| Modification
|
Gas filled dampers.
|
| Why it works
|
Makes suspension a bit stiffer. Reduces body roll as you go round corners.
|
| Doing it
|
See lowering section.
Rear shocks are reasonably easy.
Front ones require a coil spring compressor or else you will risk shooting yourself with the nut that holds the spring down.
Need to separate ball joints and take
drive shaft nut off, and brake caliper. Bit of a fiddle if you've never taken it apart before.
Also main nut that holds cartridge in can seize. I drilled one in half to get it out.
Buy a huge can of WD 40, ball joint separator tool (both big fork and a bolt operated one are useful),
coil spring compressor.
|
| Rough cost / sources
|
Cheap - I can't remember the price but all four were cheap say £15 or £20 each.
Came from Halfords parts store.
|
| First impressions / was it worth it?
|
First impression was that the ride was too hard - every bump showed up. After a few
days this got better.
Handling improved by a massive amount. Whereas before the car would wallow round corners
you could now enjoy feeling the wheel go light. Hard to tell whether this was just because they
were new though.
Really definitely worth it.
|
What I've learnt
Chances are that you want to modify your engine for more power. You can certainly get 10 or 20% more power
with a bit of effort and money (work on £40 per HP for DIY jobs on a 1.3). To get this power you'll need to
wind the revs right up. What you won't get is much more torque in the low-mid range engine speeds. To get better mid range torque
you really need a bigger engine (peak torque is roughly speaking proportional to engine capacity). Have a look at Astra engine data.
For a car to have good acceleration it needs decent torque across it's operating range. Do not be blinded by large BHP figures per se. It is easy to tune an engine for large BHP by increasing the high speed torque but at the same time losing mid range torque. Therefore it is possible for a 100BHP 1.3 engine to be better than a 130BHP 1.3. Here better means faster away from the lights and more driveable at low revs.
The standard car has been designed to satisfy a number of requirements. In power tuning you
might lose out in a few areas such as:
Fuel economy
Comfort
Driveability under range of speeds and loads
Life of engine
Rally Novas have been tuned up to 120-130BHP. It's not advisable to do the same
with a road car - you'll want to do less maintenance than a rally team, get more mpg and
might want to hear your ICE above the engine noise. The cost of achieving these sort
of power figures would make buying a larger engined car attractive.
One thing that might trouble you is the chance of wrecking an engine by tuning it up. The good news
here is that manufacturers will design an engine with a safety margin. A safe limit is +25%. In the Vauxhall 1.3's case
the margin must be decent. Look in any car park or city street and you will see stacks of Astras and Novas.
They can easily do 200,000 miles - they just tend to rust away before that.If your engine's in
reasonable condition then don't worry about a bit of tuning. The scrap yards are full
of spares - get on with it.
A further point to remember is that manufacturers will tune an engine to a marketing power figure. Introductory 1.4i engines will be tuned for 75BHP say, whilst the more expensive 1.6LXi will be 95BHP. The 1.8GLi will want to be 115HP. It is not in the car company's interest to tune the 1.4 into 1.6 terrority. They can charge a premium for larger engines. This is good news for the home tuner. There's potential locked away in the engine which you can release by spending some money.
It pays to be realistic about tuning. You can get reasonable results if you spend a few hundred pounds or maybe just into the second thousand. After that the cost per Lb Ft or BHP will rise and rise. You could make a 1.0 Micra engine pump out 80BHP say, but for what it'd cost you could buy a complete Peugot 309 GTi and a Citroen ZX Volcane, or something a bit newer. Race and rally teams can afford to go to extreme lengths. If you want power always start with the largest engine you can lay your hands on. If you want fun tune what you've got.
Here's some rolling road results for Novas.
Reasonably easy - relaxed 3 hours. Weber supply a kit containing all of the
necessary brackets,clips, fuel pipe etc. K&N make filter to fit directly (will need 4 screws to fit it on).
Only fiddle is feeding choke cable through bulkhead. Standard filter will nead some reshaping so that
it doesn't touch the bonnet.