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AL Pulley Kit?

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TR4A_IRS

TR4A_IRS

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Has anyone installed an AL pulley kit on their TR? Are there any real benefits besides looks? I know they have less rotating mass, but I cant imagine the horsepower draw is all that much.

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I am thinking of removing my fan over the winter to replace the bushings and to clean it up and put on a fresh coat of paint. If I am doing that, it would be a good time to swap my pulleys with these, if they are worth installing.
 
I have that setup on the 3A engine I'm building - it was from an opportunity purchase from a couple a years ago which made the price much more reasonable. I'm not thinking at all about horsepower gains - using it allowed me to easily add a narrow pulley Denso alternator. If I could get a wide pulley for the Denso I probably wouldn't have used it - but now that its there the belt will be much easier to change out than the wider version.
 
I think the real seduction is to be able easily to replace fan belts. All TR3/4 drivers are aware how little fun this can be.

The notion that the smaller belt eliminates bearing/bushing wear on the generator or on the water pump seems to me relatively trivial; so, as you note, does the weight issue, unless one intends to race. Racetorations says that if you replace the pulley, water pump, and water pump housing with aluminum elements, you'll go from 11 to 4.4 lbs. for these items. Just go without a meal or two for the same result.

There was a moment when eliminating TR3/4 fans, changing to aluminum radiators and electric fans, adapting alternators, and small belt pulleys sounded very snazzy. It does, I'm sure, look nice and new. But, then, whenever I am tempted, I think: I've driven fifty plus years with all those original TR elements, and they do, in their own fashion, work pretty well.
 
Perrymip said:
Just go without a meal or two for the same result.
Click to expand...
Not to belabor the point, but reducing rotating mass (well, inertia actually) has a much larger effect than just reducing the weight of the car+driver. Basically, rotating mass has to be accelerated 5 times over to go from stop to full speed (once for each gear plus accelerating the car).

For example, shaving 20 pounds off the flywheel has a larger effect than even having a passenger, especially in first gear. However, the pulleys being smaller diameter means they have less rotational inertia (for the same weight/mass), so the effect would be smaller there.

Personally, I can't say that I find changing the wide belt to be a problem, since I use the cogged version from NAPA. Even did it once on the way to a club meeting, and was only about 15 minutes late. But I do plan to switch to narrow aluminum pulleys for my planned "hot rod" motor, mostly because the kit I got also includes a harmonic vibration damper for the crankshaft (and I plan to use a prepared stock crank rather than investing in a Moldex).
 
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