Zedrush Posted November 4, 2007 Share Posted November 4, 2007 Ok as most of you are aware, my education concerning cars and car performance is.. well... somewhat limited to say the least, as I pour virgin olive oil in my car, and marmite in the petol gauge... just kidding. Now with my understanding, BHP is the measure of power the car can output when in motion, and that the measure obviously differs from the engine bay to when it reaches the fly wheel, and that if it was to be measured to the equivalent of a watt out put, 1bhp = 745.7 watts. I also know that whilst you have power its no good without a respectable amount of torque which is the force at which the power in pushed or rotated at the axle. Now running this through my head, Id imagine that to have something like 800BHP and over 500lbs of torque, youve got a pretty amazing machine, but one thing I never get to grips with is the consideration of the weight of the car. So finally heres my question, we have a 2003-2005 350z coming in at: Horsepower 287 @ 6,200 RPM Torque (lbs/ft) 274 @ 4,800 RPM Kerb Weight 1557kg If you had a car, with half its weight, half its BHP but similar torque, (say its a diesel thats been chipped, if possible to have similar torque) on a quarter mile track would it be an even race. Or at what point would the race be even on a quarter mile, because I know bhp gives top end, but that is rarely reached on the 1/4 mile. Sorry just want to learn more about car performance and how it all works. If there is an algebraic equation for this that can be universally applied that be great Quote Link to comment Share on other sites More sharing options...
Sarnie Posted November 4, 2007 Share Posted November 4, 2007 Bet your Mrs loves you. 08:50 on a sunday morning and your posting about algerbraic bhp equations?????????? Get a life you nerd Quote Link to comment Share on other sites More sharing options...
Beavis Posted November 4, 2007 Share Posted November 4, 2007 Bet your Mrs loves you. 08:50 on a sunday morning and your posting about algerbraic bhp equations?????????? Get a life you nerd Quote Link to comment Share on other sites More sharing options...
Trev-the-Rev Posted November 5, 2007 Share Posted November 5, 2007 I'm not aware of any algebraic equations for this calculation, mind you that's not to say that there isn't one, but a good idea of performance measurement can be attained from a power to weight ratio. Generally speaking, the lighter the car, the quicker it will be in terms of acceleration, braking and cornering. Quote Link to comment Share on other sites More sharing options...
ir_fuel Posted November 5, 2007 Share Posted November 5, 2007 If you had a car, with half its weight, half its BHP but similar torque, (say its a diesel thats been chipped, if possible to have similar torque) on a quarter mile track would it be an even race. Or at what point would the race be even on a quarter mile, because I know bhp gives top end, but that is rarely reached on the 1/4 mile. It also depends on the gear ratios. The gears (and the wheels) determine the torque which is transfered to the street. Bigger wheels/longer gears mean more torque is needed to accelerate at a certain rate. Considering the weight, if I recall correctly there was some formula that states F = m*a. So the force is equal to mass times acceleration, which means a = F / m. So acceleration equals the amount of force divided by the mass of the object you are trying to accelerate. Now this is hugely simplified ofcourse, not taking into account tyre grip issues and all that stuff. Why this gear ratio stuff? Well thats the reason a diesel engine with X torque will never accelerate as well as a petrol engine with X torque. Because the rev range of the petrol engine is bigger you will be running in lower gears for the same speed in the petrol engine one, giving you extra acceleration potential. Of course when magazines compare accelerations in-gear at a certain speed usually the diesel is faster, but thats just because those tests are usually done in "petrol-unfriendly" ranges. (imagine doing an acceleration test from 50-80mph with the Z in 6th gear .... ) So, supposed you have the same car, the same weight, the same gearbox etc. And you put in an engine which gives high torque from 3000-6000 rpm, redlining at 7k rpm, or you put a diesel engine with the same amount of torque but which gives it from 2000-3500 rpm, redlining at 4.5k rpm the petrol one will be faster. I drove a friend's A3 once, 170hp and approx. the same torque as the Z, but i spent more time changing gears than accelerating it, 2000 rpm of powerband really isnt that much Quote Link to comment Share on other sites More sharing options...
Zedrush Posted November 5, 2007 Author Share Posted November 5, 2007 Thanks Trev and Ir, I just find it really interesting all the factors that come into play here. Originally I couldnt understand how a 400bhp car could get beat by a 300bhp car, but guess I simplified it too much just to the stage of the higher the bhp the faster it will be, but I guess thats not the case considering all the other elements. Still amazes me how they get ll the geometries set in professional racing and all the formulas they mut work with to get the best out their cars even to the milli second Quote Link to comment Share on other sites More sharing options...
ir_fuel Posted November 5, 2007 Share Posted November 5, 2007 Well, stuff in real life is much more complex. My guess is that even the amount of text already written by Sarnie on this forum wouldn't be sufficient to contain the full explanation of how to tune a racing car. And that says it all methinks Quote Link to comment Share on other sites More sharing options...
