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Hey there gang. Just wondering how much of a difference I'm likely to notice by running some higher octane fuel in a stock KR. Out here, the best pump super is 91 octane, and that's got some alcohol in it to get it to 91... Not the best fuel in CA. I haven't tried it yet, but yesterday bought a 5 gal. can of F&L "extreme" 100 octane unleaded to mix in. I suspect it's mostly toluene. I've added 2-1/2 gallons of that to completely fill a tank of Chevron 91. Hoping for 93 octane, or thereabout. Should I feel much difference with stock boost and tune?

 

Duane

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Hey there gang. Just wondering how much of a difference I'm likely to notice by running some higher octane fuel in a stock KR. Out here, the best pump super is 91 octane, and that's got some alcohol in it to get it to 91... Not the best fuel in CA. I haven't tried it yet, but yesterday bought a 5 gal. can of F&L "extreme" 100 octane unleaded to mix in. I suspect it's mostly toluene. I've added 2-1/2 gallons of that to completely fill a tank of Chevron 91. Hoping for 93 octane, or thereabout. Should I feel much difference with stock boost and tune?

 

Duane

 

 

 

Not really,

The stock tune and boost is basciacally design to run on 87 octane.

 

You could take advantage of the fuel with a tune or a blower pulley (or both)

You can put a blower pulley on a KR without needing to change the tune

Edited by BlackShelby
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As stated by BlackShelby already, the stock tune is designed to run on lower octaine fuel. Using octaine additves and/or higher octaine fuel (certain 76 stations in CA sell 100) is just a waste of your hard earned money. And for clarity, higher octaine fuel is only forumlated to arrest detonation and does not increase engine performance (other than preventing damaging detonation) or H.P.

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.. And for clarity, higher octaine fuel is only forumlated to arrest detonation and does not increase engine performance (other than preventing damaging detonation) or H.P.

 

Thought it may allow the computer to advance ignition timing a bit more with higher octane.

Oh- and I didn't know I could pulley it without a new tune.. Tell me more! :)

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Thought it may allow the computer to advance ignition timing a bit more with higher octane.

Oh- and I didn't know I could pulley it without a new tune.. Tell me more! :)

 

 

The only way it would be able to advance timing or allow more timing is if it had knock sensors(which is what a 2010/ 2011 gt500 has, no 2009 and older gt500 or KR have them)

 

Yes you can pulley a KR without a tune , there is plenty of room in the mass air curve which will adjust or keep the air fuel ratio correct/consistent. ( not like a regular gt500 which a blower pulley swap will peg the maf ).

 

A mass air is a calibrate sensor which measures air flow/CFM(flowed on a flow bench from ford) which is the only correct way any MAF curve should be created( ford does it this way and so does all the other manufactures that use MAF setups.(and really anybody else who understand how a MAF setup works)

 

Not a good idea to tune a car like some tuners do using short terms or an A/f sensor , then start adjusting the maf curve in the tune to get the correct air fuel ratio . If the correct MAF curve is used there would be no need to tune like that. Adding a pulley to a tune that was done like this might not be a good idea to add a pulley(since the MAF curve might not be correct all the way up to 5volt/max airflow.

 

Anyway since you have a ford tune in the car, the MAF has been flowed up to 5 volts/Max flow and is definitely correct from 0-5volts (don't have to worry if a tuner went in and messed with it) The complete MAF curve in the tune will be correct and will be an accurate when measuring the additional air the blower pulley will allow in the motor.

 

A MAF meter in a KR can read up to 2400kr grams which is 1200cfm or in HP is enough to support 800HP flywheel (which is about 680 RWHP) The injectors and fuel pumps can also support that power range

 

The mass air meter will tell the computer how much air is moving through it and will reference an A//F table,which will then tell the injectors to open more or less depending on how much air the meter is measuring at that time(this is just a simple way to explain it. It is a little more complex then that but thats the basic principle how it works)

 

The stock KR torque tables in the tune also have enough room in them to support well over 650RWHP before they would come a problem

 

The stock KR tune only has 18 degrees of timing a WOT which is plenty safe even with a pulley.(just to use as another an example for boost/power Ford's TVS procal tune when running a TVS 12psi has 18 degrees of timing in it)

 

I would not recommend going with anything smaller then a 2.7 pulley (smaller then that really just starts spinning the stock blower to fast and out of its efficiency range). a 2.7 will pick up about 3.7-4 pounds of boost , a 2.8 will pick up around 3psi (HP gain expect around 30-45RWHP depending on pulley) The stock pulley is 3.0

 

Another way/option to pick up another 1.2 PSI-1.5psi of boost and roughly 20rwhp would be a L&M 66 TB which is also another piece that works well with the stock KR tune.

Another TB option which works well with a stock KR tune is the ford CJ65 TB which will pick up about .75-1 psi and roughly 10-12RWHP.

 

So its pretty simple to pick some HP up in a KR without even messing with the tune.

Edited by BlackShelby
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...Yes you can pulley a KR without a tune...So its pretty simple to pick some HP up in a KR without even messing with the tune.

 

BlackShelby, thanks for your info! I'll be looking around at the "stock look" pulleys and the throttle body you mentioned. I like the idea of not having to change the tune, for CA smog check reasons.

I'm curious; does driveability become an issue with both of those mods and the stock tune, or will it still drive as smoothly and reliably as stock? I'm all for more zoom, but not a racer. My KR is used mostly for one day tours and cruises with my wife. :)

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BlackShelby, thanks for your info! I'll be looking around at the "stock look" pulleys and the throttle body you mentioned. I like the idea of not having to change the tune, for CA smog check reasons.

I'm curious; does driveability become an issue with both of those mods and the stock tune, or will it still drive as smoothly and reliably as stock? I'm all for more zoom, but not a racer. My KR is used mostly for one day tours and cruises with my wife. :)

 

 

 

Exactly like stock maybe even better.

 

I have a 2.83 stock looking pulley which I just took off went to a 2.72 now.

Can get any size stock looking pulley made you want

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87 octane? I was under the impression that standard GT-500's, as well as the KR are tuned for 91 octane.

 

 

I know for fact that is true of the 2010's.

 

My owners manual says 91 octane MINIMUM and recommends running 93 octane for best performance. It makes it real clear that you are not to run any lower than 91 octane.

 

The 10's are different in that they use KS technology, which is why you'll get better performance from 93 than 91 octane. With the "high performance tune" the KR's receive (540HP vs. stock 500HP) I'd be REAL surprised if it had a 87 octane tune on it.

 

I don't know...maybe they (Ford/SVT/Shelby) figure "better safe than sorry".

 

 

Phill

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Yes they all say 91 min and suggest 93

But again the tune was created using less octane.

They tuned with a safety factor in mind.(remember guys these cars have no knock sensors like the 2010/2011 do).

They do not want to put the car on the edge in case the octane varies around the country.

Most tuners run 21-24 degrees of timing in tunes that will use for sure 91-93 octane.

2010/2011 run 24 degrees of timing and will pull timing if they knock(they recommend the same fuel rating the KR does)

 

The stock KR tune is very safe even if only running 91 octane fuel

Edited by BlackShelby
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