SVX Engine cooling "Again & Again"

[icingdeath88]

Yea I got that but overall it seemed like you misread.

[teamilluminata]

I found the solution. I sold my EG33 powered Legacy and bought a 911 Carrera


Seriously though, this is fascinating stuff. Keep it up. I'm still reading it as you can see.

[Tapani]

A substantial increase in bypass flow capacity might not be a bad idea to try. Maybe controlled by a solenoid valve - open above 4500 rpm? Might not be that difficult to arrange. There are big plugs in the lower surface of the block. The pump inlet can be drilled for the fittings. Eh? T

[BRZCory]

Originally Posted by Tapani

A substantial increase in bypass flow capacity might not be a bad idea to try. Maybe controlled by a solenoid valve - open above 4500 rpm? Might not be that difficult to arrange. There are big plugs in the lower surface of the block. The pump inlet can be drilled for the fittings. Eh? T

And if you want to get cheap on the management of it, just tie the on/off valve into the IRIS system. You've got a signal at what? 4krpm right there. Pretty easy to tap off of.

[Tapani]

Good idea ! But ain't that open until 2500 rpm, then closed, and opened again at 4500 rpm or so?

/T

[Tapani]

Bazza, have you seen this product?

http://www.ebay.com/itm/350590711709

This is also interesting. ECU controlled electric thermostat

http://prodcds.bmwuniversity.com/lib...2%20Engine.pdf

The intelligent heat management including better efficiency with high engine temperatures is explained.

There's also the DISA intake system, very nice and works the same as ours !

Tapani

[Tapani]

Further on map thermostats and other stuff:

http://www.behrthermottronik.de/file...thermostat.pdf

http://www.behrthermottronik.de/file...ervice_lay.pdf

http://www.meeknet.co.uk/e38/e38_map_thermostat.pdf

http://www.volkspage.net/technik/ssp/ssp/SSP_222.pdf

Electrically heated and electrically actuated thermostats

http://www.wahler.de/fileadmin/wahle...schuere_en.pdf

http://www.clemson.edu/ces/crb/publi..._2_15_07_1.pdf

Check out the two port valve here.... could be used to control an extra bypass circuit per engine speed.

http://www.thermotion.com/topic/18-e...rol-valve.aspx

/T

[Tapani]

This has been touched on before, but has anyone tried the Evans waterless coolant?

It's supposed to be superior to glycol/water against cavitation - see here:

http://www.evanscoolants.co.uk/techn...-no-erosion/47

I know cavitation in large diesel engine cooling systems cause cylinder liner erosion problems - I've seen it many times.

Here's a test result from SwRI (used to work there a long time ago )

http://www.evanscooling.com/assets/U...n-Results2.pdf

The liner erosion caused by cavitation was significantly reduced compared to the reference coolant.

I know the heat transfer is somewhat less than standard coolants, but if that is not the limiting factor.... someone who actually has this problem might want to try, eh ?

/T

[icingdeath88]

Originally Posted by Tapani

This has been touched on before, but has anyone tried the Evans waterless coolant?

It's supposed to be superior to glycol/water against cavitation - see here:

http://www.evanscoolants.co.uk/techn...-no-erosion/47

I know cavitation in large diesel engine cooling systems cause cylinder liner erosion problems - I've seen it many times.

Here's a test result from SwRI (used to work there a long time ago )

http://www.evanscooling.com/assets/U...n-Results2.pdf

The liner erosion caused by cavitation was significantly reduced compared to the reference coolant.

I know the heat transfer is somewhat less than standard coolants, but if that is not the limiting factor.... someone who actually has this problem might want to try, eh ?

/T

(Chemist here) If the boiling point of the waterless coolant is much higher than the bp of water, then it should help at least some with cavitation. Their website says the BP is 180*C, water's BP is of course 100*C. says their coolant (the one branded npg+), is mostly ethylene glycol. Long story short, the increased bp should mean that the coolant is less susceptible to cavitation caused by low pressure on the inlet side of the water pump. At least, it should significantly raise the rpms that cavitation starts to occur at.

Seems to me that it would be worth a try. Maybe the combo of reducing the wp efficiency, plus the waterless coolant would give a decent compromise of high enough flow at low rpms to keep things cool and low enough flow at high rpms to prevent cavitation.

I'm still liking the electric water pump route more myself, but Evans/drilling wp could be a lower cost alternative that gets the job done.

Out of curiosity, is the waterless coolant usually allowed by competition rules?

[Tapani]

What do you guys think - should we try to describe how the SVX cooling system works? And how different issues affect the system with a holistic perspective?
Please feel free to argue, correct, add and comment :-).... my sole purpose is to get an agreement on the basics. This is just free flow of thoughts.... not a comprehensive description nor written in the most logical sequence.

