Anyone tried these turbo boost adjusters??

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RichG
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Post by RichG »

Simon,

The engine is unmodified and max boost was reached at about 3000 rpm IIRC. I agree that the amount of boost is relative to the throttle position but it is also affected by the load on the engine. However not many of us drive with our foot to the floor all the time. When I did my tests the boost pressure rose uniformly up to 1 barg where it would not go any further. This made me assume that the waste gate was operating like a 'safety valve' to prevent over pressure and not leaking a progressive amount all through the range. Being progressive on a Diesel engine does not make sense to me as the waste gate is only there to prevent over-pressure causing damage during combustion.

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Richard
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Post by fastandfurryous »

In order to boost torque at lower engine RPM (and thus make the engine more responsive) you need to start making adjustments to the injection pump. By increasing the fuelling at lower rpm, there is then more fuel being burned, more heat in the exhaust, and the turbo spins up faster at lower RPM.

If further adjustments are then made to change the relationship between boost pressure and fuelling, and then the wastgate actuator is adjusted to raise the pressure at which it opens, you can develop some serious torque at lower revs, and then go on to develop even more torque as the revs rise.

Done properly, with a big fat intercooler, I'd guess you can get at least 200lbf-ft of torque out of a 1.9TD.
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Post by Mandrake »

RichG wrote:Simon,

The engine is unmodified and max boost was reached at about 3000 rpm IIRC. I agree that the amount of boost is relative to the throttle position but it is also affected by the load on the engine.
Yes, in so much as having load on the engine allows for a greater throttle opening at lower RPM.

Ok so if it's not reaching the regulated boost pressure until 3000 rpm a MBC won't have much effect below that RPM, but will possibly have a large effect above it..
However not many of us drive with our foot to the floor all the time. When I did my tests the boost pressure rose uniformly up to 1 barg where it would not go any further. This made me assume that the waste gate was operating like a 'safety valve' to prevent over pressure and not leaking a progressive amount all through the range.
Yes, thats exactly how it works. It doesn't start opening until nearly full boost is reached and then it starts progressively opening to regulate the boost pressure - as you rev higher and higher beyond that point it has to open even further to keep the boost pressure down to the regulated amount, which is what I meant by progressive - it doesn't just abruptly snap "open" or "closed" at the threshold pressure.
Being progressive on a Diesel engine does not make sense to me as the waste gate is only there to prevent over-pressure causing damage during combustion.
Thats exactly the reason why a waste gate is there on diesel or petrol - both would suffer damage if the boost pressure was not limited to a safe and controllable amount...

Regards,
Simon
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Post by RichG »

Simon,

I am glad that we agree on the way that the waste gate works. Unfortunately I have a KKK Turbo on my Xantia so an MBC would not be much use to me.

Regards
Richard
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Post by Stewart(oily) »

So your route to more power RichG is to adjust the wastegate pushrod, I think you need to shorten it , in addition to adjustments of the fuelling, and the benefits come right across the range, more pulling power as soon as any boost is being made, which seems to begin around 1500 rpm.
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Post by RichG »

Stewart,
There is no pushrod on the KKK turbo and the adjustment screw is in the most inaccessible position imaginable. Nobody can seem to give me the approximate ratio between turns on the adjustment Allen screw and raise in boost pressure.

I have downloaded and read the 1.9TD tuning guide but have not, as yet, made any alterations. I am always wary when I read of the many head gasket problems on this engine.

Richard
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Post by davek-uk »

I've tuned using the TD Tuning Guide (and comments from this forum) and it makes loads of difference to the standard set-up - faster, more flexible and more economic. My Xantia estate was pretty mediocre when I brought it at 90k. I tuned it at 95k and now at 144k everything's still fine (I really shouldn't have said that).

The turbo used to start pulling at about 2k rpm, now it starts around 1.3-1.5k. Much more useful. Coming out of a 30mph limit it sometimes feels a bit sluggish, and then I realise I've left it in fifth! The car is so much more comfortable to drive with flexibility in the gears. I drive it much harder than I used to but I get at least a couple more miles to the gallon.

Where I live it's fairly hilly and I found the first two gears a bit on the short side. Now I don't have that problem. And the extra grunt is so useful - I hate revving a noisy diesel higher than I have to!
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Post by Mandrake »

davek-uk wrote:I've tuned using the TD Tuning Guide (and comments from this forum) and it makes loads of difference to the standard set-up - faster, more flexible and more economic. My Xantia estate was pretty mediocre when I brought it at 90k. I tuned it at 95k and now at 144k everything's still fine (I really shouldn't have said that).

The turbo used to start pulling at about 2k rpm, now it starts around 1.3-1.5k. Much more useful. Coming out of a 30mph limit it sometimes feels a bit sluggish, and then I realise I've left it in fifth! The car is so much more comfortable to drive with flexibility in the gears. I drive it much harder than I used to but I get at least a couple more miles to the gallon.

Where I live it's fairly hilly and I found the first two gears a bit on the short side. Now I don't have that problem. And the extra grunt is so useful - I hate revving a noisy diesel higher than I have to!
Hi Dave,

Can you give some more detailed information on what you did exactly ? I'm sure it would come in useful on my mum's 1.9TD :D Although the torque in the midband is ok, the power band is woefully narrow compared to the petrol so if there are some not-too-difficult mods that can be done I'd love to know the details...

Regards,
Simon
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1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
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Post by davek-uk »

The best threads are:

http://www.frenchcarforum.co.uk/forum/v ... php?t=7327
http://www.frenchcarforum.co.uk/forum/v ... php?t=5183

I did all my initial adjustments in about half an hour. Later I went inside the boot compensator on the top of the pump - but before that (with just the external adjustments) a lot of gain was achieved.
Pug Rifter long (20) - 41mpg - Gutsy for a 1.5!
Xantia 1.9 TD Temp.2 Break (97) - 208K@42mpg - Resting again.
Berlingo Multispace 1.6 16v (51) - 184K@36mpg - My shed! Still runs 15° retarded...
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