Is your F 100% stock?

[Flytvr]

23 minutes ago, tomRCFcarbon said:

In EVO, the long term end of test report refers to a pencil in a vacuum pipe that results in the sound enhancer thing in the cabin always being on. Does anyone know what that referred to?

Open the bonnet, and looking from the front of the car, on the left hand side, you'll see the air intake. 

When the car gets between 3k / 4k rpm, there's a flap that moves. This is why you get the induction noise. 

The pencil trick changes this operation so that you always have the induction noise

[Flytvr]

See here - 

https://www.edmunds.com/lexus/rc-f/2015/long-term-road-test/2015-lexus-rc-f-making-it-louder-with-office-supplies.html

[Guest]

One should ask why lexus went to the trouble of having it closed at lower revs.

Sent from my STV100-4 using Tapatalk

[Flytvr]

1 minute ago, Comedian said:

One should ask why lexus went to the trouble of having it closed at lower revs.

Sent from my STV100-4 using Tapatalk
 

And there speaks the master of loaded statements. 😃

[SMorris]

16 minutes ago, Comedian said:

One should ask why lexus went to the trouble of having it closed at lower revs.

Sent from my STV100-4 using Tapatalk
 

I'd guess to be more aligned to the Lexus ethos of comfy cruiser at low revs, sporty GT at high revs.  I did the mod a few months ago (though with a proper vacuum cap, not a pencil!), can't notice any loss of power or pickup at low revs but it does sound nicer on-throttle.

[Guest]

1 hour ago, Flytvr said:

 And there speaks the master of loaded statements. 😃

Nooooo, this time I am being serious. I think it's important to try and understand it before altering it.

[Flytvr]

2 minutes ago, Comedian said:

Nooooo, this time I am being serious. I think it's important to try and understand it before altering it.

So why post that? Why not explain what you know - straight out of the box? 

[Guest]

1 hour ago, SMorris said:

I'd guess to be more aligned to the Lexus ethos of comfy cruiser at low revs, sporty GT at high revs. 

I think you made that ethos up  

I'd be worried about heat soak in heavy traffic and also how the extra air in matches up with the fuel curve. Maybe ECU can adjust and it is for emissions or economy, or maybe it's to protect engine. The point is we don't actually know. And also due to the different body work I believe the ISf had a cold feed from the wheel arch which wouldn't fit in the RCF.

 

[Guest]

Just now, Flytvr said:

So why post that? Why not explain what you know - straight out of the box? 

I don't know anything about it - that's the point.

[Flytvr]

Just now, Comedian said:

I don't know anything about it - that's the point.

What a man of such engineering prowess? If you don't know.........

[Guest]

Loaded statement that.

[Flytvr]

4 minutes ago, Comedian said:

Loaded statement that.

Ummm - nope - sincere.

[Guest]

I'll give an example that illustrates my point. I feel I may be coming over wrong.

On the M4 it has a large visible muffler. Miltek were telling us at goodwood how their design lifts and hides it. I was curious about it so researched and turns out BMW use it for airflow, lifting it up turns the rear bumper into a parachute collecting airflow, which = bad. So one has to assume miltek did not know that aspect of the design and probably most M owners don't either.

 

[SMorris]

54 minutes ago, Comedian said:

I think you made that ethos up  

I'd be worried about heat soak in heavy traffic and also how the extra air in matches up with the fuel curve. Maybe ECU can adjust and it is for emissions or economy, or maybe it's to protect engine. The point is we don't actually know. And also due to the different body work I believe the ISf had a cold feed from the wheel arch which wouldn't fit in the RCF.

 

I did. 😁

I'm not worried about heat soak, at the end of the day at high revs when the engine is under maximum load and needs more air that flap is open anyway, and if you are driving rather spiritedly it will be open all the time.  Therefore, at low revs, I don't see how that would ever be an issue .

Similar for the ECU, it's no different than having a hi-flow filter in there.  I was worried it might throw a warning light, but no, seems totally fine.

[SMorris]

44 minutes ago, Comedian said:

I'll give an example that illustrates my point. I feel I may be coming over wrong.

