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Decreasing accessory pulley belt tension for improved performance
Am investigating use of the slightly longer LS430 (2245 mm) serpentine belt over that of LS400's (2230 mm) to lower system tension on the harmonic balancer (crankshaft snout), alternator, A/C compressor, power steering pump fan bracket bearing, idler pulley, and tensioner so bearings will last much longer and operate more efficiently.
Serpentine belt tensioners provide constant tension on engine driven accessories.
Too little tension, you encounter excessive belt wear, belt squeal and inefficient accessories performance.
Excessive tension decreases bearing life in the alternator, A/C compressor, fan bracket bearing, idler pulley, tensioner pulley and power steering pump.
Increased pulley friction further reduces engine efficiency, decrease engine power, increases emissions and increases bearing noise
It appears accessory pulleys are same diameter on the LS400 and LS430 ( Recall reading the alternator pulley on the LS430 is slightly smaller(?)
So if all pulley diameters the same suggests the longer LS430 serpentine belt reduces tensioner force imparted on belt driven accessories.
Lower serpentine belt tension through use of a longer belt is possible on the LS430 because the fan bracket bearing is not lugging around a 5 pound fan clutch assembly and driving airflow due to the electric fan system.
However, I was contemplating how the longer LS430 serpentine belt would affect belt slippage on an LS400.
It occured that belt also maintains tension on the alternator that is turning at several times crankshaft speed, and so increased tension is necessary to prevent slippage on deceleration.
Would you gain more by replacing the belt driven fan with an electric fan? Yes, more work for sure, but is there enough gain using the longer belt to bother with?
Would you gain more by replacing the belt driven fan with an electric fan? Yes, more work for sure, but is there enough gain using the longer belt to bother with?
The LS430 employs electric fans so does not require a fan clutch assembly.
LS430 also has a 130A alternator offering more power under the curve necessary to power electric fans at idle.
An electric fan system is on my radar, but am not satisfied with aftermarket junk and will source better quality components and present my findings later.
So first wanted to present a project using quality off the shelf parts; OAD alternator clutch pulley and LS430 serpentine belt to increase component life, decreases NVH, increase efficiency, increase engine power and reduce emissions.
This project in tandem with an OAD entails using incrementally longer serpentine belt to reduce tension on crank pulley and driven accessories...
In order to accomplish that must somehow reduce the inertial mass of the system so as not to incur belt slippage and wear.
The LS430 elimainated the 5 pound fan clutch pulley assembly and fan blade drag, so decreased belt tension works.
Lower belt tension is accomplished through a lower spring rate in pulley tensioner or slightly increasing the length of the serpentine belt.
It appears Toyota chose the latter (unless someone has more specific information)
However, the LS430 alternator did not employ an alternator clutch pulley...
The plan is to use an OAD to significantly reduce intertial mass of the alternator in the LS400
Inertial mass of the alternator rotor is significant when driven at several times crankshaft speed, so already determined to eliminate that issue with or without a longer serpentine belt.
Alternators are heavy, and a major portion of that weight is in the rotor. Never mind the totational inertia the belt and tensioner must control upon engine deceleration.
Using an OAD makes the case for a longer belt.
Meanwhike, looking forward to reading your post on electric fans.
The 2240 mm LS430 belt works well without slippage or squeal. (Previously reported it is 2245 mm...this information was obtained from Lexus website...belt spine reads 2240)
So Lexus Dealer offers 2240 mm, not 2245 mm serpentine belt for LS430..so only 10 mm difference than 2230 mm LS400 belt Ls430 2240 mm serpentine belt P.N. 90916-02586 is Made In Japan. Two yellow bands on belt spine for some purpose... LS400 OEM Mitsuboshi 2230 mm belt.
All LS400 pulleys appear to be same diameter as those on the LS43O, save for the LS430 alternator pulley, which is slightly Smaller diameter.
The tensioner pulley spring is no longer stretched to the stops..
Zero belt flutter at idle or upon engine deceleration...!
Coupled with the OAD, the 10 mm longer belt should works well and reduces bearing friction while increasing life of belt driven accessories and increasing fuel economy-
~ 1% has been reported...
Transmission shifts much smoother..especially on upshift...literally cannot feel it except to discern shifting through tachometer.
04-06-20, 09:13 PM
Decreasing accessory pulley belt tension for improved performance
