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2017 sportage sx
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Discussion Starter #2
Thanks for the info and your dealership link. Nice to see a dealer presence on this site.

Are you seeing any incidents of pull left condition in Optimas and an effective factory fix?
 

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2017 sportage sx
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448 Posts
Discussion Starter #3
we are located next to port hueneme which serves all of southern cals importing....we are the service department chosen by the factory to fix them all...so it's raining optimas at my lot...I came to work a few days ago and saw about 10 turbocharged optimas and was elated...then i heard the story from the service writer.....
Well since you drive a 600HP GTO it's really nice to have an enthusiast dealer here.

Would you please post update threads about this most pressing issue to current and prospective owners?

It can surely promote and benefit customers in your area and be a great boost to your business too...

Thanks for being here.
 

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Volvo S60 T6 on order, 1974 Mercedes 240D, Saab 93 Convertible, Ford F150, Nissan Xterra
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With that much boost, shouldn't the owner be running 93 octane despite Kia saying 87?
 

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2017 sportage sx
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Discussion Starter #5
With that much boost, shouldn't the owner be running 93 octane despite Kia saying 87?
Good question but with only 9.5 compression, direct injection, computer control of timing and an intercooler it must work very well on 87. Course you could always run 89 or 91 if you're worried but I'm sure it doesn't ping.
 

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Since they're direct injected and low compression engines they're designed to work on lower octane fuel. Higher octanes are not needed in lower compression engines. Higher octane fuels prevent pinging in high compression engines but are of no benefit in engines designed to run on lower octane fuels. You would essentially be wasting your money by running a 91 octane fuel in this car.
 

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Volvo S60 T6 on order, 1974 Mercedes 240D, Saab 93 Convertible, Ford F150, Nissan Xterra
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Since they're direct injected and low compression engines they're designed to work on lower octane fuel. Higher octanes are not needed in lower compression engines. Higher octane fuels prevent pinging in high compression engines but are of no benefit in engines designed to run on lower octane fuels. You would essentially be wasting your money by running a 91 octane fuel in this car.
But doesn't boost have a direct affect on final, dynamic compression ratio?

Boost Compression Ratio Calculator

My Saab has a compression ratio of 9.2 and 1 bar of boost (14.5psi). It requires premium.

For Kia to run 20 psi and only require 87 octane they must have dialed the compression back significantly.

I'm sure the engine monitoring system prevents the engine from having issues with low octane fuel. This used to be achieved by retarding the igntion timing. If so, won't this cause the engine to be "downgraded" and sap power? So I'm wondering, then, if running premium would achieve the advertised power rating?
 

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2017 sportage sx
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Discussion Starter #8
But doesn't boost have a direct affect on final, dynamic compression ratio?

Boost Compression Ratio Calculator

My Saab has a compression ratio of 9.2 and 1 bar of boost (14.5psi). It requires premium.

For Kia to run 20 psi and only require 87 octane they must have dialed the compression back significantly.

I'm sure the engine monitoring system prevents the engine from having issues with low octane fuel. This used to be achieved by retarding the igntion timing. If so, won't this cause the engine to be "downgraded" and sap power? So I'm wondering, then, if running premium would achieve the advertised power rating?
Meltdown ( great name for a tubo discussion!),

I think cam design has a greater effect on DCR than boost. Early exhaust opening would bleed-off
compression. Mr. Holden told us the Optima makes 17.5 psi boost and compression is greater than your Saab-9.5. I suspect your Saab does not have an intercooler which KIA has. Direct injection alone accounts for a power increase and better efficiency. Quench in the combustion chamber may be a factor as well.

As your excellent link says "It's the system (as a whole)-not the parts".
 

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2017 Kia Niro Touring w/Tech Pkg, Blue/Grey
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Meltdown ( great name for a tubo discussion!),

I think cam design has a greater effect on DCR than boost. Early exhaust opening would bleed-off
compression. Mr. Holden told us the Optima makes 17.5 psi boost and compression is greater than your Saab-9.5. I suspect your Saab does not have an intercooler which KIA has. Direct injection alone accounts for a power increase and better efficiency. Quench in the combustion chamber may be a factor as well.

As your excellent link says "It's the system (as a whole)-not the parts".
Maximum boost is supposed to be 17.4 psi but I don't believe it.........

The compression ratio of the engine is not low being 11.3..
 

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Discussion Starter #10

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2017 Kia Niro Touring w/Tech Pkg, Blue/Grey
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Audi A4, Saab 9-3 Aero SC
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Meltdown ( great name for a tubo discussion!),

I think cam design has a greater effect on DCR than boost. Early exhaust opening would bleed-off
compression. Mr. Holden told us the Optima makes 17.5 psi boost and compression is greater than your Saab-9.5. I suspect your Saab does not have an intercooler which KIA has. Direct injection alone accounts for a power increase and better efficiency. Quench in the combustion chamber may be a factor as well.

As your excellent link says "It's the system (as a whole)-not the parts".
I believe Saab has been using DI for over a decade now.

I'm too ignorant to know if an IC alone allows for a significantly lower compression ratio.
 
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