Home made intake scoop

I

iranmeba

Member
Hey there guys. So I don't really frequent on this forum, I usually stick to bimmerforums.com but I thought you guys may take interest in a project I've been working on. If posting a link to a competing forum is against the rules then I ask the mods to please delete the post.

http://forums.bimmerforums.com/forum/showthread.php?t=1089062

Cheers
 
I went to bimmerforums and read 3 pages of product development. I would be interested in proven HP gains. Please post them as soon as they are available.
 
20ducks said:
I went to bimmerforums and read 3 pages of product development. I would be interested in proven HP gains. Please post them as soon as they are available.
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Unfortunately it's almost impossible to measure gains from ramair products as they only start to function as the car moves forward through the air and the faster the car travels the higher the ramair effect. Dyno's can't replicate this scenario because the car is stationary ie no ramair and the dyno cooling fan is not a substitute for airflow around and over a car! It can only be tested in a wind tunnel.
 
Curtis, so would you pay Dinan or RPI or this guy a minimum of $128 for no substantiated gains? :?

No sarcasm meant nor directed, just looking for justification of a unique item. :)
 
Since HP cannot be really measured in this case I would be interested in see if there is any change in the amount of air going in. Several softwares let you graph air mass against RPM.

Again it is not gonna measure HP directly but if more air goes in, more torque is generated.
 
20ducks said:
Curtis, so would you pay Dinan or RPI or this guy a minimum of $128 for no substantiated gains? :?

No sarcasm meant nor directed, just looking for justification of a unique item. :)
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It's much easier to justify a purchase if you can see proof of the increase on a graph but with this type of thing you just have to judge the logic and theory behind the design and as somebody mentioned you can measure the increase in airflow so that you have some kind of proof that it's doing something constructive but without an actual hp figure. A company like Dinan will probably invest in a method of recreating variable airflow into the intake and they must have done something along those lines because they actually quote a specific hp or percentage increase although it's possible that they are purely speculating! A home made effort without recreating an airflow or using software to measure increased flow through the intake while moving may or may not work, it all depends whether the manufacturer thought out the physics and aerodynamics of it properly. I would say that an intake like Dinans where a forward facing "tube" which leads directly to and seals around the OEM intake will definitely produce positive results especially if you take the time to seal the joints so that the intake pressure isn't lost. The type of "ramair" in question here however isn't a true ramair system in that it's simply trying to deflect air towards the intake rather than force more air through it. It's all a bit hit or miss to be honest and certainly won't produce anything as good as a true ramair intake.
 
The Dinan type of system certainly is because it definately works but because this type of system has no ramair effect and hasn't been properly tested ( or has it? ) I would personally avoid it until substantiated gains were published.
 
20ducks said:
ZetaTre said:
...Again it is not gonna measure HP directly but if more air goes in, more torque is generated.
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How exactly is that calculated?
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You can go from torque to HP pretty easily: bhp = torque * RPM / 5252. However, I'm not aware of a mathematical way to calculate engine's torque. I believe torque is always measured.

The idea of measuring the MAF sensor reading comes from a popular mod done to the original air box of the M44 engine (used on the 318ti and the Z3 1.9): the air inlet in the air box was creating a restriction to the airflow. The mod was originally made by Shawn Fogg and the air box took the name of "Fogged Air box". The way he proved the air inlet was creating a restriction was done by measuring the reading of the mass airflow sensor before the modd and after the modd and graphing it against RPM. He proved that there was an increase in airflow at a given RPM figure which would determine and increase in torque. He then assumed that torque increased linearly with air mass, which is, IMHO, a fair assumption.

A similar test could be done on the scoop, to prove it indeed increase the air that enters the engine. It will not tell you how much your torque increased... IMHO, however, there are too many variable which determine how much torque the engine can deliver that makes any comparison difficult, if not complete nonsense.

Here's the graph:
149-m44_airflow.gif


Here's the reading if anyone is interested.
 
Just had another look at the pics and had another thought. Although it may be a good idea to try and direct airflow towards the intake the part itself creates an obstruction in airflow to the cavity behind the grilles where the intake collects from. It's also hard to judge whether it creates turbulence in the airflow or assists with compressing the air entering the intake. Will it direct water into the intake? These are the kind of factors which could create either a positive or negative effect and would require some kind of testing before jumping to the conclusion that it would definitely make a positive difference.
 
It's not easy but you can calculate theoretical engine torque (and HP) based on mass flow (air flow). It's been over 20 years since I've looked at the equations, but if I recall correctly, if you know the mass flow, the dynamic compression ratio, and some assumptions about efficiency you can get a reasonable estimate.

I agree with ZetaTre that for this mod, measuring an increase in airflow would prove that there was a corresponding increase in both HP and torque.
 
I checked mine at the weekend, and can confirm it was dry and no dust was in the air box. The filter looked clean as well, this was after fitting it 5000 miles ago.
 
ay8306 said:
It's not easy but you can calculate theoretical engine torque (and HP) based on mass flow (air flow). It's been over 20 years since I've looked at the equations, but if I recall correctly, if you know the mass flow, the dynamic compression ratio, and some assumptions about efficiency you can get a reasonable estimate.
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Let me know if you ever find it... I tried to look on the Bosch book but couldn't find anything...
 
If you ask what time it IS then the answer is simple however asking what time it WAS could get very complicated! :D
 
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