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Underdrive Pulley-need your opinion!

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Old 02-10-2003, 05:36 PM
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Has anyone ever thought about lightening the flywheel for the 3.4L, since flywheel lightening gives a little more power just like underdrives?? maybe someone has done this already for a few extra HP and better gas mileage... ( i had it done on my 90 toyota truck and it was nice)

tim
Old 02-10-2003, 06:02 PM
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It is not that the lighter pulley takes less power to turn, which it does not, it is that it takes less power to accelerate it. With less mass there is less inertia to over come. Once it reaches a steady state there will be no power difference. Now if you alter the drive diameters then there maybe less power consumed by the accessories in a steady state and while accelerating, in most cases.

The stock 3.4 pulley has three belt drives on it. If you are making one for the supercharger, just leave that one diameter stock and reduce the others.

You may also want to contact Jason at www.F2uning.com. He is having custom aluminum pulleys made for the 3.4 for other reasons, but while those are being made, I am sure he could easily crank some out to your specs and I will bet you a box of donuts that they will be cheaper through him. Tell him I sent you.

This sound interesting, do keep us posted.

Gadget

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Old 02-10-2003, 06:11 PM
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Perfection is reached inch by inch ($ by $ I think)! This should get us one step closer to Toyota heven! But a word of caution, dont make it too racy! Id rather buy gas and performance parts than alternators!

Im in for a 3.0!

_travis
Old 02-11-2003, 09:39 AM
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Check this site out <http://sportruckspecialties.com/22Perf.htm>.
They have pulleys for the 3.4 and 4cyl trucks.


As another former Mustang guy, I can attest to the gains from underdrive pulleys. I haven't put pulleys on my S-Runner yet, but I will probably do that in the next couple months. I've had it for more than a year now, and am just starting to do mods, starting with what I know works.

Jayguy
'01 S-Runner - BSP
'94 M900
Old 02-11-2003, 09:44 AM
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Check this site out <http://sportruckspecialties.com/22Perf.htm>.
They have pulleys for the 3.4 and 4cyl trucks.


As another former Mustang guy, I can attest to the gains from underdrive pulleys. I haven't put pulleys on my S-Runner yet, but I will probably do that in the next couple months. I've had it for more than a year now, and am just starting to do mods, starting with what I know works.

Jayguy
'01 S-Runner - BSP
'94 M900
Old 02-11-2003, 10:18 AM
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Thanks for the link Jayguy and welcome to the forums!

I hope you enjoy your stay here!
Dr. Z
Old 02-11-2003, 10:24 AM
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Thanks, Dr. Z.

I've been lurking for a couple of weeks, and even passed on your info on the SMT-6 to the guys on CustomTacos.com. I've been amazed at how much info on modifying tacomas I've found in the last few weeks. Makes me wish I had a fatter wallet.

Jayguy
Old 02-11-2003, 10:38 AM
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Thanks, jayguy, for the link!
Those cost as much as the Unorthodox and they're already made!

I'm going to call them and see if we can maybe get a group buy together on those. Anyone else interested?
Old 02-11-2003, 10:40 AM
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You're welcome jayguy! And we ALL wish we had fatter wallets.

Except maybe Gadget.

Peace!
Dr. Z
Old 03-07-2003, 02:05 PM
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UPDATE ON UDPs!!!

Hey all-
Just thought I would pass this along.
I did a lot of research on underdrive pulleys. The general concensus is that, although they do free up power, increase throttle response, etc., they can significantly shorten the life of an engine. I have read several articles and spoken to several people who have said the gain is not worth the proce in the long run.
One person I spoke to installed a UDP on his Prelude. He said is deffinately made a difference off the line and through 3rd gear, but, when he had a complete tear-down and rebuild performed at 55K miles, the tech noted that the crank and bearings showed the life of a 80K mile engine. He had the pulley on there for 15K miles.
The shortened engine life was do to the lack of a harmonic balancer. Without he harmonic balancer, the cranks and rods experience elevated Torsional vibration .
There is some light to this, though. Lighter accessory pullies (alternator, power steering pump, etc.) will require less power to turn and aren't subject to the same punishment as the crank. I might call around to see if anyone makes accessory pullies or find out how much it would cost to make them.
Old 03-07-2003, 02:18 PM
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On a related note...

