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Old 07-08-2012, 04:35 PM   #1 (permalink)
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Shift points for TDI

Hi, I had searched a lot of info about how to drive TDI, and at which RPM to change gears. A lot of people in other forums recommend to shift at 2500-3000 RPM, because they think that shifting early is bad for VNT turbos and engines.

Personaly I tend to shift between 1600-1800 RPM and my conclusions is that shifting early is better for greater MPG. The question is how do other forum members shift and drive their TDI for greater MPG?

P.S I am driving VW Lupo 1.4 TDI, upgraded to VNT turbo and chiptuning. In my driving experience have had only vw diesels, two of them TDI`s.

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Old 07-09-2012, 04:35 PM   #2 (permalink)
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I can't say for the best mileage where to shift as that depends on several things like terrain and traffic. Also I have only owned my 02 Golf TDI 1.9 for two weeks as of today, at 75mph mostly highway I have been getting 42 with each tank a few points higher.

If the car is not warm I shift at 2000-2500 depending on gear. When it is warm I will shift between 1500-3000.

In the city without traffic on mostly flat ground I shift as follows.
1-3 3100rpm
3-5 37 mph (or about the same speed to 4th if there is a hill trafic)
All of those are when taking it slow.

The issue with the VNT as I understand it is from always shifting at low RPM. If you wind it out with heavy peddle on occasion when warm you should be fine. I do this from 2nd when entering the HW till I get up to 70-80mph. (Speed limit is 70mph)


It all depends on the conditions you are driving so look ahead and have some fun at times with the go peddle, just do not do it from 800-1200rpm.
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Old 07-09-2012, 05:38 PM   #3 (permalink)
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I shift at 1500 rpm usually, 17- 1800 rpm if i need to step on it.
In town i use 5th gear starting at 50 kmh or 30 mph, the motor stumbles at about 40kmh in 5th so I get away with cruising in town using 5th gear 30 mph at 1000 rpm.
I put a cheapo 60 dollar ebay fuel pump tuning box on my tdi and gained a ton of low speed torque, which makes driving in 5th at 1000 rpm a breeze.
My motor is the AGR 1.9 tdi with the ko3 waste gated turbo.
The people saying to shift at 2500 to 3000 rpm must have a need for speed or are under the false ideology
that they must race their motor before they shift or else like you suggested will break the turbo.
I have heard people saying that you should shift at your peak hp rpm's or else you lose economy(hogwash) they reason that your car is at peak efficiency while in your peak hp rpm. That is simply untrue, the lower the rpm the better your fuel economy, i say that from my personal experience as well as others.
I bet you would blow your turbo from years and years of high revs, not by babying it, its the design of the vnt turbo that causes frozen fins.
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Old 07-10-2012, 05:13 AM   #4 (permalink)
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Quote:
Originally Posted by Phantom View Post
.

If the car is not warm I shift at 2000-2500 depending on gear. When it is warm I will shift between 1500-3000.



The issue with the VNT as I understand it is from always shifting at low RPM. If you wind it out with heavy peddle on occasion when warm you should be fine. I do this from 2nd when entering the HW till I get up to 70-80mph. (Speed limit is 70mph)
If i would shift ta 2500- 3000 RPM and press acelerator pedal about 70%, then it feels like I am going on drag race So there is no point off reving engine up to 2500 - 3000 when presing acelerator pedal up to 30%

All I know that driving at peak torque would kill turbo and engine a lot faster, because at that RPM engine is developing peak torque and all engine components are at maximal stress. (I am also a car mehanic and i know what I am talking about). In my lupo I already had rebuilt my engine, including new turbo.

vw also suggests that shifting early is better for MPG. And as I know, construction of PD TDI engines and new bluemotion engines are not so different either, both have direct injection and VNT turbos.

Last edited by amdown; 07-10-2012 at 05:25 AM.. Reason: adding information
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Old 07-10-2012, 02:17 PM   #5 (permalink)
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Quote:
Originally Posted by amdown View Post
All I know that driving at peak torque would kill turbo and engine a lot faster, because at that RPM engine is developing peak torque and all engine components are at maximal stress. (I am also a car mehanic and i know what I am talking about)...vw also suggests that shifting early is better for MPG.
This doesn't make sense. You are saying the engine wasn't built strong enough to handle the loads it is likely to see on a regular basis (which is probably true coming from VW). Accelerating at peak torque is most efficient. Shifting earlier would be less efficient.

