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Discussion Starter · #1 ·
Everyone needs one of these.

Video: Insane '69 Camaro - Twin-Turbo, Supercharged With Nitrous - StreetLegalTV


Bradley built the car to be different, not only is it powered by a 454ci. big-block Chevy that is punched out to 468 cubic inches, it also has a 14-71 supercharger on it piggybacked with two 68 mm turbo's that feed the giant bug catcher. Just in case that induction system isn't up to par, there is a fogger nitrous oxide system jetted for an additional 200 hp! When it comes to a compound induction set up, Bradley's Camaro has all the bases covered.
 

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Mr. Negative Pants, ,
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That's just nuts. But i think the writer got things backwards... doesn't the bug catcher feed the turbos, and not the other way around? :scratch:
 

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Nobody Has Seen Me Lately
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Actually, the turbos feed the lower plenum on the bug catcher. Insane amount of work into that car. Extremely hard to dial in the carburation with that setup...probably why he has never dynoed or raced it.
 

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Guiterrorizer
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How does one see past the engine bay :lol:
 

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Discussion Starter · #7 ·
How does one see past the engine bay :lol:
When all your car does is go crazy stupid fast in a straight line, who needs to see where you're going anyway? :lol:

Though this carpet queen probably doesn't go very vast all that often. :(
 

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Jigsaw?
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Actually, the turbos feed the lower plenum on the bug catcher. Insane amount of work into that car. Extremely hard to dial in the carburation with that setup...probably why he has never dynoed or raced it.
Yep, way too easy to fuck up with that one and wind up scooping 50 grand off the pavement with a snow shovel.
 

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sex. murder. art.
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******* engineering at its finest :lol:

I admit it does look cool, but actually getting benefits from twincharger setups takes serious engineering and pretty advanced electronic engine management. Just running a couple of turbos into the intake of your supercharger basically defeats the point of it, you'd be better off with one or the other.

The actual nerd explanation is that the supercharger delivers boost almost immediately when the throttle opens, without the lag caused by the need for the turbo to get up to speed. Roots/lobe pump superchargers also operate most efficiently at lowish RPM and boost levels. Using a smallish supercharger which doesn't draw a great deal of power from the crank is therefore a good solution for low-end power. As the revs come up and exhaust mass flow increases, your turbo(s) come up to speed and, appropriately sized, can deliver all the high-end boost you can deal with. The VW 1.4TSI engine was an example of twincharging being done right, delivering both a broad torque curve and relatively high power from a small displacement engine. (They don't make it any more as it was expensive and complicated, though).

The problems come from actually controlling it - basically you need to take the supercharger out of the equation (bypass it and then clutch it out) as the turbos come up to speed, and tuning the engine to do that smoothly is pretty tricky to say the least. If you just run one into another like this guy's done and don't remove the supercharger at high rpm, you end up getting the worst of both worlds - the supercharger will be operating in by far its least efficient range and sucking power from the engine while heating the intake air to all fuck. (Adiabatic efficiencies for compressors in series are multiplied, so if your turbo is delivering 70%ish and, in basically its worst possible operating environment, your supercharger is delivering 50% - not uncommon - your overall efficiency will be 35%!

The theoretical output temperature of a compressor (assuming an adiabatic process - in practice it'll be a bit less, but not a huge deal) is equal to intake temperature * (pressure ratio^(k-1)/k) where K is the heat capacity ratio - 1.4ish for air at sensible temperature ranges. For our theoretical (and crap) 35% efficiency of the combined turbo and roots supercharger setup, assuming 10psi of boost (pressure ratio of 1.7) and intake temperature of 25c (298k), we get a theoretical (100% efficiency) output temperature of nearly 100 degrees C. At 35% efficiency (theoretical temperature rise over actual temperature rise), however, we get a manifold air temperature of 236C (457F). WAY too hot for decent performance (the hotter the air is, the less dense and therefore the less fuel/air mass you get into the cylinders) and likely to overheat the supercharger, too - and you're wasting a lot of engine power just making heat which you are going to need a big intercooler to get rid of. If just the turbo was being used, meanwhile, the temperature rise would only be half that...

tldr: this car is dumb
 
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