him to pick his brain by now.

The only bad part is that after speaking to Will my build timeline mysteriously gets longer. :stunned:
You were unable to corrupt your build with a full set of completion-date-delaying wide body fenders. I guess Will is more influential :laugh:

Trust me, talking to Will severely limits one's ability to set a timeline....he is great in the research department, often providing insight and suggestions on issues some of us didn't even know existed.
 
Thanks for the response Will
On the GTM forum, this is one of the most discussed subjects.

I find this helpful:
LS Cooling System

The "warm-Up cycle is built into the water pump, as it has a dual stage thermostat. When the thermostat is closed, the bypass port is open, allowing coolant flow through the pump. When the thermostat opens, it closes the bypass port, & all coolant flows through pump normally. No "warm up feature" needs to be added to the system, as it is already built into the pump.
See item 6 in diagram
 
ArtGirl,

Any updates for us?

Thank you!
No updates. We've got a lot on our plate at the moment and decided shortly after purchase to push delivery out quite a bit, which coincidentally now aligns better with the expected availability of the Griffen.

More to come in a few months.

Cheers,

Ruth
 
Hi Ruth,

I just read through this thread in it's entirety, and have learned quite a lot about the SL-C build in comparison to the GTM build. Your questions have been spot-on, and the answers that come back from the SL-C crowd are extremely helpful. I'm glad that you've made this choice. Seems to be a great fit.

I'm also glad to see that you're sticking to your guns as far as budget, and component choices. I think when it's all said and done, you guys are going to find that you have yourselves a nice little street rocket.

If I can add anything, I would say this: If there is any question of whether or not the nose of the SLC will clear any speed bumps, driveways, etc., do your self a huge favor and buy a lift kit for the front of the car. I have the RamLift kit on my car, and without it, I wouldn't be able to get in and out of my driveway. There are a couple of videos posted on my build thread.

Take care, and enjoy the build. I think that I can see one of these in my future...
 
Look at this.

Look--at--this!

The cooling system has been a real issue on the GTMs . . . There was (& still is) a lot of discussion about bleeding/solving this problem.
The other issue on the GTM was the corvette expansion tank . . .
Current solution is to . . .
We had success on the GTM-R race car with the standard system, but had to bleed system 2-3 times after running the car on the track to purge system completely. We now run the rear coolant tank, with few issues.

I have thought about the factory heater system on the LS engines . . .

I believe that installing a heater "bypass valve" into our aftermarket systems is a bad deal . . .
Good Honk!

Team GTM freely giving good information to Team SL-C!

Could you imagine the same situation in Formula 1?

Ron Dennis casually walks over to Luca di Montezemolo. When Mr. di Montezemolo's bodyguards put finally down their machineguns, Mr. Dennis says,

"Oh, I say, old bean, so sorry about that rotten lump you've got in your car this year.

"We at McLaren have had the same problem. No wonder we could not beat (a racing team named after an energy drink) last year!

"Well, hundreds of us at McLaren have been beavering away on the problem, and we have spent untold millions developing it. It uses hitherto proprietary electronics, and an entirely new kind of superlight, superstrong composite material.

"It will gain you four seconds a lap and make your engines last four times as long.

"Here you go: all for free. Cheerio."
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Do you see how great and wonderful and amazing this is?

Bassanio
 

Fran Hall RCR

Moderator
I am pretty sure we did not have any coolant issues this year on our first year race car...but I get the point....:lipsrsealed:....:thumbsup:

We are all going to have a great time....
 
I have a question regarding sequencing on the installation of the seats. How did folks deal with attaching upholstered seats to the brackets? Is the bolt through the seats epoxied to the seat before upholstery is done? Also, are seat brackets attached to the floor OVER the sound damper/carpet?
 
I have a question regarding sequencing on the installation of the seats. How did folks deal with attaching upholstered seats to the brackets? Is the bolt through the seats epoxied to the seat before upholstery is done? Also, are seat brackets attached to the floor OVER the sound damper/carpet?
shazam :D

 
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