Opening OEM Grille Cells With Router Technique — For Maximum Air Intake Flow

[GTP]

For maximum air intake on track days, I have opened virtually all the grille cells in my GT PP1 grille. This was also to save money over purchasing an aftermarket grille, and to keep the OEM look.

I used my Bosch Colt 1/4" router and the Bosch offset base. I call this base a "flushing" or "facing" base because it allows to machine down a material that is proud of an otherwise flat reference surface. Basically it is an exposed bit that is offset from the router motor shaft and is driven by a toothed belt. I tried to keep in mind the "exposed bit" feature during the machining. This accessory served me well during my speakerbuilding days.

I came into a good deal on a used upper grille, so I had a chance to do a better job the second time around. Even though I had done it before, this technique still took me around 3 hours for setup, machining, cleanup, and then some detail trimming of excess flash around the cells with a small knife.

And it made a big mess as you can see.

The advantage of this technique is that all the cells retain their maximum depth and the frontside definitely keeps that OEM look.

MORE PHOTOS:
The pony is removable, so I can be stylin' back on the street. Notice the 6-32 flathead stainless screws at the head and tail.

For track days, I ventilated the pony recess area with a 1/2" step drill. The rivet nut inserts were plastic welded in place:

Retainer clips were pushed onto them from the back. This was a safety backup, because I don't want to be That Guy on track whose pony badge fell off on the straightaway.

Offset router setup (tooth belt not visible):

Machining from the back side:

The big mess:

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[NightmareMoon]

nice, yeah I used a dremmel to open up a few, but a router would be a whole lot faster.

 

[SnowFox]

nice, yeah I used a dremmel to open up a few, but a router would be a whole lot faster.

Amazon was even quicker

@op looks good. I would have done the same but I don't have the patience.

 

[2morrow]

Great work! Do you have a plan for getting all that air out of your hood now?

Not saying this is the answer for you but for example...

 

[WildHorse]

Yep.. as long as it doesn't overheat, I wouldn't touch it.

Not saying this is the answer for you but for example...

Nice hood . Aftermarket ?

 

[2morrow]

Yep.. as long as it doesn't overheat, I wouldn't touch it.



Nice hood . Aftermarket ?

Thanks man, it's an OEM hood with TrackSpec vents and some vinyl applied to it.

Note that the center vent is forward mounted to get all the airflow out of the radiator void. This is due to the open grills.

 

[NightmareMoon]

Amazon was even quicker

@op looks good. I would have done the same but I don't have the patience.

Quicker, I highly doubt, unless it arrived same-day. Heck I didn't even remove my grill from the bumper.

 

[AZ_Ryan]

I'm not going to lie, this seems a little silly. I highly doubt the running horse is blocking airflow enough to make a difference.

 

[2morrow]

I'm not going to lie, this seems a little silly. I highly doubt the running horse is blocking airflow enough to make a difference.

Looks like it’s more than just the horse.

If you run hot tracks then I think this is a great idea.

 

[GTP]

Thanks for the responses.

Anyway, I wanted to gain every square inch of air intake possible. Hence going after the removable badge. I run dual VT Big Mouth intakes and I even cut open the back of the passenger side for more airflow.

I run a lower horizontal 70kBTU oil cooler and a second OEM trans cooler for the A10.

I have run 45 minute session on track with steady state temps.

I have been thinking of extra hood vents but I like the OEM look of my uncut hood and stripes. However I did open up some of the small OEM air flow by removing their rain trays.

 

[WD Pro]

I did a similar mod, but only on the section of the grill that the VT big mouth feeds the air box from.

I used a mini belt sander and worked from the rear.

It worked really well and it was neat, but it took a while, and made a lot of mess (on the rug in the front room … lol).

WD

 

[KeyLime]

Off topic. I enjoyed looking at your website. I'm not an audiophile, but those are some awesome speakers you have out there.

 

[Paddles]

Badass dude, my GT has been getting pretty damn hot in Texas this summer, I may have to try this.

 

[WildHorse]

As long as the coolant is in liquid form, cooling won't be an issue. But boiling has to be avoided, as steam pockets that can cause major issues like cracking, melting, and distortion. Exhaust valve seats and spark plug seats can get so hot that they can cause pre-ignition. And this can significantly reduce engine life. Another trick would be running 30% antifreeze and 70% water .

Reason being at 21 psi for a 30% ethylene glycol and 70% water mixture with a mass flow rate of 70 gallons per minute and a temperature difference of 10°C between the coolant and the heat source, the heat exchange rate would be approximately 4,729,059 J/min. This is higher than the heat exchange rate the 50%/50% , which we calculated to be around 4,264,844 J/min under the same conditions. This demonstrates that a higher proportion of water in the mixture leads to a higher heat exchange rate, as water has a higher specific heat capacity than ethylene glycol.

 

[GTP]

As long as the coolant is in liquid form, cooling won't be an issue. But boiling has to be avoided, as steam pockets that can cause major issues like cracking, melting, and distortion. Exhaust valve seats and spark plug seats can get so hot that they can cause pre-ignition. And this can significantly reduce engine life. Another trick would be running 30% antifreeze and 70% water .

Reason being at 21 psi for a 30% ethylene glycol and 70% water mixture with a mass flow rate of 70 gallons per minute and a temperature difference of 10°C between the coolant and the heat source, the heat exchange rate would be approximately 4,729,059 J/min. This is higher than the heat exchange rate the 50%/50% , which we calculated to be around 4,264,844 J/min under the same conditions. This demonstrates that a higher proportion of water in the mixture leads to a higher heat exchange rate, as water has a higher specific heat capacity than ethylene glycol.

You seem good at math. How much coolant would I have to drain out and then replace with water to go from 50%/50% to 30%/70%?

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