For those of you who desire a similar performance gain to UDP's, you can always pull your AC belt during the cold months/spring.

Keep in mind, this will do two negative things:

1. Your Defrost works off the AC, and therefore it wont work right
2. This belt take about 1/2 and hour to take off, unless you slice it off with a razor blade and replace it later.

But, for the power hungry person, or someone who is going to the track and desires a little more power, this works good. I dont suspect many to go for this on the boards, but you never know. I did it on my Tacoma, and noticed a slight gain.

I dont want to hassle with it on my 4Runner.
Old 03-07-2003, 02:44 PM
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I did that on my old Chevy and I did notice a slight increase in power and mileage. I don't think I'll do it to the 4Runner, though. I don't use my a/c but once in a great while.
Good tip!
Old 07-21-2003, 06:30 PM
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Has there been any updates on this. Also is the alternator pully the same on all 3.4 engines ie.. Tundra , T100 , Tacoma and 4Runner.
If so then I can use the pullies from www.sporturckspecialties.com/22Perf.htm since the set is only the crank and alternator.
Old 07-21-2003, 07:07 PM
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I know some people that are going to produce a lightweight crank shaft pulley for the 3.4 very soon. All the design work is done and there is one truck running a prototype now.

You should hear more in the coming weeks. I should have the very first production pulley to test on my truck.

Gadget

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Old 07-21-2003, 07:11 PM
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Seems like such a small rotating mass, so do do you think they'll be that much of a difference?

Chris
Old 07-21-2003, 07:29 PM
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I think every little bit of HP and TQ helps IMHO.
Old 07-21-2003, 07:32 PM
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That is definitely a true statement, but I have to weigh my dollars to HP gain to see if it's worth the money, as I'm sure most people, except Gadget, do!!

Chris
Old 07-22-2003, 12:53 AM
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Gadget
Do you know if the Alternator and Crank pullies are the same in all 3.4 engines..ie.. Tundra, Taco and 4Runner. I found a crank and alternator pully for the V6 Taco and was wondering if it can fit with out any issues. Also does the crank pully have a HARMONIC BALNCER on the crank. If not wouldn't that put alot of premature wear on the engines. I read on Tundra Solutions that without it would make the crankshaft bend and twist and that would led to premature wear.
Old 07-22-2003, 05:26 AM
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Re: UPDATE ON UDPs!!!

Originally posted by HaveBlue
The general concensus is that, although they do free up power, increase throttle response, etc., they can significantly shorten the life of an engine. I have read several articles and spoken to several people who have said the gain is not worth the proce in the long run.
One person I spoke to installed a UDP on his Prelude. He said is deffinately made a difference off the line and through 3rd gear, but, when he had a complete tear-down and rebuild performed at 55K miles, the tech noted that the crank and bearings showed the life of a 80K mile engine. He had the pulley on there for 15K miles.
The shortened engine life was do to the lack of a harmonic balancer. Without he harmonic balancer, the cranks and rods experience elevated Torsional vibration.
There is some light to this, though. Lighter accessory pullies (alternator, power steering pump, etc.) will require less power to turn and aren't subject to the same punishment as the crank. I might call around to see if anyone makes accessory pullies or find out how much it would cost to make them.
This an excellent point! The harmonic balancer is definately not something to mess with because of the engine vibration it absorbs. Without it, all the vibration must be taken up somewhere else (usually the main bearings suffer the most) This is not a problem if you plan on tearing down your engine on a regular basis but I guarantee you won't see a 200K mile engine with no balancer on it. It may be possible to remachine the stock crank pulley (and maintain the balancer) to drive the items slower but again you are lowering the rotating mass which will reduce the balancer's effectiveness. The best way would be to increase the size of the other pulleys so they will be driven slower.....this may cost more (cause you need a pulley for each ascessory) but think how much an engine rebuild is worth. I personally wouldn't even think of getting rid of my balancer. The difference with the 3.4L is that they made the pulley and balancer all one piece versus the old mustang and chevy 350s had them separate....so you could just bolt a smaller setup right on. Good luck to any who try it but you won't see me run that mod.......
Old 07-22-2003, 06:57 AM
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I'd be interested in one for the 3.4L, sounds like an interesting idea...


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