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Discussion Starter · #1 ·
Did some searches on the pulley swap and haven't found that much specific info. Will it boost earlier then the stock system (3k rpms)? Will the by-pass valve still function normally to reduce unwanted boost when cruising? And Finally are any of you worried about boosting 10+ psi on a 10:1 comp. ratio on a stock block? Thanks for the education and please excuse my ignorance, what I know is very limited. Just want to make my $3500 purchase worth while. Thanks
 

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No longterm tests from what I know, but...

It does boost earlier.
Sounds like bypass is venting when I cruise at 85mph.
Bypass valve still works, but I don't have the OEM one. (the one I have got louder though)
I think it's 9psi, and it's only at redline. I'll make sure when I get home and put the boost gauge back in to test.
 

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Discussion Starter · #3 ·
Thanks. 9psi isn't bad especially since I don't ever redline my car, maybe if I race an Si or something. But thats only a 2psi gain, people were talking of 3-4psi. Anyways what brand do you have on the pulley (if there is more then one) and why did you switch by-pass valves?
 

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OEM (Bosch 102) BPV is suspected of leaking, even under stock boost.
 

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Does a pulley swap increase horsepower or just reaction time? I don't know much about super chargers.
 

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Originally posted by filmnews@Jan 2 2006, 08:16 PM
Does a pulley swap increase horsepower or just reaction time? I don't know much about super chargers.
20whp+ on a tC. That's what my dyno showed.
 

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That is really good. How much does the pulley's cost?
 

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There are currently two pulley options available for the TRD charger. These are pulleys that mount onto the shaft on the topside of the motor, and are smaller than the stock pulley up there. One is made by NST, and the other is made by ZPI.

From www.NonStopTuning.com 2.5psi increase $90


From www.zpiracing.net 2.0psi increase $100


Boost on a supercharger is linear and builds as you go up the rpm range. Spinning the SC faster than stock will result in a higher overall speed of the SC, which means more boost overall


The guys at NST say the stock ECU should be able to support 10psi pretty nicely as long as the TRD reflash has been done. So make sure you reflash your ECU. You can find them on AIM at NSTonAIM, I get a lot of good information by talking to those guys.

Have fun
 

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Discussion Starter · #9 ·
Any 0-60 times on that mod? Still hoping to see someone in the low to flat 6's without going crazy on the boost with a stock block. Can't help but wounder how many miles I'll be able to put on my engine before it gives in with this S/C, being good to the car that is.
 

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Originally posted by Robs_tc@Dec 31 2005, 02:12 AM
Did some searches on the pulley swap and haven't found that much specific info. Will it boost earlier then the stock system (3k rpms)? Will the by-pass valve still function normally to reduce unwanted boost when cruising? And Finally are any of you worried about boosting 10+ psi on a 10:1 comp. ratio on a stock block? Thanks for the education and please excuse my ignorance, what I know is very limited. Just want to make my $3500 purchase worth while. Thanks
Just to remind you. If you change the pulley the warranty went out the window for your s/c. I was also informed that if you change the crank shaft pulley (underdrive pulley) to a smaller one you will toast the warranty on your s/c. By putting a smaller pulley on the s/c you will increase the boost but according to TRD you will also lean out your engine.

Not trying to scare anyone or anything. I just want everyone to know what could potentially happen if they start changing thing.
 

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From the SC+pulley dyno runs I've seen on ScionLife - the AFR stays very close to stock with SC, so scary lean does not look like a real threat for now. On the other hand, I've seen catalytic coverters burn out on SC'd Matrix after just installing an aftermarket intake - so there is still a good chance that TRD is right when they warn people.

Thanks for the reminder, Josh.
 

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How is belt slip since the pulley is smaller. I have been debating getting the pulley.
My two concerns are:

Can the current AF ratio handle the extra Air input?

Will the belt slip due to the smaller circumfrance?

From what I have found the AF ratio is ok. But I dont know to well.
 

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Diameter difference is minimal. Tensioner compensates for it and then some.
 

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Thanks. As long as it doesnt slip and fray the timing belt I will be happy. Hopefully the scion techs wont notice if I ever have to take it in.
 

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if you get one the same color as the stock TRD one, they probably wont, that is if you were lucky like zoltiz (and many others) whose kit didnt include the warranty cap on the pulley...
 

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Yeah mine didnt include the cap. But I wonder if we are really lucky.

What happens if they go in and say, no cap no service. Then I have to prove the cap wasnt there. Luckily I took pics in the parking lot of the dealer, but I dont know if that will hold up.

Anyone have a pic of the tamper proof cap?
 

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Call the dealer and make them put this info in the work order. That's what I did.
 

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You guys are nuts to change pully's IMO. After reading a couple of horror stores on scionlife, no way in hell am I doing this when I get my SC in a few months. Not only could you end up with a wrecked engine/sc, but no warranty? No thanks. That's why I decided to go with the SC from the get-go, b/c of the peace of mind.

But whatever. If you're a motor head, more power to you. I just know what people have said.
 
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