sti-spec-a

JDM cars have a 180kmh limiter fitted as a requirement of Japanese law When we import them into the UK one of the fist things we do is convert the speedo reading by means of a gear reduction So instead of the limiter activating at 180kmh it will cut in at 180mph The engine management unit and fuel system can supply enough fuel for quick runs up through the gears the car can sit at 112mph without cylinder temps climbin excessivly high Thats why after 1995 Subaru stopped using closed deck blocks on standard JDM WRX When we bypass the limiter and exceed 112mph the load increases on the engine due to the work the engine has to do pushing the car through the air At 120mph the uk spec turbos have an enrichment feature The extra fuel supplied is used to cool the piston temps The JDM cars dont have this enrichment facility because its never been designed to exceed 112mph and when have our fun even only for a couple of minutes the crown of the piston heats rapidly due to the ECU thinking that the car is at 80mph and not having the fuel map present to lower the piston temps

What im basically saying is the general opinion that its because the JDM cars are mapped for 100ron fuel and when we give them 98.6 optimax they will go bang if you give them some stick I say its because we taking them further and faster than what thay cars were originally designed for not because our fuel is 1.4 away on the RON scale

Some JDM Ra versions have a fifth injector fitted for the purpose of supplying the extra fuel because the type ra was designed to operate in the upper end of the rev range for the majority of its life being an off the shelf factory built rally car

Cheers Grunt

Tone Loc

iTrader: (1)

Disagree.

What is this fuel enrichment that UK cars have??? Pre97 ecu maps for jap cars and UK cars are very similar... if you don't look closely the Prodrive fuel map is almost identical to the MY95/96 WRX.

Plus the ecu has a totally seperate speed input to that of the speedo so the ecu knows exactly what speed the car is going.

Plus plus the RA 5th injector does nothing on the road car, it's there purely for rally car homologation. The rally car does not spend most of it's life in the high rev range, due to it's restictor (and other factors) it's torque is mostly in the mid range.

SO what im saying is every arguement you mentioned is not true..... all IMHO

Tony.

Bob Rawle

I've advocated this for a long time, the UK car is speed (and by virtue of its longer gearing) rpm limited in the high gears, the JDM's are shorter geared, more aggressively mapped and set up for 102 ron !!! They then speed limit at 112 (ish) mph, so we remove the limiter, lower the fuel quality and try and red line them in 4th and 5th, cylinder temps then shoot and the pistons nip the bores, big ends bye bye.

Elementary my dear Watson !!!

However, as always, I would say that is not the sole factor, oil quality and servicing procedure are also BIG factors in this.

Treat with respect, thats the watchword, and do not hold in 5th at high rpm for extended periods, asking for problems. If you are going to do that then you need an engine building to suit.

Its confusing though as some engines will keep on going however much they are thrashed, piston to bore clearance varies a lot though ...

There is no "enrichment feature", the speed limiter is boost related. The JDM pistons in an STi are far superior to the UK ones (on GC8's), the extra fuel theory is definately wrong, its simply not there.

The engines are designed to rev, but the ecu MAPPING is NOT designed/intended to allow it in the high gears.

BTW the knock detection is non existant above 6800 rpm for sure on GC8's... food for thought?

New age cars are similar in ecu function but not archetecture.

cheers

Bob

zakesm

i dont know much about anything technical, but here in kenya, most of the imprezas are jdm wrx's. and they run on 93 octane leaded. havent heard of too many problems with big failures unless the sensors go AWOL due to lead deposits. luckily mine is a uk spec turbo so it is supposed to run on 95 octane. 93 does it then for me.

G00ner

My mate brought an RA, thrashed it titless for 12 months, ran it on 95, never serviced it and was told to rev the engine before switch off to keep the turbo spinning so it would cool the oil.

14,000 miles later and his old pig of a car is still running, some cars are just indestructable imo.

[Edited by G00ner - 1/20/2004 11:16:19 PM]

jason4656

when you talk about long runs at high revs, what would you class as a long run at high revs? how about a couple of miles just to see what its like?? dangerous??? i dont do hardly any motorway driving, but now and again i do a little run, like to open it up late at night for a few miles

DaveD

iTrader: (2)

Hmm,

several half hour sprints on the continent at sustained speeds in excess of 120mph, red-lined in 5th, many thrashes on the UK roads.....and my 100k MY93 WRX is still chugging along just fine.

When not being driven as it should be, it is looked after - always warmed-up, cooled down, regular oil chenges etc.

Luck of the draw?

Jay m A

iTrader: (2)

Dave, kiss of death saying that in public

quicksprint

so how come just recently there has been a lot of UK cars gone **** up then ?

speed has little to do with it....its more to do with incorrect fuel grade ,aggressive fuel and ignition timing (JDM MAPS)and unknown Jap history.

steve

jason4656

so this is not an issue with a brand new jdm car then? if you have it remapped?

DaveD

iTrader: (2)

Jay, I did have think twice before posting that!

However, I think it's a bit of a generalisation to say that every JDM car will go bang if you drive it over 112mph for more than 2 seconds. Most of my sustained high speeds have been in ambient temps of around 30degC. <touches wood>

dnb

I didn't think the OE knock detector was even as good as that - I though about 6000 RPM.

mutant_matt

What about on the new cars Bob (like the MY02 STi UK for example )

Matt

mikeesingh

iTrader: (3)

dave,

you will ok as you never go above 3000rpm

mikee

DaveD

iTrader: (2)

Mikee,

only when I'm stuck behind you!!