IS F (2008-2014) Discussion topics related to the IS F model

Anyone have pics of the "dual" intake design/setup?

Thread Tools
 
Search this Thread
 
Old 04-20-08, 03:03 AM
  #1  
RX Renesis
Driver School Candidate
Thread Starter
 
RX Renesis's Avatar
 
Join Date: Mar 2008
Location: B.C.
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Default Anyone have pics of the "dual" intake design/setup?

anyone on the forums who owns an IS-F have taken apart their intake yet? i'm curious on how it's a "dual" intake design and what makes the noise pass 3000rpm...
Old 06-29-08, 11:14 PM
  #2  
vraa
CL Folding Team Starter

iTrader: (2)
 
vraa's Avatar
 
Join Date: Sep 2002
Location: TX
Posts: 4,669
Received 358 Likes on 207 Posts
Default

I'm gonna try to open mine up

I want that second intake open all the time

The exhaust note is INTOXICATING
Old 06-30-08, 12:05 AM
  #3  
flipside909
Lexus Connoisseur
 
flipside909's Avatar
 
Join Date: Mar 2001
Location: USA
Posts: 19,802
Received 534 Likes on 283 Posts
Default

Dual intake meaning it has a spring loaded flap inside that opens up after 3600rpm at WOT. You can find this by uncovering the secondary part of the intake box closest to the passenger side fender/apron area.
Old 06-30-08, 12:05 AM
  #4  
flipside909
Lexus Connoisseur
 
flipside909's Avatar
 
Join Date: Mar 2001
Location: USA
Posts: 19,802
Received 534 Likes on 283 Posts
Default

Originally Posted by vraa
I'm gonna try to open mine up

I want that second intake open all the time

The exhaust note is INTOXICATING
That's not the exhaust note you're hearing, it's the intake box.
Old 06-30-08, 05:27 AM
  #5  
vraa
CL Folding Team Starter

iTrader: (2)
 
vraa's Avatar
 
Join Date: Sep 2002
Location: TX
Posts: 4,669
Received 358 Likes on 207 Posts
Default

Originally Posted by flipside909
That's not the exhaust note you're hearing, it's the intake box.
Correction

That intake box is INTOXICATING
Old 06-30-08, 05:45 AM
  #6  
nuttybar08
Driver
 
nuttybar08's Avatar
 
Join Date: Jun 2008
Location: SC
Posts: 100
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by flipside909
Dual intake meaning it has a spring loaded flap inside that opens up after 3600rpm at WOT. You can find this by uncovering the secondary part of the intake box closest to the passenger side fender/apron area.
Yep. I went to an Lexus IS-F dyno day last week and the intake was one of the parts they had on display. It's actually a very simple mechanism. The normal low power intake path is intentionally restrictive and designed to increase intake velocity; the flapper opens up at 3600 rpm to reduce restriction (it opens a larger and shorter path to the manifold) and increase intake volume. It all seems to work pretty well.
Old 06-30-08, 06:15 AM
  #7  
vraa
CL Folding Team Starter

iTrader: (2)
 
vraa's Avatar
 
Join Date: Sep 2002
Location: TX
Posts: 4,669
Received 358 Likes on 207 Posts
Default

So does that mean by having the flapper open up at lower than 3600rpm would lead to performance loss?
Old 06-30-08, 09:42 AM
  #8  
nuttybar08
Driver
 
nuttybar08's Avatar
 
Join Date: Jun 2008
Location: SC
Posts: 100
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by vraa
So does that mean by having the flapper open up at lower than 3600rpm would lead to performance loss?
Theoretically "yes" because higher intake velocities at low rpm improve mixing due to swirl and promote faster flame front propagation...i.e. faster burn rate therefore more power output. At higher rpm the focus shifts to simply getting more air in via the least restrictive path possible.

The real answer will lie with tuners but a good first guess is that opening up the intake (with no other tuning) would improve high rpm breathing and peak horsepower but sacrifice some low end grunt, which is a typical trade-off. This will also depend on how restrictive the stock exhaust is...
Old 06-30-08, 07:31 PM
  #9  
ToothDoc
11 Second Club
 
ToothDoc's Avatar
 
Join Date: Apr 2006
Location: IL
Posts: 963
Likes: 0
Received 2 Likes on 2 Posts
Default

If I recall correctly, somebody here had their IS-F taken to a company for test fitting an intake. After dynoing before and after, they actually LOST power so that intake is not on the market.
Old 06-30-08, 07:42 PM
  #10  
vraa
CL Folding Team Starter

iTrader: (2)
 
vraa's Avatar
 
Join Date: Sep 2002
Location: TX
Posts: 4,669
Received 358 Likes on 207 Posts
Default

The more and more I think about it, the more and more I really don't want to mess with the car

It all seems so well put together

Anyways, I had a cursory look at what's under the hood
Tips on getting the main parts disassembled?
Is asking my dealer for some schematics the best bet or are there already guides online?

