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valvebounce
Tire Chirper
New Zealand
17 Posts |
 Posted - 06/12/2009 : 00:57:30
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| probably a dumbass question, but I gotta ask. I'm toying with the idea of slapping one onto a chrysler 318 that i'm in the throws of freshening up at the moment. Either that, or maybe a pair of toyota S/C14's. |
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Mick
Tire Chirper
Australia
44 Posts |
Posted - 06/12/2009 : 20:35:42
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| The original numbering was for 2 stroke diesels, ie: a 4 cylinder with 71 cubic inches per cylinder, although I don't think it was a direct multiplication of 4 x 71. |
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valvebounce
Tire Chirper
New Zealand
17 Posts |
Posted - 06/13/2009 : 01:02:44
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| curious. With a two stroke an engine displaces is dispalcement per revolution. But four stroke are half this. |
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Mick
Tire Chirper
Australia
44 Posts |
Posted - 06/13/2009 : 17:46:04
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| I remember years ago when I was a kid one of my mates fathers showing me a 2 stroke, supercharged diesel 6 cylinder. (6-71 blower maybe!) Any way, being a diesel, they didn't have to worry about blowing fuel/air charge out the exhaust ports, so the blower charge was actually used to clear the cylinders of exhaust by blowing through. Also the crankcase wasn't used to transfer fuel/air charge to the cylinder as in a normal petrol 2 stroke, the compressed charge blew straight into the cylinder. |
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valvebounce
Tire Chirper
New Zealand
17 Posts |
Posted - 06/13/2009 : 22:31:54
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that makes sence. You'd have to have your injector timing arranged so that no fuel was delivered untill the exhaust port had been closed.
Some blokes on a hotrod site I visit now and again reckon a 4/71 will be okay on a smallblock of 300ish cubes. |
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Mick
Tire Chirper
Australia
44 Posts |
Posted - 06/27/2009 : 03:15:16
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From Wikipedia!
The GMC types are rated according to how many two-stroke cylinders, and the size of those cylinders, it is designed to scavenge. GMC has made 2-71, 3-71, 4-71, and the famed 6-71 blowers. For example, a 6-71 blower is designed to scavenge six cylinders of 71 cubic inches each and would be used on a two-stroke diesel of 426 cubic inches, which is designated a 6-71; the blower takes this same designation. However, because 6-71 is actually the engine's designation, the actual displacement is less than the simple multiplication would suggest. A 6-71 actually pumps 339 cubic inches per revolution.
(I guess that makes the 4/71 about 226 cubic inches per revolution) |
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valvebounce
Tire Chirper
New Zealand
17 Posts |
Posted - 06/27/2009 : 04:08:30
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| well a 318 is only gonna push 159 cubes per revolution. So even at 1:1. it'll make okay boost. (well enough for an un beefed up motor anyway!) |
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Mick
Tire Chirper
Australia
44 Posts |
Posted - 06/27/2009 : 17:17:58
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| Without taking losses into account, it should make around 6 psi. |
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valvebounce
Tire Chirper
New Zealand
17 Posts |
Posted - 02/06/2010 : 17:22:19
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rebumping my old thread,
excluding losses and inefficiencies, what boost would this blower make geared 1:1 on a 245ci motor?
122.5ci per rpm. Have to be around 10+psi wouldn't it? |
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Mick
Tire Chirper
Australia
44 Posts |
Posted - 02/09/2010 : 16:59:38
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| About 12.5 if my maths didn't let me down. At 1:1 the blower is turning pretty slow, which means a lot of time for leakage passed the rotors. You're better off with a small blower turning fast than a big blower turning slow. |
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How much air does a 4/71 displace per revolution?
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