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Swallow Or Spit?


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#1 DeadSquare

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Posted 16 May 2018 - 04:33 PM

Something about which I have often pondered, is whether it is better for the blower to swallow air or spit it, through the carb.

 

Compared to the tomes about the compression ratios, rocker ratios, bore/stroke ratios, gear ratios, cam profiles and gas flowing for a plethora of engines, so little is written about blowing that I have never read of a comparison.

 

Leaving aside the added problems of plumbing and carb pressurising, I always seem to go for swallowing because:- 

(1)  The blower beats up the charge which mixes it and the compression heat enhances evaporation.

(2)   Evaporation through the carb lowers the temperature, delivering a greater charge to the blower.

 

Facts gratefully valued, but opinions also welcome.



#2 Turbo Phil

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Posted 16 May 2018 - 08:54 PM

On a suck through install blower efficiency is also increased by quite a margin due to improved rotor sealing on roots type blowers, but there's no option to intercool. Whether a decent intercooler install in a blow through would match or better charge temps in a suck through install would be interesting to see. Same engine same boost etc ….

 

Phil.



#3 DeadSquare

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Posted 17 May 2018 - 07:09 AM

I used to have a huge Roots from a Commer 2 stroke on the front of an 1172 Ford Pop, Bentley style.

 

It wasn't connected, but was much admired.






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