So I have already looked around to try and find a thread that outlines the basics about what you need to replace when doing a serious build, but I really can't find anything useful. So I decided to make a thread to find out.

This is something I'm planning for the far future since I like to be prepared in advance. My father and I are going to be building an extra garage on the side of our current garage so we can use it for a build that we want to do when he retires. After we are ready to buy the car we plan on turning it into a beast that we can do racing with. I want to get another B5 1.8t, but I don't quite know what type of pieces we would have to replace on the engine in order to handle a big turbo like a GT2871r or 28rs. I have read the turbo upgrade thread, but that just touches upon it. I would like to completely rebuild the engine so we don't have to worry about blowing it up with the turbo.

Any help is appreciated. And please don't flame, I have tried finding these answers to no avail.

Thanks,
Chris

 

Depends largely on what type of racing you want to do and how crazy you want to get with the build. What are your power goals? Budget? Drag racing or auto-x? Full on race car or are you going to want to be able to drive it on the street?

 

I'm looking for somewhere around 400awhp, budget isn't really solidified since this is something we will be piecing together over a long period of time, auto-x and want it to be street legal/usable.

Thanks CC, you're always helpful.

-Chris

 

In that case, I would start by doing some research on your local auto-x club and see what the class definitions look like. In many cases, upgrades like turbo swaps, chips, and fueling, and the fact that your car is AWD might bump you into a higher class that you won't be competitive in. If you don't care or it works out that you can get away with it, no worries.

Also, the fact that you want to do auto-x instead of drag racing is important in your choice of turbo. You don't want to put a huge turbo on the car that doesn't hit full spool until 5k rpm because you'll have a hard time staying in the power band. I would argue that for auto-x a smaller, quicker spooling turbo on stock displacement would be a better option than a 2.oL build with a GT28xx. I'm waiting for Redline and Mike Hood and those guys to chime in here, but that's just my $.02

 

Okay great thanks. Hopefully others do chime in, I'd love to get a bunch of perspectives.

Thanks,
Chris

 

There's another thread on the front page about best bang-for-buck turbos, you might give that a look. It's like I was saying, seems to me running a smaller turbo on stock displacement that hits full boost before 3k rpm but runs out of breath at 6k would be better than a larger turbo/larger displacement set up that holds full boost until 8krpm but doesn't make power until 4500-4700 rpm.

 

This is a very good point, I'm not trying to be a downer, but 400awhp on a small displacement engine and wanting to do autocross are in 2 totally different spectrum's.

To get 400awhp you're going to be looking at a lot of mods, a gt30xx sized turbo (or comp/PTE whatever you choose) and at that point I would look into building the head as well with at least aftermarket (non sodium filled) exhaust valves and probably meth. 400awhp seems to be the tipping point from normal BT build, to all out engine build.

Now if you want to use it for autocross then what Chris said is a perfect idea, 2.0 with a gtrs or gt2871r. But you wont be able to hit the 400awhp mark.

Just for some insight, I have the gt2871r elim and I love to do autocross, its a little laggy for autcross but still works great. Now with that said I'm planning on moving up to a holset hx35 and if I do that it will kill my chances at autcross. So what I'm trying to say is you really just need to figure out what your goals are.

 

400awhp was really just a feeler for power. I definitely don't want to have huge turbo lag. So I'm guessing that 300-350awhp range would be more reasonable for auto-x then? I'm not building this just for straight up autocross. I want to be able to go out and enjoy some speed as well. So that why I had such a high number to start with.

Thanks,
Chris

 

You don't have the car yet so you might want to consider buying a built one, one in progress or different stages. Building is fun but there's a lot to be saved and said for getting a great price on someone else's abandoned project.

/2 cents

 

Yeah, but that requires me to find someone selling their build. If we get the opportunity to do that then it would definitely be an option.