i am looking to replace my 87 turboIIS engine soon with an s4 engine, but i have been told that the s5 is a better engine. is this true and why? if i decide to go wqiht the s5, would all of my components swap correctly from my factory engine?

 

Off the top of my head, the S5 has higher compression rotors, makes a little more power, DOES NOT have the crappy twin scroll design of the S4 turbos, has electrical OMP's ( good OR bad depending on what you want to do ) ... Thats all I can think of right now .. Im kinda tired

Im not sure what parts can swap over.

 

OMPs?

twin scroll design?

 

For TURBO low compression rotors (heavier) are better. Search and you will find a discussion on this one. As for swapping S5 Jspec motor you will have to swap alot of stuff from the Jspec. In other words you are only using the bareblock and the turbo/manifold..The rest of the parts from your S4 needs to be installed including the front cover. Front cover you ask??..well your computer can only control the mechanical oil metering pump. Remember the 89+ has the electrical one..If i were you i'd go with S4 Jspec motor for ease of installation. good luck!

 

Look, if you don't know these things, and you don't want to search, then stick with the S4. This stuff is complicated, you've got a steep learning curve.

But to answer your question..

Unless you have access to an S5 parts car, to swap everything in, stick with the S4. Yes, you can make an S4 car work with an S5 block, but for 20HP, it's not worth the trouble, and with the turbo cars, you can make that up in a heartbeat.

PaulC

 

Oil Metering Pumps

Twin scroll design was on the S4 turbo turbine housing. It had two runners of different diameter to help low end. But, as with anything that helps low end, it hurts high end.