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

 

[brandonwh64]

Hmmm yea this would be interested to know as well cause i have read that 87 used for a period of time will kill your engine

 

[DSM1G90]

If he's a 1992 NT TSI, (since you didn't mention that he's an AWD) he can use 87 since that's a standard 4G63 aspirated motor. But, when a turbo senses knock via the knock sensor when using 87, it definitely retards the timing over TDC and the results is gradual loss of power.

Yet, the actual HP output due to the loss is dependent on many factors, like engine condition, setups and mods, timing, atmospheric conditions, and the like - why you'll never see actual HP numbers when knock occurs. (and this could easily turn into bench racing, if not careful..)

Let him be right - it's his problem, not yours. Plus, don't let his problems be yours. Know-it-alls are actually fun to watch -you'd love to throw a custard pie in their face and walk away laughing..

used for a period of time will kill your engine

.. and that depends on also a lot of factors as listed above: a ping here and there: better get it tuned up pronto, but a whole lot of ping here and one hits just right, it can immediately blow a hole in the top of that piston...and I've seen that happen with big block V-8's

 

[iguanahotsauce]

Hmmm yea this would be interested to know as well cause i have read that 87 used for a period of time will kill your engine

I don't think that's true. Because I can almost guarantee the guy who gave me my car, a family friend, ran 87 all of the time because he didn't want to spend the extra for the 92 and my TSi runs great, other than a boost leak from the compressor housing o-ring which I will fix as soon as I get some $ to change the oil, coolant, and transmission fluid at the same time

 

[brandonwh64]

I thought TSI was the turbo model and Base/ES was n/t?

 

[iguanahotsauce]

If he's a 1992 NT TSI, (since you didn't mention that he's an AWD) he can use 87 since that's a standard 4G63 aspirated motor. But, when a turbo senses knock via the knock sensor when using 87, it definitely retards the timing over TDC and the results is gradual loss of power.

Yet, the actual HP output due to the loss is dependent on many factors, like engine condition, setups and mods, timing, atmospheric conditions, and the like - why you'll never see actual HP numbers when knock occurs. (and this could easily turn into bench racing, if not careful..)

Let him be right - it's his problem, not yours. Plus, don't let his problems be yours.

oh sorry yeah it's an AWD turbo TSi
<--- and I was talking about my talon which if you look to the right it says 92 Talon TSi AWD

I know it depends on a lot of factors but I just want to get a general number to show him that it has an actual noticable effect on hp. It's completely stock with a rebuilt head, because of a timing belt that broke , and the timing is perfect as of a couple weeks ago

 

[Below Ambient]

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...

 

[97gst_spyder]

If you run 87 and knock. It will decrease performance. Even with 93 and knock you'll lose performance. Now if you knock enough, you'll lose all performance with a blown engine.

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.

 

[boostNmetal]

The boost control solenoid is likely closed when you are running 87 octane which will lower your boost pressure. If you like a slow car, have at er

 

[greengoblin]

The ECU cannot pull infinite timing. Knock kills engines. Tell your friend to jump up while at the same time you hit him in the top of the head with a sledge hammer. Then he will know what the pistons would feel like at full boost with massive knock. It hurts.

 

[DSM1G90]

Is he running 87 with his turbo, or does he even have one - why I though the conversation was with his car, not yours. Yes, for you should have the "Premimum Fuel Only" labelled in the gas gauge cluster being a '92.

If he doesnt even own a DSM, or similar with turbo (or, even a car in that matter...), then why the argument in the first place since he has nothing to back his theory up.

...he's just wasting your time in as well has your wasting your time with him.

 

[joescool2008]

You can loose all power with knock, after it detonates and pockmarks your pistons and cylinder walls.

 

[LandoAWD]

and my TSi runs great, other than a boost leak from the compressor housing o-ring which I will fix as soon as I get some $ to change the oil, coolant, and transmission fluid at the same time

I can't wait for you to feel a properly running DSM, much less a "great" running one.

Make sure to post in this thread when that day comes.