Zedrush Posted November 5, 2007 Author Share Posted November 5, 2007 Well, stuff in real life is much more complex. My guess is that even the amount of text already written by Sarnie on this forum wouldn't be sufficient to contain the full explanation of how to tune a racing car. And that says it all methinks Quote Link to comment Share on other sites More sharing options...
H5 Posted November 5, 2007 Share Posted November 5, 2007 Ok as most of you are aware, my education concerning cars and car performance is.. well... somewhat limited to say the least, as I pour virgin olive oil in my car, and marmite in the petol gauge... just kidding. Now with my understanding, BHP is the measure of power the car can output when in motion, and that the measure obviously differs from the engine bay to when it reaches the fly wheel, and that if it was to be measured to the equivalent of a watt out put, 1bhp = 745.7 watts. I also know that whilst you have power its no good without a respectable amount of torque which is the force at which the power in pushed or rotated at the axle. Now running this through my head, Id imagine that to have something like 800BHP and over 500lbs of torque, youve got a pretty amazing machine, but one thing I never get to grips with is the consideration of the weight of the car. So finally heres my question, we have a 2003-2005 350z coming in at: Horsepower 287 @ 6,200 RPM Torque (lbs/ft) 274 @ 4,800 RPM Kerb Weight 1557kg If you had a car, with half its weight, half its BHP but similar torque, (say its a diesel thats been chipped, if possible to have similar torque) on a quarter mile track would it be an even race. Or at what point would the race be even on a quarter mile, because I know bhp gives top end, but that is rarely reached on the 1/4 mile. Sorry just want to learn more about car performance and how it all works. If there is an algebraic equation for this that can be universally applied that be great From what I remember there is something to do with final drive, drive efficiency and drag co-efficient to go in there too! Quote Link to comment Share on other sites More sharing options...
ir_fuel Posted November 5, 2007 Share Posted November 5, 2007 in the latest edition of Moto Tech magazine they explain this drag stuff, and how it relates to acceleration and torque. I ll see tonight if i can be arsed to summarize it a bit Quote Link to comment Share on other sites More sharing options...
Kev946 Posted November 5, 2007 Share Posted November 5, 2007 Buy a Lotus. Mine weighs nearly half a Zed.... Quote Link to comment Share on other sites More sharing options...
Mitchell Posted November 5, 2007 Share Posted November 5, 2007 Does Lotus not stand for Loads Of Trouble, Usually Serious? or does yours have that new Toyota engine? Quote Link to comment Share on other sites More sharing options...
H5 Posted November 5, 2007 Share Posted November 5, 2007 Does Lotus not stand forLoads Of Trouble, Usually Serious? or does yours have that new Toyota engine? It may have done if you're old enough to drive when the Esprit was launched...... Never had a problem here. Both the K series and Toyota lumps are pretty strong. Quote Link to comment Share on other sites More sharing options...
Mitchell Posted November 5, 2007 Share Posted November 5, 2007 No, not that old. I was looking into buying a Lotus and was told only to buy the Toyota Engine. I suppose the 1.8 unit was used on a lot of Rover models so must have been pretty tough going. Whats the Z engine like in terms of general reliability (Pre 07 model)? Quote Link to comment Share on other sites More sharing options...
H5 Posted November 5, 2007 Share Posted November 5, 2007 No, not that old. I was looking into buying a Lotus and was told only to buy the Toyota Engine. I suppose the 1.8 unit was used on a lot of Rover models so must have been pretty tough going. Whats the Z engine like in terms of general reliability (Pre 07 model)? Always ask why when given advice like that. Could stop you buying a great car! Generally, people have had no problems with the engines. The rev-up (300ps) engines can consume oil a bit quicker than most, but (touch wood) there are no known weak spots. There are a few out there with 90k + miles on them and still going well. Quote Link to comment Share on other sites More sharing options...
Kev946 Posted November 5, 2007 Share Posted November 5, 2007 Mines a "Yota" engine. Lotus switched to these a while back now. Not sure on year. The K series engine is a cracking engine too. There was some reported head gasket failures, but this is easily fixed and doesn't normally do any damage. Being a car that often gets driven hard, e.g. corning, acelerating etc. it actually fairs pretty well. BTW, there was a guy in the 350Z OC who had a Zed engine in a GT4 blow up at about 20k miles. Nissan were refusing to replace it under warranty blaming the light weight UR pulleys he'd fitted, even though the rest of the engine was standard. What a load of B'locks. How could these cause a piston to go through the block. This went on for months and I'm still not sure whether he eventually got them to cough up with a new engine. Quote Link to comment Share on other sites More sharing options...
