JDM - UK Fuel Effects
Discussion
Hi, I currently have a mark 1 MR2 which i'm intending to change for something different, although sticking with the Jap theme i've been looking at classic Imprezas and also GT4s, (ST185 and ST205). Now bearing in mind that a significant number of this type of car out there are JDM imports my question is this: Is running a car such as an STI or a GT4 on UK fuel likely to do damage to the engine over a period of time.
I've been told by a rally mechanic that has considerable experience with Subarus that it will do big damage to the engine eventually but i've also been told by numerous other people that the ECU will adapt to suit the octane rating of whatever's in the tank.
Anybody that can clarify the issue would be much appreciated.
Russ
P.S. I did do search but didn't uncover anything of real relevance, if i've missed a similar thread please do point it out.
I've been told by a rally mechanic that has considerable experience with Subarus that it will do big damage to the engine eventually but i've also been told by numerous other people that the ECU will adapt to suit the octane rating of whatever's in the tank.
Anybody that can clarify the issue would be much appreciated.
Russ
P.S. I did do search but didn't uncover anything of real relevance, if i've missed a similar thread please do point it out.
the jap imports are mapped for high octain fuels, if you get an sti impreza then its bye bye pistons if you use regular fuel.
if you get an import turbo always run it on high octain fuel.
shell optimax or bp ultimate, you cant go wrong with these, i have an impreza sti and it runs a bit lumpy on tesco 99 so i only use bp ultimate and its superb, realy smooth, full boost all way to the red no hesitations at all
if you get an import turbo always run it on high octain fuel.
shell optimax or bp ultimate, you cant go wrong with these, i have an impreza sti and it runs a bit lumpy on tesco 99 so i only use bp ultimate and its superb, realy smooth, full boost all way to the red no hesitations at all
Edited by steve_bmw on Tuesday 26th January 22:11
Edited by steve_bmw on Tuesday 26th January 22:11
I've researched this very thing......
....
...and the answer I've found is
Nobody actually knows!!!!
However to offer some help this is my take on it.
1. It depends largely on the car in question and more importantly the age. Apparantly in Japan they have 100 RON fuel, but this seems to be a newish thing (although I've not seen any exact dates). So some older imported cars won't have been setup to run on 100 RON but something a little lower.
This is good because 99 RON is available in the UK from places like Shell and Tesco.
2. Some ECU's that make use of knock sensors will be able to cope with lesser fuels better. But not all cars or model years of the same car can do this. And there is a question of how affective for how long. So when you decide on a car make sure you research it fully.
3. You can use octane boosters. But be warned this can be expensive and octane boosters are a strange thing. My understanding is they only increase the octane rating over a set level, e.g. if it says it increases the octane by 4 points. It may mean only 4 points above 95 RON. If you put in some 97 RON from BP It'll only give you 2 points higher. I'd go on recommendations of regular octane booster users.
4. You can buy a device which will monitor and detect engine knock (the result of low octane, also called detonation, pre-detonation, pinking, pinging). I think they are about £300, but might well be worth it if it saves an engine rebuild.
5. If really worried look for a UK spec car were possible. With an Impreza it leaves little choice, but there were official UK spec GT-Fours.
6. Some ECU's can be tuned, but again check. iirc the 99 model year Impreza is a great example of one that you can't tune or alter. To make any changes you'll need to replace the entire ECU setup.
7. While engine knock can certainly ruin an engine quickly. Don't forget if someone runs the car solely on 99 RON then they are probably ok. Knock is more likely to occur under higher streses and when ragging. If you drive hard often consider using the octane boosters as well as 99 RON.
8. If its really a worry look at buying something else. I'm a huge Impreza fan and I love the look of the GT-Four. But considering they are realistically likely to only manage 22-24mpg it makes them expensive per mile to run. Filling up with 99 RON and getting 22mpg is also most the same cost per mile as running a different car on 95 RON and only getting 19-20mpg. If you have to factor in the cost of an octane booster too then your per mile cost may be a lot higher than it would first seem.
....
