how do you figure? did i miss the part where the op mentioned he has paneled underneath to make a flat bottom? all it takes is a little heat control wrap or wall blocking off that area. and thats regardless of wether or not he makes that duct to the hood.

 

One of the benefits of ducting is evacuation of general engine bay pressure - if you don't evacuate it, it pushes up on the hood and creates lift.

Sealing the radiator to the hood is a cool idea in theory, but in practice there are other benefits that you're negating that don't justify the gains IMO.

Seal the front, vent the hood right behind the radiator, but don't let the rest of the engine bay miss out on the party.

 

You might want to check out the Georgia Tech Wreck Racing car. They have something similar on their V8 lexus motor miata. They might be able to give some additional advice.

 

It is hard to tell from your pics, but it almost seems like you will be creating a high pressure zone right behind the radiator, which would make it more difficult for air to pass through there.

On the other hand, if the airflow guide works well, and air flows right through the radiator and out of the bonnet, then you could easily end up running too cool, which would be problem.

I have a small extractor on my hood and do not use any ducting to/from it. My car often runs too cool on track, which requires me to block off a large portion of the radiator. Sometimes I struggle to hit 150°F! Even with the front blocked, and on a moderate/cool day, coolant takes a while to hit 180°F.

I think you may be fixing a problem you do not have. There is such a thing as "too cool".

 

Hopefully this will help people imagine whats going on here.



Im not sure how there can be engine bay pressure due to the fact that the high pressure area would be totally sealed off. The high pressure area at the bottom of the windshield is also sealed by the rubber seal on top of the firewall.



In the above sketch, its the front of an na facing left, green is airflow, red in front of the radiator is ducting already there, the regular ducting most people have, and red behind it is what im building, and the maroon is the pipe tat I will set into the rear duct to let air pass straight through the radiator, straight through it and onto the turbo.

Dann

 

People forget that the total area that the radiator covers is NOT the total flow area, the factory opening represents the size of the hole necessary for maximum flow through the radiator, this is because a lot of the frontal area on a radiator is the radiator fins and tubes, therefore the actual airflow gaps total the same size as the radiator opening or less. My design has at least the square area of the factory opening the whole way through the duct.

This is a pic of georgia techs angled setup, and for the noobs a sketch as to how theirs is different than mine.





Dann

 

Duct the front, use a hood vent, win at life.

 

Post edited due to general useless of hustlers post

Dann

 

He speaks the truth though.

 

Come now curly, now your following hustlers lead.

Dann

 

Where would your intercooler play into all of this? I like sav's split ducting. Similar to how I am doing mine.

 

Intercooler is mouth sized and half the height of the rad, so half of the mouth air will be split into it.

Update morepics of build











This is not all final, Im considering this a mock up.

Dann

 

Double post sorry

Dann

 

Hey newb, ever heard of a "thermostat"?

@ OP: I was having overheating problems in the summer with the A/C on during freeway driving - I know it's not racetrack driving, but hear me out - I put a vented hood on the car and it completely cured my problem. Even more surprising: after installing the vented hood, I would turn my A/C on going down the freeway, (which turned the radiator fans on) and the radiator fans were now able to increase airflow so much because of the low pressure engine bay that my coolant temps actually went DOWN with the A/C on - all the way down to thermostat temp - which means the hood vents were working so well that my thermostat actually had to close on a 90+ degree day with A/C on full blast with nothing more than a simple extraction hoood...

Just sayin'

 

Just to repeat some concerns, you really need some air flow through the engine bay. You might think about some way to direct cool outside air to help with that that won't increase pressures too much. Something like brake ducting but for your intake and exhaust to help keep underhood temps from building up.

 

These wheels. Want. Now.

 

Exactly.

 

I like it! As long as it works that is. Fast work.

 

I've been looking at this for a while trying to figure out the ideal design. The best example I have come across is the BMW ALMS car:




Good luck making something like that work though.

 

now that **** is awesome. Where do the two smaller ducts go?