H5 Posted November 5, 2007 Share Posted November 5, 2007 Mines a "Yota" engine. Lotus switched to these a while back now. Not sure on year. The K series engine is a cracking engine too. There was some reported head gasket failures, but this is easily fixed and doesn't normally do any damage. Being a car that often gets driven hard, e.g. corning, acelerating etc. it actually fairs pretty well. BTW, there was a guy in the 350Z OC who had a Zed engine in a GT4 blow up at about 20k miles. Nissan were refusing to replace it under warranty blaming the light weight UR pulleys he'd fitted, even though the rest of the engine was standard. What a load of B'locks. How could these cause a piston to go through the block. This went on for months and I'm still not sure whether he eventually got them to cough up with a new engine. I think the vast majority of the head gasket failures were on the engine in Rover cars. The weight etc of the Elise doesn't put that much strain on the lump so it is pretty strong. Yep, there is that one, and he posted on here recently when he was selling it IIRC. He put a new engine in it out of his own pocket..... Quote Link to comment Share on other sites More sharing options...
Kev946 Posted November 5, 2007 Share Posted November 5, 2007 Mines a "Yota" engine. Lotus switched to these a while back now. Not sure on year. The K series engine is a cracking engine too. There was some reported head gasket failures, but this is easily fixed and doesn't normally do any damage. Being a car that often gets driven hard, e.g. corning, acelerating etc. it actually fairs pretty well. BTW, there was a guy in the 350Z OC who had a Zed engine in a GT4 blow up at about 20k miles. Nissan were refusing to replace it under warranty blaming the light weight UR pulleys he'd fitted, even though the rest of the engine was standard. What a load of B'locks. How could these cause a piston to go through the block. This went on for months and I'm still not sure whether he eventually got them to cough up with a new engine. Yep, there is that one, and he posted on here recently when he was selling it IIRC. He put a new engine in it out of his own pocket..... That stinks. He won't be buying another Nissan then. I've heard so many cases of Nissan not standing by their warranty. It's one thing having reliability issues, but surely a lot worse if the try and wriigle out of it. Performance cars need good warranty IMHO. We had a gearbox issue on our Jeep, (which we've now sold), and on the second occasion of a breakdown the dealer fitted a new gearbox under warranty with no questions asked. Got the car back within a week. Quote Link to comment Share on other sites More sharing options...
H5 Posted November 5, 2007 Share Posted November 5, 2007 Mines a "Yota" engine. Lotus switched to these a while back now. Not sure on year. The K series engine is a cracking engine too. There was some reported head gasket failures, but this is easily fixed and doesn't normally do any damage. Being a car that often gets driven hard, e.g. corning, acelerating etc. it actually fairs pretty well. BTW, there was a guy in the 350Z OC who had a Zed engine in a GT4 blow up at about 20k miles. Nissan were refusing to replace it under warranty blaming the light weight UR pulleys he'd fitted, even though the rest of the engine was standard. What a load of B'locks. How could these cause a piston to go through the block. This went on for months and I'm still not sure whether he eventually got them to cough up with a new engine. Agreed. My recommendation is to bypass the pain and write to the MD of NMGB straight away. Failing that, we all get together and blockade NMGB until they submit!! Yep, there is that one, and he posted on here recently when he was selling it IIRC. He put a new engine in it out of his own pocket..... That stinks. He won't be buying another Nissan then. I've heard so many cases of Nissan not standing by their warranty. It's one thing having reliability issues, but surely a lot worse if the try and wriigle out of it. Performance cars need good warranty IMHO. We had a gearbox issue on our Jeep, (which we've now sold), and on the second occasion of a breakdown the dealer fitted a new gearbox under warranty with no questions asked. Got the car back within a week. Where did my post go?! Anyway..... Agreed. I would recommend bypassing the pain and writing directly to the MD of NMGB. Failing that, we all get together and blockade NMGB until they give in! Quote Link to comment Share on other sites More sharing options...
