I've heard the Series 5 motor is quite a bit better then the S4 and can handle more boost? Is this true?
What other differences are there as well?
I searched for a while too.

cheers,
heb.

 

S5, I think it's better because it has higher compression and lighter rotors, and the ports are a bit bigger. I think it's a better motor. As far as which one can handle more boost, I truly don't know. But it seems like the S4 would, since it has lower compression rotors (but they're heavier). But remember because the S5 has higher compression rotors it will make more power at the same psi. I'd go with the S5, it's a better motor in my opinion.

Best of luck,
Alex

 

Forget the fact they are both FC engines.
The S5 is exactly that - better than an S4 but not as good as an S6.

Stronger internals (ie: stationary gears)
Better porting
Lighter rotors

The lower compression S4 rotors do not become an advantage until you want to run more than 99.9% of people will want to run (ie: 2 bar)

I don't see why you didn't find any search matches, this topic has been covered literally hundreds, maybe thousands of times.
Did you search the 2nd Generation Forum and read the FAQ?

Have a good day!

 

g00000000000 spongebob!!!!
my gf calls him: "Squar Bob Sponge Pants" :p

 

Application determines use. So what if it can handle more boost? How much boost do you plan on running. The S5 engine can certainly handle more than enough boost for street applications.

I have a S5 engine in my 87, and the higher compression certainly helps down low.

 

Out of all the (small) differences, the biggest change is the turbo system itself.  The "independent twin scroll" on the S5 makes for a much smoother and earlier spooling turbo, which is easily felt on back-to-back driving.



-Ted

 

Hmm things that are better.....

S5 has lighter rotating assembly.
Some what stronger internals.

I guess the porting is different.

External..
Turbo has been updated with a better compressor I think.
Turbo has a divided exhaust manifold with a dual opening wastegate for better control.

S5 UIM and LIM are better flowing

S5 has dual TPS
Better TID(less rough stuff inside)

It uses an electronic boost controller to manipulate boost instead of the dumb twin scroll thing.

Now if you are not using an EMS you will want to stay with your series.

So if your S4 stay with S4 if your S5 etc......

Although a S5 into an S4 car isn't terribly hard.
Just swap the front cover to S4 so you can use a mechanical OMP and switch over to S4 injectors and TB and your pretty much set.

I'm running a frankenstein block.
It's S5 externally but has S4 rotors and front cover.