Author Topic: Engine Cooling capacity needed per HP, or similar calculation  (Read 10599 times)

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Offline SteveM

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Engine Cooling capacity needed per HP, or similar calculation
« on: September 29, 2016, 04:18:25 PM »
I seem to remember seeing a thread a while back about how much cooling capacity was needed to run an engine using a "reservoir" style cooling system as opposed to a radiator style heat exchanger.  I can't find the thread now.

Since I can't find any previous discussion, how about starting a new one.... 

Let's say I have a 300 HP engine and want to use a non-pressurized cooling system with "X" gallons of water in circulation, is there a rule of thumb to solve for "X" when designing a system?

Steve.
1/2 of the Rampage Brothers

Offline SteveM

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #1 on: September 29, 2016, 04:36:30 PM »
Ooops - nevermind, I found the original threads....

Steve.
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Offline Frankie7799

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #2 on: September 29, 2016, 05:06:38 PM »
Post the link for the original  :-D

Offline Captthundarr

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #3 on: September 29, 2016, 05:12:20 PM »
What Frankie said....
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Offline SteveM

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Offline SteveM

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Offline Frankie7799

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #6 on: September 29, 2016, 06:22:40 PM »
Thanks Steve. I have one of those non radiator type cooling systems in the race car. Wanted to see if I was close in capaactiy

Offline Rex Schimmer

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #7 on: September 29, 2016, 06:28:35 PM »
Mike,
You should really reconsider using a non pressurized system, especially with a turbo motor. The increased water pressure helps prevent the water from boiling especially around the exhaust port, which can be critical in a turbo engine, especially with 16+:1 compression ratio!

Rex
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Offline Ron Gibson

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #8 on: September 29, 2016, 07:15:48 PM »
I think I remember, (CRS) that the big Cummins water pumps run 40 to 45 psi normally at road rpm.

Ron
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Offline Jack Gifford

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #9 on: September 30, 2016, 01:49:53 AM »
SteveM- thanks for posting those links. I must have neglected to read that discussion the first time around- good info.

I don't know that I'll ever need to answer this question, but anyway- is tap water (at ambient temperature, for replacing hot water in tank) available on the salt? At El Mirage?
« Last Edit: September 30, 2016, 01:54:59 AM by Jack Gifford »
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Offline Stainless1

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #10 on: September 30, 2016, 09:13:40 AM »
Jack... of course water is available.... all you have to do is bring it.  :wink:
We've been doing that for about 38 years...  :cheers:
Stainless
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Offline SteveM

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #11 on: September 30, 2016, 11:59:14 AM »
Lots of thermal transfer thoughts swirling through my head right now.

I'm looking into tube-and-shell type heat exchangers for my applications. 

The industry in which I'm employed may be able to provide a source of cheap-ish, used industrial tube and shell units that would be pretty easy to package in a race vehicle, and not require much fabrication.

Steve.
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Offline awelker

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #12 on: September 30, 2016, 02:21:14 PM »
Steve,

I switched to a heat exchanger type setup last year and an ice tank after reading through the posts you referenced earlier.  What I ended up doing was having a custom aluminum radiator made that the core is enclosed to have water flowing across rather than air.  The radiator core size is only 15" wide x 5.5" tall x 2.75" thick. I have an ice water tank which will hold about 9 gallons of all water (or about 40lbs of ice + water) and has it's own electric pump to circulate across the radiator core.  I have this circulating pump set up that I can manually turn it on or it can be automatically turned on by a trigger point from the engine water temperature gauge, serving as an electronic thermostat. 

I'm running Flathead Ford which is not at the 300hp your talking of, but it dumps a lot more heat into the cooling system compared to that new fancy overhead valve stuff, so probably a decent comparison.  This year at Bonneville with the engine starting temp around 110-120 the ice tank would begin to circulate right around the 2 mile and maintain whatever set point temp I had it at (usually 180-190).  Once on the return road and turning all the pumps on it would cool the engine down to about 140.  The really nice thing was we could take out some warm water from the ice tank, put in a bag or two of ice, run the pumps and it would be right back at 100 degrees and ready to run again. I am really satisfied with the setup I ended up with, which will have enough cooling capacity to an eventual goal to be able to run the long coarse, if I can make enough horsepower.

When I was considering the change to this system I also looked at heat exchangers and I stayed away from them mostly because of space constraints.  However if you do go that route pay attention to their BTU transfer rate at different fluid temps.  A lot of these are intended for much higher temperature differentials than you will be dealing with and can be misleading when looking at the numbers.

In the pic below the tank at the back of the engine is the "radiator/heat exchanger", the one with the cap off is the ice tank.  The engine runs fully pressurized and the ice tank is vented and the water could boil off if need be.  I agree with Rex and would avoid a fully unpressurized system for the localized boiling.

Untitled by Andrew Welker, on Flickr

Offline Rex Schimmer

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #13 on: September 30, 2016, 10:48:42 PM »
Steve,
If you are considering using a water to water heat exchanger then go with the new(er) brazed plate style which is much more efficient than a shell and tube and much smaller. Check this site out and you can see what I am talking about. http://www.brazetek.com/brazed-plate-heat-exchangers (Also much more efficient than a "radiator in a tank" application and much smaller and probably less expensive.

Rex
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Not much matters and the rest doesn't matter at all.

Offline SteveM

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Re: Engine Cooling capacity needed per HP, or similar calculation
« Reply #14 on: October 03, 2016, 01:19:53 PM »
WOW - lots of good ideas flowing here.  AWelker - the setup you have developed on your lakester looks like it's as well thought out and executed as anyone could ask for.  That is a super-tidy package!

Rex:  thank you for the link on the brazed plate heat exchangers.  They definitely look more compact than a tube and shell exchanger of similar capacity.  At my day job, we use a mix of plate-and-frame and tube-and-shell exchangers for different applications.  The link you provided is the first place where I've seen appropriately sized plate-type heat exchangers.  As of right now, this looks like the most practical solution for future development.  I need to dig a little deeper - I didn't immediately see any BTU/Hr ratings on those brazed units.

Since my vehicle is still a truck, the good news is that it has a bed which can be used to haul stuff like water, tanks, pumps, etc.  I will definitely be digging deeper into this topic!

Steve.
1/2 of the Rampage Brothers