November 19th
Slowly slowly catch monkey
Hi guys and gals
I’m slowly working my way toward the ultimate goal of an imp that works, the plenum chamber has been a real pain, only getting one that is acceptable on my third go!
(please excuse the photographs, my camera is on its last legs. It’s not done to bad, it’s been all round the world but has never been the same since I spent three days on an island made entirely from sand. Either way the photos are grainy and slightly blurry, sorry chaps and chapesses.)
I got some new carbon that was a lighter grade compared to the last stuff I imported from the US.
It is a harness weave, this is good for complex curves as it drapes very well. It strangely also holds together well at its edges, compared to plain weave that just falls to bits!
To consolidate the carbon better and remove more of the air bubbles, I purchased some vacuum storage bags from Woolworth’s. These use a household vacuum cleaner to remove all the air through a silicone valve.
I prepped the mould with a wax polish and PVA release agent, the carbon was cut in once section as per last time and laid in the mould. The mould and carbon was covered with Clingfilm to ensure the vaccum bag didn’t stick to the resin, and then the whole caboodle was popped into one of the bags and the air evacuated. It took a while to remove the air and try to remove all of the creases, fortunately it was cold and the resin took a long time to go to the gel stage.
Once the resin had gone to the gel stage but not dried completely, I removed the Clingfilm, if I had not done this at this stage it would have stuck to the resin.
This was left until the next day for the resin to completely cure, and then pulled from the mould. Unfortunately not all of the air was removed, the extra flexibility provided by the lighter fabric caused it to raise up off the mould and follow some of the creases in the vacuum bag.
A dry patch can be seen here –
A bubble here –
So yet again I prepped the mould, I decided to use the heavier fabric again but in three separate sections, one main section around the top and sides and two bits for either end.
Bagged –
Pulling the Clingfilm –
This time it got an almost perfect piece from the mould, there are a few tiny air bubbles and one small dry patch, all easily fixable with final finishing.
Then the stainless parts that I had ordered a couple of days earlier arrived, and they were not the same dimensions as shown on the site
The reducers were 1/3 the length I had designed for, not good as the flow would be no where near as smooth, but hey, not much I can do really.
I cracked on sizing up the parts –
The bends were to have their straight sections removed to make them as short as possible without ‘cheating’ the bend angle. The cut was made with an angle grinder along a marked line, I worked from four sides to make it as straight as is possible with a hand tool.
Still not too good! This is where my birthday present comes in, it’s a belt sander supposedly just for wood, but it bashed my stainless pipe in seconds!
Mmmmm straight
–
Lined up with the reducer –
I welded the reducers onto the bends, this left some oxidation on the inside of the join where the weld penetrates –
This was ground back with a tungsten burr –
I balanced the whole assembly together to see how it all looked –
Assembly on the engine to assess the space available –
I’m pretty happy with it all really, it’s not perfect as there are many things that I will change over time. Here are all the parts together but unassembled –
Tomorrow I am going to get a lift into town, there I will get pipe to make some spacers for the end of the intake manifold pipes and an M4 tap for the aluminium back plate. I think I will also put a second layer of carbon into the plenum to make it stiffer and to provide a flat surface to seal the flange.
My leg is really getting me down at the moment too, hopping round the garage is just plain dangerous and I’ve tripped and fallen quite a few times. I really don’t want to do anymore damage, but I hate just wasting time
Ahh well, only one more week before the cast comes off, and then I can learn to walk again. The joy!
More soon
J