Coolant Cap Pressure

I don't think you'll go wrong with either one.

Yes, the .9 has been superseded with the 1.1, but 2 tenths of a bar doesn't make much difference.

 

I thought all 3x8s were on 1.1 now - the 328's definitly are. Operating temps should be about the same & so the pressure build up in the system should be about the same. I'd have thought 1.1 was the way to go.

Suggest you ask F UK - perhaps Malcolm can chime in with the answer.

I.

 

.9 bar = 13 psi
1.1 bar= 16 psi

Either will work on a '77. The part for the earlier .9 bar cap has been superseded by Ferrari. In other words they no longer make (or sell ) the older .9 bar cap. If the 1.1 bar cap was not a suitable replacement they would not supersede the part number but would simply say it is no longer available.

 

Ian, yes the original pressure cap #101499 was rated 0.9 bar, but as said, Ferrari superceeded it to cap #137644 which is rated at 1.1 bar.

 

Thanks for that Malcolm.

FWIW I just had to replace the cap on my 328 - it was a 1.1 Bar cap that was about 5 years old but was no longer holding. In fact it tested at about 0.7 - 0.8 bar & the car was losing coolant at quite a rate when in traffic - nearly a gallon on one occasion.

I.

 

1.1 definitely. The .9's are available, but as far as I can tell, they're "dead stock".

 

The difference between a .9 bar and a 1.1 bar cap is 3 psi which translates into a difference in boiling temp of about 9 degree's. This is the reason you have pressure in the system....to raise boiling temp (approx 3 degree's per pound)

So instead of your engine boiling over at about 260 degree's with a 1.1 bar (figuring proper coolant/water ratio)compared to boil over at 251 degree's with .9 bar cap.

Seems to me that if your temps are anywhere near this region the 9 degree's will not make much of a difference as you will have other problems to worry about.

But then again I run zero pressure and have a boiling point of 351 degree's (no pressure = no burst hoses)...evans coolings NPG+ and no water what so ever.

 

I looked them up and found them at www.evanscooling.com/main25.htm

How long have you been using their stuff, and what is your observations? Does the engine run cooler, or are you merely increasing boiling temp?

Added/edited: In reading more on their site, it looks like it's not just a change in fluid, but requires (or just prefers?) a different radiator and pump since the fluid is thicker than 50/50 EGW mix. Do you have the entire system, or did you just use their fluid?

Their Propolene Gycol sells for around $30 per gallon but it apparently never needs changing!

Thanks

 

There are several posts about Evans products that I have made (most recent is in Nicks 4.0 project thread) some go back 3 + years.

I have used it (NPG+) for years with stock pump and radiator and it performs great. The key reason for my use is it allows a far greater advance set up without fear of detonation as it has far better cooling properties and does not create steampockets where coolant is unable to remove heat from those affected area's. A hotter running engine creates more power but until NPG you were limted by old fashion coolant technology as to operating temps and thus ignition advance limits.

I now run the 4 liter radiator and modified pump but still have little testing time due to other fabrication issues that I am still working on.

Do not confuse NPG with NPG+ there is a bog difference is applications there.

This may seem far fetched but by running NPG+ you really no longer need to pay much attention to temp guage but still need to monitor oil temp.

You are not going to damage an engine when coolant temp reaches 260 degree's as long as THAT coolant can perform at those temps and NPG+ can. The limitation of water based systems is water.

 

Hi Sloan,
The engine may not be damaged at 260 degrees but think what it might do to the rubber hoses! Is there something I'm missing here?

 

My car bubbles out the overflow with the 0.9. It DOES NOT do it with the 1.1. This is a problem I have dealt with twice with the same results. If you drove a QV I would absolutely say get the 1.1 . I cannot speak from experience with your 77.

 

What I meant is at those temps water/coolant mix has lost its ability to remove heat and that you may suffer damage including but not limted to Head Gasket and hoses. Due to steam pockets that form at those excessive coolant temps internal metal surface area's could be reaching temps far above 300 degee's+++

With NPG+ the product can remove heat up to its boiling temp and steam pockets do not form as their is no water in the system.