# 2.5l 5 cylinder swap info and discussion



## Forty-six and 2 (Jan 21, 2007)

I figured this would be a subject to get a good discussion going. Seems that the TT world is somewhat ignorant to the idea of swapping to a 2.5l. I was the same before someone brought it up to me, now huge believer. I wanted to start this thread for discussion sake, to bring the idea into the light, and, if James is ok with it, possible sell a full swap to someone that might be interested in making it happen with their car.


I have read through the 1.8t technical forums for years, trying to decided what type of big turbo setup would be best for me. I am have been looking for a way to make good power, 450+, but didn't care for causing a crazy lag issue. With all of my searching, it doesn't seem to be possible to keep in the rpm range I was hoping for, while being capable of my top end goals. In the end, I was disappointed with the cost of building a 1.8t and having 4000+ near useless rpm.

A friend of mine mentioned a 2.5l, one taken from a mk5 Rabbit, Jetta, or Beetle. Since I already knew about the old 5 cylinder's reputation, this spared my interest. After a ton of research I was hooked.

The motor has a 4 cylinder bellhousing bolt pattern, so the TT's trans was no problem to bolt to it. The passenger engine mount can even work out with using the 2.5l's mount. With a little work, the engine management can even be adapted to the TT, giving to the ability to retain full function of the haldex system. The other option is to simply use the Jetta's engine harnes and ecu to run the motor, and use a SQS manual Haldex controller. This would also work with a standalone management system.

All os that seemed too good to be true, but it is! Now you are looking at a fairly easy swap, that has awesome low end torque and an extra cylinder to spool a larger turbo at near factory 1.8t ko4 range! The motor can handle a whole lot more power before imploding, as a 1.8t will. It's dyno proven to make EASY power. I have seen the upper 400's on stock everything at 18psi. Doug at Frankenturbo has succefully completed the swap and is currently developing a turbo kit for it, so there is tech support and first hand knowledge backing it all up.

You can get your car setup with a 2.5l for quite a bit less that you can build a 1.8t, and in the end, you have a much better motor. I have changed my the direction of my build to a pretty wild one, so no, I will not be using my collected swap anymore, but I still love the thought of it. I really would like to see more 2.5's getting dropped into Mk1 TT's! There really isn't a good reason not to do it.


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## bwdz (Jan 21, 2015)

I didn't realize this could be done fairly "painlessly". I have some fabricating skills and worked as a welder for a while but I bought my TT as a winter ride that would be fun (a lot more fun than my BMW both snow and not snow). It's been so much fun that now I am considering messing with it in the spring when I don't need to drive it everyday. How much hp can stock 2.5 internals handle, what is the stock compression?


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## Forty-six and 2 (Jan 21, 2007)

So far I have seen 523 whp with a haldex system on 23 psi, using a PTE 5862. He was using it as a weekend drag car, and did break the crank after a day of hard launches. So, the true failure point is still a little unknown under "normal" circumstances.

Edit for cr: it's 10:1. Which make it good for e85 and/or water method injection.


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## tfifeco (Aug 4, 2014)

Fifteen52 started a build like that back sometime around 2010.. and they have big write up on it.. they called the write up "The Most Inconvenient Project Car Ever" very interesting write up. They never got it finished due to internal business circumstances.. Not the swap, they show it can be done for sure

http://fourtitude.com/news/Audi_News_1/find-day-2-5-turbo-converted-mk1-audi-tt-1552/


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## Forty-six and 2 (Jan 21, 2007)

They did finally complete it. I talked to Brad about it at the beginning of collecting my parts. He said it was at it's wiring stage right as they were moving to a different shop location. A couple balls were dropped, and it was pushed to the back burner. It is running now and for sale.


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