I'll try to mess around with whatever physically controls the opening/closing of the 2nd intake and record some informal results
Old 06-30-08, 10:33 PM
  #11  
trdsolara
Driver School Candidate
 
trdsolara's Avatar
 
Join Date: Dec 2003
Location: Maryland
Posts: 16
Likes: 0
Received 0 Likes on 0 Posts
Default

I have a feeling the intake is vacuum operated similar to how the corvette z06's exhaust opens up at about 3000 rpm.
Old 07-01-08, 12:39 AM
  #12  
f=ma
Lexus Test Driver

 
f=ma's Avatar
 
Join Date: Sep 2007
Location: California
Posts: 1,211
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by trdsolara
I have a feeling the intake is vacuum operated similar to how the corvette z06's exhaust opens up at about 3000 rpm.
yeah bmw's exhausts has a flap that is vacuum operated as well and all we did is unplug and the flap stays open.
Old 07-02-08, 12:41 PM
  #13  
PHXDiesel
Driver School Candidate
 
PHXDiesel's Avatar
 
Join Date: Jun 2008
Location: Arizona
Posts: 36
Likes: 0
Received 0 Likes on 0 Posts
Default

It doesn't seem like just opening the intake a bit is the only thing that makes the car scream. I'll bet that the variable cam timing changes drastically at 3600 and that is truly the cause of the change in sound.
Old 07-02-08, 09:27 PM
  #14  
vraa
CL Folding Team Starter

iTrader: (2)
 
vraa's Avatar
 
Join Date: Sep 2002
Location: TX
Posts: 4,669
Received 358 Likes on 207 Posts
Default

What would be the surest way to find out?

I already know emailing my sales / service will get me blank stares
Old 07-02-08, 09:46 PM
  #15  
flipside909
Lexus Connoisseur
 
flipside909's Avatar
 
Join Date: Mar 2001
Location: USA
Posts: 19,802
Received 534 Likes on 283 Posts
Default

Originally Posted by vraa
What would be the surest way to find out?

I already know emailing my sales / service will get me blank stares
I already gave you the answer above.

This is quoted directly from the IS-F Product Press Release:

https://www.clublexus.com/forums/sho...87&postcount=2

Originally Posted by Lexus USA
Innovative Breathing

High-flow cylinder heads designed by Yamaha have a lightweight valvetrain, contributing to the IS F V8's high-rpm capability. The horsepower peak arrives at 6,600 rpm (just 200 rpm before redline), and the torque peak at 5,200 rpm. The resulting performance character, while quite responsive in low-speed situations, provides a rush of power at higher engine speeds. Carefully chosen ratios for the 8-Speed Sport Direct Shift transmission help ensure responsiveness at all vehicle speeds.

The IS F V8 engine employs innovative new technologies to maximize efficiency and reduce emissions, including the SFI D-4 (direct-to-cylinder injection system with secondary port injectors) fuel injection and the Electronic Throttle Control System with intelligence (ETCS-i). Essentially, SFI D-4 integrates two types of fuel injection: A direct-type high-pressure fuel injection system, which provides a cooling effect in the cylinders and enables the high compression ratio (11.8:1) employed to extract maximum energy from the fuel; and a set of low-pressure port fuel injectors that help produce a precise burn to optimize power and efficiency under light- and medium-load conditions.

A dual air-intake system uses a primary intake passage for low and medium engine speeds. In the higher engine speed range (above 3,600 rpm), both the primary and secondary passages are opened, helping boost high-rpm power. Both intake passages share a common high-efficiency, low-restriction air filter.

Lexus optimized the intake system down to the smallest details. For example, the throttle valve shaft has been tapered down from 10 mm to 7 mm diameter in the center to expand the intake air passage. The intake manifold uses a simple plenum design with equal-length runners.

Last edited by flipside909; 07-02-08 at 09:51 PM.


Quick Reply: Anyone have pics of the "dual" intake design/setup?



All times are GMT -7. The time now is 02:09 AM.