ForumSage
SupporterI keep reading about the performance increase that people are able to get with various additions, adjustments or maintenance.
I heard about the problem of turbo hoses delaminating and softening, so I replaced mine with silicone. There was no change whatsoever in the measure that I use to test performance. However, it has been suggested that my mistake was buying black hose. Apparently red is faster.
I heard that tappet adjustment is critical, so I checked the tappets. There was minimal adjustment required on one or two. Once again there was no change in the performance.
I have heard it suggested that normal wear on the timing belt might retard the injection timing by a miniscule amount, so I thought that when I did the timing belt that I might notice an improvement. To make it even more likely that there would be an improvement, I flushed out the intercooler. However, the performance remained unchanged.
My testing method is to approach a hill near home at 100kph indicated speed and press the accelerator to the floor. If there is no wind from any direction, the speed is 85kph indicated at the top and that 85 is held unchanged for some time as the hill flattens out slightly near the top. I would have expected that any change in the performance would show up in that section near the top where the power is just sufficient to maintain speed with no increase or decrease.
So, I wonder what the problem is.
Maybe my testing method is inadequate.
Maybe none of the changes were enough to have a noticeable effect. The turbo hose was just a bit soft, but not damaged. The tappets were very close to perfectly adjusted, the old timing belt showed no visible wear and there wasn't what I would have thought was a lot of oil in the intercooler.
Maybe I just don't have enough faith. In which case, I have the feeling that if I fitted a hiclone, that wouldn't help either.
1973 Series III LWB 1983 - 2006
1998 300 Tdi Defender Trayback 2006 - often fitted with a Trayon slide-on camper.
Swaggie
This one.Originally Posted by vnx205
Your method would be +/- what - 3+ km/h??? (speedo reading error, temp and humidity variation wind speed variation).
Which would probably require at least 1/2 kW improvement to be measurable.
But I agree - a lot of "improvements" are really the placebo effect. The "Butt dyno" is notorious for its poor calibration
Moderator
No one wants to hear that their bum dyno really gives them a bum steer though.[snip]
But I agree - a lot of "improvements" are really the placebo effect. The "Butt dyno" is notorious for its poor calibration
Of course some of us have finely tuned bums, or so the girls say
TopicToaster
I had a big increase in 'butt dyno' power readings when I fixed the manifold gasket leak on my County, because I don't cringe every time I open it right up now so now I'm heavier on the throttle and hence have better acceleration
If you actually did have a problem that was detrimental to performance, maybe you would have found a difference, but you either pre-empted the failure with maintenance or it wasn't out of spec, so of course you wouldn't feel any difference afterwards.
Master
Have you checked your throttle cable, most Tdi's i see are running around with only half throttle. Just tighten your adjuster knob until you see the arm on your fuel pump just move and you will be very happy. I have customers who have spent thousands on performance mods and tightening the cable gave them the most improvement.
Either that or he has a faulty "go pedal".I had a big increase in 'butt dyno' power readings when I fixed the manifold gasket leak on my County, because I don't cringe every time I open it right up now so now I'm heavier on the throttle and hence have better acceleration
If you actually did have a problem that was detrimental to performance, maybe you would have found a difference, but you either pre-empted the failure with maintenance or it wasn't out of spec, so of course you wouldn't feel any difference afterwards.
YarnMaster
I've heard it said by a number of VAG remappers that a power increase of anything under 10% generally isn't noticeable in everyday driving.
ForumSage
SupporterI was assuming that the speedo error, which I know is 10%, would not change from day to day.
About the only thing that seems to make a difference is the wind, so I only take notice of the speed on days when there is no wind.
The thing that has been most noticeable is the consistency of the results. Another thing I didn't mention is that a lot of people comment on how well their engine performs when the air is colder and therefore denser. I know there is scientific validity for that claim, but in practice, I don't see an improvement. I have put that down to the fact that all the transmission oils are slightly thicker when the air is cold and that they take longer to warm up in the cold air. It seems that the extra viscosity balances the extra power available from the denser air.
I had hoped that measuring speed would be slightly more accurate that the usual "Gee it goes a lot better since I painted it red" that some people rely on. I found out years ago how useless the mere sensation of performance is. I thought a 2 stroke MT 125cc Honda accelerated much better than my 4 stroke SL 125cc Honda. When we lined up the two bikes side by side, we quickly discovered that the 2 stroke with its peaky power was no faster than the 4 stroke with its smooth, consistent power delivery.
1973 Series III LWB 1983 - 2006
1998 300 Tdi Defender Trayback 2006 - often fitted with a Trayon slide-on camper.
Master
Have you done any exhaust work on it at all...
YarnMaster
All of those items are effectively maintenance not performance items. Turbo hoses will degrade performance if they are stuffed, tappets will degraded performance if they are so far out of adjustment they are effecting timing, as will the timing chain, and a clogged intercooler will effect performance.
But if your stock turbo hoses haven't delaminated, or gotten so soft they balloon under boost, your tappets aren't loose and rattly, or the intercooler clogged, you aren't going to see "performance gains". I reckon anyone who claims it does has been neglecting maintenance.
cheers
Paul
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