240zip Posted December 13, 2018 Share Posted December 13, 2018 I'm replacing the OEM harmonic balancer. The ATI makes a couple of different harmonic balancers (different weights, different diameters) http://www.atiracing.com/products/dampers/charts/damnissan.htm 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? Quote Link to comment Share on other sites More sharing options...
turbogrill Posted December 13, 2018 Share Posted December 13, 2018 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. Quote Link to comment Share on other sites More sharing options...
bradyzq Posted December 17, 2018 Share Posted December 17, 2018 (edited) 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: http://hokeperformance.squarespace.com/store/l-series-crank-angle-sensor-kit 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 December 17, 2018 by bradyzq Quote Link to comment Share on other sites More sharing options...
jp 280 Posted December 27, 2018 Share Posted December 27, 2018 I would also like to hear how people choose the diameter of the ATI damper. I plan to use one of the trigger wheels that ATI offer. Quote Link to comment Share on other sites More sharing options...
turbogrill Posted January 9, 2019 Share Posted January 9, 2019 I asked ATI " it’s high HP up around 1000HP I would recommend the 7” version P/N 917800." Quote Link to comment Share on other sites More sharing options...
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