It got very hot at the track Sat. and had to dial the psi back from 15 to 11 to keep things from getting to hot. I am going to install a air inlet to the oil cooler in the bumper cover and I want to do something with the hood, either add vents that really work or change out the hood. Does anyone know anything about these and their build quality?? http://www.aerokits.net/cart/index.p...th=75_195_1875 . Also any others out there for an NB? Thanks alot, John

 

The OEM Aluminum hood is usually lighter than aftermarket carbon ones. Your best bet is probably adding vents to your stock hood.

 

Agreed on the weight issue. Do you know what a stock hood weighs? I like the large vents in this hood and where they are located as that is where it should be a low pres. area, but mainly the large vents, should move alot of air through the rad. and out of the engine compartment.

 

Build quality and Chaser/Aerokits do not belong in the same sentence.

I have the Scoote NB hood and I think it works. My scientific testing consists of seeing heat waves coming out and it obscures your vision a bit

Large gaps. The hood mount holes on the car need to be enlarged to move the hood forward. The gap on the stock hood and front bumper is probably 1/3 of this if not less.

 

dgmorr Nice looking car. Do you know what the weight of the hood is verses stock. They didn't seem to be sure what the weight was. This is for a track only car, so a little bit of gap I guess is okay, I really didn't expect it to fit like stock. Do you track the car, and if so have you noticed an improvement in temps and down force? Thanks again

 

I can feel the weight difference when holding them in my hands. I'd guess 2-4 lbs over stock.

I only had a chance to go to the track once with the hood. I overheated. There were other contributing factors to that. I don't know if the hood helped or made anything worse.

 

Several other people with track cars here have vented the stock hood between the radiator and the front of the valve cover with great success. They used the Mini Cooper S scoop turned backwards or the GT500 hood vent or something similar. Levnubhin did this with his car. I'm trying to remember who else. There were several.

 

Any issues with the rigidity of a stock hood after a vent install?

 

The extraction in the Chaser hood should help a bunch. Do that in conjunction with careful ducting to force ALL of the air going through the nose directly through the heat exchangers. Air is lazy and it will go wherever is easiest and going around the radiator/intercooler/oil cooler is a lot easier than going through them.

Also, always think in terms of pressure differentials. The ducting to force air to the radiator will dramatically increase pressure in front of the it. A splitter and extraction hood will help lower the pressure in the engine compartment behind it. It is pressure differential that moves air.

With this in mind, there has been some descent nanometer testing done above the hood to show the low pressure zones and IIRC, the Chaser design is pretty good. Unfortunately, I have never seen any data on the pressures at play under the hood. They are certainly much more chaotic than the flow outside the car, but they are still pressures. If you could find an area that is on the higher end of the spectrum that corresponded to a relatively low pressure area on top, that would be the perfect place for a vent.

Lowering pressure under the hood is good in about every way you can conceive including cooling and to help there be less pressure under the car in general. Lower pressure under the car equals less lift. Less lift means you need less wing to hold the damn thing on the ground which means less drag so you need less power to go fast.

*John knows all this - I'm blabbering on for the benefit of someone reading in the future that doesn't...

 

I believe it was curly. I also have one, but haven't gotten around to putting it in yet.

 

Thanks all, I ordered a hood, it just looks like it should do a really good job of what I am trying to acomplish. I not only want to help the airflow for cooling, but want to help with more down force up front so I can dial in more rear wing, which well mean even stiffer springs probably next, man ain't it fun going faster and faster. Brian, I like your babble.

 

You have my sympathy. I will never deal with chaser again.

I went back to stock and cut some vents



PS: someone asked me about Chaser a few months ago. I warned him and told him to stay away. He decided for the $, it was worth the risk. They shipped him a hood cracked in 4 places and told him it was his fault and they would not do anything about it.

 

smokesr

I love the look of your car.

I will do a mini scoop soon when I put on my undertray along with some form of exit hole in the rear bumper for any air that ends up above the undertray.

duct your rad and you should fix most of your cooling issue.

 

Please show these in more detail. They look great.

 

More details on the stock hood? The thin aluminum around the skeleton was cut out. It's not aerodynamically ideal, but the cutouts are placed in low pressure zones (the rear most one is borderline). This also helps a lot during stop and go traffic since I still DD this car and the MP62 sitting under there is quite hot.

There are more pictures on www.automotofoto.net under the coverage for Sigma Racing Time Attack #1 (which was on Sunday). Gallery is at the end of the article. I especially like the picture when my wheels were getting checked.

 

Does rain / snow cause any problems with the vents? I'm looking at doing something similar to my DD, but don't have the option of simply not driving in the elements.

 

This is my summer DD so I have no choice but to drive in the rain as well - but not snow. My intake filter sits in a box (heatshield) under the vent and gets air from the fog light. Without that box, the filter would get soaked and you would have problems. You could run a hydroshield over your filter if your'e concerned about water. All my wiring is done properly but if you have some hack job wiring, it may not be a good idea.

 

this is how my track car is cooled:



the builder said that the hole in the bumper and the hood was the only way to keep the car cool, and he tested the crap out of different set ups before building the cars.

 

Wrong vent locations. I'll let someone else explain why because it's more fun that way.

 

To keep the car cool, you want to reduce the air pressure behind the rad to make the largest pressure difference between the 2 sides of your rad. Basically, your vent should be right behind the radiator with the rad sealed to the bumper opening. Your windshield area is a high pressure zone.