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930s rule the wasteland
 
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Reversed firing order

Can this be done on a boxer motor, or do 911 builders do this ? I was taking to a v8 builder and he said you can get the cams ground to reverse the firing order so it will fire from the middle to the outside cyls and it creates balance and some serious HP. Just trying to get enlightend.
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1980 930 Turbo
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2001 VW golf TDI
Old 04-03-2008, 05:19 PM
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Macht Schnell
 
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Quote:
Originally Posted by h20cooled7 View Post
Can this be done on a boxer motor, or do 911 builders do this ? I was taking to a v8 builder and he said you can get the cams ground to reverse the firing order so it will fire from the middle to the outside cyls and it creates balance and some serious HP. Just trying to get enlightend.
Hmmm, Porsche has been working on this motor for almost 50 years. You'd think they would have thought of this!
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---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 04-03-2008, 07:23 PM
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Max Sluiter
 
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I think that the conventional firing order for a flat 6 is as balanced as a street motor can be. It is balanced better than any other configuration so I do not think that a change in firing order would help much because there is no problem to eliminate.
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Old 04-03-2008, 08:16 PM
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It is common for MOTOGP engineers to play with firing order...you'll know doubt have heard of "big bang" engines.

Doesnt produce more power but rather changes the power & torque characteristics

http://www.motorcycledaily.com/08april05_bigbang.htm
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Old 04-03-2008, 09:12 PM
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Straight 6, Flat 6, or in line triple are perfect engines. All are 120 degree cranks. A great read is "The Design and Tuning of Competition Engines". It is EXTREMELY hard to improve on perfection!
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---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 04-03-2008, 09:13 PM
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Quote:
Originally Posted by les_garten View Post
Straight 6, Flat 6, or in line triple are perfect engines. All are 120 degree cranks.
Well.... Mostly, anyway....

Just as a point of interest, the Laverda Jota (a 1000cc triple, originally a UK-only importer-tuned special based on the Laverda 3C) used 180 degree cranks for most of the production run, although Laverda did switch to 120 degree cranks towards the end.

Sounded rather special - you could clearly hear the gap in the firing order when it was at cruising RPM, like a 4 with a cylinder missing...
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Old 04-03-2008, 11:52 PM
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Macht Schnell
 
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Originally Posted by spuggy View Post
Well.... Mostly, anyway....

Just as a point of interest, the Laverda Jota (a 1000cc triple, originally a UK-only importer-tuned special based on the Laverda 3C) used 180 degree cranks for most of the production run, although Laverda did switch to 120 degree cranks towards the end.

Sounded rather special - you could clearly hear the gap in the firing order when it was at cruising RPM, like a 4 with a cylinder missing...
Heh! Drunk Italian Engineering notwithstanding...

Here's the sound the Laverda makes, I don't have the associated pic of it vibrating like a freakin washing machine!!

http://www.thecreeper.net/laverda/jota1000.wav

Les
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---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT

Last edited by les_garten; 04-04-2008 at 06:53 AM..
Old 04-04-2008, 05:50 AM
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930s rule the wasteland
 
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Cool cool ,just throwing it out there. Thanks for the a$$ kicking.
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Old 04-04-2008, 06:14 AM
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