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TDI Power Enhancements Discussions about increasing the power of your TDI engine. i.e. chips, injectors, powerboxes, clutches, etc. Handling, suspensions, wheels, type discussion should be put into the "Upgrades (non TDI Engine related)" forum. Non TDI vehicle related postings will be moved or removed. Please note the Performance Disclaimer.

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Old April 3rd, 2012, 03:04   #1
Join Date: Jun 2010
Location: UK
Default Repercussions from simply fitting a larger turbo?

Hey guys,

I have a 130bhp variant of the TDI engine fitted to my T5. There is a 174bhp version and I have a brand new Garrett VNT turbo from the 174. I am told it is a straight swap.

I have had my 130 remapped to ~160bhp but although it has made a big difference there is a large flat spot in the power band from 2000-3000rpm. I don't know what causes this?

Other than that issues I have no other problems that I know of.

What would happen if I simply fit the 174 turbo and do nothing else?
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Old April 3rd, 2012, 12:19   #2
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Join Date: May 2009
Location: Leam
TDI(s): Leon BKD
Fuel Economy: 50+mpg

It would be a waste of the turbo, get a new custom map to go with it. You might need bigger injectors too though...
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Old April 3rd, 2012, 23:22   #3
Ed's TDI
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Join Date: Jan 2001
Location: Victoria, BC, Canada
Fuel Economy: 5.7 / 5.1 / 4.5 L/100km

Originally Posted by ruds View Post
What would happen if I simply fit the 174 turbo and do nothing else?

Without more specific info on the turbo size/model, I'd guess te result would be a laggier response in spool up down low and possibly an even more noticeable "flat spot" . I agree with m1ketdi that you would likely need to get bigger injectors to supply more fuel, and you'd definitely need a remap for all the new hardware, otherwise why even bother. Just my 2 cents' worth.
First documented MK4 VNT20 Installation in North America!!
Done by JS Performance in Abbotsford, BC, Canada

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Old April 4th, 2012, 07:34   #4
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Join Date: Sep 2004
Location: Merseyside, England

If your current tune overfuels then fitting the larger turbo might result in this unburnt fuel now being used making more power.

Personally I'd get it mapped to suit the new turbo. What's the details of the turbo?
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Old April 4th, 2012, 08:22   #5
Join Date: Jun 2010
Location: UK

Thank you for your replies guys!

The reason I asked was incase there was no downside to fitting it now and having it remapped to take into account the turbo upgrade within the next month or two. I had wondered if the flat spot in the tune at the moment was due to a lack of airflow but I don't see any smoke at WOT so maybe it's something else.

I do not know the exact specs for the turbo in there now but the replacement says the following:

Garrett GTB1752
M68 A/R .74 (hot side)
M53 .45 9 (cold side)

Some guys have sent them away to be upgraded but I'm not sure what I would ask for...

The company that I will have remap it have said the injectors have been good so far up to 220bhp and even at that are still not at their limit so hopefully I can keep the stock injectors for now.
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