Who still drives their cobra in the summer heat

[TimG427]

I had the Bronze car out for a quick spin to see if it was running well. I cleaned and gaped the plugs as they seemed to be fouled from on and off a trailer for eight years. I tried the Italian tune up idea and it helped. It's 91 degrees here is Austin.

[IMLost]

Well guys... if i din’t drive in the heat, I’d never drive it. Oh.. bu the way, it’s never been wet either. Yea right. If your cars never been hot or wet well you get it. Plan you time and trips and go. I’m just lucky enough at 68 that i can still push it.

[IMLost]

BTW, that’s also why i installed a Holley Sniper. It starts up and goes at all elevations from Florida sea level to Mt Washington. Looking to go west and get Pikes Peak and Mt. St. Helens if the damn Virus would let me. But again i have a small block. It’s a go car not a show car.

[twobjshelbys]

To answer the OP's question: All the (Phoenix) Arizona guys. Almost every weekend. It's dry heat.

[1795]

Originally Posted by twobjshelbys

To answer the OP's question: All the (Phoenix) Arizona guys. Almost every weekend. It's dry heat.

Yeah, I remember hearing that, "Don't worry, it's dry heat" sh@@t when I had to go to Scottsdale in August 15 years ago. I got off the plane and it was 123 degrees and the first breath dried my lungs right out. Hell, nobody was outside after 9 am until the sun went down. I couldn't stand being inside so I would go for a run at about 6 am and then late in the afternoon go for a walk around town and check things out. I was the only one outside except for a few unfortunate people working construction and landscaping.

[eschaider]

Originally Posted by Ace23

Thanks Ed. The QF750 with mechanical secondaries was setup on the dyno by Wayne Presley of very cool parts down in Alabama. I have no cranking issues or fuel boiling in the bowls...no sputtering or anything of the matter in the heat.

If I was going to go EFI it would be multi-port injection. FAST is local here due to comp cams. I would probably try to hook up with a local engineer for install and tuning. I would also go with an in tank fuel pump. I have no idea what fuel injection would do for me...I would just want it done right. The carb runs smooth idle through WOT but I’m sure EFI still wins. As I previously mentioned I just don’t like the down on power feel in the summer.

Any time air temp goes up air density goes down and so to does engine power, but proportionally. Here is a graph that visually illustrates the phenomena;



The hard numbers look like this;

Air Density at 70˚F is 0.0749 lbs per cubic foot,
Air Density at 120˚F is 0.0685 lbs per cubic foot.

That is a decrease of air mass equal to 8.5%. An 8.5% loss of air mass will produce an 8.5% loss of power when properly tuned. For many people this is around the threshold or just past the threshold where they become aware. When not properly tuned, the 8.5% loss of air mass will produce a much larger loss of power because you not only have less air available, you now also have a surplus of fuel that makes the engine run rich,

Your Cobra should not loose proportionally more or less power than a daily driver across the same temperature change. If the Cobra is noticeably more lazy across the same temperature change, then your Cobra is not properly tuned and/or you carb is also out of whack.

Both sutuations need to be attended to. EFI will not create power but it will, when properly installed and tuned, optimize the power available for the ambient conditions at hand.

I took a quick look at the FAST website because I was unaware of a MAF based system they offered. There might be one but, the website doesn't seem to indicate they offer one at this time. That of course could change with time.

A speed density system will be better than your carb but you will still have some level of summertime blues form the temp changes that will still require some level of attention to a speed density EFI system to optimize engine power output.


Ed

[fastd]

Originally Posted by IMLost

BTW, that’s also why i installed a Holley Sniper. It starts up and goes at all elevations from Florida sea level to Mt Washington. Looking to go west and get Pikes Peak and Mt. St. Helens if the damn Virus would let me. But again i have a small block. It’s a go car not a show car.

+1 for holley sniper. It manages the heat and today’s gas to make the car drivable across a broad range of conditions.

[twobjshelbys]

Originally Posted by IMLost

BTW, that’s also why i installed a Holley Sniper. It starts up and goes at all elevations from Florida sea level to Mt Washington. Looking to go west and get Pikes Peak and Mt. St. Helens if the damn Virus would let me. But again i have a small block. It’s a go car not a show car.

Mt. Washington is only about 6200', which is well within the range of a carburated system without rejetting so DFI doesn't need to work too hard. Trying it on Pikes Peak or on Trail Ridge Road is the acid test.

[eschaider]

Originally Posted by twobjshelbys

Mt. Washington is only about 6200', which is well within the range of a carburated system without rejetting so DFI doesn't need to work too hard. Trying it on Pikes Peak or on Trail Ridge Road is the acid test.

