How to cut out a hole in the bonnet?

[boss351]

Hi guys. Finally got my ITB's in and with the sausage filter on I need to make a hole in the bonnet. Being an SV it doesn't have to be accurate and surround the filter, its more to put a mesh grill in for clearer air flow. The filter does protrude a few mm's at the front but it will compress in a little with the hood on.

What is the correct tool/method to cut a painted bonnet? Any tips appreciated.

Adam

[slomove]

I don't have much advice for the cutting other than "take the air nibbler and go for it". But I would recommend finding a way of allowing outside cool air to the intake (and shutting off from the engine compartment). That is probably the cheapest way of gaining a few horsies. If the common rule of thumb is right, a 50 degree lower temperature taken from outside is worth about 10% gain of power. It could make your car an SV187 ;-) Well, assuming the ECU knows about it.

[boss351]

Power wise already a little past that, I had to get an unlocked ECU to tune with the mods I made. It was closer to the R400 spec than R300. Now hopefully somewhere between a R400 and R500..

I want to start with the simple approach rather than fabricate an airbox etc. Getting the hole cut cleanly is the next big task!

[Doug Liedblad]

Where do you live?

Send me a PM and I will tell you how I enlarged mine and folded over a bead around the cutout, the bead makes it more rigid around the cutout but I don't think the paint will do well. Mine is unpainted. If you don't want the bead some use a strip of rubber edging around the hole. I don't know where to get the edging material. Maybe Caterham?

If you are going to use the bead, just get a nibbler as Gert says, make a layout and start cutting. Practice first on some of the area that is being removed to see how it cuts.

[slomove]

........I don't know where to get the edging material. Maybe Caterham?.......

Autozone/PepBoys/Napa have self-adhesive door edging. You heat it with a hot air gun which makes it pliable and melts the hot glue inside the groove. I used it around the edges of my aluminum dashboard.
McMaster has a dazzling veriety of rubber and plastic edging but you need to glue that down.

[Rod]

I have a nibbler that I bought to do this job and I can loan it to any 7 builder

[Doug Liedblad]

Harbor Freight sells air nibblers for under $30 they work just fine on thin gauge aluminum

I highly recommend the air nibbler and if you practice cutting to your layout lines it should come out OK.

Layout a hole or two smaller than you need and practice a time or three and it will come out OK.

[boss351]

Thanks, thats the plan.

[slomove]

Harbor Freight sells air nibblers for under $30 .....

Put a drop of oil on the nibbler cutter every couple of minutes. The aluminum tends to gum it up to the point it may get stuck.

[moosetestbestanden]

Mine's covered w/ something similar to this. Disguises any little, um, variances in the edge.

[Doug Liedblad]

Gert is correct, the oil will help.

[boss351]

The hole came out great, we used a air saw. cut was clean but the trim made it look better still:

8413_3.jpgintake grill1.jpg

[centerfireman]

Nicely done! Looks great.

[boss351]

Nicely done! Looks great.

Thanks. Now the decision on making a matching hole on the exhaust side....

[werthie]

nice job!!

two questions:

first, how did you mount the mesh to the inside of the bonnet?

second, did you consider adding an aluminum scoop to the hole? that's what i'm thinking . . . has anyone done this? if so, any advice on making the scoop and attaching it? rivets? do any of the after-market sources make a scoop?

thanks!

alan