Big Radiator advice, 68 Mustang.

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Author Topic: Big Radiator advice, 68 Mustang.  (Read 6856 times)

Offline AussiePhil

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Big Radiator advice, 68 Mustang.
« on: February 28, 2020, 07:41:00 pm »
Hi all,  I'm looking for some advice on a radiator!
My engine temperature rises to about 190-200F in traffic and takes some time at speed to cool!
I've cut out the radiator support and fitted a wider HQ Holden radiator, but it's 50mm to short.
The engine is stroked, supercharged, intercooled, runs big injectors,  haltech ECU, and runs 400HP.
The intercooler heat exchanger in front of the radiator is way overkill,  I'm now changing to a smaller one.
I'd like to keep it a downflow radiator. I'd love a PWR or equivalent but can't justify the cost.
I can afford something like Afco, Northern, Scott Drake, Max-core etc.

Has anyone had experience with larger radiators!

Cheers Phil


« Last Edit: February 29, 2020, 05:01:11 pm by AussiePhil »
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Offline AussiePhil

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Re: Big Radiator advice, 68 Mustang.
« Reply #1 on: February 28, 2020, 07:56:59 pm »
PS, I have a high flow water pump, an overdriven supercharger pulley with an underdriven accessory pulley which I'm fitting a smaller water pump pulley at the moment.

Cheers Phil
« Last Edit: February 28, 2020, 07:59:31 pm by AussiePhil »
If you've never buggered anything you've never done anything!
But if you've buggered a lot maybe you're not very good at it!

Two for one is good but four for two is better!

Offline unilec5544

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Re: Big Radiator advice, 68 Mustang.
« Reply #2 on: February 28, 2020, 09:40:21 pm »
Nice looking engine bay, do you have an infrared thermo heat gun, if so take a reading at the radiator inlet and outlet, should drop at least 25degF, you may find that your fans are to small.
Not sure if a high flow pump is such a good idea and tends to flow through the radiator to fast.

Offline Juanball mustang

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Re: Big Radiator advice, 68 Mustang.
« Reply #3 on: February 29, 2020, 07:41:20 am »
Are your hose inlet and outlet on the same side or diagonally opposite ?

Offline AussiePhil

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Re: Big Radiator advice, 68 Mustang.
« Reply #4 on: February 29, 2020, 08:36:04 am »
Hi, Thanks for your input.
No I don't have a thermo gun, and yes you could be right about the flow.
I also have a high flow 170f thermostat. Thermos come on at 150 and 155f
I've got restricted room to overdriven supercharger crank pulley, have replaced one thermo were I've got room and working on fitting a bigger motor on the other without making it longer.
Radiator outlets are diagonal.
Big problem is the intercooler heat exchanger is way to big and there's nothing between this and one that's to small.
I want to protect my engine but also want the intercooler to work well also.
Cheers Phil
If you've never buggered anything you've never done anything!
But if you've buggered a lot maybe you're not very good at it!

Two for one is good but four for two is better!

Offline scollist

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Re: Big Radiator advice, 68 Mustang.
« Reply #5 on: February 29, 2020, 11:21:09 am »
Is 190 to 200 degrees really a problem?

If you Google "what temperature do cars run at" you'll see that normal operating temperature is stated as 195 to 230, with 210 being about normal.  All modern cars supposedly run at around 210 as it is more efficient environmentally.

I suppose the question is if it is getting to 200, will it continue to go higher?

And I think that the thermos coming on at 150 is way too low. Even early Mustangs only had a 160 thermostat (meaning they only open to commence cooling once 160 is hit), but 180 is very acceptable.
« Last Edit: February 29, 2020, 11:22:48 am by scollist »

Offline USA066

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Re: Big Radiator advice, 68 Mustang.
« Reply #6 on: February 29, 2020, 12:14:19 pm »
I agree with Shane, I think the normal operating temp for that engine should be 195 degrees, so 190 to 200 should not be a problem. Having said that, with your high flow water pump and thermostat, thermo fans, etc, the temp should be lower.
Comments:
1. I think your problem is restricted air flow, vertical fins (radiator) and horizontal (intercooler) causes restricted air flow. How strong are your thermos, I would be looking at least 2800cfm but 3000cfm would be better. You could also install an intercooler fan.
2. The small heat exchangers, what are they for - transmission/engine oil coolers? B&M do small ones for big engines.
3.  I would set the thermos coming on at 180 degrees. Do you have mechanical or digital or other thermo switch? Go digital or better.
4.  I presume the Holden HQ radiator is an upright, if you are looking to change, I would consider a thinner cross flow, with the radiator cap on the lower pressure side. These are more efficient
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Offline BAC

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Re: Big Radiator advice, 68 Mustang.
« Reply #7 on: February 29, 2020, 12:23:07 pm »
Is 190 to 200 degrees really a problem?
:agree: There seems to be an obsession with getting operating temps down to the 170-180F range.  Engines are fine with running between 190-200F and there are reasons why it is preferable to do so.

