Mazda Rotary Club

General => General Technical => Topic started by: Spartacus on August 20, 2008, 04:42:30 PM

Title: Bonding/filling a duct on a bonnet
Post by: Spartacus on August 20, 2008, 04:42:30 PM
Hi,
I’m having a go at fitting a naca duct to the bonnet of my fd and I was wondering if you guys could answer a couple of questions.

1) What is the best substance to bond the duct to the underside of the bonnet?
2) What would be best to fill the edge between the bonnet and the duct once bonded?

Many thanks,
Title: Bonding/filling a duct on a bonnet
Post by: skybusr34 on August 20, 2008, 06:48:46 PM
when i did stuff on my corrado going back a few years, i was told to use a stuff called sycalex.

it held side skirts on with no screws
Title: Bonding/filling a duct on a bonnet
Post by: Spartacus on August 20, 2008, 08:09:17 PM
Quote from: harris2182;525947when i did stuff on my corrado going back a few years, i was told to use a stuff called sycalex.

it held side skirts on with no screws

Thanks, was that just to bond or can you use it as a sandable filler too?
Title: Bonding/filling a duct on a bonnet
Post by: Nik da Greek on August 20, 2008, 08:23:21 PM
I\'m quite a fan of Sikaflex adhesive/fillers. I think they\'re originally designed to stick boats together, so once it goes off, you never get the stuck bits apart again. I\'ve used it to stick, like, carbon engine case covers to bike engines for crash protection and it\'s lasted years of direct engine heat, freezing cold rain, and, ermmm, crashing, of course! REALLY tough stuff
Title: Bonding/filling a duct on a bonnet
Post by: skybusr34 on August 20, 2008, 08:49:35 PM
its just for the bonding side of the task. as nick said, it drys off really hard. which you can then fill to.

great stuff
Title: Bonding/filling a duct on a bonnet
Post by: Spartacus on August 20, 2008, 09:48:03 PM
Ok sikaflex it is. Cheers.
Title: Bonding/filling a duct on a bonnet
Post by: connor66 on August 21, 2008, 09:33:57 AM
Spartacus, just out of interest, are you ducting air in to the engine bay for general cooling purposes, or as a cold air feed direct to your filter / intake? Are you V8?

Cheers
Gary
Title: Bonding/filling a duct on a bonnet
Post by: Spartacus on August 21, 2008, 03:00:58 PM
Quote from: connor66;526062Spartacus, just out of interest, are you ducting air in to the engine bay for general cooling purposes, or as a cold air feed direct to your filter / intake? Are you V8?

Cheers
Gary

Yes LS1 V8, as you can see in this pic the duct is for a "coldish" air feed to the front of the airfilter which should help a bit . Idealy the filter wants to be somewhere it can get more cold air, like behind one of the brake ducts etc but unless I loose the popup lights there is no way to get it there (space is a bit tight).
I might add some ally sheet around the back of the filter too to keep some of that cold air around the filter once it\'s done.
To be honest it\'s a bit of an experiment to see what happens.:2Rolleyes

I\'ll post some pics of it when it\'s completed.
Title: Bonding/filling a duct on a bonnet
Post by: connor66 on August 21, 2008, 06:49:42 PM
I\'m also LS1 and thinking about cold air feed solutions (my current set-up is very similar to yours and I don\'t want to lose the pop-ups either). I\'m considering removing my elbow / filter and using a flat panel type filter mounted directly in front of the throttle body (shielded from heat) then getting creative with my front bumper / reinforcement bar. With a little work, I reckon it may be possible to duct cold air from the top of the bumper opening, through a "modified" reinforcement bar to the bonnet latch area and directly through to the filter (without robbing airflow to the radiator and retaining the stock look). I may even replace the latch with bonnet pins and remove the thin centre section of the cross-over frame (it\'s not structural), that way there will be a considerable airflow direct to the filter. We\'ll see how it turns out?

Gary
Title: Bonding/filling a duct on a bonnet
Post by: Spartacus on August 21, 2008, 09:39:51 PM
There are one or two like that in the US (have a look on v8rx7 forum) using a sort of corvette arrangement but to get the room I think on most they have used a speed density tune so can do away with the MAF. I might have been able to put another elbow on mine so the filter is down by the chassis rail but I would need to move the rad forward a bit which would mean moving the relay box etc etc. I\'m guessing your using Tinkers rad arrangement? If so I would guess you have more room in front of the intake than me?
These pics might give you some ideas.
Let me know how you get on.
Title: Bonding/filling a duct on a bonnet
Post by: connor66 on August 21, 2008, 11:11:59 PM
Yes I have tinkers set-up. The radiator lies pretty much against the cross-over frame with the bonnet latch on, so there\'s zero room to go over the rad from within the engine bay. There\'s also only about 1" gap down each side so not exactly spoiled for space there either. Will keep you posted.