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Old 11-23-2022, 08:52 AM   #31 (permalink)
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Talos have you tried header air for keeping warm in the winter? I really don't believe in EGR or warm air having more of a benefit over keeping a prius warmer so it can run like a normal corolla would without having to have the engine on 24/7 like a corolla would.

I think manufacturers dyno their cars at 77F so I usually just aim for around this temp for winter air for my car. If you go too crazy I wouldn't want to deal with the horsepower loss.

Also, WAI for me is just helpful for around town. The car does fine at steady state, but that can be a very small percentage of my driving a lot of the time.

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Old 11-26-2022, 01:51 PM   #32 (permalink)
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Exclamation Lessons learned

Quote:
Originally Posted by Logic View Post
Here's the exhaust next to the number plate on an early Lotus Europa:
(my project car if I ever get the damn Anglia sold)


But it was moved to the more conventional spot in later models.
So the second version of the boat-tail that I did had the exhaust moved to be at the end just like this. Not only did I reason similarly (the low pressure would help suction) but also that the hotter air might actually provide slight thrust. We can show that, aerodynamically, that's the optimal placement for an exhaust.

Unfortunately, from an engineering standpoint, it's crap. What I didn't know at the time was that exhaust fumes contain a crapton of water vapor (I later realized from the combustion, duh). That water pooled in the pipe where it bent upward, corroded it, busted it, and then filled the rear tail with hot gas. Which was of course as airtight as I could make it.

Oh, but it gets better. I actually discovered this pretty early, and if I were at home I could have fixed things promptly. But I found this out while on a trip in Alaska. So I was 400 miles from nowhere and 2800 miles from home. While I limped home the exhaust melted my rear bumper, cracked all the plastic on the tail, fused all the wiring, and destroyed all the electronics. And that was *after* I cut open half the tail to let the fumes out.

I have since discovered that regulations clearly state that the exhaust pipe needs to be at least level with the ground, and they recommend having a 30 degree down kink with a slight grade downward afterward. So the only way to get the exhaust to come out mid-level on the car would be to raise the entire muffler assembly. That would almost certainly impact performance worse that the gains of having the exhaust in a better spot.
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Piwoslaw (11-27-2022)
Old 11-26-2022, 02:16 PM   #33 (permalink)
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I think ram air is over rated. I once calculated how fast I'd have to go to make up for the thinner air at my high altitude. I figured out I'd have to go about 400mph to make it work! I believe I calculated that at 12,000ft above sea level. No wonder airplanes ususally use turbochargers or superchargers to make up for lost air density instead of ram air intakes.
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Old 11-27-2022, 07:19 PM   #34 (permalink)
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Other than faster engine warmup WAI are a waste of time for fuel savings. They just increase energy lost to the cooling system and increase polution.

Ram air on a gasoline engine are of no use for fuel savings. They can provide a small bump in power though. On a diesel they will provide a benefit in both power and performance.

At sealevel 70 degrees F and 70mph you can get a theoretical maximum of 0.09 psi of boost.

Ram Air Calculator
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Old 11-27-2022, 07:39 PM   #35 (permalink)
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Quote:
Originally Posted by ConnClark View Post
Other than faster engine warmup WAI are a waste of time for fuel savings. They just increase energy lost to the cooling system and increase polution.

Ram air on a gasoline engine are of no use for fuel savings. They can provide a small bump in power though. On a diesel they will provide a benefit in both power and performance.

At sealevel 70 degrees F and 70mph you can get a theoretical maximum of 0.09 psi of boost.

Ram Air Calculator
According to that Ram Calculator I'd have to go more than 400mph to make up for the lost air density at my altitudes...

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