On the M4 it has a large visible muffler. Miltek were telling us at goodwood how their design lifts and hides it. I was curious about it so researched and turns out BMW use it for airflow, lifting it up turns the rear bumper into a parachute collecting airflow, which = bad. So one has to assume miltek did not know that aspect of the design and probably most M owners don't either.

 

No, but I'm an aerodynsmicist so I could have. 😁

[Guest]

14 minutes ago, SMorris said:

I did. 😁

I'm not worried about heat soak, at the end of the day at high revs when the engine is under maximum load and needs more air that flap is open anyway, and if you are driving rather spiritedly it will be open all the time.  Therefore, at low revs, I don't see how that would ever be an issue .

Similar for the ECU, it's no different than having a hi-flow filter in there.  I was worried it might throw a warning light, but no, seems totally fine.

What revs does it normally open at?

[Guest]

13 minutes ago, SMorris said:

No, but I'm an aerodynsmicist so I could have. 😁

Well, it's a good job you don't have to know how to spell it to be one 

[SMorris]

33 minutes ago, Comedian said:

What revs does it normally open at?

I think it's about 3800rpm

[SMorris]

30 minutes ago, Comedian said:

Well, it's a good job you don't have to know how to spell it to be one 

That's only a 5mm error on a phone screen.  🤔

[ColinBarber]

2 hours ago, SMorris said:

I'm not worried about heat soak, at the end of the day at high revs when the engine is under maximum load and needs more air that flap is open anyway, and if you are driving rather spiritedly it will be open all the time.  Therefore, at low revs, I don't see how that would ever be an issue .

At high revs the air will never get the chance to be heated, too much flow. At idle it is a different story, enough to be a problem I don't know.

[SMorris]

Not sure, I guess it depends how much air passes through the engine bay, and how much it warms up.  I take your point though.

[Guest]

Need to get 2 RCs to cruise on the motorway together - 80mph is about 2000rpm  so one flap will be closed and one open, and see if MPG is different.

[designo]

My GSF is 100% stock with the exception of Suspension, Intake, Exhaust and Chassis!  🙂

[NothernDan]

My ISF has the following mods;

20mm H&R spacers all round.

TEIN H-Tech Springs (front only) - 25mm drop.

Takeda Retain Intake.

Actuator Mod - Vacuum hose delete and capped so flap is fully open all the time.

H&S Cat-back Exhaust.

High-level roofline rear spoiler (body colour).

Carbon fibre rear bootlid spoiler.

Tom's carbon fibre rear diffuser.

Novel carbon fibre duct panels.

Plasti-dipped front grill.

With a Lexon front splitter (carbon fibre but I'm actually going body colour with it..... Controversial!) and Auto-Technic carbon fibre front fog light surrounds ready to go on soon. 

So, definitely not standard.

[NothernDan]

To weigh in on the "Actuator Mod" debate. Here are my views based on a year of experimentation and observation with various set-ups.

On the ISF the flap opens at about 3600RPM with the hose plugged in which Lexus say is when the car comes 'on-cam' (for want of a better description) and therefore demands more airflow. At this point the volume of air available is more important than the temperature of that air which is why the MAF sensor sits in the intake pipe so the ECU can adjust fuelling to suit both the volume and temperature of the intake air.

All of the aftermarket intakes on the market bar none (RR racing and the factory intake included) will heat sync as none of them are fully sealed. The aftermarket ones all do not make a sufficient seal against the hot air in the engine bay and the factory one opens a flap into the (hot) engine bay which again , will increase intake air temperature (albeit by a small amount at full speed).

That flap on the ISF opens into the engine bay and although there is a duct into the wheel well it is not very free flowing and has no 'push' (RAM) so you are just getting ambient air from the wheel well into the (hot) engine bay which is then sucked into your intake. It's 'hotter than ideal' air.

As previously mentioned I am midway through a project to create a fully sealed intake box for the ISF (no RCF and GSF yet) housing a much larger wet cone filter (larger than any current competitors) leading to 83mm ID intake tubing. It will need an ECU map so the MAF can deal with the airflow and will include instructions to increase flow from the wheel well and insulate current intake routing from the front grille.

My design will increase the availability and flow of the coolest possible air at all times but given it will be fully sealed it may not be the loudest intake out there..... Apologies to all you boy racers.