Anyone have pics of the "dual" intake design/setup?
04-20-08, 03:03 AM
#1
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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...
06-30-08, 12:05 AM
#3
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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.
06-30-08, 12:05 AM
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06-30-08, 05:45 AM
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06-30-08, 09:42 AM
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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...
06-30-08, 07:31 PM
#9
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.
06-30-08, 07:42 PM
#10
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
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
07-01-08, 12:39 AM
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07-02-08, 12:41 PM
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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.
07-02-08, 09:46 PM
#15
Lexus Connoisseur
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.
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.