quote:[HR][/HR]How much performance should a GTI have?
Depends on what you think a GTI should be! From the enthusiasts point of view, it's a small light car which handles precisely and has a big potent engine. For others it's a posing machine for Saturday nights. For some, a classy car for impressing the neighbours.
As the GTI has evolved, it's got bigger engines (good) and got heavier (bad). How do those original GTI's stack up against the modern ones? Well, it's interesting! You'd expect a GTI to be quick, right? Bigger engine means faster car, right? So a modern 2.0 Litre sixteen valve is going to wipe the floor with a old 1.6 litre eight valve, right? Er no...wrong. You have forgotten about weight. Take a look at the following table, comparing power (Bhp) against weight (kg).
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As you can see, the Golf GTI has been piling on the pounds over the last few decades. The Mk4 Golf is a whopping 48 percent heavier than the original Mk1. All this means that the later cars need much more power just to stay in the same league as the originals. Despite its 20 valves, turbo and modern electronic engine management, the latest Mk4 GTI Turbo can't match even the earliest humble 1.6 GTI on power to weight ratio. To have the same power to weight ratio as that early 1.6 GTI, the modern Mk4 would need 162 bhp, to catch the Mk2 16v, a whopping 180bhp!
In the same vein, look how the Mk3 2.0 16v is outclassed by the Mk1 1800cc GTI, remembering that the Mk1's are 8v engine, with much broader torque ranges. Result? The Mk1 Golf can outrun it's successor with ease. Even the Mk3 VR6 struggles to shake off the Mk2 16v despite an extra 1.0 litre capacity. The Mk3 8v and the Mk4 8v do not really rate as GTI's, being close to and infact dropping under the 100bhp/1000kg mark in the case of the Mk4. Disgraceful. This is not the whole story. Give a heavy car the right amount of power to catch a light car and it will still be a heavy car. Handling/direction changing/chuckability will never be as good.
So.....Given that everything else is the same, which is faster?
A Car with 200 bhp?
A Car with 170 bhp?
It's a trick question, both could be right, because a raw horsepower figures tell you almost nothing about how that car will drive. The car with 200 bhp could develope that 200bhp at 7000rpm, and the car with 170 bhp could develope that 170bhp at 4000rpm. The 170rpm would be far quicker in almost any driving scenario you would car to name... It's all down to TORQUE! Mathematically, torque is defined by the following equation HP=(TQ x RPM)/5252. Torque and horsepower are related by engine rotation speed. In practice, torque is the 'pulling power' developed by the engine, the low rev oomph that makes the car a pleasure to drive, unless you like using high revs all the time. This is one of the major deficiencies of relatively small capacity 16v engines. They generate a lot of horse power, but their peak torque measurement is also way up the rev band, with the result that, at moderate engine speeds, they are much less torque than their 8v equivalents. Take a look at the following graph...
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Here we have a graph for the torque generated by the common GTI engines. To make the comparision fair we have normalised the torque figures so they all represent 3500 rpm, which is a midrange point for acceleration. Notice how the 16v engines are lacking here, drop a gear and get the revs up to 5000 and they will take off like a bat out of hell, but left in 5 gear up an incline at 50 mph, they will be outrun by their 8v counterparts.
(NB the 16v mk2 does in fact have a higher peak torque of 123 lb/ft, but at 4600 rpm. The Mk3 16v has 132 lb/ft at 4800)
Also notice how good the VR6 and new 1.8T engines are. This is what makes the mk3 VR6 and the mk4 GTI Turbo such nice cars to drive despite the relatively modest 0-60 times, in gear times (eg 3rd between 30-50mph) will have them wiping the floor with a 16v car. Also note how much of an improvement the original mk1 1800 was over the 1600. Even the Mk3 and Mk4 2000cc cars make a bit of a comeback. Torque rules, and this is before you starting talking tuned diesel turbo's. How does 230 lb/ft of torque at a mere 2000 rpm sound? Enough to pull a train, and all possible with VW's TDI engine in the 150bhp Golf TDI!