For anyone wondering what is the most efficient way to accelerate, just find the peak torque and try to keep the engine RPM in that range during acceleration. Once up to cruising speed, bring the RPM way down.
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Old 07-10-2012, 03:34 PM   #6 (permalink)
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Quote:
Originally Posted by amdown View Post
Personaly I tend to shift between 1600-1800 RPM and my conclusions is that shifting early is better for greater MPG. The question is how do other forum members shift and drive their TDI for greater MPG?
That's OK.
VW TDis are good at shifting at low rpm.

If you want to go fast, shift at the point where the rpm drop to just above the rpm at which you get max. torque
Usually even that means shifting at only 2500 rpm
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Old 07-10-2012, 03:58 PM   #7 (permalink)
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Quote:
Originally Posted by amdown View Post
If i would shift ta 2500- 3000 RPM and press acelerator pedal about 70%, then it feels like I am going on drag race So there is no point off reving engine up to 2500 - 3000 when presing acelerator pedal up to 30%

All I know that driving at peak torque would kill turbo and engine a lot faster, because at that RPM engine is developing peak torque and all engine components are at maximal stress.
You may have noticed that I did not mention how much fuel to give it at any time. Also I believe what you tried to say is "If I would shift at 2500- 3000 RPM and press acelerator pedal about 70%, then it sounds like I am going to drag race " If you think that your TDI FEELS like you are drag racing then you should take a ride in my stock 98 Bonniville when it down shifts from 4th at 60mph to second and run it to 86mph before it shifts to 3rd (actually back to 4th since I let off the gas)

All aside I repeatedly said that shifting depends on conditions. When cold I hold the RPMs a little higher to warm it faster. When warm I often skip gears some times 2-5. If I do not need to crawl at lower speeds I will wind out 1st to ~3000 and shift to third that places the RPMs around 1300.

As it was mentioned the VNT needs to be worked to keep it from sticking.

The Torque will not kill the engine and if you want to stay out of the TQ then you should keep the motor away from 1600rpm as it produces the most TQ there when stock. My engine produces max TQ at 1900rpm so that is where I like to keep it when I need to have some response from the engine.

Just a note the approximate change in RPM between gears on my Golf.
1-2 1250
2-3 700
3-4 500
4-5 500
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Old 07-10-2012, 04:06 PM   #8 (permalink)
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Quote:
Originally Posted by redpoint5 View Post
This doesn't make sense. You are saying the engine wasn't built strong enough to handle the loads it is likely to see on a regular basis (which is probably true coming from VW). Accelerating at peak torque is most efficient. Shifting earlier would be less efficient.

For anyone wondering what is the most efficient way to accelerate, just find the peak torque and try to keep the engine RPM in that range during acceleration. Once up to cruising speed, bring the RPM way down.
I agree, engine can withstand such loads, but if I would drive my car within max torque, my tyres would be up in smoke and with 4th and 5yh gear after month of such driving my clutch would be gone
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Old 07-10-2012, 04:13 PM   #9 (permalink)
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Quote:
Originally Posted by Phantom View Post

Just a note the approximate change in RPM between gears on my Golf.
1-2 1250
2-3 700
3-4 500
4-5 500
On lupo gear ratios ar something similar.

I know that best BFSC is at max torque for TDI, But I have seen that my MPG drops when I try to shift at higher RPM (2200-2500)

My car is far enough from stock. Stock lupo 1.4 TDI has wastgate turbo, 75HP and about 200 Nm torque.

MY car is chiptuned several times, has been upgraded to Hybrid VNT turbo from lupo 3L and now it develops 110 HP and 250 Nm, my peak torque is at 2300-3000 RPM
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Old 07-10-2012, 09:21 PM   #10 (permalink)
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As some have stated, it's all about the terrain, road conditions, traffic, etc. I've been driving a 2000 Jetta TDI since March of '02. It has virtually no mods and has attained a life time average above 50 mpg. (Over 400 fill-ups, all in a rather detailed Excel Spreadsheet)

I generally shift above 1900 RPMs (peak torque) up to 3000 RPMs. But, I do a lot of shifting in the 2300 to 2500 RPM range.

The Turbo can be "exercised" for working purposes without taking the engine up to 4000 or more RPMs. If you get on it (above 2100 RPM) with a steady push on the pedal taking the RPMs up to 3000 ..........the boost will max for an instant!..... shift and do it in the next gear. That means the Turbo actuator went full range. I've practiced that method and have never had any issues with my Turbo (still original). I do take the RPMs up to 3600 to 4000 at least once per tank of fuel.

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