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      12-14-2013, 01:10 PM   #67
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Quote:
Originally Posted by Candide13 View Post
I think the main trick is keeping the turbos spinning under braking, provided you are in the two highest engine mapping modes.

Otherwise I think you just get used to driving at constant power, ie anything above 5500 revs has full power. So shifting up leads to no drop off in the rate of acceleration, unlike in the present S65. On the other hand, accelerating in any gear after 5500 revs leads to a reduction in the rate of acceleration, again unlike the s65, which maintains constant rate of acceleration until redline.

It's different, that's for sure.
Your rate of acceleration is most certainly going to fall with every gear change, regardless of how long max power is held.
Each consecutive gear would require an increase in power equal to the same percentage of difference between each gear ratio for that statement to hold any merit, and that doesn't even take into account any drag, which increases exponentially with speed.

Last edited by <-3VOM; 12-14-2013 at 02:25 PM.
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      12-14-2013, 02:07 PM   #68
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Quote:
Originally Posted by Tokay444 View Post
Your rate of acceleration if most certainly going to fall with every gear change, regardless of how long max power is held.
Each consecutive gear would require an increase in power equal to the same percentage of difference between each gear ratio for that statement to hold any merit, and that doesn't even take into account any drag, which increases exponentially with speed.
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      12-14-2013, 03:05 PM   #69
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Quote:
Originally Posted by Tokay444 View Post
Source=any other di platform, running meth and or catch cans...
I don't think you've been reading much of what you're talking, b/c I have. Water/meth *helps some*, it doesn't prevent it. People running meth have *still* reported buildup that requires cleaning. There was even a guy running it on his VW/Audi since new and @ less than 30k (IIRC) his engine looked no better than others. I'll post the link when I find the thread again.

Additionally, w/ w/m, you have to have a nozzle for each port, not just one.

http://www.golfmk6.com/forums/showpo...9&postcount=49

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Originally Posted by crew219
I had a CC as well as W/M and there was zero reduction in carbon deposits when I sprayed at the throttle body.

Dave
The only thing that prevents it is DP, which is why you see it being used by Toyota. That DP has no other logical purpose other than to keep carbon buildup away @ low RPMs.
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Last edited by whats77inaname; 12-14-2013 at 03:17 PM.
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      12-14-2013, 03:56 PM   #70
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Run more meth and use oil catch cans. Spotless valves.
And no, that's not the only reason to run direct injection, and port injection.
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      12-14-2013, 04:17 PM   #71
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I used to spray 100% methanol on my MINI JCW(boy did that engine love meth) and after 25k miles, things still looked clean. I did get a walnut blasting done at 30k miles prior to installing a meth kit. No catch can but was meth tuned. That JCW had more torque than my current M3 too. Yikes.
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      12-14-2013, 04:26 PM   #72
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^this.
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      12-14-2013, 05:45 PM   #73
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Quote:
Originally Posted by Tokay444 View Post
Your rate of acceleration is most certainly going to fall with every gear change, regardless of how long max power is held.
Each consecutive gear would require an increase in power equal to the same percentage of difference between each gear ratio for that statement to hold any merit, and that doesn't even take into account any drag, which increases exponentially with speed.
Well, ignoring air resistance, the rate of acceleration will truly not drop in the new car, provided you manage to shift late enough such that the revs stay above 5500. Such is the unusual magic of having a wide band of constant peak power!

Of course, as you hold the gear and accelerate above 5500 revs, the acceleration will continuously tail off, for the same reason: constant power going through the drive train.

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      12-14-2013, 08:39 PM   #74
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No. You're still wrong. Even taking out the wind resistance.
If you had one gear from zero to top speed, and made max power from 0rpm to redline, and redlined at top, and still ignored drag, that would be the only time the rate of acceleration would not change.
Your rate of acceleration will decrease with every upshift, for reasons already explained above.
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      12-14-2013, 10:51 PM   #75
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Quote:
Originally Posted by Tokay444 View Post
No. You're still wrong. Even taking out the wind resistance.
If you had one gear from zero to top speed, and made max power from 0rpm to redline, and redlined at top, and still ignored drag, that would be the only time the rate of acceleration would not change.
Your rate of acceleration will decrease with every upshift, for reasons already explained above.
Hm, acceleration is basically power divided by speed divided by the mass of your car. So at constant power your acceleration decreases as you increase your speed. Conversely, at constant torque, as in the s65, the power is itself proportional to engine speed, so the ratio of power and speed stays constant as you rev out a gear. That's why the s65 has nearly constant acceleration to redline.

