So how do I make my bonnet?

[Enoch]

Just finishing off some engine work and a few other bits so have started to think about my bonnet. I have to make a huge bulge in mine to clear the DOHC manifold and cam covers. I have never done anything like this before so am unsure of where to start. I know that all the edges need to be nice and rounded to keep mr IVA happy and so it does not end up looking pants.
I was thinking of making the bonnet with a hole in it so it sits over the engine ok then making up a wooden structure that can be screwed to the bonnet. I could then fibreglass over the wooden bits and finish off with some body filler. Does this sound completely mad? Is there an easier way? I am no good at panel bashing, I have tried it before and just ended up with saome badly dented bits of metal:(
Any thoughts or guidance would be much appreciated.
Enoch

[mark]

I would start how you have described make the bonnet then cut a hole that clears everything then buy or make the scoop.

Have a look at some of the aftermarket scoops you can buy, you may get lucky and find one that covers up your plenum and looks nice, stick it on fill sand prep etc

[Enoch]

Thanks Mark, I read a book once about making boats out of plywood and they used the wooden former covered in fibre glass idea. I thought it would work on the car but wanted a sanity check to see if any other ideas were floated.
Best and all that,
Enoch

[ozzy1]

Dunno how big a bulge/vent you need but these might give you some ideas :confused:



http://www.shopwiki.co.uk/Lester-Universal-Bonnet-Vent,-Bonnet-Vents,-PA265A


http://www.m-99.co.uk/Car_Bodykits/Bonnet_Air_Vents/bonnet_air_vents.html

[davidimurray]

Depending on how brave you are - a mate of mine did something similar by building up over his airbox with clingfilm and plasticine and then laad straight up over that to make his female.

[Enoch]

Thanks guys. I think I need to make my own, I have had a look at "stock" ones and have not found one the right size and shape. It will be a while before I get to it but want to think about it up front so when it does come around I know what to do.
Best and all that,
Enoch

[DStanley1809]

If you can get a CAD drawing showing how high, wide and long the hump needs to be I can try and get it made up at uni. The design department has a machine that "prints" layers of plastic to any shape you like. I think this is the same process that was used to make the model chassis that was raffled at Stoneleigh. The only costs involved are for the materials used (I'm not sure how much this would be, I've never used the machine) and the postage to you.

Then you would just need to find a way to attach it to your bonnet and you would have a perfectly sized bonnet hump.

[spud69]

I may have something for you next week Dave, bonnet with a different designed scoop to give more clearance. Its on top of the office at the moment but will get it down and take some pics later on today. Mold needs finishing yet but it may be of use.

AndyH

[twinturbo]

May be of use to clear my 2.9 ;)

TT

[Enoch]

Wow, thanks guys:)
I would not know where to start with a CAD drawing so "Andy's big hump" sounds the most appealing option, despite it sounding a bit like a pervy game show:D
I intend to do some measurements at the weekend so I can get a better idea of what I need to achieve.
The DOHC is a big old lump, especially with an unmodified inlet.
Thanks a lot guys, Andy will ait to hear from you.
Best and all that,
Enoch

[spud69]

Hello dave,

Here are some pics of the plug so far for the bonnet. The new bulge gives you an extra 1/2 an inch depth and a lot wider and longer bulge. There is quite a bit of work to do on it yet but wont take too long.

Will see how it turns out.

Cheers...AndyH

[HandyAndy]

Hello dave,

The new bulge gives you an extra 1/2 an inch depth and a lot wider and longer bulge.
Cheers...AndyH


:eek: :D :D

I,m lost for words :D

cheers
andy

[spud69]

:eek:

I,m lost for words

cheers
andy

Hadn't even crossed my mind - ;) :D ;) you dirty old man

AndyH

[mr henderson]

I worked on an MK Indy with that engine in it a while back, and the bulge needed to come all the way to the edge of the nosecone, in fact, if I recall correctly, the original builder had actually taken a bit out of the nosecone too. Obviously whether the new Saturn bulge will do it or not will depend on how high and how forward the engine is mounted.


Have you looked into modifying the inlet manifold?

[Enoch]

Hi Andy, you have mail.
Mr H, on my build it's the plenum height at the rear of the engine that's the big issue. i think Andy's standard bonnet would clear the cam covers at the front but it's the shere height and enormity of the DOHC inlet that's the nightmare.
I did try making a cut down inlet but it turned in to a complete fiasco - I would need to tig weld it to do it properly and I don't know how to do that.
I might have to revisit it but thought the bulging bonnet would be easier.
It appears that Andy's bulge is huge but still not big enough for my needs.
Pick the bones out of that one handy yer dirty ole man:D :D :D

[spud69]

It appears that Andy's bulge is huge but still not big enough for my needs.
Pick the bones out of that one handy yer dirty ole man

Oh no, word has finally got out....:eek: :) :eek:

Mr H, now that i have seen the profile pics of the engine you are right the new shape wont cover the plenum chamber. It will still come in use to builders needing any extra room for the cam cover. Maybe it will be worth doing a version with a bulge sited for the dohc engine since more builders are using these, and a good engine they are.

We'll See....AndyH