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1999 2.5L Underdrive Pulley?


jpark6491

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I am curious if anyone has tried an underdrive pulley setup on the 2.5l engine? I have been searching through the forums but I have not found anything specific to the engine. Esslinger Engineering produces one that I think would work, but it is $75 right now. So if there are alternatives that would be awesome.

I am also curious if a larger alternator would be necessary for that setup to maintain proper electrical current? I already have plans to upgrade to a 130 amp alternator, especially if I opt for an electric cooling fan and interested in the Volvo EPAS conversion.

My main goal for the truck is to squeeze a little better fuel efficiency out of the stock engine.
 


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RonD

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I think you would have more downside that up on the 2.5l with smaller drive pulley, especially if you add an e-fan into the mix

The gain in HP is a % of total HP so on the 4cyl Lima it won't be much of a gain, maybe 3HP, that's the upside

Power steering and alternator is the downside
Both of these need a minimum RPM to work well which was calculated by the vehicle maker to set current pulley sizes
And both of these are used the most at idle or low RPMs, especially if you add an e-fan

You don't need much power assist steering at higher speeds, lol, so power steering pump is mostly used at idle and low speed driving

The e-fan is the same, at speeds above say 30mph the air flow thru radiator is enough for cooling so e-fan would usually be off
When stopped or driving slower the e-fan comes on, so in either case I would use a 100+ amp alternator

General rule of thumb is that an alternator will produce 60% of total amp rating at engines warm idle RPMs
So a 90amp alternator would produce 54amps at engine idle, 650-800rpm.
It would produce full 90amps when engine RPMs are above 1,600
Car makers put in alternators that can make about 10-15% more than vehicle requires at idle RPMs
So in the above example this vehicle would need approx. 45amps with all lights on and power windows, or other electrics being used at the same time

So with an e-fan you would want to bump up the minimum amps by at least 10amps, giving you a 20amp window
110amp alternator would give 66amps at idle
130amp would be more than enough

If you reduce drive pulley size you would need to do the math to see what alternator would produce at idle.
Easiest but not the most accurate would be, if you reduce drive pulley by 10% then alternator would produce 50% of rating not 60%
 

88workcar

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I have the 3.0 I like the underdrive pully on mine.
 

jpark6491

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I think you would have more downside that up on the 2.5l with smaller drive pulley, especially if you add an e-fan into the mix

The gain in HP is a % of total HP so on the 4cyl Lima it won't be much of a gain, maybe 3HP, that's the upside

Power steering and alternator is the downside
Both of these need a minimum RPM to work well which was calculated by the vehicle maker to set current pulley sizes
And both of these are used the most at idle or low RPMs, especially if you add an e-fan

You don't need much power assist steering at higher speeds, lol, so power steering pump is mostly used at idle and low speed driving

The e-fan is the same, at speeds above say 30mph the air flow thru radiator is enough for cooling so e-fan would usually be off
When stopped or driving slower the e-fan comes on, so in either case I would use a 100+ amp alternator

General rule of thumb is that an alternator will produce 60% of total amp rating at engines warm idle RPMs
So a 90amp alternator would produce 54amps at engine idle, 650-800rpm.
It would produce full 90amps when engine RPMs are above 1,600
Car makers put in alternators that can make about 10-15% more than vehicle requires at idle RPMs
So in the above example this vehicle would need approx. 45amps with all lights on and power windows, or other electrics being used at the same time

So with an e-fan you would want to bump up the minimum amps by at least 10amps, giving you a 20amp window
110amp alternator would give 66amps at idle
130amp would be more than enough

If you reduce drive pulley size you would need to do the math to see what alternator would produce at idle.
Easiest but not the most accurate would be, if you reduce drive pulley by 10% then alternator would produce 50% of rating not 60%
That all makes sense, you've definitely given me a lot more to think about.

I also like the idea of an electric power steering pump just so it doesn't sound like a pig being murdered each time I turn the wheel when pulling out of the garage lol
 


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