Tuning the Mini A-series - Part 1 - A Stage 1 kit 17Jun07
If you’ve got a Mini and want a bit more of a "spark" on the performance side-of-things, then there are many options to choose. This’ll depend on the model and engine size of your Mini at the moment, but if you’ve got a carburettor (SU) 1275cc or 998cc then a "stage 1 kit" is the way to go.
A stage 1 kit is an easy and affordable way to increase the performance on your car and to give better throttle response. It doesn’t involve removing the engine and you don’t need a Masters Degree in mechanics to fit one. Infact, its easy, but first lets run through what a stage 1 kit is, and does.
As with most performance modifications, a stage 1 kit helps the engine flow better. The quicker and more smoothly the gases enter and exit the engine, the better the engine will perform. So, to get some air into the engine it starts with the air filter…
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Air Filter - a good amount of clean air is essential! The air filter on a standard Mini is contained within an air box which is somewhat restricted. It has a heated valve which is open most of the time to give the car a helping hand on a cold day, but hot air is not as good (performance-wise) as nice cold air, so that’s a waste of time. Also the air filter is very restricted compared to today’s standards of performance air filters. |
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Inlet Manifold - smooth flowing fuel/air mixture into the engine Next up is the inlet manifold which fits between the carburettor and the engine itself. The original designed inlet manifold as fitted to standard Mini’s is somewhat dated. It does not flow well and is designed as cheaply as possible. A performance version is a lot better and allows the fuel and air to mix well and flow smoothly into the head, where the mixture will then flow into the engine for the "spark" to happen (excuse the pun!). |
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Exhaust manifold - getting those gases back out as quickly as possible Once that mixture is in the engine, and after a split second later, it’ll be done with, now it needs to exit rapidly too. The exhaust manifold carried the non-used gases out of the engine and out of the exhaust at the back of the car and its important that the exhaust manifold flows well too. Again, the original design of the manifold on a standard Mini is terrible and doesn’t flow very well at all. A performance version, however, it far improved and will allow the engine to breath better, and quicker. |
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Exhaust system and back box - carrying the gases out of the back of the car Once the gases are well and truly out of the engine and in the manifold, they then need to continue through the car and exit at the back, down the exhaust pipe. Once again, the exhaust on standard Mini’s are also very bad and have terrible flow properties, and they also have a small diameter, or bore. |
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Carurettor needle - making that fuel/air mixture just right Since all of the other things above have been replaced and now flow and breath a lot better, the fuel and air mixture will have to be tweaked to compensate. Before I start, this doesn’t necessarily mean any more fuel will get used, it will use the fuel more effectively. The needle is a needle-shaped devise hidden inside the carburettor which is found in any SU-based carb, as found on standard Mini’s. As the rev’s increase, as must the fuel/air entering the engine, and the ratio between them may have to change as well. Its a complicated game, and the needle is what sorts it out for you. |
And that’s pretty much the end of things. After a stage 1 kit is fitted, it is HIGHLY recommended to take a trip down to the nearest rolling road specialist who will re-adjust the timing, the mixture and a lot of other things to make your car run just perfect. You may find your car might not start at all, or will run very badly until you’ve had a rolling road tune-up done, which is why it is highly recommended to do as soon as you can.
And finally, enjoy your new power!
(Photos from Minispares)
Ok, so I know asking for donations is really lame, but I'm trying to save up for an 
Someone Says:
17 Jun 2007
You might want to add a disclaimer in case anyone follows the guide and blows up their car as a result, it wont happen, but cover you back just in case.
Collin Says:
17 Jun 2007
It’s a great write up Daze, nice one.
A couple of points to add:
1. Buy the best you can afford. Many vendors will supply a no-brand air filter. These are way inferior to the proper items. K&N filters are generally acknowledged as the best on the market for good reason.
2. Seriously consider purchasing a decent exhaust system from someone like Maniflow. Again, there are many many generic exhaust systems on the market which just don’t perform as they should.
3. Highly recommended for a rolling road session? I would have said it was mandatory. Your car just WILL NOT perform at its full potential until you have done this.
Classic Mini Stage One Kit « The Mini Blog Says:
17 Jun 2007
[…] Mini Stage One Kit Daze has a great write up about what to purchase for a Stage One tuning kit for your Classic Mini. He […]
Nige Says:
17 Jun 2007
Great write up Daze !!
Just one thought, you say the fuel/air mixture has to flow smoothly into the engine. In actual fact the fuel/air “charge” has to be swilrling to reach optimum burn with the siamesed port engines. Hence why when you polish the inside of an inlet you loose charge pressure.
Nige
Daze Says:
17 Jun 2007
Yep, thanks. Three very good points to take in. It goes without saying that the more you spend on each part, the better it will perform on a general basis.
As you say, K&N, Pipercross or (my favorite) ITG are the best filters out there for good reasons. Copies are just not worth bothering about as you rightly point out.
As with exhaust systems! Maniflow is the king, by far, and well worth the money.
Thanks!
Retro Says:
29 Aug 2007
I just love a cool classic car like a convertible Cutlass. I see them all the time in movies and TV now.