Anyhow, this has been discussed in a number of threads so let's not start another one even if we disagree on this....
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      12-15-2013, 12:12 AM   #76
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Quote:
Originally Posted by Candide13 View Post
Hm, acceleration is basically power divided by speed divided by the mass of your car. So at constant power your acceleration decreases as you increase your speed. Conversely, at constant torque, as in the s65, the power is itself proportional to engine speed, so the ratio of power and speed stays constant as you rev out a gear. That's why the s65 has nearly constant acceleration to redline.

Anyhow, this has been discussed in a number of threads so let's not start another one even if we disagree on this....
No need to start another thread, it's been beaten to death, he is completely wrong and you are absolutely right in every word. Misconceptions about torque, power, and acceleration are a constant return over the years on the forum, you can count on it like tax.
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      12-15-2013, 12:16 AM   #77
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Quote:
Originally Posted by Tokay444 View Post
Run more meth and use oil catch cans. Spotless valves.
And no, that's not the only reason to run direct injection, and port injection.
Quote:
Originally Posted by IzzyGray View Post
I used to spray 100% methanol on my MINI JCW(boy did that engine love meth) and after 25k miles, things still looked clean. I did get a walnut blasting done at 30k miles prior to installing a meth kit. No catch can but was meth tuned. That JCW had more torque than my current M3 too. Yikes.
this carbonising effect is an inevitable byproduct of direct injection, it cannot be prevented. The use of additives in the fuel itself is useless, as the fuel does not come into contact with the intake tract or the valves at all; the use of water/methanol injection may slow down the carbonising somewhat (depending on where the methanol is injected and provided it is not yet completely vaporised when it reaches the valves), but cannot prevent it either.
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      12-15-2013, 12:23 AM   #78
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Quote:
Originally Posted by sunsweet View Post
this carbonising effect is an inevitable byproduct of direct injection, it cannot be prevented. The use of additives in the fuel itself is useless, as the fuel does not come into contact with the intake tract or the valves at all; the use of water/methanol injection may slow down the carbonising somewhat (depending on where the methanol is injected and provided it is not yet completely vaporised when it reaches the valves), but cannot prevent it either.
^this.
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      12-15-2013, 12:34 AM   #79
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Meth paired with two oil catch cans and 230000kms of direct injection, and my valves are spotless.
Power would have to increas by the same percentage each gear ratio differs, in order to maintain equal acceleration rate. Also, does the car run the same final drive on all forward gears? I doubt it.
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      12-15-2013, 12:51 AM   #80
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      12-15-2013, 10:46 AM   #81
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Quote:
Originally Posted by Tokay444 View Post
Your rate of acceleration is most certainly going to fall with every gear change, regardless of how long max power is held.
Each consecutive gear would require an increase in power equal to the same percentage of difference between each gear ratio for that statement to hold any merit, and that doesn't even take into account any drag, which increases exponentially with speed.
Any given vehicle will accelerate at the same rate, given it's making the same power at the same speed, regardless of torque or gearing. Horsepower is the great simplifier in this regard.

In the extremely unusual case of this engine, shifting from one gear to another in the upper gears at 7300 gets you back to something over 5500 rpm, which is where the peak power range begins. Therefore, acceleration at that point will be the same as just before the shift.

Yeah, I know it sounds weird, but think of it this way: The drop off in rpm is proportional to the change in gearing, so the drop in torque to the drive wheels will also drop - but the rise in engine torque at 5500 (compared to 7300) is exactly enough to offset the gearing change, given that engine power stays the same.

Power equals torque times rpm over 5252.

Bruce

PS - You could in fact make the case that acceleration right after the shift point will actually increase in this case, since rotational inertia will be less in the higher gear. That has implications for shifting even a little earlier.

This will be a very cool car coming out of corners and absolutely blasting down the straights.
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      12-15-2013, 11:14 AM   #82
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Let's just say, you can accelerate from 60-100mph in 3rd gear, and stay within the 5500-7300rpm powerband, now you shift from 3rd to 4th, and remain above 5500rpm, and accelerate from 100-140mph. It WILL take longer to go from 100-140mph than it did to go from 60-100mph.
Both differences of 40mph. Both within the max power band. The only differences being gearing and elapsed time.

