View Full Version : Engine Differences - UK vs Jap WRX

Andy Tang
7th January 2001, 14:18
I was told by a VERY reliable source that the UK engine and the Japanese WRX engine are basically the same. Granted the STI's are completely different!

If that's the case the UK quoted at 215bhp and the Jap WRX quoted at 280ps (100 octane fuel excepted) I don't know, let's say 260bhp from the WRX engine with UK fuel.

So the question is, what do I need to change on my UK MY99 car, to obtain the WRX power? So if it's a case of changing of a few bits to get an extra 45bhp, it might be worth a go!!! http://bbs.22b.com/ubb/biggrin.gif

So whats the difference?? If it's cheap enough, I maybe better off keeping a UK car, rather than trading it in!!!


Andy Tang
7th January 2001, 14:20
Sorry due to my stupidity, I've just spotted this post!!!

7th January 2001, 21:29

information you have been given is still deemed to be correct. There will, however, be no discussion with whoever may have stated otherwise!

You have a choice to believe whatever suits you best.


Jan Shim
8th January 2001, 07:50
I have been told that UK spec WRX have high compression ratio in the area of 9.5 : 1. This cant be right coz if this were the car, there would be many blown engines by now. I am having a hard time with my own Japan spec 9.0 : 1 WRX wagon running 1.2 bar boost ..

Andy Tang
8th January 2001, 14:24

I don't think there's a dispute about whether it's true or not, rather what are the actual differences?


9th January 2001, 11:36
Absolutely right, Andy. And the list of differences is, according to my source of information, nowhere near as long as (authoritatively, I dare say) stated elsewhere.

UK cars do not have 9.5:1 compression ratio and Jan is right saying "it can't be".


Andy Tang
9th January 2001, 15:38

Could you tell me the actual engine differences, other than the turbo and ECU? As I have other plans for the turbo and ECU!!

Which bit's should I be looking to get added to my car??? http://bbs.22b.com/ubb/wink.gif

Thanks for your help

Gary Foster
17th January 2001, 21:04
Andy, I think Quattro has answered your question mate, this is of course only his opinion however.

Read the thread(s) again.


17th January 2001, 22:42
Gary, I am sorry but what I posted was not my "opinion". There is no such thing as an opinion when technical specification matters are discussed. Parameters of the kind either are or are not (and I can always be wrong in what I say as "are").

To reiterate, "basically the same" is still far from identical. Consequently, apart from a different turbocharger and ecu/map the only other difference is a slightly lower compression within the cylinders. It was necessary to enable the engine to develop the required power with (compared with the STi engine spec/parts) somewhat weaker parts and with a turbocharger (VF22) that moves more air than one in either the STi or Euro/UK specification car.


[This message has been edited by quattro (edited 17 January 2001).]

18th January 2001, 12:19
Hi All!

I was having an interesting discussion yesterday about compression ratio, whilst deciding whether it was a "good idea" to stuff a UK engine in my car for the timebeing (as opposed to another WRX or STi engine). Among the "cons" was that the UK has higher compression, I was reasonably sure that it did not, so just to be on the safe side (I've been wrong before, and will be again...) I checked "the bible", or more accurately the Subaru Workshop Manual for the MY97 engine. It states quite categorically that the compression ratio is 8.0:1, so it would appear that, in 1997 at least, the UK and WRX engines were "the same".

What it not certain is if the pistons are of a different design (it is possible to achieve the same compression ratio with vastly different combustion space geometry), whether there are differences to the crank and rods etc. BUT having seen cast pistons and an open deck block in an STi engine, it makes you wonder if even STi lumps are "that much better" :)



Gary Foster
18th January 2001, 23:23

An opinion implies a conclusion thought out yet open to dispute (Websters). This is not what you meant ?

Sorry for any confusion caused, no offence was meant.

19th January 2001, 07:44

absolutely no offence taken! Your quote from Websters is 300% accurate, but not applicable to what you and I said before. The point is that technical specification of something like an engine is not subject to opinions - things are clearly defined on paper as per those who have written the specification and designed/built the item in question. So, there is no place for an "opinion" in the context of the issue and that only is what I commented on.

Hope it is clear now and I very much enjoy enlightening dialogues like this, even if 99% of others see no point in them taking place.

take care

Gary Foster
19th January 2001, 09:26

Yes, thanks for going over that, I understand now what you are saying. Your first paragraph explains it very eloquently, rgds specifications are not an opinion.

I sometimes need these things explained a couple of times for them to sink in.

28th January 2001, 14:09
A good site for scoobie types inc engine id's is homepages.enterprise.net/srb/wrx.html the site gives the histories,engine differnces etc.
The sti has blueprinted engine with larger intercooler and turbo as well as a variety of other part differences

29th January 2001, 12:24
Sorry Robertski,
Couldn't get the link to go anywhere.
Can you repeat it?


29th January 2001, 13:40
I think he means here: