Engineer@Uni

Hiya guys, I was just checking out stats of the US 2.5 litre STi and noticed it's about 40kg lighter than the EU model (at least, according to autoindex.org). This coupled to the 2.5 litre engine (that has to be heavier than the 2 litre) probably means that somewhere along the way 50 kg or so have been ditched. The only thing I can think of is the front diff. In the Evo 8 in the states they ditched the 6-speed gearbox and the active yaw control diff, so I'm wondering if they did the same with the STi, maybe they killed the suretrack. Maybe it's my overactive imagination. Or maybe it's the overabundance of straight roads in the US...

Also I'd like to ask, if there is a front LSD diff in place in the latest US STi, can anyone confirm if it's a suretrac or the new helical design one in place now on EU and JDM STis?
Thanks
-Antonis

john banks

I heard that there were some Spec C style weight saving methods to put the weight under a group limit for the class they wanted it to be in. The 2.5 engine is not obviously heavier - same external dimensions, reciprocating internals of larger bore and throw may be a little heavier, but not much in it I reckon.

Pavlo

I believe the US car has indeed got such things as forged wheels (or some other lightweight part), the spec-C bumper subframes and various other things to get them under 1400kg in dry spec. The method of determining kerb weight may also vary, as the euro spec may include fluids while the US method does not, but that is just a guess on my part.

Paul

Engineer@Uni

Thanks guys, i hadn't thought of that. Both of you have good points.

I'd still like to know if theyre going to have the helical diff and the rest of the chasis upgrades of the 05 euro version

AJbaseBloke

Defo got BBS lightweight alloys, and some of the spec C shell details too.

However, AFAIK the bumper beam up front is a whopper for US crash testing. They already got DCCD-A from the get go... I've not kept up with all the gory details of diffs etc tho.

When back to backed vs a JDM @ Tuskuba circuit the US model was a couple of seconds slower than the JDM spec C of the time (I believe a C revision car was used). It was still a second or so off the pace of a std JDM STi, and IIRC the testers noted a lot more understeer was dialed into the US model.

Eitherway, still a great car, whichever model IMHO