Maybe diesel is the future of the GTI ?![HR][/HR]
discuss amung yourselves...Depends on what you think a GTI should be! From the enthusiasts point of view, it's a small light car which handles precisely and has a big potent engine. For others it's a posing machine for Saturday nights. For some, a classy car for impressing the neighbours.
As the GTI has evolved, it's got bigger engines (good) and got heavier (bad). How do those original GTI's stack up against the modern ones? Well, it's interesting! You'd expect a GTI to be quick, right? Bigger engine means faster car, right? So a modern 2.0 Litre sixteen valve is going to wipe the floor with a old 1.6 litre eight valve, right? Er no...wrong. You have forgotten about weight. Take a look at the following table, comparing power (Bhp) against weight (kg).
As you can see, the Golf GTI has been piling on the pounds over the last few decades. The Mk4 Golf is a whopping 48 percent heavier than the original Mk1. All this means that the later cars need much more power just to stay in the same league as the originals. Despite its 20 valves, turbo and modern electronic engine management, the latest Mk4 GTI Turbo can't match even the earliest humble 1.6 GTI on power to weight ratio. To have the same power to weight ratio as that early 1.6 GTI, the modern Mk4 would need 162 bhp, to catch the Mk2 16v, a whopping 180bhp!
In the same vein, look how the Mk3 2.0 16v is outclassed by the Mk1 1800cc GTI, remembering that the Mk1's are 8v engine, with much broader torque ranges. Result? The Mk1 Golf can outrun it's successor with ease. Even the Mk3 VR6 struggles to shake off the Mk2 16v despite an extra 1.0 litre capacity. The Mk3 8v and the Mk4 8v do not really rate as GTI's, being close to and infact dropping under the 100bhp/1000kg mark in the case of the Mk4. Disgraceful. This is not the whole story. Give a heavy car the right amount of power to catch a light car and it will still be a heavy car. Handling/direction changing/chuckability will never be as good.
So.....Given that everything else is the same, which is faster?
A Car with 200 bhp?
A Car with 170 bhp?
It's a trick question, both could be right, because a raw horsepower figures tell you almost nothing about how that car will drive. The car with 200 bhp could develope that 200bhp at 7000rpm, and the car with 170 bhp could develope that 170bhp at 4000rpm. The 170rpm would be far quicker in almost any driving scenario you would car to name... It's all down to TORQUE! Mathematically, torque is defined by the following equation HP=(TQ x RPM)/5252. Torque and horsepower are related by engine rotation speed. In practice, torque is the 'pulling power' developed by the engine, the low rev oomph that makes the car a pleasure to drive, unless you like using high revs all the time. This is one of the major deficiencies of relatively small capacity 16v engines. They generate a lot of horse power, but their peak torque measurement is also way up the rev band, with the result that, at moderate engine speeds, they are much less torque than their 8v equivalents. Take a look at the following graph...
Here we have a graph for the torque generated by the common GTI engines. To make the comparision fair we have normalised the torque figures so they all represent 3500 rpm, which is a midrange point for acceleration. Notice how the 16v engines are lacking here, drop a gear and get the revs up to 5000 and they will take off like a bat out of hell, but left in 5 gear up an incline at 50 mph, they will be outrun by their 8v counterparts.
(NB the 16v mk2 does in fact have a higher peak torque of 123 lb/ft, but at 4600 rpm. The Mk3 16v has 132 lb/ft at 4800)
Also notice how good the VR6 and new 1.8T engines are. This is what makes the mk3 VR6 and the mk4 GTI Turbo such nice cars to drive despite the relatively modest 0-60 times, in gear times (eg 3rd between 30-50mph) will have them wiping the floor with a 16v car. Also note how much of an improvement the original mk1 1800 was over the 1600. Even the Mk3 and Mk4 2000cc cars make a bit of a comeback. Torque rules, and this is before you starting talking tuned diesel turbo's. How does 230 lb/ft of torque at a mere 2000 rpm sound? Enough to pull a train, and all possible with VW's TDI engine in the 150bhp Golf TDI!
Maybe diesel is the future of the GTI ?![HR][/HR]
