which motor actually holds up BETTER to boost? and turbo usage? looking to have something safe stock, and upgrade the seals in future, maybe a year at earliest

 

frum wut i hear...the s5 turbo is less prone to boost creep...something im running into with my s4 t2...the s4 t2 only has a 16mm wastegate....sumthing to look at wen upping the boost and installing a high flo exhaust and intake....

 

so if i get a nice blow off valve and do an fmic will i still have to worry about that? what exactly is boost creep? i am new to turbo.. have gained a bit of knowledge on rotary motor though

 

Boost creep is when boost begins to rise above what it normally should be at. for a S4 5.6LBs I believe. This is caused by a more free flowing exhaust like when you delete your cat, and a undersized wastegate. In a S5 this is not as much of a problem because it has a double wastegate port. If this happens and you are running stock ecu you will experience fuel cut.

 

The s5 is a newer design. It has straight through exhaust on the manifold.

The s4 has a twin scroll setup in which it has a flapper gate that closes to help build more boost at low rpms. It then opens up to let more exhaust flow for higher rpms.

I have an s4 engine with an s5 turbo

 

no...that wont solve it...do a search and youll find lots of info....what exactly are u planning to do with the car as far as tuning?...you have to tune for wut you want use the car for or u could end up with problems....

 

want her to be a good street car with the power and stability to do a good bit of track running as well

 

are you talking about the turbos or the motor?

 

everything, motor mainly though, can and will upgrade turbo at some point

 

well.. the s5 is electronically based OMP for instance
on the s4 it uses a rod attached to the throttle body
on an s5 the OMP is all electrical

when deleting cats both turbos will cause fuel cut with the stock ecu like he said above
just get a fuelcutcontroller from mazdatrix.

all in all the s5 turbo is better but if an s4 turbo is easier to access just buy it.. and have bnrturbos port your wastegate, you can keep your stock ecu, but recommended to get a piggyback system such as a SAFC and a better fuel pump/injectors. cheap upgrade. porting FTW

 

know how to get a hold of bnr?..i have an extra s4 turbo laying around...i wanna get the wastegate ported...

 

http://www.bnrturbos.com/2ndGen.htm

 

thanks alot for that link!

 

As far as turbo goes, the s5 is better. Slightly larger turbine.

As far as motor goes, they both have pos and neg. S4 is great because of the low compression rotors. But the S5 has a stronger stud area on the rear plate. They are known to crack on S4s.

 

how much is a rear plate? lol