Supercharger Discussion For all you misguided souls.
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Old 12-13-2018, 04:58 PM
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The temperature drop allows you to use more timing without detonation. The pressure actually drops with the temperature of course, but this actually aids in reducing the stress and parasitic load because the supercharger is working against a lower back pressure in the inlet tract.
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Old 12-13-2018, 05:11 PM
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Originally Posted by sixshooter View Post
The temperature drop allows you to use more timing without detonation. The pressure actually drops with the temperature of course, but this actually aids in reducing the stress and parasitic load because the supercharger is working against a lower back pressure in the inlet tract.
I don't believe this is the case because the supercharger is fighting the air pressure on the hot side of the intercooler, which would be at least as high if not higher than a non-intercooled setup due to the additional restriction of the intercooler. Only the cold side pressure will be lower.
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Old 12-13-2018, 05:33 PM
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Originally Posted by Spaceman Spiff View Post
Making the air cooler, and thus more dense, quite literally changes that number of individual oxygen molecules per unit volume of air. 250F IAT to 60F should net you a density increase somewhere in the 20% neighborhood. The more O2 in the combustion reaction each engine cycle the more power you make, all timing, fueling, and tuning aside.

I also think a 20% assumption on IC pressure drop is probably too conservative.

But end of the day, why even bother crunching the numbers when you have 15 years of empirical evidence that an IC does wonders for your setup?
20% was a conservative estimate, but not far off your data which suggests ~15%.
Yes, I have seen evidence of intercooled JRSC setups making more power. But I have only seen data for pump gas setups, which are highly knock limited prior to intercooling. Since I am on E85, I get the added cooling effect from the higher latent heat of vaporization of ethanol and detonation resistance of higher octane, which allows me to run significantly higher timing much closer to MBT. This is where I am stuck. Most of the articles you guys linked above (very interesting, thanks for sharing) suggest that increased timing and boost are the real benefit to intercooling. I'm still trying to make sense of the Corky Bell article. The fact I can't get past is that a positive displacement supercharger pumps a FIXED volume of air, the intercooler principle make perfect sense for turbos, which can just pump more air. (Yes I know turbos are better, etc.etc. but I'm sticking with my sc for now.)
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Old 12-14-2018, 06:21 AM
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Your supercharger is tiny. A decent-sized intercooler would offer nearly zero flow resistance at the volume you are producing.

I feel like I'm done belaboring the point. Do as you wish.
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Old 12-14-2018, 09:58 AM
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I'm not trying to start an argument or be intentionally contrary. I'm most likely going to install an intercooler and upgrade to a larger crank pulley as I'm sure it will be beneficial by adding both. I'm just the kind of person who likes to understand the science behind things. Feel free to drop out of the discussion.
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Old 12-14-2018, 10:10 AM
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http://kennebell.net/tech/supercharger-tech/supercharger-efficiency-explained/

Check out the section on temperature efficiency, that is the argument I was trying to make. A fixed volume of air cannot magically acquire more oxygen, it can only allow you to run more boost or timing.
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Old 12-14-2018, 11:06 AM
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I understand what you are saying but there is more than one way to contribute and generate additional power.

If the air contracts due to the of the intercooler the pressure will drop in the entire tract between the supercharger and the engine. This reduces the effort required by the supercharger and therefore parasitic losses are reduced.
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Old 12-14-2018, 01:35 PM
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Originally Posted by sixshooter View Post
I understand what you are saying but there is more than one way to contribute and generate additional power.

If the air contracts due to the of the intercooler the pressure will drop in the entire tract between the supercharger and the engine. This reduces the effort required by the supercharger and therefore parasitic losses are reduced.
Now correct me if I'm wrong, but I have always been told that the real gains come from the timing increase you get from the charge air being cooler. Meaning, whatever pressure loss you are getting from the intercooler is vastly countered by the amount of extra timing that one can run. I know on my tune, I believe I had to pull like an extra 4 or something rediculous up top to keep it from detonating before I put the intercooler on.
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Old 12-14-2018, 02:22 PM
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Originally Posted by Balto View Post
Now correct me if I'm wrong, but I have always been told that the real gains come from the timing increase you get from the charge air being cooler. Meaning, whatever pressure loss you are getting from the intercooler is vastly countered by the amount of extra timing that one can run. I know on my tune, I believe I had to pull like an extra 4 or something rediculous up top to keep it from detonating before I put the intercooler on.
You are correct when you are talking about certain fuels. He's on e85 so he's not going to gain as much from timing because he wasn't limited. But he may gain a little with some timing due to a colder air charge. But that part is probably already close.

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