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I want to verify this, supercharging my fj would not benefit me in mud ridding even though it would be nice to have the power to push the 35s
A TRD type supercharger requires higher RPM than a URD type in order to generate power to overcome the parasitic loss of the belt/gear and screw/fan it needs to spin, and to be able to compress enough air to give you good performance.

Short answer - probably not very much benefit. Read the centrifugal supercharger writeup below.

'Roots' supercharger (TRD)


Twin screw supercharger


Centrifugal supercharger (URD)


More supercharger information.

Basic - Supercharger Basics

Advanced - Part 1 - Superchargers A-Z (Part 1 of 3)

Advanced - Part 2 - Superchargers A-Z (Part 2 of 3)

Advanced - Part 3 - Superchargers A-Z (Part 3 of 3)

More info on centrifugal (URD type) supercharger - The Centrifugal Supercharger Explained

- SK
 

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A TRD/URD type supercharger requires higher RPM in order to generate power to overcome the parasitic loss of the belt/gear and screw/fan it needs to spin, and to be able to compress enough air to give you good performance.
What a great, comprehensive response!

I am looking at buying a URD in the next few months. I don't anticipate any advantage to low speed operation from the supercharger (note the reasons above) but the added freeway horsepower is worth the investment in my case.
 

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A TRD/URD type supercharger requires higher RPM in order to generate power to overcome the parasitic loss of the belt/gear and screw/fan it needs to spin, and to be able to compress enough air to give you good performance.

Short answer - probably not very much benefit. Read the centrifugal supercharger writeup below.
Thank God for someone else who knows what the hell they are talking about with superchargers and their value (or lack thereof) as far as an application to our trucks...

Rep points for you!
 

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Yes, thank you it seems that it wouldnt help me in the louisiana mud. I wonder if it will hold up when im offroading and ill be able to quickly transverse back to onroad.
Hi again

Superchargers (these days) are quite reliable and resiliant. (I think I spelled that right.)

There are a couple places where the type of supercharger needed for our off road activities would cause some problems.

A gear driven twin screw supercharger (Whipple for those of you who are familiar with them) would need some way to blow off backpressure when you rev the engine to get out when stuck. The URD (and I presume TRD) one, since it is centrifugal and a fan type, will allow this pressure to flow back over the fan without a problem. As far as the engine goes, very high rpm is what causes problems and so no worries there.

I *might* suggest very closely logging your engine specs without the supercharger and seeing what kind of use you are putting your truck to. Then, after getting the supercharger installed I would see about getting a custom PCM tune made for it. (Note: URD might offer this I do not know.)

Check into an upgraded fuel rail. Not a lot of use to have more air in there if you can't feed in enough fuel.

ABSOLUTELY check into beefing up the following things:
transmission mounts
engine mounts

Optional but advised
As Air2Air mentioned, you probably want to upgrade the transmission itself
if you are using this for highway and more speed, brakes, BIGGER ONES!
spark plugs - I always advised getting a 1 range colder as you are pushing denser, colder air into the system and as such your combustion chamber temp will be a little lower, plus it helps a little to control any tendencies to precombustion. (this is a BAD THING*)

- SK
 

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Thank God for someone else who knows what the hell they are talking about with superchargers and their value (or lack thereof) as far as an application to our trucks...

Rep points for you!
Thanks :)

This is the first non-FI vehicle I have ever owned. My daily driver has a custom twinscrew stage 3 and my toy has just over 260hp with a race level centrifugal supercharger, as well as weighing only 1747 pounds. :bluecap:
Spent quite a bit of time playing around with the DD to turn it from a slightly peppy car to something that most people are suprised by. In the process I learned a lot about FI and how to make a vehicle go faster.

This is not to say that I won't be getting a supercharger for the FJ, just that I will make some mods to it and that it won't help me a lot in my type of off-roading. Any of the desert race FJ owners should get a lot of benefit.

- SK
 

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Just bumping this up for people new to the site and interested in some information on the TRD and URD type superchargers.

- SK
 

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Just bumping this up for people new to the site and interested in some information on the TRD and URD type superchargers.

- SK
The TRD supercharger for the FJ must be similar to what I have on my 1998 Sienna (3.0 V6 IMZFE) engine). Root type or dual impeler to compress the incoming air from the intake.

 

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Interesting comments..
I have an EAton on a project car and I PM'd acouple FJ owners who have the TRD(EAton) setup - and who offroad... They were satisfied.
An SC doesnt require higher rpm, an SC will provide boost from idle on up... boost is power and as long as the SC is sized correctly, and the pulley is matched correctly it produces more power than is lost in the force required to turn it. A roots type SC has a fixed displacement so every rev provides a certain volume of air - more revs more CFM.
Since TRD developed the unit in conjuncton with Eaton I'm sure it does just what its supposed to. Eaton has chargers on everything from GM products to the Mercedes and Mini (BMW) they are quite capable of engineering a setup for an offroad vehicle.

If you don't like the boost you're getting from an SC, you change the pulley to a smaller size so the SC turns faster....

A turbo or charger like the URD is not a positive displacement so it requires higher revs. Maybe thats where the "higher rpm" comment originated???
 

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I opted for the TRD supercharger. Reason why? It's still under factory warranty. I've got 35's on mine and it doesn't skip a beat. The URD would be a tempting way to go if it didn't void my warranty. If I'm spending all that money I want to have some reassurance in case something goes wrong.
 
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