My 2010 ISF vs. my buddy's 2010 M3 DCT!
06-09-10, 09:00 AM
#46
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sorry I was wrong about the M3's tq it's 295 not 262. Regardless that is a SUBSTANTIAL difference in power. Torque is the measure of rotation force while HP is a theoretical number derived from torque (tq * rpm / 5252). Since the whole game is power to weight torque is the most important figure while HP is mostly for bragging rights (lol i feel some flames coming my way).
In all my years in performance cars i have never heard of the term power to torque ratio
06-09-10, 09:04 AM
#47
HP matter quite a lot. I know lots of turbodiesels with 300ftlb of torque and only 140hp. They are **** slower than a torqueless Honda Civic SI.
F1 cars can be fast because they are geared to compensate for the 'lack' of torque, much in the same way the M3 is. They also have higher redlines to make up for the shorter gearing. Torque is one thing, but hp is the amount of work the engine can put out.
The M3 and ISF are neck to neck in a race, despite the M3's torque deficit.
F1 cars can be fast because they are geared to compensate for the 'lack' of torque, much in the same way the M3 is. They also have higher redlines to make up for the shorter gearing. Torque is one thing, but hp is the amount of work the engine can put out.
The M3 and ISF are neck to neck in a race, despite the M3's torque deficit.
06-09-10, 09:16 AM
#48
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where did I say 'power to torque' ?
GSteg - what you're reffering to is the ability to apply the torque produced over a given range (engine speed). The reason many turbo diesels with high torque have no hp and slow acceleration has to do with the very narrow rev range. (300tq * 2500rpm / 5252) = 142hp. if that same turbo diesel were able to continue producing 300tq all the way up to 5000+ rpm you would have very quick acceleration. This is why F1 cars are so fast. Assuming it only makes 200tq (200tq * 22000rpm / 5252 = 837hp).
It would be very interesting to see a dyno graph of the M3 overlayed with one of the IS-F. Anyway it's all bench racing, I say you go out race him again starting at higher rpm like others have said
GSteg - what you're reffering to is the ability to apply the torque produced over a given range (engine speed). The reason many turbo diesels with high torque have no hp and slow acceleration has to do with the very narrow rev range. (300tq * 2500rpm / 5252) = 142hp. if that same turbo diesel were able to continue producing 300tq all the way up to 5000+ rpm you would have very quick acceleration. This is why F1 cars are so fast. Assuming it only makes 200tq (200tq * 22000rpm / 5252 = 837hp).
It would be very interesting to see a dyno graph of the M3 overlayed with one of the IS-F. Anyway it's all bench racing, I say you go out race him again starting at higher rpm like others have said
06-09-10, 09:37 AM
#49
You cannot say horsepower is a bragging rights when you've just proved otherwise. I gave a simple case of a turbo diesel to show torque isn't the limiting factor. If the engine can produce that torque figure at a higher rpm, the car gets faster because it produces more horsepower. Where the engine makes that torque is far more important.
Torque, while it is a good thing, is not the most important figure. Torque can be manipulated through gearing.
I gave a simple case of a turbo diesel to show torque isn't the limiting factor. If the engine can produce that torque figure at a higher rpm, the car gets faster because it produces more horsepower. Where the engine makes that torque is far more important.Torque, while it is a good thing, is not the most important figure. Torque can be manipulated through gearing.
06-09-10, 09:43 AM
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Ask and you shall receive
The torque on the ISF is obviously more but with the M3 when they shift at 8300rpm, the next gear starts at about ~6500RPM depending on the gear. This allows them to stay in the 330-360whp range for close to 2000rpm of band width. In my ISF when i shift, the RPMs drop to about 5500rpm and by the time i get to 6500-6600 i have to shift to avoid hitting the limiter so the power band width is very narrow. Here is a M3 dyno on a dynodynamics
And here is a typical ISF dyno:
Last edited by alpha6164; 06-09-10 at 09:49 AM.
06-09-10, 10:03 AM
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How high the m3 revs dosnt mean much in this case. Both cars shift within a few MPH of each other. The isf creates power for the entirety of its powerband. The M3 takes a few hundred rpm to start making over 330whp according to your dyno sheet. Damn i havent had this much fun bench racing in a long time. NICE THREAD!
06-09-10, 10:10 AM
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How high the m3 revs dosnt mean much in this case. Both cars shift within a few MPH of each other. The isf creates power for the entirety of its powerband. The M3 takes a few hundred rpm to start making over 330whp according to your dyno sheet. Damn i havent had this much fun bench racing in a long time. NICE THREAD!
I dont get what you mean. It doesnt matter what the ISF makes at 3000 or 4000RPm since when racing neither cars are not in that part of the power band. Do you disagree with this? What matter is that when racing and shifting at red line the M3 stays in the 6500-8400 range which is the sweet spot. The ISF makes its 330whp at about 5500 RPM and when racing the RPMs stay between 5500-6700 when shifting close to red line.
06-09-10, 10:21 AM
#54
How high the m3 revs dosnt mean much in this case. Both cars shift within a few MPH of each other. The isf creates power for the entirety of its powerband. The M3 takes a few hundred rpm to start making over 330whp according to your dyno sheet. Damn i havent had this much fun bench racing in a long time. NICE THREAD!
