Custom "ram air??" hood....
10-03-2006, 09:21 PM
#1
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Custom "ram air??" hood....
I don't know if you can call it a ram air hood. But i have been working on this idea for the 928..I spen all the time, $$$$$$$, and energy redoing the motor and now it will be hidden by the intake tubes !!! I think not..So here is what Ihave so far. A 21x49x2 hood scoop from "evilbay" and a $100 doner hood from a fellow rennlist member (FBIII 
} I still need to make a duct fror the intake end that scoops air off the top of the rad. The rear will also be open to allow the air pressure at the dase of the windshield in. I made it so it can be unbolted and removed if adjustments are needed..Here are some pics. I only sits 2" off the hood at any point. The front and rear edges match the same curves of the edges of the hood.
} I still need to make a duct fror the intake end that scoops air off the top of the rad. The rear will also be open to allow the air pressure at the dase of the windshield in. I made it so it can be unbolted and removed if adjustments are needed..Here are some pics. I only sits 2" off the hood at any point. The front and rear edges match the same curves of the edges of the hood.
10-03-2006, 09:47 PM
#2
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Nice...but I think you will have a couple of issues to contend with. The first thing I would have done before all of this, is tape some ribbon to a few areas of the hood to see where your air pressure levels are at different speeds. I think based on the 928 design, it somewhat slices through the air, but causes an up lift of the approaching air and raises it over the roof, so at 60mph, the pressure is almost non existant over the hood and windshield. Imagine the air pressure curve as rising over the nose and over the roof in a semi smooth curve. The rake of the windshield eliminates a lot of pressure to grab some air.
The other thing I would have done is raise those ribbons off the hood to see how high I need to go to catch any of that air flowing over the car.
Another issue is the front intake...if you are providing two areas of intake, you cause static pressure build up...then you got nuthin!
I know there are guys who say cowl induction is the way to go, but I haven't seen ANY substantial evidence to justify the trouble on a 928. I think you may find in the end, you have a cool looking hood scoop...
Good luck though! Maybe you will be the guy that figures it out.
The other thing I would have done is raise those ribbons off the hood to see how high I need to go to catch any of that air flowing over the car.
Another issue is the front intake...if you are providing two areas of intake, you cause static pressure build up...then you got nuthin!
I know there are guys who say cowl induction is the way to go, but I haven't seen ANY substantial evidence to justify the trouble on a 928. I think you may find in the end, you have a cool looking hood scoop...
Good luck though! Maybe you will be the guy that figures it out.
10-03-2006, 11:10 PM
#4
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Thread Starter
I am not really looking for any h/p increase. If it does have a possible increase that will be a bonus. i am increasing the overall intake size for the radator area and the volumn of the intake tubes. I hope that the increase in volumn will allow for something ??? the rear opening will have a divider that separates the front and rear intakes so there is no added turbulance. Also the interior duct will be finished smooth to reduce air resistance.
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10-04-2006, 11:39 AM
#8
Race Car
So those band clamps really seal the intake sufficiently? Hm. Rubber underneath?
I'll be interested to see whether Kibort has thoughts on the hood- you've almost created an extractor. The intake will be trying to draw pressure in and the airflow will be the opposite, one would think. Sometimes the base of the windshield is a beneficial location for intake, but I'm not sure that the cowl induction hood with the sunken intake is going to function that way. Interesting, for sure.
I'll be interested to see whether Kibort has thoughts on the hood- you've almost created an extractor. The intake will be trying to draw pressure in and the airflow will be the opposite, one would think. Sometimes the base of the windshield is a beneficial location for intake, but I'm not sure that the cowl induction hood with the sunken intake is going to function that way. Interesting, for sure.
10-04-2006, 02:53 PM
#9
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I think some of you may be missing an aspect of what it looks like he is trying to do.
It looks like the scoop will be taking in the air that comes in from the front of
the car, but instead of going through the intake tubes, back to the air cleaner,
it's being routed up over the hood, and down into the air cleaner.
It does not look like the scoop will be open in the front. It will simply be ducting
the air from the stock intake locations, and sending it over the hood, to the back.
It seems like the same design as the stock tubes, but set on top of the hood,
instead of in tubes underneath the hood...
It may be open in the back also, for a little cowl induction action.
But it looks like the stock functionality is still going to be there.
The size of the scoop may even make it have more capacity
than the stock intake tubes. Less restriction, but the same source
for cool air. It will be like a giant airbox on top of the hood, fed
from the front...
It looks like the scoop will be taking in the air that comes in from the front of
the car, but instead of going through the intake tubes, back to the air cleaner,
it's being routed up over the hood, and down into the air cleaner.
It does not look like the scoop will be open in the front. It will simply be ducting
the air from the stock intake locations, and sending it over the hood, to the back.
It seems like the same design as the stock tubes, but set on top of the hood,
instead of in tubes underneath the hood...
It may be open in the back also, for a little cowl induction action.
But it looks like the stock functionality is still going to be there.
The size of the scoop may even make it have more capacity
than the stock intake tubes. Less restriction, but the same source
for cool air. It will be like a giant airbox on top of the hood, fed
from the front...
10-04-2006, 03:17 PM
#10
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Slick Idea.
10-04-2006, 05:59 PM
#11
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We're going to need G-Tech data for before and after this mod.
It has been dicussed here before that Porsche's stock air intake systems, especially on the front-motor wasserpumpers, are very hard to improve upon and usually out-perform custom set-ups.
But so far it DOES look cool...
It has been dicussed here before that Porsche's stock air intake systems, especially on the front-motor wasserpumpers, are very hard to improve upon and usually out-perform custom set-ups.
But so far it DOES look cool...
10-04-2006, 07:13 PM
#12
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Well, the "volume" of the airbox will be increased a lot.
So it all depends if there is any restriction in the stock tubes.
If there is, this will solve it.
There will be a ton of air available for the engine to ingest.
I just still think that even the cowl intake, or open airbox designs,
really don't give you that great of a benefit. Maybe 5hp?
So it just does not seem like it's worth the effort.
But hey, give it a shot...
Anything that keeps the air out of the hot engine compartment is a good thing.
So it all depends if there is any restriction in the stock tubes.
If there is, this will solve it.
There will be a ton of air available for the engine to ingest.
I just still think that even the cowl intake, or open airbox designs,
really don't give you that great of a benefit. Maybe 5hp?
So it just does not seem like it's worth the effort.
But hey, give it a shot...
Anything that keeps the air out of the hot engine compartment is a good thing.
10-04-2006, 09:54 PM
#13
Three Wheelin'
I think he is trying to achieve two purposes. Possibly improve on the cold air cowl affect and equally important to remove the intake tubes from the engine compartment.
10-04-2006, 11:08 PM
#14
Pro
Thread Starter
bcdavids and FBIII and correct..I am not trying to re-invent the wheel....I am tring to route the air into the air box from a different path than ste stock tubes. Purely cosemetic at this time. to see all of the deatil on the motor that the air tubes hide. If there is a h/p gain as a result than that is the icing on the cake..Thanks again for all of the input.
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DAVID