How much of a power loss can knock cause

[iguanahotsauce]

So I am having an argument with a friend and I was just curious if anyone could give me some actual numbers so I can prove to him that for a 1G TSi it's good to use 92 octane instead of 87 octane. Now I know from all the reading I have done since I got the car, because it wasn't working when I got it so I read tons of articles about talons, that if you use the 87 octane gas you can have more detonation in the engine which will cause the ECU to retard the timing to reduce the detonation which effectively reduces the power of the car. What I am wondering is does anyone know an estimate of how much the ECU might reduce the timing with 87 octane and what kind of a hp loss that would mean. Any help would be greatly appreciated so I can argue back because he thinks he knows everything

 

[DSM1G90]

..defintely confusing, for you really don't see that many NT ESi's out there since the TSi-AWD was their more famous line..and horribly pricey in 1990 when they came out - over $20k out of the factory.

There was one 1990 on eBone a few years ago (yet, this was the Eclipse GS-X line) that was in mint, showroom condition-always covered and garaged, only had 26k on the odometer, and still had the window sticker showing the dealer price..over $21K ... it did go for almost $14k.

 

[YanDsm]

If you're running regular fuel to save some money!! You don't have the right car for you. Sell it and buy something that's not turbo. Run regular instead of premium fuel and you will break something instead of saving money.

 

[iguanahotsauce]

Easy on us BMW guys we're not all pricks ......


Obviously a car tuned on 93 with as much boost and timing as you can throw at it could detonate enough to cause engine damage... but a bone stock DSM that has 87 poured in it instead of 93 will eventually learn that its running 87 and just have a richer AFR and less timing w/o causing damage to the engine... Performance will suffer..but the engine will be fine..... Imagine if this safeguard wasn't in place... Mitsubishi would have had a bunch of engine failures coming back under warranty when people were too lazy to read the book that said put high octane fuel in it.

Agreed....... although nothing to do with DSM's though,I have seen box stock Subaru STI's kill engines breaking ring lands directly off the top of pistons due to ping the ecu couldn't get rid of and on these cars the first sign of det usually results in a 10-15 degree lop in the timing map which overall timing is 45 degrees at WOT with a map of about 14.5psi......not all cars can take that kind of a beating for extended periods of time.......

Sorry I didn't mean all BMW guys just it seems like most are pricks

..has anybody seen a DSM NT AWD - course, don't know what your point was in bringing this statement out since it had NOTHING to do with the topic of motor knock ....


Tell him to get back in his Yugo then, for he's wasting your time.

I know he's wasting my time, but I like to rub it in his face that I'm right and he's not

Im not understanding why your running 87 octane??

I'm not running 87, I run 92 which is the highest you can get around here.

If you're running regular fuel to save some money!! You don't have the right car for you. Sell it and buy something that's not turbo. Run regular instead of premium fuel and you will break something instead of saving money.

I run premium all the time I could never get rid of my TSi. It is by far the best car I have ever owned, but the only other car I have owned is a 91 Toyota Tercel

Just saying, TSI shouldve been enough to get it was Turbo, I have never seen a non turbo TSI and TSI alone could be FWD. so yea AWD has nothing to do with being turbo...............

Yeah I thought all TSi's were AWD Turbo models as well

FWIW, The ECU has a 2 tables each for AFR and Timing (MAX and MIN)... When you run 93+ it almost always runs strictly off the MAX AFR and Timing tables (which are pretty conservative tables themselves) ... When running 87 the engine will detonate a little and over time the ECU will learn that it needs to run richer/less timing so it will start running somewhere on an averaged value between the MIN and MAX AFR and timing table to get rid of the knock.

Obviously a car tuned on 93 with as much boost and timing as you can throw at it could detonate enough to cause engine damage... but a bone stock DSM that has 87 poured in it instead of 93 will eventually learn that its running 87 and just have a richer AFR and less timing w/o causing damage to the engine... Performance will suffer..but the engine will be fine..... Imagine if this safeguard wasn't in place... Mitsubishi would have had a bunch of engine failures coming back under warranty when people were too lazy to read the book that said put high octane fuel in it.