...and the answer I've found is
Nobody actually knows!!!!
However to offer some help this is my take on it.
1. It depends largely on the car in question and more importantly the age. Apparantly in Japan they have 100 RON fuel, but this seems to be a newish thing (although I've not seen any exact dates). So some older imported cars won't have been setup to run on 100 RON but something a little lower.
This is good because 99 RON is available in the UK from places like Shell and Tesco.
2. Some ECU's that make use of knock sensors will be able to cope with lesser fuels better. But not all cars or model years of the same car can do this. And there is a question of how affective for how long. So when you decide on a car make sure you research it fully.
3. You can use octane boosters. But be warned this can be expensive and octane boosters are a strange thing. My understanding is they only increase the octane rating over a set level, e.g. if it says it increases the octane by 4 points. It may mean only 4 points above 95 RON. If you put in some 97 RON from BP It'll only give you 2 points higher. I'd go on recommendations of regular octane booster users.
4. You can buy a device which will monitor and detect engine knock (the result of low octane, also called detonation, pre-detonation, pinking, pinging). I think they are about £300, but might well be worth it if it saves an engine rebuild.
5. If really worried look for a UK spec car were possible. With an Impreza it leaves little choice, but there were official UK spec GT-Fours.
6. Some ECU's can be tuned, but again check. iirc the 99 model year Impreza is a great example of one that you can't tune or alter. To make any changes you'll need to replace the entire ECU setup.
7. While engine knock can certainly ruin an engine quickly. Don't forget if someone runs the car solely on 99 RON then they are probably ok. Knock is more likely to occur under higher streses and when ragging. If you drive hard often consider using the octane boosters as well as 99 RON.
8. If its really a worry look at buying something else. I'm a huge Impreza fan and I love the look of the GT-Four. But considering they are realistically likely to only manage 22-24mpg it makes them expensive per mile to run. Filling up with 99 RON and getting 22mpg is also most the same cost per mile as running a different car on 95 RON and only getting 19-20mpg. If you have to factor in the cost of an octane booster too then your per mile cost may be a lot higher than it would first seem.
RevoHJC said:
VPower,
Thats all you need.
It wont explode on lower octane, but it will knock until the ECU retards the ignition suitably but you'll lose power.
Dont bother with BP Ultimate or anything, my skyline ran rubbish on anything other than Vpower so they must be doing something right
Agreed I run my UK STI on Vpower and Ultimate 102 (now and again). If I try and use anything else it knocks badly under load. I'd imagine a JDM car would be worse. The big ends suffer when you get too much det / knock, hence the reason Subaru won't warranty the P1 and why so many have had rebuilds.Thats all you need.
It wont explode on lower octane, but it will knock until the ECU retards the ignition suitably but you'll lose power.
Dont bother with BP Ultimate or anything, my skyline ran rubbish on anything other than Vpower so they must be doing something right
99/00 Subaru ECU can be remapped, its pre that year that require a new ecu, or a scubbyecu or esl board.
The JDM Subaru's all have knock sensors, but do not seem to retard the timing enough to stop a JDM knocking on 95. Some even knock on 97 as well, Use Tesco 99 or V power and you should be fine
The JDM Subaru's all have knock sensors, but do not seem to retard the timing enough to stop a JDM knocking on 95. Some even knock on 97 as well, Use Tesco 99 or V power and you should be fine
I use BP ultimate in my Evo but i still add octane booster if i am going to be driving it hard as whilst its ok 99% of the time it will det on high sustained boost
V power is fine though
Lots of octane boosters are a waste of money this one isnt and i buy it by the crate of 12 for £110 inc post on ebay , lasts me a year good enough for the 6000 miles i do in my car
http://www.lucasoil.com/products/display_products....
V power is fine though
Lots of octane boosters are a waste of money this one isnt and i buy it by the crate of 12 for £110 inc post on ebay , lasts me a year good enough for the 6000 miles i do in my car
http://www.lucasoil.com/products/display_products....
