LI-S4

And, I am hopeful that your tests are conculssive!!

Good luck!

Flyboy

topic, but it's frustrating to have to go and repeat what I've said already.

So to address your remark that I don't think pressure loss is important, here's what I wrote:

<b>Pressure loss may, or may not, be as important as temperature recovery.</b>

<b>I realize pressure drop does play a part in how much power is produced, ...</b>

As for your comment that <i>"If you have turbos/supercharger that can overcome pressure loss, it will still be pushed farther out of ideal efficiency island which causes loss of power because of increase in temperature output of charger. Really this stuff is common knowledge in the real world."</i>

You are assuming that the compressor will be pushed to operate in an area of reduced efficiency. Compressors have a range where the efficiency is maximized, not a single PR and flow rate. Look at a compressor map and you'll see the efficiency island covers an area on the map, not a single point. It's entirely realistic to have a compressor function at peak efficiency over several boost pressure values. Take the K04 compressor map for instance, peak efficiency is 0.73 and spans a PR range of 1.5-2.2, that's about 6psi-16psi. If they were installed on a car pushing stock boost levels, 9-10 psi, you could have 6psi of pressure loss and not push the compressor out of the 0.73 range. A second point about compressor efficiency, any idea what the post-IC temperature increase is when the compressor efficiency drops from 0.73 say down to 0.7? Crunching some numbers with a 80% efficient IC I get a 1F temperature increase. Assuming that's an accurate number, I doubt it's going to knock HP down very much.

Now go back to the supercharger that doesn't rely on exhaust gas to drive the compressor. If it can make the boost that the engine requests, and the IC can cool the air adequately, the pressure loss is irrelevant. It's a factor for turbochargers because the exhaust gas exiting the engine has to sufficiently vacate the cylinders to allow for good volumetric efficiency, but it also has to turn the turbine, which obstructs the passage of the exhaust gases out of the engine. If you can lower the pressure drop on the cold side then the turbine doesn't need as much energy to turn it, lowering resistance to the escaping exhaust gases and helping VE. But I'm talking about a supercharger that doesn't operate that way.

Your numbers, 12/13 HP per psi, are you referring to boost pressure? The point I'm trying to make is that if the engine requests 20 psi of boost, and the compressor can supply 20 psi of boost, regardless of whether the pressure drop through the IC is 1 psi or 10 psi, if the temperature out of the IC is the same, then the pressure drop doesn't matter, at least on the charge air side. Now it will matter as far as the turbine side is concerned, but your numbers don't seem to address the affect on that side, and that's what matters for HP production if boost level and charge temp are held steady.

And no, I haven't read Maximum Boost. I did look through Forced Induction which I think is along the same lines. That type of book is good for the overview it gives to a lot of material, but I found it to be a mile wide and an inch deep. A. Bell didn't really go into the depth I was hoping for.

Have you found an IC efficiency definition that includes pressure drop as part of the equation?