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-   -   dyno charts for underdrive pulleys? mpg? (http://forum.e46fanatics.com/showthread.php?t=748936)

tylerc 03-16-2010 02:01 AM

dyno charts for underdrive pulleys? mpg?
 
I have an 04 zhp 330. I have searched and couldn't find any dyno charts from you guys before and after with under-drive pulleys. Also I didn't see any mention of mpg after install. I have gotten a new job where i put a LOT of miles on my car and can justify a performance mod to the better half if the mpg are there:rofl:.

Anyone have some info/charts for me?

SL Blak Soldier 03-16-2010 03:54 AM

correct me if i'm wrong, but underdrive pulleys don't make any power. they just make the accessories that are run off the belts use less of the motor's energy.

roastbeef 03-16-2010 05:08 AM

Quote:

Originally Posted by SL Blak Soldier (Post 11473088)
correct me if i'm wrong, but underdrive pulleys don't make any power. they just make the accessories that are run off the belts use less of the motor's energy.

true, i believe how they work is by using a larger diameter pulley to create a reduction in the force it takes to turn them. thus, less engine power is consumed by the acessories.

aggieE46 03-16-2010 05:45 PM

If you're going to be using cruise control, any mod is great. When you increase volumetric efficiency, you'll increase gas mileage... as long as you're not on the throttle. I still get around 30mpg with headers, cams, 3.46, but only when I don't touch the gas and cruise at around 70.

Quote:

Originally Posted by tylerc (Post 11472648)
I have an 04 zhp 330. I have searched and couldn't find any dyno charts from you guys before and after with under-drive pulleys. Also I didn't see any mention of mpg after install. I have gotten a new job where i put a LOT of miles on my car and can justify a performance mod to the better half if the mpg are there:rofl:.

Anyone have some info/charts for me?


tylerc 03-17-2010 01:19 AM

How underdrive pullies work is exactly as you describe. (in the e46's case) They spin the alternator, water pump and power steering slower. They don't 'make' extra horsepower they just let the engine use less of the power it produces to drive accesories and it instead goes towards the rear wheels.

On my mustang it was a noticeable difference. People seem to say its not on the e46 and that doesn't make much sense to me. That's why I would like real dyno and mpg observations.

I used to get about 27-28 mpg and lately I have been getting 24-26 but it is colder out as well. those # are at 70-75mph.

So any anecdotal evidence of mpg or power or hopefully a dyno?

TxZHP04 03-17-2010 08:16 AM

I believe this is from a '95 M3 FWIW:
http://www.turnermotorsport.com/imag...ulley_dyno.jpg

various combination of mods on a 330:
http://www.turnermotorsport.com/image/dyno/330_dyno.jpg

tylerc 03-17-2010 10:57 PM

Very cool, thats a great dyno chart! answers a lot of questions about modifications!

any mpg improvement estimates?


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