Kev946 Posted November 5, 2007 Share Posted November 5, 2007 Mines a "Yota" engine. Lotus switched to these a while back now. Not sure on year. The K series engine is a cracking engine too. There was some reported head gasket failures, but this is easily fixed and doesn't normally do any damage. Being a car that often gets driven hard, e.g. corning, acelerating etc. it actually fairs pretty well. BTW, there was a guy in the 350Z OC who had a Zed engine in a GT4 blow up at about 20k miles. Nissan were refusing to replace it under warranty blaming the light weight UR pulleys he'd fitted, even though the rest of the engine was standard. What a load of B'locks. How could these cause a piston to go through the block. This went on for months and I'm still not sure whether he eventually got them to cough up with a new engine. Agreed. My recommendation is to bypass the pain and write to the MD of NMGB straight away. Failing that, we all get together and blockade NMGB until they submit!! Yep, there is that one, and he posted on here recently when he was selling it IIRC. He put a new engine in it out of his own pocket..... That stinks. He won't be buying another Nissan then. I've heard so many cases of Nissan not standing by their warranty. It's one thing having reliability issues, but surely a lot worse if the try and wriigle out of it. Performance cars need good warranty IMHO. We had a gearbox issue on our Jeep, (which we've now sold), and on the second occasion of a breakdown the dealer fitted a new gearbox under warranty with no questions asked. Got the car back within a week. Where did my post go?! Anyway..... Agreed. I would recommend bypassing the pain and writing directly to the MD of NMGB. Failing that, we all get together and blockade NMGB until they give in! Didn't he try all that? Quote Link to comment Share on other sites More sharing options...
H5 Posted November 5, 2007 Share Posted November 5, 2007 No idea. Pretty sure a Zed blockade would've made the news if he had! Quote Link to comment Share on other sites More sharing options...
ir_fuel Posted November 5, 2007 Share Posted November 5, 2007 BTW, there was a guy in the 350Z OC who had a Zed engine in a GT4 blow up at about 20k miles. Nissan were refusing to replace it under warranty blaming the light weight UR pulleys he'd fitted, even though the rest of the engine was standard. What a load of B'locks. How could these cause a piston to go through the block. This went on for months and I'm still not sure whether he eventually got them to cough up with a new engine. Well, you know that if you tamper with your engine, no matter how or what, you loose your warranty.... And it is not up to them to prove it did come from that modification, it's up to him to prove it didn't. The only pieces "allowed" are Nismo S tune, and only if installed by an authorized dealer. Quote Link to comment Share on other sites More sharing options...
Kev946 Posted November 5, 2007 Share Posted November 5, 2007 BTW, there was a guy in the 350Z OC who had a Zed engine in a GT4 blow up at about 20k miles. Nissan were refusing to replace it under warranty blaming the light weight UR pulleys he'd fitted, even though the rest of the engine was standard. What a load of B'locks. How could these cause a piston to go through the block. This went on for months and I'm still not sure whether he eventually got them to cough up with a new engine. Well, you know that if you tamper with your engine, no matter how or what, you loose your warranty.... And it is not up to them to prove it did come from that modification, it's up to him to prove it didn't. The only pieces "allowed" are Nismo S tune, and only if installed by an authorized dealer. Yea right..... Who's got the biggest lawyers you mean. How on earth can a lighter pulley cause an engine to blowup. This guy did get an independent engineers report saying it was casued by con rod failure I seem to remember. This was just a case of Nissan wrigglin out of paying a warranty claim 'cause they don't care about their customers. A decent manufacturer would have replaced the engine. They'd rather fight in court 'cause it's cheaper. NMGB are pants..... Quote Link to comment Share on other sites More sharing options...
H5 Posted November 6, 2007 Share Posted November 6, 2007 BTW, there was a guy in the 350Z OC who had a Zed engine in a GT4 blow up at about 20k miles. Nissan were refusing to replace it under warranty blaming the light weight UR pulleys he'd fitted, even though the rest of the engine was standard. What a load of B'locks. How could these cause a piston to go through the block. This went on for months and I'm still not sure whether he eventually got them to cough up with a new engine. Well, you know that if you tamper with your engine, no matter how or what, you loose your warranty.... And it is not up to them to prove it did come from that modification, it's up to him to prove it didn't. The only pieces "allowed" are Nismo S tune, and only if installed by an authorized dealer. I think legally it is as long as it is designed specifically as a replacement part for the car, and fitted by someone fit to carry out the work, they have to honour it. eg someone fitting EBC pads themselves would not mean they can get out of a warranty claim if the caliper fails. Quote Link to comment Share on other sites More sharing options...
ir_fuel Posted November 6, 2007 Share Posted November 6, 2007 I think legally it is as long as it is designed specifically as a replacement part for the car, and fitted by someone fit to carry out the work, they have to honour it. eg someone fitting EBC pads themselves would not mean they can get out of a warranty claim if the caliper fails. You would be surprised I don't think Nissan has actually ever "approved" 3rd party manufacturer parts, like brakepads and so on, except for the ones they provide on the car when it leaves the factory. It is not because in reality it didn't happen (yet) that they could not pull it off if they wanted to. Quote Link to comment Share on other sites More sharing options...
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