I know I'm prbably gonna get flamed for asking this question but here goes... I've been doing research on eco builds for a month or so now, and I've read about balance shafts. I just saw the GM Racing Balance shafts on allecotec.com, and I need to know, what are balance shafts and what are the for?
1997 Sunfire SE
They are a pair of weighted shafts that rotate at twice the engine speed. Inline 4s are naturally one of the less smooth engine configurations and some people who buy cars don't like the roughness inherent in a balance shaftless design. They are tuned to remove vibration from the engine but their drawback is they limit the overall maximum engine speed you can safely run. For a fully built engine they can be removed and I believe either eliminated completely or replaced by blanks. Also its a job that must be done with the engine out of the car. I hope that helped.
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<<<<<2003 Sunfire Sedan>>>>>
So If someone is building a high reving engine, they'd either replace them with Blanks, or remove them all together?
1997 Sunfire SE
It may not be totally necessary on the eco unless you're going extreme, but I believe so, they produce frictional losses in the engine so removing them nets some reclaimed horsepower. Also they become a problem at high revs due to oiling, because if you were to rev up to say 7500rpm, they are spinning at 15000 rpm. there are members on this site who have replaced and those who have removed them. I would assume fully removing them would reclaim more horsepower but that would be more of a custom solution than simply installing neutral shafts.
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<<<<<2003 Sunfire Sedan>>>>>
PJ removed his in his LS61 Hybrid and i believe he wasnt running any in his L61.
To be honest I don't know I'm not experienced enough to tell you that as I havent built an engine, but if you do take the balance shafts out to reclaim some power, and you're shooting for high revs, you will probably need to have the engine balanced. 9000 RPM is pretty high for our engines, what cam shafts would you be using to get the power band up there? The highest power band i see from the usual cams used in our motors is 7500 RPM so i guess it would be something custom, but what are you doing for springs, retainers, etc, what head? And do you plan on actually being able to drive this on the street because something with a power band that high is probably going to be pretty annoying or tough to drive daily. I know that Ben Wenzel Jr and PJ have two of the most popular N/A builds on this site, i'm sure they can help you more if you're shooting for those kinds of high revs, or try contacting Karo or calling the company and asking what they think. Sorry i can't be of more help. But good luck.
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<<<<<2003 Sunfire Sedan>>>>>
if you're really planning to rev to 9000, the delete kit would be best.
Desert Tuners
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