Is there somewhere I could find these tables?

its says "premium fuel only" for a reason on his dashboard... anything else, i.e. lower octane, e85, will lower the performance of your engine and may cause damage if the ECU can't compensate enough...

Mine actually says Unleaded Fuel Only. Which is weird because I have the Special price class with everything except sun roof and power locks

 

[dacowgod]

Is there somewhere I could find these tables?

Here's a link to the different tables used by various 4g platforms.
v3configs [ECMTuning - wiki]

You will have to download the ECMLink application from ECMTuning, Inc. to open the files...but its free to download and have a look..

FWIW these tables have been extended past stock... I believe stock only goes out to 8,000 RPM and down to somewhere in the 2.2ish load factor... beyond those values the ECU just uses the last row closest to it.

Take a good look at the timing tables... Especially on a 1g.. You will notice how agressive they are at 100% VE (5500-6500 RPM) on the MAXOctane table... and they are down 10 degrees or so on MinOctane... Its a huge difference..10 degrees less timing should be sufficeto to stop the detonation on 87 octane at stock boost unless theres some other issue..

 

[dacowgod]

Agreed....... although nothing to do with DSM's though,I have seen box stock Subaru STI's kill engines breaking ring lands directly off the top of pistons due to ping the ecu couldn't get rid of QUOTE]

I don't disagree...but that is the STI...which is factory tuned for performance by Subaru... My dad had a Baja Turbo (basically same thing as standard WRX in terms of engine) .. He ran 87 in it for a good 20,000 miles before I realized he was doing that... It never had any isues...and EVOScan read no detonation but it was definitely down on power........We bumped it up to 93 and reset the ecubut in terms of damaging the engine....nothing...

.. I'd venture to say a bone stock EVO would be safe..but the MR or Ralliart that are factory tuned for more power would not but thats because the safeguards have been lessened on those to produce more power...

 

[dacowgod]

I ran 87 once by accident (2gal only, thank god) and I was knocking out of boost on the hwy. Drained it out and a full tank of 93, never knocks.

This makes no sense.... if you are out of boost on the highway your car is running in vacuum with less compression then a stock Non-Turbo car...theres no way you'd see detonation then.

 

[Black-Out]

Agreed....... although nothing to do with DSM's though,I have seen box stock Subaru STI's kill engines breaking ring lands directly off the top of pistons due to ping the ecu couldn't get rid of QUOTE]

I don't disagree...but that is the STI...which is factory tuned for performance by Subaru... My dad had a Baja Turbo (basically same thing as standard WRX in terms of engine) .. He ran 87 in it for a good 20,000 miles before I realized he was doing that... It never had any isues...and EVOScan read no detonation but it was definitely down on power........We bumped it up to 93 and reset the ecubut in terms of damaging the engine....nothing...

.. I'd venture to say a bone stock EVO would be safe..but the MR or Ralliart that are factory tuned for more power would not but thats because the safeguards have been lessened on those to produce more power...

The Baja is 2.0liter....for some reason the better pistons were in the 2.0's.....they can take det alot longer than the STI......those engines had issues with
rod bearings,go figure.....I always wondered why they couldnt have an engine with out these two problems that was boosted ...... I guess Fuji Heavy just wants to keep Scooby owners on their toes...

 

[DSM1G90]

Small prob with turbo boxer STi motors is that the turbo is mounted next to No.3 cylinder (back left cylinder) and when that turbo starts cooking hot, it overheats that section of the motor.....I've heard turbo Sti's tht sounds like it's lobbing on one cylinder when they get mileage on them...

They're good little rally motors and that's about it..

I ran 87 once by accident (2gal only, thank god)

Just wire open the wastegate where this disables the turbo - that'll keep you off the pedal and out of boost for sure.