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03-30-2010, 05:32 PM | #25 | |
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03-30-2010, 05:35 PM | #26 | |
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This engine doesnt have a 5200 RPM redline it has a 7K redline...I hate the cliff that the torque jumps off of after 6K. |
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03-30-2010, 05:42 PM | #27 |
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03-30-2010, 06:03 PM | #28 | |
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03-30-2010, 06:55 PM | #29 | |
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The last time I checked HP is a function of Torque...without torque there is no HP. Here is a stock N54 dyno chart...look at what happens after 5K, torque and HP dropoff Last edited by BrokenVert; 03-30-2010 at 07:22 PM.. |
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03-30-2010, 07:19 PM | #30 | |
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03-30-2010, 07:33 PM | #31 | |
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What's your point? pge |
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05-23-2010, 12:11 PM | #32 | |
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The point is it would be nice to maintain a flat torque curve all the way to redline so the car pulls hard all the way to redline.. BMW chose to size the turbos for low end torque. They can't support the airflow required to maintain the same boost to 7k. I don't really like it but after driving the car for two years I enjoy having the low end torque for daily driving. My S4 has plenty of top end boost with GT28 turbos but no boost below 3600 rpms. Everything is a compromise but I'm pretty sure most people would rather have low end torque for a daily driver. That doesn't mean they still can't complain about how they miss the upper end torque.
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05-23-2010, 01:04 PM | #33 | |
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The point I was trying to make is the current power/torque curves are more than adequate for driving on public roads. Perhaps not sufficient for drag strips or tracking, but that's a totally different purpose. And I'm aware there are a few who want to use their DD for the track on the weekend, probably not the best of both worlds there and they'll just have to accept those compromises. This forum appears to do a great job allowing members to express their opinions, disagree with others' and to just plain ventilate, in addition to providing an incredible amount of useful information from those same members. I think that's great, so everyone on this thread should be feeling much better now. pge |
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07-09-2010, 11:10 AM | #35 |
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07-12-2010, 04:08 PM | #37 |
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Are you kidding? You should read a physics book. A dynometer doesn't "predict" anything, it measures force. If you know the force that is exerted at any given RPM, you can calculate the horsepower being produced. If anything, a crank dyno reading is less relevant for real world application than a wheel dyno, because the crank dyno can't predict driveline losses. For comparing car to car, apples to apples, a wheel dyno is far more effective. Granted, you need to run both cars back to back on the same dyno for the purposes of direct comparison, but a dyno is a very effective tool for assessing the real output of your modifications.
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07-12-2010, 04:13 PM | #38 |
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On the topic of torque vs horsepower:
As TrackRat has already so eloquently put, one is a function of the other. Ultimately, horsepower is the number you should be concerned with if you're after performance, and more specifically, the curvature of horsepower production. Peak horsepower is an interesting number, but if you look at a lot of dyno charts, you'll find that a strong performing car has a dyno chart that rises early, stays strong, then drops after its peak. As far as performance goes, torque numbers aren't terribly important. Why is that? Because for any specified horsepower output, you can generate equal torque through gearing. That is to say, two engines that generate 300 HP at a given RPM can generate equal torque at any given RPM. An example using the following formulas: hp = tq(rpm)/5252 tq = hp(5252)/rpm Engine 1 300 HP @ 5000 RPM Engine 2 300 HP @ 8000 RPM Q: Which of these engines, when operating at peak HP, is capable of producing more torque at 2500 RPM (through a gearbox)? A: Neither, they would both produce roughly 630 lb ft through a gearbox (unaccounted for loss). Engine 1 would require a gearing factor of 2:1 and engine 2 would require a gearing factor of 3.2:1. Since both engines must operate through a gearbox, both will suffer losses and we can assume any discrepancy between gearboxes will be negligible. This is why tq vs hp doesn't matter. With the appropriate gearing, you can apply the same force at the ground. Torque is a measure of force only. I can generate 400 lb ft of torque with a torque wrench. If you put me under the hood of your car with that torque wrench attached to the input shaft of the transmission, how fast do you think you'll go? If you want to go fast, you need lots of horsepower. End of story. |
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07-24-2010, 08:28 PM | #39 |
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Hello i am new here, just bought a brand new 2011 and the sales guy didnt even know anything about the new N55 engine plus in the details that was posted on the car it still says twin turbo....what the hell???
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07-24-2010, 11:39 PM | #40 | |
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My bottom line is, I agree with what you said, 100%. It's just frustrating to read conversations where people (not you) talk about torque and horsepower as if they're two distinct measurements, and that engines either have one or the other.
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08-03-2010, 04:32 PM | #41 |
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I just got 2011 135i dual clutch trans and I am wondering if anyone has taken one down the 1/4 and if they make any parts for it ?
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08-03-2010, 06:05 PM | #42 |
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I was wondering what the blacked out 5er was doing camped outside my house for the last few days. I've always had a suspicion I was under surveillance
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08-03-2010, 06:14 PM | #43 |
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You have one tailing you too??
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08-23-2010, 08:06 PM | #44 |
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