Kokeln Ram Air

[savowood]

I've been working on getting my 2000 Boxsera (Boxster with a Carrera 3.4l motor) to pull a little more speed on the straights, and I think the problem is clear. I'm not getting enough air into the airbox (replaced with aftermarket product from Italy) for the motor to make any power above about 85-90 m.p.h. so I end up capping out at about 125 at Summit Point instead of the 145 I'm expecting by the end of the straight. I was hoping the airbox change would help, but the way the air intake is angled on the car, I don't think enough air is getting down there. I've put my hand down the side of the car at various speeds, and I find the faster I go, the less air appears to get into the intake. I'm hoping the Kokeln scoop will help, but I want to see if anyone has used them and can comment on whether or not it actually does what I'm expecting.

-Michael

[catmanluge]

I've been working on getting my 2000 Boxsera (Boxster with a Carrera 3.4l motor) to pull a little more speed on the straights, and I think the problem is clear. I'm not getting enough air into the airbox (replaced with aftermarket product from Italy) for the motor to make any power above about 85-90 m.p.h. so I end up capping out at about 125 at Summit Point instead of the 145 I'm expecting by the end of the straight. I was hoping the airbox change would help, but the way the air intake is angled on the car, I don't think enough air is getting down there. I've put my hand down the side of the car at various speeds, and I find the faster I go, the less air appears to get into the intake. I'm hoping the Kokeln scoop will help, but I want to see if anyone has used them and can comment on whether or not it actually does what I'm expecting.

-Michael

When you figure it out tell me as I have the same problem. I have replaced the stock airbox with a larger open type airbox that has 3.5 inch tubing to the intake. I had a custon K&N filter made to flow the maximum amount of air. I cut the vent cover so that all lovers are open but part of the side cover is over the intake inlet tube (for lack of a better word). I was wondering if you have a photo of the Koklen scoop?

I also have a Dynolicious set up in my I phaone that shows that my 60 foot times are 2.43 sec with 330 foot times 6.27 sec and 1/8 mile at 9.44 sec at 79.2 mph pulling 1.13 g's. Times for a 2000 3.4 ltr 911 are 60 foot .963 sec 330 foot 5.243 times 1/8 mile 8.018 sec at 89.98 mph.

It also seems that short shifting produces faster times.

catman

Edited October 8, 2008 by catmanluge

[tholyoak]

Micheal,

Personally I really doubt the intake is the issue with the setup you are using. I'd bet money on another issue, most likely your exhaust is undersized. Take a look a the stock pieces on a 996, I am willing to bet they are much larger than what you are running. According to the dyno the same airbox on my car flows more than enough air for my X51 3.6.

-Todd

[Brad Roberts]

I've put my hand down the side of the car at various speeds, and I find the faster I go, the less air appears to get into the intake.

This is true :( The actual intake is too low on the side of the car. We found this after running the car through CFD tests and corrected it by running a completely different setup into the trunk (race car)

According to the dyno the same airbox on my car flows more than enough air for my X51 3.6.

He may actually have a problem at speed, however??

I'd like to hear what he has for exhaust. I agree, that is probably his problem.

The Kokeln/Vision piece is not expensive. I will tell you that many of us tested it, but all went and moved the air cleaner to a totally different area in the car.

B

[Brad Roberts]

Picture of the Kokeln piece :)

B

[tholyoak]

Brad,

Perhaps you are correct, but unless the speed is creating a vacuum not just a void of the ram effect, it shouldn't be any worse that a stationary dyno run with no fan forcing air into the intake duct.

I think the reason that the intake was designed this way (lack of a ram air effect at speed) was to prevent filling the airbox and intake piping with water when driving in rain as the intake is almost level with the throttle body making sucking of water into the motor very easy. They modified it further with the later lip on the intake trim due to airbox fires from sucking cigarette butts into the airbox when tossed out the window.

Just my $0.02.

-Todd

[savowood]

I won't be able to get the scoops installed in time for tomorrow's event, but next Friday the Aston Martin dealership is holding an event I'm instructing for. I'll have them installed for that one. I don't think we'll see much of a temperature difference so the results should be telling.

I also need to install my "racing" exhaust. The problems I have with it though are it's too loud for the street, and it doesn't fit with the normal tubing off the cats. I should just break down and get the B&B.

-Michael

[catmanluge]

I have headers with 2.25 stainless tubing hiflow cats plus a fee flow muffler. I ran with a straight outlets but had to modify them in order to stay under the required sound levels. I'll try and post a photo of the main section of my exhaust system.

[blue2000s]

Brad,

Perhaps you are correct, but unless the speed is creating a vacuum not just a void of the ram effect, it shouldn't be any worse that a stationary dyno run with no fan forcing air into the intake duct.

I think the reason that the intake was designed this way (lack of a ram air effect at speed) was to prevent filling the airbox and intake piping with water when driving in rain as the intake is almost level with the throttle body making sucking of water into the motor very easy. They modified it further with the later lip on the intake trim due to airbox fires from sucking cigarette butts into the airbox when tossed out the window.

Just my $0.02.

-Todd

I haven't seen the flow over the side of the car, but if it acts as Brad describes, then the air at the intake follows the air flowing over the side of the car, which increases with the speed of the car. This lowers the pressure at the mouth of the intake, which makes it harder for the engine to pull in air. This is referred to as static pressure.

When you add an effective scoop, and it's hard to tell if the Kokeln unit is just by looking at the picture, the pressure at the intake will increase as speed increases as the car catches and pools air in the scoop. From a technical standpoint, it's called total (stagnation) pressure. It's the addition of the static pressure and the dynamic pressure (the pressure resulting from bringing the air to a stop). This will actually improve the ease with which the air can be pulled in by the engine.

Now there are some complicated things going on with recirculation when you add the bump to the front of the intake like they did in the 2000+ cars. That can actually create some of that scoop effect without the drag associated with the scoop.

Edited October 9, 2008 by blue2000s

[efedor]

Brad is that a picture of your Porsche? I think I saw It in barstow, Except the scoop was a perfect match to the custom car paint.

[70Sixter]

Interesting that the Boxster concept car had low mounted intakes. At least one tuner mounted the intakes low. I'll be watching this thread closely because I'm really interested in the Kokelns.