TeamRX8

iTrader: (25)

Stop p-ssyfooting the throttle

etzilon

Bring the white beast over and let's have some fun.

TeamRX8

iTrader: (25)

Think I may do a few NASA events once it's back together and sorted

etzilon

Well... Get chop-chopping. ECR is in November and local for you.

skc

My comment is based in a 15 minute run. And most sprint type of races that I run also go for a similar duration.

For racers running for longer durations then cooling for engine, gearbox and diff would all be up for consideration. Even the engine harness would need to be addressed.

dannobre

iTrader: (3)

If you are having heat problems in 15 minutes you should do something.

I can beat on mine with the turbo and not overheat at all unless I am in the paddock at 100 degrees and not moving.

etzilon

Good point. I agree. I run 20 min sessions; if I were running for 45 minutes or more, I would have made different choices.

TeamRX8

iTrader: (25)

Here is something I don't see discussed much and the service manual doesn't really show it at all. You have to look at the parts diagrams to see it well.

There are several bypass lines in the cooling system that route hot coolant back around to the inlet side of the water pump, i.e. bypasses the radiator. In reality for max cooling you want every thing to go back to the radiator and only cold outlet of the radiator feeding the water pump inlet.

If you look at the where the radiator hose to the water pump inlet is on the upper front RH side of the engine you can see all the additional lines coming in there, three of them. They are

Throttle body hose - pulls hot coolant from rear iron through throttle body to water pump inlet
Heater hose - pulls hot coolant from rear iron through heater core to water pump inlet - continuously recircs whether you use the heater or not.
Coolant tank hose - lets hot coolant go to water pump inlet.

A street car may want to install valves in those lines to block them off when on the track and then open them back up for street use. A race car could block them all off, though the line to the coolant tank will help purge air out when filling the system after a drain so a valve is an option instead.

Cooling diagram - RX8Club.com


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MagnusRacing

iTrader: (2)

Good point Team. On my race car the throttle body hose and heater hose are blocked off. Not the coolant tank hose - I think that's an important part of the system.

As I stated earlier in this thread I tried everything and the only thing that really worked well for hot days at the track was a good thick DUAL PASS (not dual core, dual pass) radiator. Mine was made by Ron Davis but I'm sure there are other custom fabricators.

Currently I run the Ron Davis Dual Pass Radiator, REmedy water pump, underdrive pullies, stock airbox and battery tray removed (in my opinion these must block lots of airflow). Have not had any problems even at 100F track days.

The stock oil coolers SEEM to be just fine for me. Just make sure they're in good condition. They tend to get beat up.

Arca_ex

iTrader: (10)

Sorry I didn't see this earlier.

I doubt it is the radiator causing overheating issues since there are other people running them with no issues at all. There are also multiple 500+ AWHP Subarus out here at the track that run the same core, and they even have front mount intercoolers in the way and their temps are fine.

If I were trouble shooting, the radiator is the last place I would look. Start with thermostat, then pump, REALLY make sure your ducting is good. It's hard to get good cooling on a track with the A/C condenser in the way.

Are you running an underdrive pulley?
System properly bled?
What mix of coolant?
How many miles on the engine? Any other issues with the car?

TeamRX8

iTrader: (25)

I found some diagrams last night that indicate coolant flowing from the radiator hot side (and also the thermostat outlet), to and through the baffled coolant tank, and then back to the water pump inlet.

Another diagram shows this hose and the heater both bypassing the radiator and bringing hot coolant to the water pump inlet.

The heater line path is easy to understand; take coolant from the hot end of the engine and provide a path of least resistance to generate flow.

The coolant bottle purpose of flowing hot coolant through it and back to the water pump has me perplexed though. I can see how it might allow coolant level to be more stabilized in the tank. With it connected to the radiator hot side and having a line feeding it also from the thermostat outlet I'm not convinced of it being required. The only thing I can think of is when the engine is started cold with the t-stat closed it provides some relief for expansion and also possibly stabilizes level more directly to a high point in the system (the coolant bottle) rather than letting it dynamically occur on the long path back through the coolant supply hose and up through the radiator instead. It seems like a rather large hose for this purpose though.

For high load engine use I just don't like the idea of bypassing hot coolant back around to the water pump inlet for anything other than warming a cold engine up to operating temperature. This has to be contributing to a less efficient heat load capability during extended hi-performance operation.

Any way I was working on getting an engine ready for installation last night studying the lines etc. and it made me think of this thread ..

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9krpmrx8

iTrader: (46)

Good stuff. Makes me think having my turbo on the TB coolant circuit is not such a good idea.

etzilon

I removed the TB line about two years ago thinking more about keeping IATs as low as possible but it does impact ECT.

My engine builder sealed off the heater line.

It all contributes a bit at a time.

logalinipoo

Im sure od would be reminding yall about the restrictor in the heater hose.

Brettus

iTrader: (2)

It does have a restrictor in the header tank supply hose, so flow is minimal .............................

TeamRX8

iTrader: (25)

it turns out that most RX8s did not come with the heater restrictor/orifice there is an orifice in the air bleed line from the T-stat discharge housing to the coolant tank and supposedly one on the coolant tank discharge nipple for the hose to the water pump inlet as per the diagrams below







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RIWWP

iTrader: (2)

Derailing posts moved to their own thread here: https://www.rx8club.com/new-member-f...bforum-253216/


It's more effective if you use the report button, rather than hoping that someone else will use it, or hoping that I* will see your comment





*Yes, me. There are no other active staff members right now

RIWWP

iTrader: (2)

Derailing of technical threads by people who are off topic falls under "problematic" in my opinion, regardless of how new the member is. I have to remove plenty of such posts by long time members too...

hufflepuff

Does the Remedy water pump reduce cooling at low RPM? For example, idling after an autocross run?

9krpmrx8

iTrader: (46)

The Remedy pump doesn't improve cooling at all as far as I could tell and I have had gauges forever. I got rid of mine and installed a new stock pump.

blu3dragon

iTrader: (1)

Did you mean to say does not improve cooling?

9krpmrx8

iTrader: (46)

Sorry, yes it did not improve cooling at all.