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Help with L6 Harmonic Balancer Size for L28ET


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I'm replacing the OEM harmonic balancer.  The ATI makes a couple of different harmonic balancers (different weights, different diameters)




917801 is 5.45lbs and 7.074" diameter


918040 is 3.9lbs and 6.325" diameter


This is for a L28ET build.  We're going to be using a SDS (Simple Digital Systems EMS) with crank ignition.  So magnets will be added to the balancer.  


Any recommendation on which balancer to go with?  Should we forego the ATI altogether?  


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There has been a lot of discussion about what brand but not what size, to summarize:


BHJ Dampers: Close stock replacement but most expensive.


ATI Dampers: Needs different fan belt (very common has the autozone part number somewhere). Slight underdrive so alternator might not charge on idle. Note that this has nothing to do with size. Reading the chart they have, it seems like race is bigger than street. 


Rebuilt stock damper: Cheapest but good alternative if not race and modest rpms.


Everything else seems to be a bad choice.


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Sorry for answering a question you didn't ask, but since you're tackling your crank trigger issue anyways, I strongly suggest you do better than SDS and its one tooth/magnet every 120 crank degrees, and go with a standalone that can take advantage of a much more modern and precise trigger setup such as a 60-2 (every 3 or 6 degrees) or 36-1 (every 5 or 10 degrees) trigger wheel. BHJ offers both options on their dampers.


Another option is to build your crank trigger wheel and damper with parts from Hybridz member Hoke Performance:



SDS works. I've tuned a few. They have good tech support on the phone, they're friendly, and they're Canadian, all big plusses.


But time marches on. There are many other ECU options that can be had for the same price or better, and that provide much more precision and tunability than SDS.

Edited by bradyzq
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