Modular Hood Louver Kit - Verus Engineering
 

We have been working on a hood louver kit for a few months now and with the units in production now, we thought it time to start a thread regarding the development of the units. These should be available sometime in January.

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Purpose:
This thread contains information and notes regarding the construction, features, and testing on the hood louver kit for the ZN6 chassis, including the FR-S, BRZ, and GT86 cars.

Design:
Placement for the vents was a combination of multiple factors. We used CFD to pick placement on the hood based off low pressure. We avoided the structural sheet metal below the skin of the hood, retaining hood rigidity. Final decision clarifying our choice in location is that it is above the exhaust, one of the hottest components in the engine bay, and right behind the radiator, which aids in extracting that hot air. See below for photos clarifying these points.

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Fig. 1: Iso Surface on front half of vehicle, highlighting areas of low pressure.

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Fig. 2: Pressure plot, the lighter green/teal color representing the lowest pressure on the hood.

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Fig. 3: Under hood view showing structural sheet metal in-tact.

The hood louvers feature a modular design, allowing the end user to pick from multiple configurations. There are quick removal rain guards for those that want to protect the engine bay from water by collecting and dumping the water further forward, onto the radiator. The wickers are also an optional installed piece. However, the wickers greatly increase evacuation of engine bay air and thus heat.

We chose to use 0.040 thick aluminum for its weight, ability to conform to the hood, and for available coating processes. The wickers are also bent aluminum, designed to be just tall enough to make full use of the vents while keeping drag at a minimum. We found the minimal height for the wickers through tuft testing.

Video Data:
Using tuft testing we were able to visualize the flow and effectiveness of the louvers at low and high speeds. This is how and why we were able to optimize the height of the wickers.

[ame="https://www.youtube.com/watch?v=ZRsbvvJrC5Y"]Velox Motorsports Hood Louver FRS BRZ Tuft Test - YouTube[/ame]

Thermocouple Data:
Using thermocouples and data logging, we were able to test two conditions with the OEM hood and then with the louvered hood. The two tests were a heat soaked idle condition and race simulated condition. We tested multiple locations through the engine bay, the passenger side coils, the driver side coils, under the intake manifold, and at the air box above the radiator. Tests were conducted as soon as possible between the two scenarios, ambient temperatures between tests were negligible (87-90 deg. F).

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Fig. 4: Passenger side coil thermocouple taped in place.

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Fig. 5: Driver side coil thermocouple taped in place.

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Fig. 6: Air box thermocouple taped into place.

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Fig. 7: Intake manifold thermocouple placement.

Idle Test:
The idle test was time-consuming but simple. From a cold start, we started the vehicle and let temperatures equalize at idle. This took roughly 45 minutes to an hour. We then took the highest temperature with the radiator fans on and the radiator fans off, as they cycled, as that affected readings considerably. If we had to open the hood, we would let the temperatures equalize under hood yet again, which took approximately 20 minutes. The results are below.

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Fig. 8: Idle test data.

Race Simulation:
Due to time and funds, we were unable to test these on the track. However, we came up with a simulation that was held constant between tests to accurately depict how these perform at speed under load. We found a one-mile spot of road that has little traffic and a nice pull off. We then would accelerate to 60 MPH quickly, staying in 2nd gear. This is very near redline in 2nd gear, then applied the same amount of clicks on the e-brake to induce a load. For those good at math, that is over a minute, high RPM, moderate load condition. We did this two times, and then took measurements for each test. The results are below.

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Fig. 9: Race simulation test data.

Conclusion:
We have heard from multiple track day enthusiasts that they are killing the ignition coils. These malfunctioning coils are thought to be caused by overheating. It appears that hood vents dramatically reduce under hood temps and the air around the ignition coils as well.

These louvers will also reduce pressure build up in the engine bay, also known as hood flutter. The side benefit would be a slight increase in front end downforce, something we cannot simulate in CFD currently, nor do we think it major enough to make a large note of it.

It is highly recommended to use wickers to increase evacuation. Rain guards will dramatically reduce effectiveness of the louvers.

Updates:
Current photos show a button head cap-screw, which will be changed to flush head captive studs. The wickers are currently 3D printed plastic, for production they will be sheet metal. We will be offering both raw aluminum units and satin black powder coated units.

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Half Kit Photos:

http://i.imgur.com/W2nsQ8T.jpg

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Rain Guard Kit

https://static.wixstatic.com/media/b...93644555f1.jpg

https://static.wixstatic.com/media/b...bc15af5f35.jpg

Small Louver Kit, PN A0055A: https://www.velox-motorsports.com/pr...ents-only-ft86
Large Louver Kit, PN A0056A: https://www.velox-motorsports.com/pr...ents-only-ft86
Slanted Design, PN A0065A: https://www.velox-motorsports.com/pr...ood-louver-kit
Rain Guards, PN A0051A: https://www.velox-motorsports.com/pr...guard-kit-ft86

Thanks,
Eric

Nice design, however, I'm more interested in intake air, oil, coolant temps since I've not had any issues with coil packs. I want to know the effect on engine cooling and power output.

Would it be worth it to make some ducting to try and guide the air from the back of the radiator up to these vents? Or would the vents need to be redesigned/larger?

Lovely work

@NotEric6
Jeezus, you guys are seriously going to take all my money and not leave a dime!

Keep up the good work :D

Put me on the list! :thumbup:

Your coils will go, just wait.

2 years... 30 track days... Ceramic coated UEL with additional heat wrap near coils... I doubt it.

Anyway, the point is that I'm far more interested in engine cooling/power than coils blowing out.

How much downforce gain?

How easy is it to take the rain guards on and off? Really liking what I see here...have P0351 issue whenever it's hot.

Each rain guard will be held on by (4) nuts, it should be relatively easy to uninstall then reinstall.

We have no way of estimating this at this time.

It depends on your goal(s) with the car. Perhaps if you explain what you are trying to accomplish we could help make a decision with you?

We did not notice a difference in intake air temps but each vehicle and application will differ. The test vehicle was still on OEM intake which we all know combats heat soak pretty well. I could see a turbo car with stainless/aluminum tubing to improve in intake air temps though.

Oil temps were not effected in our test vehicle.

Coolant temps were also not effected in our test vehicle. We are not pushing our cooling system to full capacity yet.

What issues are you experiencing, at what times, in what conditions, with what components, etc and maybe we can help you diagnose what is happening.

Thanks,
Eric

Thanks for the data Eric. I'm not experiencing an issues. I have the JRSC and track the car heavily and while the temps seem reasonable, I'm curious if oil/coolant temps would be reduced on track with your vents. I would assume the answer is yes, but before cutting holes in my hood, I'd like to know for sure.

So, hopefully someone that is having some issues or is braver than I at cutting their hood, will post some FI/track temp results before/after the vents.

I would be down for a set like the v12 Vantage with the long and and short ones, of just a set of two styled similarly to the stereotypical Aston Martin hood vents

Looks yummy!