pagemaster

[QUOTE=Och;4512506]The 4.7 is an iron block. http://www.lexus.com/models/GX/detai...fications.html


1UZ and 3UZ engines are aluminum blocks.

pagemaster

Its not worth it in the 4.7. For 5k it can be done in the Tundra. The issue I would have with supercharging or modifying the 4.7 in the GX is the fact that the power goes through a mechanical centre differential. Long term reliability and durability would likely be comprimised. This is not the case with the Tundra.

I also believe that the 4.7 TRD supercharger only works with non VVTi 4.7 models.

mann777

I'm a am no auto tech but I need some advice or someplace completely out of my element and talk to someone who's knowledgeable and willing to break it down for GX mod. I hear a lot talking about improving low end torque, seriously starting from the Exhausts such as the Flowmasters But it is really crap as they really restrict or reduce flow unlike what they have been advertising .I did a study with another brands and guess what have a look at this link. http://www.dynomax.com/images/UltraF...risonChart.gif. It clearly shows a Flowmaster 40 series has a measly 35% of the flow of a Dynomax UltraFlo. That's pretty darn pathetic IMO. Consider also that no-one, AFAIK, has ever presented documentary evidence here that any Flowmaster model has improved low end torque. There are a lot of reports about the great sound but few, if any, credible reports about improved low end power (there have been a number of complaints about power loss though). My impression is that Flowmaster has done a wonderful job of designing an audio device for the exhaust...a pipe organ. But not a known performance enhancing device, at least for RPMs below 3000.

Frankly speaking GX changing back to the stock intake from an AEM or a K& N probably won't make a really noticeable improvement in low end torque until the engine has to really do some work.

I know for GX members who do mod dual exhaust as a show piece consider this V8 and Toyota really did a great job of tuning it for maximum torque (an impressive 315 ft-lbs - 345 ft-lbs on some high end model like Tundra , Sequioa and Nissan for the Titan ) at a very usable RPM (only 3400). Part of that tuning was choosing the 2 3/8 inch single exhaust (the stock system in most of the USA and Canada)...it's just the right size for optimize scavaging at mid RPM.
I think Dual pipes or overly large single pipes result in too much cooling, density increase, and loss of energy/velocity in the gasses until RPM gets pretty high. And I think the single 1- 2 3/8 inch stock pipe is the critical element for low end torque.

gsobol

mann777, you are right with your assumptions. Larger, more free flowing exhaust is essential for a high performance / high horsepower engine that needs to develop large amount of torque and HP in the higher rev range, at the cost of low end / low rev torque. Sure, once you mod your engine to produce 50%, 100% or more power than stock, than you need to do it, and you wont feel the loss of torque, as you are producing more than stock anyway. On the stock engine, increasing the exhaust diameter and changing the headers without increasing the intake capacity will result in the loss of low end torque. That back pressure is essential for the engine to develop the low end torque efficiently. In order to get it back you have to increase the flow of air to the engine (intake, heads, throttle body, etc.), and that also means more gas (higher flowing injectors, etc.).

Now, since I don't know Toyota's V8s well, I don't know what capacities or restrictions are there on the air and fuel flow. If the intake and throttle body are over engineered, the air capacity may be there already. Maybe the only thing that needs to be done is extrude hone the intake to improve air flow, or put less restrictive air filters, etc. I don't know. But once you go down this route, you will find out that all elements are interconnected. Keep in mind, engine is an air pump, gas goes in, gas goes out. Reduce the flow on either end, and you have a problem. Increase the flow on one end only, you are still restricted by the capacity of the other.

Often times manufacturers will show you the numbers that show power and torque increase once their product is installed. Generally that's true for a specific rpm range, usually close to the red line. They rarely show you the actual power curve that shows the gains in the top rpm range, but loss at lower rpm range. When asked about that, the general reply is that the expected installation will be in the vehicle that will launch at the higher RPM range than stock. So now you have to look for a high stall converter. And the list goes on. As I said, I haven't done this with Toyotas, but I spent many, many years with Ford V8s. Remember, once you start it's hard to stop :-)

Och

iTrader: (3)

[QUOTE=pagemaster;4513042]Wow, I didnt know that the 4.7 (2UZ) was iron. On lextreme they have some sick hybrids mating the 4.7 block to 4.3 heads.

I still wonder why they made the block iron. Is it to save cost because the 1UZ and 3UZ was used exclusively in Lexus and the 2UZ was used in Toyotas?

mann777

I think thats it you just cant do anything on the forged iron blocks, jeez no wonder lextreme are hybernating on GX mods.

Johnny Rad

I rest my case: "...the current model’s anaemic 263hp (196kW) 4.7L V8. This new 4.6L engine, incidentally, is the same unit.."

https://www.clublexus.com/forums/gx-...this-year.html

http://wardsauto.com/ar/lexus_gx_due_090515/index.html

mann777

So thats it, existing GX mod is a dead issue. Maybe I need to soon look for going one up version maybe the 570s

2007TundraDCOwner

[QUOTE=Och;4515397]
From my understanding the reasons for cast iron blocks, is because they are stronger, but they are heavier. Henceforth the reasons they are used in the Truck platform.

I'm thinking the aluminum blocks are to help with two factors, (they are less weight)

#1 is likely for performance and handling capabilities.

It cost less money to make a lighter aluminum block, than it does to re-engineer the firewal and suspension so they could move a cast iron block a few inches toward the rear of the vehicle.

#2 the lighter block means less weight, which will increase acceleration time, handling curvy roades better, and improve fuel economy when it's not being aggressively driven.