Vixpy1 said:
liner33 said:
I use BP ultimate in my Evo but i still add octane booster if i am going to be driving it hard as whilst its ok 99% of the time it will det on high sustained boost
V power is fine though
if you don't use BP ultimate, it won't det. Its sV power is fine though
te.liner33 said:
I use BP ultimate in my Evo but i still add octane booster if i am going to be driving it hard as whilst its ok 99% of the time it will det on high sustained boost
Is that with the top mount intercooler or an FMIC?I'm wondering if an FMIC is obligitory given the lack of 100 RON in the UK?
SmoothRB said:
liner33 said:
I use BP ultimate in my Evo but i still add octane booster if i am going to be driving it hard as whilst its ok 99% of the time it will det on high sustained boost
Is that with the top mount intercooler or an FMIC?I'm wondering if an FMIC is obligitory given the lack of 100 RON in the UK?
Pretty sure you'd be doing well to find an Evo with a TMIC
Its only when you're going for big power and flowing a lot of air that you need to change from TMIC to FMIC on the likes of STi Subarus though - the trend of fitting a massive shiny FMIC without a massive shiny turbo is only really guaranteed to increase turbo lag.
IronOxide said:
Thanks for all the suggestions. I think the best bet may be a fresh import and then just use the correct fuel.
Cheers all.
Russ
I use Tescos 99 most of the time, and Shell the rest. If i am on a long M-way journey i can get away with normal petrol but not reccomended if you intend to put your foot down.Cheers all.
Russ
Oh and if it is cold don't even think about using anything other than 99, the OH filled it up with BP95 last month and it felt like it was powered by Kangaroos.
GravelBen said:
SmoothRB said:
liner33 said:
I use BP ultimate in my Evo but i still add octane booster if i am going to be driving it hard as whilst its ok 99% of the time it will det on high sustained boost
Is that with the top mount intercooler or an FMIC?I'm wondering if an FMIC is obligitory given the lack of 100 RON in the UK?
Pretty sure you'd be doing well to find an Evo with a TMIC
Its only when you're going for big power and flowing a lot of air that you need to change from TMIC to FMIC on the likes of STi Subarus though - the trend of fitting a massive shiny FMIC without a massive shiny turbo is only really guaranteed to increase turbo lag.
Cooler air = less chance of knock.
SmoothRB said:
Cooler air = less chance of knock.
Yes, but beyond a certain point a bigger intercooler isn't improving cooling efficiency by any significant margin, all its doing is slowing airflow down and slowing throttle response by making you compress a much bigger volume of air when you go from less boost to more boost.What you want is not the biggest intercooler possible, but the best sized/shaped, most efficient intercooler for your specific car/engine/turbo/tune/power level/etc.
Edited by GravelBen on Monday 29th March 09:53
GravelBen said:
SmoothRB said:
Cooler air = less chance of knock.
Yes, but beyond a certain point a bigger intercooler isn't improving cooling efficiency by any significant margin, all its doing is slowing airflow down and slowing throttle response by making you compress a much bigger volume of air when you go from less boost to more boost.What you want is not the biggest intercooler possible, but the best sized/shaped, most efficient intercooler for your specific car/engine/turbo/tune/power level/etc.
Edited by GravelBen on Monday 29th March 09:53
SmoothRB said:
...stock intercoolers are generally just about adaquate.
Where do you get that idea? Saw some interesting flow tests on Subaru intercoolers and IIRC the standard newage STi (and 3rd/4th gen Legacy) intercooler was actually more efficient than many of the aftermarket replacements.SmoothRB said:
GravelBen said:
SmoothRB said:
Cooler air = less chance of knock.
Yes, but beyond a certain point a bigger intercooler isn't improving cooling efficiency by any significant margin, all its doing is slowing airflow down and slowing throttle response by making you compress a much bigger volume of air when you go from less boost to more boost.What you want is not the biggest intercooler possible, but the best sized/shaped, most efficient intercooler for your specific car/engine/turbo/tune/power level/etc.
Edited by GravelBen on Monday 29th March 09:53
Lower IAT's may well help, but it's more about the a/f ratio and the octane rating of the fuel.
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