Hood Ventilation Ideas
08-02-2007, 08:22 PM
#76
I keep reading this as you saying air comes out of the rear of the hood, while driving at speed. That is not the case at all. Air is drawn from the cowl area IN under the hood at the ouside edges (say from the outer rear corners extending 8-12" towards the middle of the car). In the very center of the hood air is not being drawn into the hood or it is being drawn-in in such small quantities it was undetectable with the crude methods I was using.
When driving the airflow is something like this in the hood and cowl area. There Is NO inward air flow in the center of the hood behind the triangle.
I would like to see where the chalks are placed to raise the hood. Raising the center won't do anything. Raising the sides would create more ambient airflow down into the engine bay and over the engine.
08-02-2007, 08:24 PM
#77
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08-02-2007, 08:29 PM
#79
RotoRocks Powered
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Theres not "no" airflow, theres just extremely little. Which is why i just recommend getting a real vented hood over the pita that it would be to chalk the hood up high enough.
extremely little is very difficult to measure in comparison to the great wash of air coming over the hood.
Also, I would only really be interested in temp differences of the coolant while driving at 95 mph for about 5 minutes in 100 degree weather. At least we know that will max out the cooling system.
extremely little is very difficult to measure in comparison to the great wash of air coming over the hood.
Also, I would only really be interested in temp differences of the coolant while driving at 95 mph for about 5 minutes in 100 degree weather. At least we know that will max out the cooling system.
I was driving with an average speed of 85 MPH (close enough to what you asked) for about 30 miles.
I monitor the condition of the engine practically all the time, so believe me i know how it runs, in what conditions and at what temps. The laptop is always open on the passenger sit.
Average temp drop is 6-10F depending on the intensity.
Oh so the cooling system is not highly variable? The first OEM radiator fan will kick in at 97 degrees C and the second at 101 degrees C. How do you know the difference isn't just the fans kicking on that run and not on the previous run? Throw in the regulating effects of the thermostat and thermal lag associated with a cooling system, and its extemely hard to get an apples to apples comparison by just looking at the temp guage for a few minutes. .
I am tired of this bullshit. For some reason i ended being in a position where I feel like I have to excuse myself. I did it. It works for me. You don't think it is good enough for you, spend $800 on a vented hood, it's your money. I'll find something else to spend mine onto.
I remember a bunch of naysayers telling me how a turbocharger won't make boost the back of the car. I built it and at some point I had difficulties keeping that turbo from over boosting pushing 16 PSI at 7K rpm...
For every good thing there will always be someone who'll try to crap on it. Apparently this case is no excetion.
08-02-2007, 09:49 PM
#82
RotoRocks Powered
Thread Starter
08-02-2007, 10:08 PM
#84
08-02-2007, 10:44 PM
#87
What about using hood dampers?
They raise the hood on the sides and rear.
That should help. Maybe not as much as you want, but do both, chalk center and dampers.
What do you say rotorocks?
They raise the hood on the sides and rear.
That should help. Maybe not as much as you want, but do both, chalk center and dampers.
What do you say rotorocks?
08-02-2007, 11:23 PM
#90
RotoRocks Powered
Thread Starter
Driving without it changes nothing as far as the effect of cooling, but driving without it for some time, and you'll begin to see the paint on the hood fading and peeling off sooner.
It's primary purpose is to shield the heat radiating from the engine, not to block the hot air.
08-03-2007, 05:24 AM
#91
Engine cover directs airflow. Search.
Hood dampers shouldn't raise the hood. If they do, you are using the wrong ones. Search.
16PSI and 10:1 compression have nothing to do with whether or not you will blow up your motor. Its all about ignition timing and fuel. That was just a stupid post, so I won't bother to tell you to SEARCH.
BTW - Its "chocks" not "chalks".
Hood dampers shouldn't raise the hood. If they do, you are using the wrong ones. Search.
16PSI and 10:1 compression have nothing to do with whether or not you will blow up your motor. Its all about ignition timing and fuel. That was just a stupid post, so I won't bother to tell you to SEARCH.
BTW - Its "chocks" not "chalks".
08-03-2007, 06:24 AM
#92
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best post all thread 
sorry for going so far back into the thread, I've just finished skimming through.
you can already get these, they're very expensive though.
Roberuta Cup Kits, sold through Top Secret
http://www.topsecretjpn.com/roberuta.shtml
ram air seems intuitive (even if wrong) - and has a cool name, it sells, that is why it is made. Being popular in the aftermarket doesn't mean much, the aftermarket is full of heaps of **** that people swear works... look at those buzzcans on hondas "its like another 50hp bro", or the open pod filters.
I've got an article where they run som CFD experiments looking at the pressure built by 'ram air' on an F1 air box with various radii for low and high speed flow, at the speeds an F1 sees it made all of stuff all difference. It isn't ram air giving you better performance - it is cooler air, and a less restrictive intake path giving better cylinder filling..erm.. combustion chamber filling in this case
IMO so much focus should not be put on just getting air out of the engine bay, that might be nice, but really the goal is to promote as much air flow as possible through your coolers - radiator, oil, ps, trans, etc. Better ducting is the way to go where possible. If you take a look at race cars like JGTC Supra, there isn't really any venting for underbonnet air, but there is MASSIVE ducting into and out of each cooler to get the air flowing through it nicely.