Air density is more altitude sensitive than most people might at first suspect. This is a graphic representation from the engineering toolbox of the effect of altitude on air density from sea level to 10000 feet;



Using sea level as a baseline the correction factor at 5000 feet is 1/1.17 or about a 15% reduction in available air which would correspond to a 15% reduction in engine power. This would be even more apparent than the summertime blues power reduction in climates like AZ. At 5000 feet the effect is so pronounced that the drag races at the Denver Mile High facility have measurably slower speeds and higher et's than the same cars and classes at NHRA sea level or near sea level tracks.


Ed

[bobcowan]

Generally speaking, you lose about 2-3% of your power per thousand feet of altitude. That's independent of temperature.

For small engines and underpowered cars, that's a noticeable change. If you're noticing a significant change in an over powered light weight car, then there's a problem. And it's not the heat or the altitude.

[twobjshelbys]

My reference is to OPERATION not POWER. My dad had an old Suburban. First year we went to Rocky Mountain Park it ran fine at the front Range (Denver @ 5280), and fine in Estes Park/RMNP. Lower power sure, noticed with the trailer. But without the trailer it struggled on Trail Ridge. By the time we hit the top it took a while to start and idled rough. Next time he rejetted the carbs...

And the DFI system on my Cobra operated worse at 5500' than the Suburban at 11000. The reason was, after much work and gnashing of teeth, the altitude compensation table in the Roush IR tune had not been populated. After a tuner in Ft. Collins touched it it worked great at all altitudes.

[desgros@vtlink.]

Here in northern Vermont if I waited for hot weather to drive my Slabside it would virtually never go out. A 90 degree day is extremely rare. Carb problems are mostly non existent using aviation fuel. Well worth the extras cost.


John
ERA #3010 Slabside 289 SB BRG

[SN8K IS Wife]

We are out no matter what the temp is. 27 is the lowest, 112 in stop and go traffic is the worst. We have cooling vest, has 12 pockets with special ice packs. Just got Aftershokz headphones, works great can hear the music. Works best with ear plugs. Great for those long drives.

[hauss]

Just drive the dam thing, stop complaining! You are in a cobra! The sickest most badass car ever made! You are already cool. Hope this helps cool you off.

[Steve Gallegos]

Two words. Bimini Top. I made one for my backdraft, around town and long trips you stay cool and if you run into rain, keeps you dry.

[Dwight]

In the hot summer here in Alabama I like to drive in the late evening or early mornings. Sunday morning is great because not only is it cooler but almost no traffic on the back roads.

My record for driving in the rain is 360 miles out of a 535 mile trip.

Out of 42,000 miles I might have driven 1000 miles in the rain. Never left home in the rain but I have returned a few times in the rain.

[Michael C Henry]

I bought my car from the original builder at Hot August Nights in 99. It was built as a competitive car in NV so hot weather was prepared for. The car is white, a practical choice for NV. Try laying your arm on the outside of one of those black cars in the summer sun. But no soft top. I moved it to Tacoma WA, it rains here. I had an old 56 Bristle for a while and the soft top made it livable. as a daily driver by a young person with a family, The practical car stayed home for the wife and kids. When I bought the Bristle in 71, my uncle in CAL told me that this is the kind of car where you do not worry about the water getting in but rather make sure it can get out. It is going to get wet. My replica gets wet when I'm stopped but when driving it's the drip from the windshield stanchion on my leg is the problem. The original builder used the biggest copper radiator and covered it with four electric fans. with adjustable thermostat controls top and bottom pair of fans. Aluminum radiators seem to work best the first season then they become less and less effective to handle the cooling mission. That is from a family friend that has s stock ca. r He plans on buying a new aluminum racing radiator every other year. Winter time here, in an unheated garage, gets messy , smoke when started from so much un burnt fuel until it's warm up. And cold oil is a problem with a high volume oil pump. It's a balance between keeping it running and not revving that will shear the distributer drive pin. Summer is great that is what it was built for. Back in Iowa winter 72-75 with the 56 bristle, when getting on Interstate 80 at 14th ST going East, snow blew through, in one side and out the other side, I wear a base ball hat with a chin strap and sun glasses that fit tight to cut any wind from the eyes. When driving take a sweat shirt or long sleeved shirt, for chill and sun burn.

[tortuga]

When its hot and still and you hit traffic...we took ours to wine country a few years back and got stuck in stop and go in 100+ degree heat. Found the first nice air conditioned Restaurant we could And spent HOURS in there , contemplating getting a rental to get home...but a warm day on the coast highway...

[lnfletcher]

Nothing feels as good as after getting burned alive driving down the interstate in 100+ sunny day, all hot and sweaty and then finding a beautiful shaded cobra curvy road with beautiful views. (Pig trail in AR?)

Maybe better than freezing your bageba's off in sub 32 weather and finally making it home to sit in front of the fire!

I love every day I can drive mine!

[DanEC]

Hate stop lights and the exhaust heat welling up over the top of the doors but cruising around on country roads in summer is just fine. But I probably go for shorter drives than many of you.