ken666 Donating Members 140 Member For: 6y 2m 2d Posted 30/07/19 12:10 PM Share Posted 30/07/19 12:10 PM Hey guys, Got a quick question about underdriven balancer and pulleys on Barra turbo motors... Do they make any worthy gains/difference when fitted? Would prefer dyno comparison numbers if anyone has some. I know that they be beneficial on a N/A motor that is tuned within an inch (mm for the new age guys!) of the setups limits, but I keep thinking that on a boosted engine that it could actually be more of a disadvantage by reducing the cooling systems low RPM flow... especially when tuned to boost levels 21psi and higher? Has anyone here experimented with big boost, hot days and underdriven setups? Cheers Ken Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 29,277 Member For: 16y 10m 21d Gender: Male Location: Melbourne Posted 30/07/19 12:19 PM Share Posted 30/07/19 12:19 PM not worth it on a turbo. Link to comment Share on other sites More sharing options...
ken666 Donating Members 140 Member For: 6y 2m 2d Posted 30/07/19 12:31 PM Author Share Posted 30/07/19 12:31 PM Cheers mate didn't think so, I am just about to buy a new one to suit the higher RPM range (7500+!!) of my engine I'm in the process of putting together and thought I'd check if there was anything I didn't miss while analysing the options available. I thought the money would be better spent on a higher quality unit instead. Ken Link to comment Share on other sites More sharing options...
BeerTurbo Donating Members 241 Member For: 6y 9m 22d Posted 31/07/19 01:50 AM Share Posted 31/07/19 01:50 AM I have an under drive pully on my na+turbo 400whp sh*tbox ute, mainly used for drift. I have not encountered any cooling related issues with the under-drive, car still has stock rad and a 82deg thermostat & functions perfectly fine with the varied rev range of drifting. I convinced myself it would be better for the higher rpm operation of the car, but honestly it was a waste of money. Na maybe you will get the claimed hp gains, but you wont notice jack on the turbo models. Link to comment Share on other sites More sharing options...
arronm Dropping a turd Gold Donating Members 9,520 Member For: 17y 4m 4d Gender: Male Location: Perth Posted 31/07/19 06:36 AM Share Posted 31/07/19 06:36 AM (edited) If you are adding a forged balancer may as well add underdrive. I have cracked 2 balancers above 6000rpm Edited 31/07/19 06:39 AM by arronm Link to comment Share on other sites More sharing options...
demon1300 Member 435 Member For: 13y 22d Gender: Male Posted 05/08/19 10:58 AM Share Posted 05/08/19 10:58 AM When I spoke to brad @ atomic about this very question, he didn't recommend it for the barras as they're very long stroke makes them quite bad for vibrations and harmonics. He recommended sticking with a standard balancer to keep the mass greater on the front of the crank. That and a heavy flywheel he said are a must.IMO I tend to agree and unless your Dion from Dynamite, turning engines to 10k rpm, the benefits are not worth the trade off... Link to comment Share on other sites More sharing options...
HI PSI Member 1,586 Member For: 18y 9m 6d Gender: Male Location: Central Queensland Posted 05/08/19 11:31 AM Share Posted 05/08/19 11:31 AM Alternators and air con compressors don't like 7500 rpm. Hence why I instslled an under drive balancer. Link to comment Share on other sites More sharing options...
demon1300 Member 435 Member For: 13y 22d Gender: Male Posted 05/08/19 11:34 AM Share Posted 05/08/19 11:34 AM Yeah agreed, but unless it's a complete race engine then how much time is the engine really spending up there. Not much id say.I reckon dampening the harmonics and not pounding the bearings and rotating assembly are more important than AC and an alternator Link to comment Share on other sites More sharing options...
ken666 Donating Members 140 Member For: 6y 2m 2d Posted 01/09/19 08:34 AM Author Share Posted 01/09/19 08:34 AM On 05/08/2019 at 8:58 PM, demon1300 said: When I spoke to brad @ atomic about this very question, he didn't recommend it for the barras as they're very long stroke makes them quite bad for vibrations and harmonics. He recommended sticking with a standard balancer to keep the mass greater on the front of the crank. That and a heavy flywheel he said are a must. IMO I tend to agree and unless your Dion from Dynamite, turning engines to 10k rpm, the benefits are not worth the trade off... And you will find that most engines turning at those RPM (the ones that last) are destroked from anywhere between 3.2-3.9L, and that changes the whole rotating/reciprocating configuration requirements. My engine has been balanced to very high standards, and while the assembly was being done I had an extra balancer and flywheel done as spares (just in case one fails) It would be a waste of good money and so much time put into getting the balance to such high standard, if and when I need to swap one out. Link to comment Share on other sites More sharing options...
ken666 Donating Members 140 Member For: 6y 2m 2d Posted 01/09/19 08:48 AM Author Share Posted 01/09/19 08:48 AM On 05/08/2019 at 9:31 PM, HI PSI said: Alternators and air con compressors don't like 7500 rpm. Hence why I instslled an under drive balancer. I can't say that I have ever experienced one fail due to higher RPM. If they are in good condition, and/or rebuilt to spec with quality bearings etc. I used to rev a cleveland to 8500+rpm on a regular basis, and that was in an XE falcon. Which didn't even run a serpentine belt, it was modded to run twin V belts though as it spat belts frequently when single! Link to comment Share on other sites More sharing options...
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