Last edited by <-3VOM; 12-15-2013 at 11:19 AM.
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      12-15-2013, 01:44 PM   #83
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Quote:
Originally Posted by Tokay444 View Post
Let's just say, you can accelerate from 60-100mph in 3rd gear, and stay within the 5500-7300rpm powerband, now you shift from 3rd to 4th, and remain above 5500rpm, and accelerate from 100-140mph. It WILL take longer to go from 100-140mph than it did to go from 60-100mph.
Both differences of 40mph. Both within the max power band. The only differences being gearing and elapsed time.
What you're saying in no way relates to my note, and you're mixing two things up here.

Here's the shorthand deal: Speed eats power. It's as simple as that.

Let's say you can attain a certain amount of acceleration at, say, 40 mph in first gear in the current car. Let's also say that 40 mph is at the power peak in first. Ignoring any changes in wind and rolling resistance, you will need exactly two and one half times the power to accelerate at that rate at 100 mph. In other words, your 414 HP M will need 1035 HP to pull as hard at 100 mph as it does at 40.

Or conversely, it will pull only 40% as hard at 100 as it did at 40, assuming both speeds are at the power peak, and of course assuming no difference in wind and rolling resistance.

The key point here is that at any given speed, horsepower governs acceleration, torque and gearing be damned, so the new car will accelerate just as hard after the shift as before, assuming the rpm differences stay between the 5500-7300 rpm window.

Of course, right after that, acceleration will begin to taper off, because the speed is rising while power remains the same - and as I said, speed eats power - in a perfectly linear way.

Bruce
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      12-15-2013, 01:54 PM   #84
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Quote:
Originally Posted by Tokay444 View Post
Meth paired with two oil catch cans and 230000kms of direct injection, and my valves are spotless.
1) Pics of meth setup?
2) How many miles were on the car before you started using catch cans?
3) How long have you been running meth?

Last edited by whats77inaname; 12-15-2013 at 02:38 PM.
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      12-15-2013, 02:27 PM   #85
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Quote:
Originally Posted by bruce.augenstein@comcast. View Post
What you're saying in no way relates to my note, and you're mixing two things up here.

Here's the shorthand deal: Speed eats power. It's as simple as that.

Let's say you can attain a certain amount of acceleration at, say, 40 mph in first gear in the current car. Let's also say that 40 mph is at the power peak in first. Ignoring any changes in wind and rolling resistance, you will need exactly two and one half times the power to accelerate at that rate at 100 mph. In other words, your 414 HP M will need 1035 HP to pull as hard at 100 mph as it does at 40.

Or conversely, it will pull only 40% as hard at 100 as it did at 40, assuming both speeds are at the power peak, and of course assuming no difference in wind and rolling resistance.

The key point here is that at any given speed, horsepower governs acceleration, torque and gearing be damned, so the new car will accelerate just as hard after the shift as before, assuming the rpm differences stay between the 5500-7300 rpm window.

Of course, right after that, acceleration will begin to taper off, because the speed is rising while power remains the same - and as I said, speed eats power - in a perfectly linear way.

Bruce
I'm in no way mixed up.
When someone says it will accelerate at the same rate in every gear from 5500-7300 rpm, they're wrong, and I've highlighted why.
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      12-15-2013, 02:31 PM   #86
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Quote:
Originally Posted by whats77inaname View Post
Pics of meth setup?
Pretty standard operating procedure.
Meth pump. Windshield washer reservoir acts as meth tank. Boost activated D10 nozzle in cold pipe about 12" pre throttle body.
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      12-15-2013, 03:38 PM   #87
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Quote:
Originally Posted by Tokay444 View Post
I'm in no way mixed up.
When someone says it will accelerate at the same rate in every gear from 5500-7300 rpm, they're wrong, and I've highlighted why.
Nobody says that. What you are wrong in saying is that this particular engine cannot accelerate as hard in the next gear after the shift as it did at the shift point.

You would normally be correct, but not with this particular engine's power/torque curves.

Bruce
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      12-15-2013, 04:16 PM   #88
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And some people buy old Lambos because of the engine sound.
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