• The thermostat controls engine (and pump) inlet flow temperature, which is the result of all bypass flows and the radiator exit flow combined. This is adjusted by the thermostat - the control "signal" is the bypass temperature. The relative flow rates are defined by flow resistances (by pass circuits vs throttled radiator circuit).
• The thermostat starts to open at 78-80C and is fully open at 91C.
• The water pump flow figures in the FSM are given at 85C coolant temperature (thermostat app 50% open).
• Normal engine exit temperatures are app 87-88C (based on my lap top).
• The fans are triggered on at 92C and off at 88C (again, based on my observation) - engine exit temperature (sort of funny). Vehicle speed sensor 2 and AC operation also have an effect.
• Based on all above, the target engine inlet temperature is 85C. Would be nice to measure at the low part of the block casting - there are plugs which could be used.
• The system design is based on high flow rates and low delta T across the engine - only approximately 7 C. Main reason is probably tight critical tolerances within the engine, efficiency and emissions.
• The bypass flow temperature to the thermostat is very close to engine exit temperature 87-92C. Heater core will have an effect on this.
• To keep the thermostat at least 50% open the radiator exit temperature must be in the order of 80C or more (to keep the engine/pump inlet temp at 85C).
• If the radiator exit temperature is significantly less than that the thermostat will decrease the radiator flow and increase the bypass flow, which - judging purely by the diameters - has a higher flow resistance and will thus lower the absolute pressure at the water pump inlet.
• Highest heat load from the engine to the coolant is in the exhaust valve seat area.
• The control signal for the thermostat is a bulk flow reading at the engine exit.
• Steady state operation may differ quite a bit from fast transients because of natural "thermal inertia" within the system.
• Sudden increase in heat flux from the exhaust valve seat area may cause local boiling because of the total system thermal inertia - the increase in radiator flow (thermostat opening) may be too slow to catch up. This is especially relevant in turbo charged engines.
• The radiator design looks "flimsy" :-) - maybe to keep the exit temperatures up (and thermostat open)?
• Tony has shown that the air flow thru the radiator is quite low - this is due to aerodynamics and other issues. The radiator sealing to the vehicle body is there for a reason - as is the underside plastic protection - the undertray.
• If the radiator is uprated w/o other modifications the radiator exit temperature goes down and this leads to the thermostat staying in a more closed position, higher bypass flow rates and lower pump inlet pressure, higher pump pressure ratio, lower mass flow - all will increase the potential of cavitation at the impeller vanes at high revs. Keeping the fans on all the time (when not required) works the same way. Relocating the thermostat to the upper hose will help in this respect, but it will work against one of the core design points - controlling the engine inlet temperature.
• The more heat we can keep within the process the higher the BMEP -> higher output and efficiency (w/o detonation)
• From the cooling systems point of view the most critical thing fighting detonation is to avoid local hot spots which either cause local boiling or are the cause of steam generation causing catastrophic decrease of heat transfer. This applies to air pockets too - and steam from any kind of cavitation, either at the pump or elsewhere in the system.
• Increasing the margin to local boiling will help in that respect - some have reported potential to increase boost and/or timing a few notches.

[SVXRide]

Tony,

When I tried to respond to your PM, the Network's system says you're not taking messages. Would you mind sending me a PM with an email addy I could contact you through?

Cheers,
Bill

[bazza]

Tapani - I've not replied as that hurts me head every time I read it haha

[Tapani]

Originally Posted by bazza

Tapani - I've not replied as that hurts me head every time I read it haha

And you're the one who makes the most mods yeehaa !

[bazza]

So bit of an update.

A bit of background - my mate has the 1000 bhp EG33. However he is testing the cooling systems and electronics with a stock EJ207 which is making about 450 bhp. The cooling system is using an 150L/min electric water pump to suck water from the radiator to the engine and another to suck water from the turbo / oil cooler and return into system post motor.

The AMAZING thing is it's works extremely well. We've been doing some track events and he is sitting at 80-85'C each session (and he is not far off lap record pace) whereas with mine (I'm also running a stock EJ207 at the moment) it tends to get a bit hot and up to 100-105'C (although I'm running my stock EJ207 up around 475 bhp and using a stock STI radiator behind a FMIC.. duh!!)

I am testing a bigger radiator next weekend on mine then I'll be gutting the pump and running an electric water pump.

Later we'll be testing the 1000 bhp EG33 engine with the electric water pump.

Seems Tony and Harvey were very wrong about a lot of things.

[Tapani]

Good to hear from you !

Keep us informed - it would be nice to get to the bottom of all this.

/T