The M3 revs does matter because it relies on revs to get through the short gearing to take advantage of the top end power. In every single gear (minus 8th gear for M3), the M3 has a higher torque multiplication ratio than the IS-F. That is how it offsets the torque deficit. However that comes at a price and that's the output shaft's angular velocity. The M3 makes it up by having an 8400 rpm redline. You may be shifting within a few mph, but the revs for both cars are definitely not close to each other.
Bench racing is fun
06-09-10, 10:23 AM
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I dont get what you mean. It doesnt matter what the ISF makes at 3000 or 4000RPm since when racing neither cars are not in that part of the power band. Do you disagree with this? What matter is that when racing and shifting at red line the M3 stays in the 6500-8400 range which is the sweet spot. The ISF makes its 330whp at about 5500 RPM and when racing the RPMs stay between 5500-6700 when shifting close to red line.
06-09-10, 10:29 AM
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^^^ Also, the isf begins every gear near peak torque.
I understand what your saying but you took my comment out of context i think . I was trying to compare the powerbands during the race.
Bench racing is so much run. Especially in a boring PHYC class
The M3 revs does matter because it relies on revs to get through the short gearing to take advantage of the top end power. In every single gear (minus 8th gear for M3), the M3 has a higher torque multiplication ratio than the IS-F. That is how it offsets the torque deficit. However that comes at a price and that's the output shaft's angular velocity. The M3 makes it up by having an 8400 rpm redline. You may be shifting within a few mph, but the revs for both cars are definitely not close to each other.
Bench racing is fun
Bench racing is fun
Bench racing is so much run. Especially in a boring PHYC class
06-09-10, 10:35 AM
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In terms of the 8ms "shift" time, this is worth the read:
"The 8ms figure has been discussed here on the forum extensively. It was given on some article on some website (again exact references are here in the forum) for the DSG unit. The vast majority of those that have either thought about, measured and or compared this figure to other units and other information realize this number is absurd.
Furthermore the SMG figures that have been floated of both 80 and 65 ms are deceptive. IIRC those figures are from BMW directly. They likely only cover the shift and conveniently leave out the clutching. SMG shift times were at best about 0.2 seconds (200 ms) which about the same as a good but fast human can shift. Again the article that shows the actual testing that concludes this figure of about 200 ms for a good typical up**** it referenced in prior posts on the forum. If you are really interested use google to search this forum rather than the forums built in search function. Just append a good boolean search with "site:m3post.com".
I've seen test data for a human in a MT at 0.25 s (250 ms). Shift time really vary for all DCTs and many of the good current units are in the range of tens of ms for ideal upshifts to tenths of seconds for non ideal multiple downshifts (maybe even 0.5 s or longer)."
Full post here: http://www.m3post.com/forums/showthr...=328813&page=2
"The 8ms figure has been discussed here on the forum extensively. It was given on some article on some website (again exact references are here in the forum) for the DSG unit. The vast majority of those that have either thought about, measured and or compared this figure to other units and other information realize this number is absurd.
Furthermore the SMG figures that have been floated of both 80 and 65 ms are deceptive. IIRC those figures are from BMW directly. They likely only cover the shift and conveniently leave out the clutching. SMG shift times were at best about 0.2 seconds (200 ms) which about the same as a good but fast human can shift. Again the article that shows the actual testing that concludes this figure of about 200 ms for a good typical up**** it referenced in prior posts on the forum. If you are really interested use google to search this forum rather than the forums built in search function. Just append a good boolean search with "site:m3post.com".
I've seen test data for a human in a MT at 0.25 s (250 ms). Shift time really vary for all DCTs and many of the good current units are in the range of tens of ms for ideal upshifts to tenths of seconds for non ideal multiple downshifts (maybe even 0.5 s or longer)."
Full post here: http://www.m3post.com/forums/showthr...=328813&page=2
This is exactly the point that I was trying to make.
06-09-10, 11:38 AM
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I'd like to comment on the shift times. 8ms may accurately describe one part of the shift process, but it seems mechanically impossible for a complete shift cycle to occur in 8ms. I find it quite funny that Lexus is able to give a real-world 100ms estimate, while BMW dodges the question and everyone has to speculate.
Like MRxSLAYx suggested, let's see what happens if you race with the stockers on. I don't know how much your 3pc weighs, but I'm skeptical that it will be a difference maker given that the majority of your runs are done from a roll, and your wheels are already spinning.
Like MRxSLAYx suggested, let's see what happens if you race with the stockers on. I don't know how much your 3pc weighs, but I'm skeptical that it will be a difference maker given that the majority of your runs are done from a roll, and your wheels are already spinning.
06-09-10, 12:04 PM
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^^^ I am definitely going to run him again and this time will take videos. This time however I will turn VSC off and start the runs at least 5000rpm. Looking at the dyno curve there is a significant power out difference between 4500 and 5000. Will keep u guys posted.
06-09-10, 12:16 PM
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Why dont you guys just start from 0 or 5 mph to 100mph , I am pretty sure the isf should be a bit quicker.