IMO the guys who keep harping on about breaking out the wool tufts (and having thermo couples all over the joint so you can log what is going on) are on the right track, without the data you might hit on something that sorta kinda works, but it is unlikely to be the best way (whether you have any constraints on how wild you wanna go or not)
sorry for the big post.
sorry for going so far back into the thread, I've just finished skimming through.
i'd love to pull into a new restaurant one evening and not worry about cracking my bumper... so would about thousands of others. +million other reasons but i'm afraid off-roading wasn't what i had in mind hehe
if you do make it, please make sure that it won't affect the handling.
but i'm afraid off-roading wasn't what i had in mind heheif you do make it, please make sure that it won't affect the handling.
Roberuta Cup Kits, sold through Top Secret
http://www.topsecretjpn.com/roberuta.shtml
If that is the case then then concept of RAM AIR is completely reduces itself to completely useless, nevertheless it is quite widely implemented.
I am pretty sure that at 80 MPH, I'll see that arrow move a little. Think of all that air being pushed into your engine compartment with nowhere to get out...
I am pretty sure that at 80 MPH, I'll see that arrow move a little. Think of all that air being pushed into your engine compartment with nowhere to get out...
I've got an article where they run som CFD experiments looking at the pressure built by 'ram air' on an F1 air box with various radii for low and high speed flow, at the speeds an F1 sees it made all of stuff all difference. It isn't ram air giving you better performance - it is cooler air, and a less restrictive intake path giving better cylinder filling..erm.. combustion chamber filling in this case
IMO so much focus should not be put on just getting air out of the engine bay, that might be nice, but really the goal is to promote as much air flow as possible through your coolers - radiator, oil, ps, trans, etc. Better ducting is the way to go where possible. If you take a look at race cars like JGTC Supra, there isn't really any venting for underbonnet air, but there is MASSIVE ducting into and out of each cooler to get the air flowing through it nicely.
IMO the guys who keep harping on about breaking out the wool tufts (and having thermo couples all over the joint so you can log what is going on) are on the right track, without the data you might hit on something that sorta kinda works, but it is unlikely to be the best way (whether you have any constraints on how wild you wanna go or not)
sorry for the big post.
08-03-2007, 06:52 AM
#93
engine cover
The engine cover does direct the air flow, but what about a s/c engine. Would it worth it to alter the existing engine cover or design a new one? With the reconfiguration of the whole throttle body area I'm not sure if it would help.
08-03-2007, 06:57 AM
#94
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I keep reading this as you saying air comes out of the rear of the hood, while driving at speed. That is not the case at all. Air is drawn from the cowl area IN under the hood at the ouside edges (say from the outer rear corners extending 8-12" towards the middle of the car). In the very center of the hood air is not being drawn into the hood or it is being drawn-in in such small quantities it was undetectable with the crude methods I was using.
When driving the airflow is something like this in the hood and cowl area. There Is NO inward air flow in the center of the hood behind the triangle.
I would like to see where the chalks are placed to raise the hood. Raising the center won't do anything. Raising the sides would create more ambient airflow down into the engine bay and over the engine.
When driving the airflow is something like this in the hood and cowl area. There Is NO inward air flow in the center of the hood behind the triangle.
I would like to see where the chalks are placed to raise the hood. Raising the center won't do anything. Raising the sides would create more ambient airflow down into the engine bay and over the engine.
I'll also add that if you pack in enough air this way, you could increase the pressure in areas under the hood and actually risk the chance of decreasing your radiator and oil cooler efficiencies by restricting their airflow path.
The proper way to increase cooling is to direct more flow underneath the car, direct it to another low pressure area, or with a vent create a low pressure area by having large amounts of flow going over top of a vent which creates suction.
race cars have sealed cowls....
Last edited by r0tor; 08-03-2007 at 07:02 AM.
08-03-2007, 07:38 AM
#95
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Why are people comparing race cars to daily drivers in terms of cooling.
Honestly please do tell how you could risk oil cooler efficiencies from raising the back of the hood 1/2 to 3/4 of an inch. This isn't a 3-4inch cowl like on a mustang.
My car gets really hott when I'm not moving and I dont like that considering it was 101deg here yesterday.
Honestly please do tell how you could risk oil cooler efficiencies from raising the back of the hood 1/2 to 3/4 of an inch. This isn't a 3-4inch cowl like on a mustang.
My car gets really hott when I'm not moving and I dont like that considering it was 101deg here yesterday.
08-04-2007, 02:59 AM
#96
Like MM said, compression and boost don't matter, it's the fuel and ignition you have.
08-04-2007, 07:56 AM
#97
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I wouldn't expect you to be spreading this age old rumor (going back to 2003 when the car was released). I've just been through dozens of threads regarding the cover. Anyone who believed it did anything also believed it forced the air out through the fender vents. 
Everyone points to Canzoomers (where the H did he go?) test where he saw 10 degree cooling. Horse manure. You're the king of "proof" and results and in this case it's non-existent.
Look at the back of the cover for any actual "channeling" capability, it's proximity to the hood (to serve the same purpose) and tell me that it really does anything.
Everyone points to Canzoomers (where the H did he go?) test where he saw 10 degree cooling. Horse manure. You're the king of "proof" and results and in this case it's non-existent. Look at the back of the cover for any actual "channeling" capability, it's proximity to the hood (to serve the same purpose) and tell me that it really does anything.
Last edited by savedsol; 08-04-2007 at 07:59 AM.
08-04-2007, 12:24 PM
#100
Driving without it changes nothing as far as the effect of cooling, but driving without it for some time, and you'll begin to see the paint on the hood fading and peeling off sooner.
It's primary purpose is to shield the heat radiating from the engine, not to block the hot air.
It's primary purpose is to shield the heat radiating from the engine, not to block the hot air.