Being in the US where there are no "engineering" requirements for engine swaps and other modifications, I'm puzzled. Why -- for a street car -- would a bigger engine "require" better brakes. For example, if a bigger displacement engine is fitted but the vehicle weight doesn't significantly change, that doesn't make the previously "adequate" brakes now become "inadequate". If you keep the car to legal street speeds, why would the stock brakes be considered "not good enough"? Originally the brakes worked at speeds of up to 100kmh, but now they don't?

I'm not saying bigger brakes are not a smart idea ... obviously the 1200 brakes aren't up to today's standards. Is that the intention of the legislators, to get people to bring the safety standards up to a higher level than Nissan originally provided? Do they also require three-point belts, airbags or door side-beams whenever engines are swapped into older vehicles?

I've heard the argument that "if you have more hp, you'll go faster and so need bigger brakes to slow down", but that presumes on the driver's behavior and not the mechanicals. Although I wouldn't be surprised if statistically a link could be established.

I can see if the modifications added significant weight to the car ... then it would make sense to require bigger brakes, so that braking performance wouldn't degrade from original.

Quote:OK, that makes sense from an engineering standpoint, although basing it on the weight change to the font and rear of the car would make even more sense. Or am I missing something?

I think the idea is to increase the braking power/performance in correspondance with the increased engine power/performance. The principle behind Engineering vehicles for road use is to ensure they are still safe, 'balanced' vehicles.

count yourselves lucky they still let us register standard 1200s with those brakes! The discs in particular are absolutely woeful! They fade before you complete one emergency stop from 100kph (60mph)

I see your point with this question.
But it would seem that most engine upgrades would come with added weight, so I guess a brake upgrade is just a precaution that is there for that exact reason, as a precaution.

In New South Wales and I would go as far as to say most states of Australia would loosely be based around this ball park, that an engine upgrade of no more than a 15% in size is considered an owner certified modification which no engineer certification is required. Only engine ; Size and Serial Number need to be changed on the cars registration papers.

Anything above 15% in size needs to be engineer signified.
For Mono Constructed cars ( meaning chassis and body combined in one) weighing less than 1100kg
The largest size engine for a naturally aspirated engine is:
In cubic inches,
Original weight (kg) x 0.183
and supercharged or turbocharged is;
Original weight (kg) x 0.153
A car with an engine within this size range is classed as A Modified Production Vehicle and requires Engineer Signification.
My Engineer said that as long as the front drum brakes are upgraded to disk brakes of the kind that were avaliable for this model car or for a car of the same or heavier weight it will be satisfactory.
Then there is the pollution side of things for engineering which states that the emissions must meet that of the body or the engine, which ever is the latest model is where this is taken from.
The only other thing to be engineered is modifications ( workmanship ) which were required to fit the engine.
( There are a few guidelines for modifications to be followed)

Now back to engines,
An engine of a bigger size then those mentioned above can be fitted and legally registered to drive on the road but,
this will require the car to be classed as Individually Constructed,
This means that the car will have to meet all of the Australian Design Rules for the year that the car becomes registered in this setup. ( so if you finish the car and register it in 2003 it will have to meet 2003 ADR's)
This is where airbags and side intrusion bars come into play.

One other thing is that just because your car meets all of the latest ADR's and can be registered doesn't mean that there is an insurance company that will cover you or your car. So this in the end will prevent your billion dollar individually constructed car from being street registered and leagally street driven.

I can tell you why.
It's because you get up to speed faster and you are therefore at a higher speed more of the time.
For instance to go down the road and turn left. You migh thave gotten to 40Kmh before you had to brake and turn. But now with your new engine you are up to 50kmh before you have to brake to turn.
So if you are in start/stop traffic alot you are continually pulling up from higher speeds than you used to.
Well thats what a mechanic told me when I asked the same question at least...

ive heard that the brakes on a car when being built in the first place require to have three times the power as the engine, maybe they are trying to hold this safety factor when engineering modified

the logical reason for having biger brakes are the more powerful engine means its faster it could get more speed quicker witch means you wana stop up a bit better and the original brakes wont do that the way you ant to they might but the stock 1200 brakes i would toss out and put new one in even with an A-12 in the front