 

[SpoollinAwd]

When I bought my car I had like 14 counts of knock check make sure your knock sensor is good.That would be the first thing I do I know mine lost power like no other.

 

[skatershawn]

e85 will NOT lower you performance if you are tuned for it!
Just to correct you.. and e85 is rated at some 100 octane!!

87oct isn't as stable as 92-93oct, it can ignite from the heat of the boosted compression alone!
Thats why you use a fuel that is more stable and has a cooler burning property, and yes e85 is awesome for that!
As far as HOW MUCH you will loose, well i wouldn't even flirt with the possibilities!
Use the proper octane and drive your car till the end!

 

[iguanahotsauce]

I can't wait for you to feel a properly running DSM, much less a "great" running one.

Make sure to post in this thread when that day comes.

I can't wait either the day that I replace the o-ring is coming soon, it's just kinda pricey to have to change the transmission fluid, oil, and coolant all at the same time for a broke college student who just payed tuition for next quarter . Oh and I also can't wait until I get some performance mods done so I can smoke those idiots who think they're big shots because they spent a bunch of money on a BMW or a Mercedes

and I know that it will reduce performance I'm just trying to get a general number. Like would say a 30hp - 40hp loss be over exaggerating or would that be relatively close for a completely stock motor with bad knock from 87 octane?

 

[SpoollinAwd]

Im not understanding why your running 87 octane??

 

[iguanahotsauce]

Is he running 87 with his turbo, or does he even have one - why I though the conversation was with his car, not yours. Yes, for you should have the "Premimum Fuel Only" labelled in the gas gauge cluster being a '92.

If he doesnt even own a DSM, or similar with turbo (or, even a car in that matter...), then why the argument in the first place since he has nothing to back his theory up.

...he's just wasting your time in as well has your wasting your time with him.

No he doesn't own a DSM which is another reason why this argument started. He thinks he knows more about a DSM than I do when he has never even owned one and probably doesn't even know what DSM stands for .

 

[dacowgod]

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.

 

[SpoollinAwd]

Not meaning to get off topic so when all I put in my car is 93 i shouldn't really have to worry about min table?
And is that table only accurate at WOT

 

[GsxEcutioner]

If he's a 1992 NT TSI, (since you didn't mention that he's an AWD) he can use 87 since that's a standard 4G63 aspirated motor. But, when a turbo senses knock via the knock sensor when using 87, it definitely retards the timing over TDC and the results is gradual loss of power.

Yet, the actual HP output due to the loss is dependent on many factors, like engine condition, setups and mods, timing, atmospheric conditions, and the like - why you'll never see actual HP numbers when knock occurs. (and this could easily turn into bench racing, if not careful..)

Let him be right - it's his problem, not yours. Plus, don't let his problems be yours. Know-it-alls are actually fun to watch -you'd love to throw a custard pie in their face and walk away laughing..

.. and that depends on also a lot of factors as listed above: a ping here and there: better get it tuned up pronto, but a whole lot of ping here and one hits just right, it can immediately blow a hole in the top of that piston...and I've seen that happen with big block V-8's

Being AWD has NOTHING to do with being turbo or not.....

 

[DSM1G90]

Being AWD has NOTHING to do with being turbo or not.....

..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 ....

He thinks he knows more about a DSM than I do when he has never even owned one and probably doesn't even know what DSM stands for .

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

 

[Black-Out]

I can't wait either the day that I replace the o-ring is coming soon, it's just kinda pricey to have to change the transmission fluid, oil, and coolant all at the same time for a broke college student who just payed tuition for next quarter . Oh and I also can't wait until I get some performance mods done so I can smoke those idiots who think they're big shots because they spent a bunch of money on a BMW or a Mercedes

and I know that it will reduce performance I'm just trying to get a general number. Like would say a 30hp - 40hp loss be over exaggerating or would that be relatively close for a completely stock motor with bad knock from 87 octane?

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.......

 

[GsxEcutioner]

..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.

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...............

 

[skatershawn]

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...............

There is a Talon ESi.. a lot of people get confused because of this!
But it is neither Turbo nor AWD.