Reducing under bonnet temps?

[takai]

I dont think you need more airflow, just more concentrated airflow. What you will probably want to do is block off all those little areas where the air can go apart from through the engine bay. Youll probably want to do this with 0.8mm sheet alloy, but if you are a bit skint, or want to test different things then just go to a realestate agent and ask them for some old For Sale signs, my local one used to give them to me. They are heaps easy to cut to size too. Stanley knife or even scissors do the trick.

So start with putting some under the car, from the very front of the front lip back to the crossmember. Remember you are doing this for cooling not ground effects, so seal it up to the edges.
Then go for the front bumper. Put some down vertically on each side of the opening for the radiator, and seal it up with some foam offcuts from Clarks. This will force air through the radiator.
Then plate the top of the radiator section. This will probably be the hardest to accomodate for the bonnet latch etc etc. But it is worth it.

After this is done 95% of the air will be forced through the engine bay. You could even put some little diversion/routing plates in to shunt air towards the exhaust to cool it slightly. Hopefully itll cool the engine bay somewhat.
If you can get the ForSale boards its quite cheap to test, but deteriorates badly under road conditions. Best to test with the FS boards, and then once you are happy make it out of 0.8mm alloy.

[o_man_ra23]

Then plate the top of the radiator section. This will probably be the hardest to accomodate for the bonnet latch etc etc. But it is worth it.

Not such a problem with a TA22 Takai... bonnet latch is behind the motor

I would suggest trying to route the exhaust heat through your passenger side bonnet vent, as the air rushing past the vent sucks the air from under the vent out (you can create a vacuum like this if you have air rushing past an otherwise sealed container).

Cheers, Owen

[takai]

Oh yeah, rear opening bonnets. Even harder Stupid hinges.

[Lambolica]

A few things to note there.

True that the back of the bonnet is a high pressure point but this helps as higher pressure more vacuum is created under the bonnet to draw air out. as the air is moving at high velocity there as well (this works up to certain speeds, after which pressure becomes too high but these are outside the road speeds.)

Simon for your case, you could try making sure the GT vents are letting air out but opening them up as much as you can. (I don't know the TA22 bonnet very well but the RA28 bonnets have a rear facing pod on the underside of the bonnet under the vent that doesn't really help things.

Doing what Takai has said is a good idea for testing and then make an item out of sheet metal. it might be an idea to do a little research into what type of setups race cars use as they would have put a great deal of time into developing them. just be careful not to block the whole engine bay up, keep in mind the same amont of air needs to get out as goes in. most of this will be drawn out from under the car due to negative pressure that will exist there at speed.

[RiceburnaGTV]

Hey mate you have already suggested it in the post open up the holes for the vents in the bonnet.I noticed a really big difference when i did it with the old red one. I had a shitty bonnet on her while taking her for a bush bash so I grinded out the holes to about 5mm short of where the last hole is for the vents. This was just a stock 2T but the difference was quite noticeable when you opened the bonnet compared to normal.The flutes were also gutted of that restrictive plate they have underneath aswell.

For my 3TGTE set up in the blue one I will also be doing this but adding angled vents under the GT flutes,on one side they will be angled to draw air in while the other side with be angled to draw it out.I plan to have a play around with different angles etc to get the best temp.

Do you think the fact you have high mounted your turbo may be contributing to the extra heat?

cheers
Nathan

[TA22 GT]

Thanks guys, I have a few ideas now.

Nathan,
My turbo isnt top mounted. The custom manifold etc does produce much more heat than the stock manifold. Probalby cause its much thinner. First I think I will cut some holes in the passenger side bonnet vent or maybe just remove the under plate. My car is almost black so it may not be noticable that the under palte isnt there. I'll have to see how it looks.

Cheers,
Simon