[mchell]

An 8 degree drop in ambient temps (mid 80’s from mid 90’s) will have more of an effect than you think. Take a drive in the evenings when the temps get into the high 70’s…… you may be surprised at how much cooler your engine will run.

My point is you may simply be running cooler because it is cooler(by fl standards)!

[72LuxuryLeMansLa.]

Originally Posted by Formulajones

My feeling on the new stuff running so warm has more emphasis on emissions, as the hotter engines burn off more hydrocarbons, cats work more effectively etc... Not that running them hotter makes for a better running engine, per say, cleaner....sure.

Most of us building these classics are pushing the pump gas envelope. Lets face it, pump gas sucks and is getting worse. Trying to make even just decent power on it with 10:1 - 11:1 compression takes a sharp tune and close control over all parameters, including engine temps. Even some 9:1 engines can struggle.

I haven't seen a car come in here yet, that makes decent HP on moderate compression ratios, with a decent timing curve, that runs around on pump gas with the engine at 220-230 degrees without complaining. You try that out here in the AZ desert heat and you'll find yourself in trouble.

What I find in most cases, keeping the engine at or below the 190 mark has been fairly safe on pump gas with decent timing curves. I'm able to do that with stock cooling systems that function properly.

Many examples here. My fathers 571 is an extreme example with 10.84:1 compression, runs 91 pump gas, completely stock issue cooling system. The car generally runs between 175 to 185 most all the time without complaint. I'm going to bet trying to make this engine run way up at 220-230 would likely end his day early.

One daily driver we use, is 11:1 with an iron head, runs on 91 pump, and it drives around in the AZ heat at about 175 most all the time. Stock cooling system. I would be a fool to run this engine at 220 degrees, damage would result.

To get away with that I'd want a steady diet of 110 octane in the tank. Not feasible in a daily driver these days.

What people also don't consider when wanting to run these high engine temps is that everything else is also running hotter. The trans for one. But what I'm more concerned with are the other components under the hood. Heat soak and vapor lock is a biggy when it comes to pump fuel. Something new cars don't have to worry about with fuel injection and 60+ psi of fuel pressure.
People want to make their classics run at 220 degrees because that's what all the OEM's are doing and then wonder why it has vapor lock and heat soak issues, lol.
I'll stick to my regimen, since I push the pump gas issue, I'll keep my engines running on the cool side and keep things safe.

I have a question about humidity. This is not a got ya or trying to start an argument....I read somewhere that in high humidity areas as compared to desert areas you have more of a margin for error because the air has more moisture. What is your experience with this? For instance our dew points right now are at 70°F

[64cabro]

Originally Posted by mchell

An 8 degree drop in ambient temps (mid 80’s from mid 90’s) will have more of an effect than you think. Take a drive in the evenings when the temps get into the high 70’s…… you may be surprised at how much cooler your engine will run.

My point is you may simply be running cooler because it is cooler(by fl standards)!

I'll try to pay attention to that, good idea. The day I had the "problem" that caused my concern was a drive around 6 am in late August, the ambient temp was probably somewhere in the 80s. It definitely was not in the 90s at that time of the day.

[Formulajones]

Originally Posted by 72LuxuryLeMansLa.

I have a question about humidity. This is not a got ya or trying to start an argument....I read somewhere that in high humidity areas as compared to desert areas you have more of a margin for error because the air has more moisture. What is your experience with this? For instance our dew points right now are at 70°F

These engines were dyno'd with 91 pump gas and have now been running for years with it. The 11:1 engine with iron heads is our daily driver now with 40k miles on it and runs perfectly. Has not been an issue. If I thought for a moment I'd have to be running 110 in the tank I never would have went this direction. I can't afford a daily diet of that stuff, lol. This particular engine does have a lot of camshaft overlap though.

You are correct, the higher humidity does add a small margin of octane tolerance. Basically water in the air lowers the octane required for a given engine. There is a formula for it. It's something like 1 gram of water equals .25 octane reduction. Don't quote me on that but it's something close to it.

We lived in Ohio (grew up there) so very familiar with high humidity and dew points. I wasn't pushing the pump gas too much back then. Most I had that I was driving was 10.5:1 with iron heads and we had 94 octane available to us at that time. That all worked perfectly fine. I've always been an advocate of making sure the engines run cool though. I think living out there I was hotter in the car than the engines were, lol.

Another thing I prefer, all these cars have fresh air intake setups (IE: factory hoods and air cleaners that draw in outside air) and I monitor inlet air temps on two of them. Cooler inlet temps help this situation as well, and if living in a humid environment referring to your question, it might even be more of a player.

[i82much]

my electric fans come on around 195 and car never gets over 200, but i drive under ideal conditions - cool nights on country back roads without any traffic at all.

[Formulajones]

We don't get to pick conditions. Most of the time it's just sunshine and hot here. Cools off at night but we usually aren't running around that much late evenings. So it's critical for us that the cars work well no matter what it's doing outside.

It is nice this time of year though as temps now are starting to come down, getting into the really nice time of year.

[HWYSTR455]

Edelbrock used to have water injection kits, Vari-Jection, in the 80s, to help ward off det. They worked. To a degree.

Meth kits are all over the place now, mostly boost people use them.


.

[JSchmitz]

Originally Posted by HWYSTR455

Edelbrock used to have water injection kits, Vari-Jection, in the 80s, to help ward off det. They worked. To a degree.

Meth kits are all over the place now, mostly boost people use them.


.

Yep. I put one on my GTO when the 100 octane leaded disappeared from the Sonoco station. It worked pretty good. Used to run windshield washer fluid in it to get a little alcohol too. That and some Vortex octane booster.