Compression ratio 11.3 only required 87 octane ???

[tsxuser]

I leaned about Hyundai Sonata and Kia optima 2011 both have higher CR than TSX, but manal only required 87 octane. How dose this happen without encountering knocking and pinging? Please advice.

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[justnspace]

Originally Posted by from wiki

Due to pinging (detonation), the compression ratio in a gasoline or petrol-powered engine will usually not be much higher than 10:1, although some production automotive engines built for high-performance from 1955–1972 had compression ratios as high as 13.0:1, which could run safely on the high-octane leaded gasoline then available.

A technique used to prevent the onset of knock is the high "swirl" engine that forces the intake charge to adopt a very fast circular rotation in the cylinder during compression that provides quicker and more complete combustion. Recently, with the addition of variable valve timing and knock sensors to delay ignition timing, it is possible to manufacture gasoline engines with compression ratios of over 11:1 that can use 87 MON (octane rating) fuel.

Hyundai might have several tools in place to allow a lower octane fuel.
Knock sensors, retarding the ECU, etc. which in turn LOWERS performance.

in the 3rd Gen TL, if we put a lower octane fuel, the ECU will retard timing thus lowering maximum HP and lowering fuel economy.

[justnspace]

You also DONT know if the Hyundai Users are experiencing ping.
I searched google for a bit, but I'm pretty busy at the moment..

[tsxuser]

despite lower performance, what about pinging or knocking possibility? Are they really able to 100% elimate by using 87 octane.
If so, why Acura can't . I use 93 octane all times, still has pinging issue. Do you think dealer can update ECU to 100% elimate pinging if i am willing to potential power loss?

[justnspace]

^one has to question why would you want lower fuel economy and power loss?

also, are you sure you're hearing knock?

[KillerG]

i wouldnt be surprised if you had knock, get it fixed via the TSB if you really have knock at 93/91

[justnspace]

^post the TSB, Please.

[Ken1997TL]

Are those engines direct injection? That might explain why.

[KillerG]

Originally Posted by justnspace

^post the TSB, Please.

did you buy a fucking tsx or something justin and ur not telling us about it?

http://tsx.acurazine.com/forums/show...&postcount=456

[justnspace]

Originally Posted by Ken1997TL

Are those engines direct injection? That might explain why.

Please, explain for every one to learn.

[KillerG]

i got this, if you got direct injection, it jizzes fuel straight into the combustion chamber instead of mixing it first with air. Since it burns more efficiently and mixes better when it gets bukkaked into the chamber you can use a lower octane rating to achieve similar performance


i think, yo

PEEEENISSSSSSSSS

[Ken1997TL]

Short answer, with direct injection gasoline is injected into each cylinder individually at very high pressure instead of in the intake tract.

The above answer is crude but accurate

[tsxuser]

Originally Posted by justnspace

^one has to question why would you want lower fuel economy and power loss?

also, are you sure you're hearing knock?

I am not saying it is knock, but i am pretty sure it is pinging around 2000rpm (dealer confirmed), mostly happen when you from stop to start. I have TSB 09-041 done about 6 months ago by dealer, but i doubt, beacuse they are not willing to have this TSB done until I asked for it. They just ask me to switch to 93, then I told them I use 93 from day 1 of owning the car. than they ask me to get Exxon 93. I have Exxon 93 for 3 tanks now, but still. It is not loud, but 100% annoyed. any suggestions.

[EL_PIC]

You might remember those Mighty Muscle cars of the 60's and 70's ...
I do ... and they knocked, pinged, and had post ignition to gazoo despite what gas used.

The Hyundai Sonata has
1. 198 hp 11.3 : 1 CR with 2.4 L Direct Injection or ...
2. 274 hp 9.5 : 1 CR with 2.0 Turbo I4 Direct Injection

F.W.I.W. on my '11 MDX with 11.2 : 1 ratio I use a mix of 93 and 89 octane {91 effective} and have no problem.

[nj2pa2nc]

Originally Posted by justnspace

^one has to question why would you want lower fuel economy and power loss?

also, are you sure you're hearing knock?

for me-: because it works=excellent gas mileage and no power loss-121,000 problem free miles and counting. Had the car serviced recently by the local acura dealer in NC. I go there when I can not get to the dealer in PA. They complimented me on how well the car was maintained and it did not need anything.

[justnspace]

^you also have a lower compression ratio at 10:5:1 where as the 3rd gen TL and the 2nd gen TSX's are at a high 11:1.

[I hate cars]

You can't have preignition with DI. You can have detonation but if the fuel is not in the cyinder yet, it can't pre-ignite. That's why guys are able to run 10+psi boost on top of 11:1 compression on pump gas.

DI has it's own issues though. I won't get one just yet until they get the intake tract carbon issues, fuel contamination of the oil, and cylinder wall washdown taken care of.

From a power standpoint, the only disadvantage is that the fuel does not mix with the air to cool it before it enters the combustion chamber but the added compression ratio and/or boost more than makes up for it.

I think this is the wave of the future but it still has some kinks that need to be worked out.

[ejongjin]

I have a 09 TSX tech and it does pinging between 2000~ 2300 rpm.

Of course I went to dealer and they were like, there is no knocking/pinging noise from my car.

I already figured out this is not a pinging noise.
this is pre ignition noise from wrong knocking sensor design.

This is common problem I think for the 09 TSX
and they should fix this problem...

I will go see my dealer to fix this problem in this week,
if I am not busy...