Nice to see that my 'seat of the pants' indication of a very noticeable improvement in acceleration, is born out with your test figures. The downside of this modification however is that on my 1.2 the engine it is still pulling like a train in second gear, with no tail off, when it hits the rev limit at 6.5K revs It really wants to go to 7K at least.........
The downside of which mod? The seats removal or intake mod?
. Ok on the weight reduction, especially on a track day, it does make a big difference on BHP/Ton, but are you not likely to need to carry more than one passenger in the car?
. Changing up from 4th to 5th gear at an indicated 100mph does surprise some people ?I can't be alone in thinking that a little extra performance could be squeezed out of the non 1.6 or diesel engined cars if the engine could breath better.
Not wanting mind numbing induction roar I steered away from open air filters, (though in hindsight, what I have finally come up with could be useful in that application as well), so the initial stage was to buy a K&N panel filter to replace the standard paper one.
The next thing I wanted to do was find a way of neatly replacing the, apparently very restrictive, air feed from the slam panel, with a resonant chamber in it, with something considerably more free flowing.
I had a look at the air feed box under the filter and soon realised that there was two variations (both with yet another resonant chamber 'stuck' on the side.
The one on my car was the post 2005 design:-
Resonant chamber integral with the box:-
The inlet spigot fouled up with support webs for the chamber on the side
The earlier version had a separate chamber attached to the side of the box with rivets:-
And with a usable inlet spigot
With this in mind I decided that the earlier version would be better to 'play with' and I managed to buy a complete early type engine top cover/ filter box on ebay, for the princely sum of £14.50 inc carriage, with the bonus that it came with a spare MAP sensor and vacuum switch and piping still attached
Having got the replacement earlier filter box to play with, I measured up the spigot, finding that the O/D was a just under 55mm and the bore tapered from 50mm at the opening to about 46mm on the inside edge.
I plan to open this up to a consistent 50/51mm to maximise flow.
The next stage was to design a suitable 'big bore' cold air feed that looked as if it was OEM
More to follow tomorrow.......
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Modification *
Looks really smart, I wouldn’t mind doing the same to my little 1.2 S. It’s a long shot as I’m not sure you are active anymore but would you mind linking the elbow and the pipe (if they still exist). Great job ??Well the clips finally arrived today, so no time was wasted fitting the parts:-
Looks neat and seems to make for a smoother acceleration through the rev range, and appears to hit the 6.7K rpm rev limiter much faster now
The old system was restricted to 39mm dia at the airbox entry, now 51mm dia there and the slam panel air gatherer had an outlet dia of 41mm, now 57mm diameter with 60 mm I/D flexi to the air box
Now we are making the most from the K&N panel filter!
Any real performance gains are made by increasing the size of the air collector and the input pipe. The difference in cross-sectional area of the 60mm inlet pipe is almost 80% greater than the original pipe and as such gets a lot more air into the filter box....I've just done this to mine but used the original air pipe flex hose so didn't have to buy anything elsea little makeshift but it works
