I've been happy with the performance I've been getting from my stock s5 turbo car, but just recently an oil seal in the turbo has started to split and so now I'm forced to swap it for something else.
Since I have a freshly rebuilt t04 turbo sitting in my garage, I thought I might give that a go, but I'm just wondering if this will be a straightforward swap of just the turbo or if further modifications will have to be carried out to the fuel system and intercooler setup.

I'm aware that to take full advantage of the bigger turbo I'd be required to change those things, but would it be possible to only replace the turbo and keep a level of performance similar to what I had before, or would it damage the engine if it doesn't get enough fuel and could the turbo be heat damaged from using just the stock intercooler?

 

Do this:

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/building-budget-hybrid-turbo-ebay-t04-parts-921510/

Rebuild the CHRA with a garrett T3 basic kit from GPopshop, put it all together, take it down to a diesel shop and have it balanced. You're looking at around $100 total, and you won't need to get a new exhaust manifold or downpipe.

 

what sort of problems would I run into if I was to go ahead and use my t4 garret turbo?

 

you will need an accepting manifold to bolt it up, re arrange or make new intercooler piping setup and new exhaust flange to bolt it up. That can be more costly to do.

And is advised to look into upgrading fuel system/injectors/ecu when upgrading turbo.

Building a hybrid with your stock turbo and your t04 will allow you to bolt up to your existing hardware, just need to take into consideration that you will need to look into upgrading your fuel system.

 

I have a manifold and dump pipe for the t04, I even have intercooler piping for it.
If I have to, then I can get a hold of a cheap intercooler and install that.
Hypothetically, If I was to keep my fuel system stock, what would happen?

 

You lean out the engine and detonate your engine, thus costing you an arm and a leg.