The rule of thumb I was taught is to have your thermostat set a few degrees below what you want the operating temperature to be.  So if looking to run around 190F then use a thermostat rated at 180-185F.

Trying to force the cooling system to run much lower than that is inefficient and saps net engine power.
Cheers,
Brian

Offline AussiePhil

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Re: Big Radiator advice, 68 Mustang.
« Reply #8 on: February 29, 2020, 07:25:09 pm »
Thanks all for your help! I've decided to go with a Scott Drake 24" radiator from Custom Mustangs.
That with smaller intercooler heat exchanger will keep the engine at a good temp!
Cheers Phil.
If you've never buggered anything you've never done anything!
But if you've buggered a lot maybe you're not very good at it!

Two for one is good but four for two is better!

Offline AussiePhil

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Re: Big Radiator advice, 68 Mustang.
« Reply #9 on: April 22, 2020, 08:56:23 pm »
Thanks all for the discussion,
I've sorted my overheating problem.
I machined and fitted a smaller water pump pulley to keep about the same engine/water pump ratio, 1:1.4 as original.
Replaced the oversized heat exchanger and fitted two Derale oil coolers in parallel keeping about the same fluid flow.
Fitted SPAL low profile thermo fans,  lowered the radiator 35mm to get the top tank in the air better.
Before the covid lockdown I took the car for a run around town and temp sat continually around 160 degrees even in heavy traffic.
Cheers Phil
« Last Edit: April 22, 2020, 08:57:54 pm by AussiePhil »
If you've never buggered anything you've never done anything!
But if you've buggered a lot maybe you're not very good at it!

Two for one is good but four for two is better!

Offline BAC

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Re: Big Radiator advice, 68 Mustang.
« Reply #10 on: April 22, 2020, 09:07:51 pm »
Before the covid lockdown I took the car for a run around town and temp sat continually around 160 degrees even in heavy traffic.

Impressive result but some might say that's actually too cool.  If the temp doesn't get high enough you don't burn off the contaminants in the oil plus it costs kilowatts from the motor to lower temps below optimum. 

Most modern cars are designed to operate around 90C/195F for maximum efficiency and longevity.
Cheers,
Brian

Offline AussiePhil

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Re: Big Radiator advice, 68 Mustang.
« Reply #11 on: April 23, 2020, 07:44:01 am »
Thanks Brian, advice taken!
Now that it's under control I'll put a 180 degree thermostat back in it.
When I say 160 degree it may be higher as I'm guessing because the marks on the gauge goes from 150 to 180, it's probably higher than 160.
Cheers Phil.


If you've never buggered anything you've never done anything!
But if you've buggered a lot maybe you're not very good at it!

Two for one is good but four for two is better!

Offline AussiePhil

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Re: Big Radiator advice, 68 Mustang.
« Reply #12 on: July 25, 2020, 08:08:58 pm »
Hi all,
Because I've fitted an underdrive crankshaft pulley I found that the water pump slowed some what,
I had trouble finding a small pulley to fit, I fitted a High Energy Gilmer pulley but it was to short, I've found that a Diecrest 32T Chev Gilmer water pump pulley fitted beautifully,  just needed to drill the holes a little as they have slightly different PCD, but the water pump shaft holds it centre and turn a taper to clear the supercharger belt. This smaller pulley gives it 1.4:1 ratio on the crank pulley, slightly faster than original.
I was a little worried that the teeth would create to much of a noise, but it doesn't,  not sure if it will damage the belt but I'll keep an eye on that! This is an old belt, I'll change it in time!
Cheers Phil
« Last Edit: July 26, 2020, 03:20:21 am by AussiePhil »
If you've never buggered anything you've never done anything!
But if you've buggered a lot maybe you're not very good at it!

Two for one is good but four for two is better!