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Originally Posted by Daggar
Over and over, on the TwEECer forums, I see folks who are complaining about the Lightning meters maxing out @ X CFM. This is mostly on blown applications.
What are your thoughts on that?
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I'm not sure of your exact question. I stay away from getting involved in SC/Turbo tuning for *many* reasons.
My *guess* is that you're asking about the fact that Super Chargers take a LOT of HP to turn. And, there's no easy way to determine that amount. So, people look at the dyno results and come up with some semi-bogus estimate of *flywheel* HP. Then, they say "heck, the SC takes only 1 HP to turn

" and they wonder why they max'ed out their MAF/Injectors when their RWHP is still 100-+ HP below their other bogus estimated max for the MAF/injectors.
Putting blowers on cars gets very involved. The VE (Vol Eff) changes. The air flow may not be accurately measured into the MAF. The air temps and the rate at which they change are not really supported. As the rest of the drive-train is pushed to it's max, the loss in HP increases. So, there could be even more HP at the flywheel then they may have estimated.
As the blower pushes more air at higher rpms, the HP required to turn the blower increases greatly. Also, as the blower pushes more air at higher air temps, the HP required to turn the blower increases greatly. But, there's no easy way to get a HP estimate since the VE is also changing.
With a 90mm MAF, and very good plumbing, people can get a *rough* estimate of how much HP, in *total*, the engine makes. Then, if they put it on an *engine dyno*, they can get a *rough* estimate of the blower loss.
To add to the problem, flew people use a Mustang-style dyno. IMHO, tuning a blower on a non Mustang-style dyno is a first-pass at BEST! Unless people fatten up the curve and lower the timing, they can get problems.
I've read about how people with blowers have had "much" different tunes on the different dyno types, with the Mustang-style being the closest to real-world driving and track conditions. But, people with blowers like to brag about their HP, so they like the HP figures from the other dynos. And, the same is true for tuners - they get business by selling high HP mods. Why use a Mustang-style dyno and have your tune with the same exact mods show 5-15% less?