[Kunz]

Hi There!


At least for the last 10 years there was this idea of catching the air right at the bumper and lead it directly tot he airbox from there. As there is never enough time, things only stay in the head then…


Well during the last few days I finally took some time after work to try something out in front of the garage.


I know very well, the little bit of pressure generated by the flow of the air would not make a big difference, I still hoped there would be an effect on the resonances in the system. After all, RAM AIR is something extremely common in racing and also in high performance production cars, like the new GT 3…


Also, I know, it would have been so much nicer to make a positive in polyurethane and then laminate in carbon… smooth, thin and light… yes, I know! But my idea was to just try it out quickly and see if it does anything to the car… without “making the doctor’s degree”, like we say in Switzerland. So I then took some INOX-sheets and welded. Please no comments on the welds: I am just a medical doctor! Also I didn’t want everything to be heat-wrapped, so I welded point for point, one here, one there…


 

So now enough of saying sorry for trying out something and post it here
J


 

What are the experiences up to now?


 

Fueling and MAF-signal:


I tuned the car to 12.7 on E85 before. After fitting the intake the car the car is now running significantly richer at about 12.4 to even 12.0 at redline / before the limiter. This is obviously due to a higher MAF-signal. Logging the values, I have some 0.2Volts more at 6000rpm and WOT then before. This could be due to slightly cooler and denser air, but most probably also more air-mass per time.


 

Drivability:


Smooth power across the band with a nice kick at 4100rpm. At least as good as befor. The car feels a bit torquier.


 

Torque and performance:


I measured this as always with the G-Tech as I need airflow and the performance on the road is what counts only. I found a slight gain over the whole rpm-band. Max torque is now 4% higher an a little bit earlier, while max performance is by about 3% higher and a little bit later in the revs. At 5900rpm – where max power was before and straight through to 6500rpm – I have at least the same power, but it continues to climb to about 6200rpm to then go straight to 6500rpm.


 

Acceleration:


Also G-Tech values.
From 40 to 100km/h in second gear the car is some 0.2sec faster.


 

So all together:


The intake does something. It alters the MAF-signal and runs the car richer, most probably due to more airflow. There is some more torque and performance in a slightly wider powerband, while drivability is at least as good as before.


 

Next step is now playing around a bit with the fueling, to see if some more has to be found
J

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[Bulti]

I like the idea a lot, but I kinda doubt this air duct has any gains over the other air box mod...

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[flash]

like any ram air setup, at speed, it does.  i have had something like that in my car for about 11 years now.  it works.  however, measuring it is hard, because it is very hard to duplicate the force of air at speed.  even the big fans at the dyno don't do that job.  the only one i know of that can replicate the air flow of road speed is the one at dinan.

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[Bulti]

Ok, but isn't the air forced through the extra holes in the airbox as well at high speeds? Although maybe a little less efficient then when the extra duct is mounted for guidance?

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[flash]

yes, assuming you have an uninterrupted path.  that's what a plenum does though.  it give the cold air an uninterrupted path, and isolates the hot air, preventing it from entering the airbox.

 

it's not a huge difference, but it's there.

 

it does tend to make it a more cold-blooded though

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[Kunz]

Yes, that is about the experiance I made as well.

Up to now I used the homemade intake on the pic. After some testing I found that opening the box in the front gives an advantage... in some rev-ranges. And the stock snorchel gives some advantage in other rev ranges...

So this was the try to combinate the two; open box, fresh air behind the bumper. It worked pretty well and gave me a good gain over the stock solution.

The Ram-Air intake above, which I crafted in a hurry, gives again an advantage over that. What was surpising to me, there is not much speed needed for it to work...

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[flash]

i hope you don't run int like that with the radiator cover missing.  you lose a fair amount of power to heat soak that way, and a whole lot of cooling efficiency.

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[Kunz]

????

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[flash]

it looks like you cut out some sheet metal.  you'll need to create a replacement piece to fill in all that space, and keep the air flowing through the radiator, and not escaping upward into the engine bay.  by having a piece there, that will reduce intake temps at low speed, giving you better off the line throttle response, and will maintain the efficiency of the cooling system.  

 

to elaborate, cooling systems require a positive pressure zone in front of the radiator, and a negative one behind.  basically you want all of the air hitting the radiator to be forced to go through the radiator.  anything you can do to seal that off, and promote that will be helpful.  porsche did this with the gaskets at the sides and bottom of the radiator, and the plastic shroud at the top.

 

similarly, you want to do whatever possible to prevent extraneous air from entering the engine bay behind the radiator, which would decrease the negative pressure zone.  porsche did this with the belly pans.

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[Kunz]

I just put that one qucikly in to show here... ?

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[flash]

i understand.  it looks like you cut out some sheet metal though, at the forward portion of that area, where the plastic piece would have clipped on

 

no worries - it will be easy enough to create a new piece to fill that area.

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[Kunz]

There is some metal cut out indeed. When it was sc, i wanted the ic to be placed right...

Now that gave me some room for the intake.

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[Kunz]

Yes. With the actual setup i crafted the little sheet of inox you can see on the right (from the front), for the rest the "new cover" is the intake itself.

Last weekend i had a great ride through the swiss alps with some friends with much more potent cars (which does not mean, they are neccessarily faster ?)

Permanent steep uphill at full trottle at relativly low speeds... Worked really great ??

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[Bulti]

Damn, I want some alps too :-)

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[ds968]

No kidding, me also ! What a superb setting for Porsches ...or anything else for that matter.

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