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Discussion Starter · #1 ·
wat is the harm of runnin 95 fuel in the jap import high performance cars? i bought a tme recently its been in irelnad 5 yrs, i run it on 95 only , wat damage can it do to engine?
 

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detonation under high boost conditions, holes in pistons etc etc

Remember these cars are set up for high octaine jap fuel 100 ron min..............
 

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I think running on 95 is a false economy. You'll get less power, hence you'll have wasted good money on a performance car that you won't get good performance out of. And there is a good chance that the engine will be damaged (as others have said) due to detonation, again costing you cash.

I think 97ron is the minimum that they are designed to run on, just pay the extra 2p!!! (Evo's arn't supposed to be cheap!) :) [NB: I've not been to Dublin, but I assume that 97 is availible over there.]
 

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gizzer24 said:
wat is the harm of runnin 95 fuel in the jap import high performance cars? i bought a tme recently its been in irelnad 5 yrs, i run it on 95 only , wat damage can it do to engine?
kabooom, get it ecuteked
 

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MAD7BOY said:
I think running on 95 is a false economy. You'll get less power, hence you'll have wasted good money on a performance car that you won't get good performance out of. And there is a good chance that the engine will be damaged (as others have said) due to detonation, again costing you cash.

I think 97ron is the minimum that they are designed to run on, just pay the extra 2p!!! (Evo's arn't supposed to be cheap!) :) [NB: I've not been to Dublin, but I assume that 97 is availible over there.]
:D 95 only , :cry:
 

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Discussion Starter · #12 ·
the guy before me had this car for 4 an half years runnin it on normal 95 petrol, i have it about 3 months now still runnin it on 95, is it to late to add octane boost or do i have to leave it in to get mapped?
 

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never too late are ya goin to the irish meet ,a week saturday if you are have a chat with johnny ai autosport (airforce1 on here),he has mapped all the evos down here that i know of, mine,gsred,funnyclub,dublin derek,kceire,to name but a few,ask any of them or get a spin off one,you will be pleasantly surprised.
 

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Contrary to popular belief, all EVOs from the VI on (and possibly earlier) have maps which will cope with 95 RON fuel. Details here

Cheers,

Simon
 

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That would explain why inside my fuel flap there's a sticker that says:

"Unleaded Premium 98+

Unleaded 95 (Opt.)"
 

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spn said:
Contrary to popular belief, all EVOs from the VI on (and possibly earlier) have maps which will cope with 95 RON fuel. Details here

Cheers,

Simon
Hi

I think you might have misunderstod that thread, it often take me quite a time to understand what johnbanks posts, him being a clever bugger and all.

Yes Evos have two sets of maps, low and high octain for fuel and ignition, but the low maps are used only after the ECU detects knock ( detonation), this will lower a peramiter called octain number which will eventualy lead to the values for fuel and ignition being read from the low maps.

This is not ideal as your engine has already suffered knock. It would be much better to get the car mapped for the fuel. Usualy the timing is retarded as a starting point, the JDM maps tend to be quite agressive in the ignition maps.

MB
 

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burgers22 said:
Hi

I think you might have misunderstod that thread, it often take me quite a time to understand what johnbanks posts, him being a clever bugger and all.

Yes Evos have two sets of maps, low and high octain for fuel and ignition, but the low maps are used only after the ECU detects knock ( detonation), this will lower a peramiter called octain number which will eventualy lead to the values for fuel and ignition being read from the low maps.

This is not ideal as your engine has already suffered knock. It would be much better to get the car mapped for the fuel. Usualy the timing is retarded as a starting point, the JDM maps tend to be quite agressive in the ignition maps.

MB
As far as I was aware, that is how standard ECUs work. After a reset, I've occasionally see some knock at high load / revs while the ECU backs off the timing to adjust to Optimax.

What I had originally been told was that the EVO ECU didn't have the lower octane map in it so that it couldn't retard the ignition sufficiently to prevent continuous det on 95 RON fuel.

I thought that the danger with det was when it occurs continuously or for multiple revs, shock loading the internals and causing localised hot spots, which then cause more det and get hotter, leading to pitting or piston holes.

Cheers,

Simon
 

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The biggest problem is with continuous knock, and the stock ECU (at least on my IX) seems superb at supppressing knock even when you suddenly restrict the exhaust and reduce the octane. I think the danger points would come with running lean because the ECU has no sensor to tell it that the mixture is lean on full throttle. The ECUs are good and save a lot of engines, but I still think it is wise to measure what is going on if the conditions are likely to encourage det (eg airflow restrictions, tuned engine, low octane fuel). Widebands are now about $200, and datalogging cables are under $100, of course you have import duties, shipping etc, but compared with the cost of an engine they are very cheap indeed.
 

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When I bought an Evo 4 nearly 10 years ago there was very little information about them. The garage I bought it from said to run it on normal unleaded. I did 50,000 miles in that car and most of it subsequently on normal unleaded. The car never missed a beat in all that time.

Either knock detection and suppression was very good or there was enough overhead to cope. The car was always pretty standard.

However, from personal experience you don't have to tune a car much to definitely induce det from poor quality fuel.

If you're worried, you could get the piston tops inspected with a borescope for signs of det.
 

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johnbanks said:
The biggest problem is with continuous knock, and the stock ECU (at least on my IX) seems superb at supppressing knock even when you suddenly restrict the exhaust and reduce the octane. I think the danger points would come with running lean because the ECU has no sensor to tell it that the mixture is lean on full throttle. The ECUs are good and save a lot of engines, but I still think it is wise to measure what is going on if the conditions are likely to encourage det (eg airflow restrictions, tuned engine, low octane fuel). Widebands are now about $200, and datalogging cables are under $100, of course you have import duties, shipping etc, but compared with the cost of an engine they are very cheap indeed.
surely the lambda sensor would tell the ecu when it was running lean and adjust accordingly?
 
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