Do you think 92 octane gas will work?
Thread Starter
Le Mans Master
Joined: Aug 2007
Posts: 8,735
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From: WV
Do you think 92 octane gas will work?
In the 383 (10.25 to 1) compression motor that Pete K built me last year the only thing I have run is 93 octane fuel. The one gas station that had 93 octane fuel thats anywhere near me has shut down, and I was wondering if you guys would know if 92 octane would be sufficent to put in without pinging or knock. I know 93 is better, but do you think I would have any problems with 92. Just thought I would ask before putting it in. Sometimes living way up in the mountains has its drawbacks...Thanks ....WW
Last edited by WW7; Feb 14, 2011 at 08:22 AM.
Safety Car
Joined: Dec 2006
Posts: 4,290
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From: St Marys GA
I don't think you'll even notice a difference in one point. Worst case scenario, the PCM will sense the knock and retard timing a tad to keep things safe, and you'll make a little bit less power at low RPM / high load situations. The best person to ask would be Pete K himself, since the engine was built around a necessary octane rating, whether that be 93 or 91, or 87.
Melting Slicks
Joined: Nov 2008
Posts: 2,765
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In the 383 (10.25 to 1) compression motor that Pete K built me last year the only thing I have run is 93 octane fuel. The one gas station that had 93 octane fuel thats anywhere near me has shut down, and I was wondering if you guys would know if 92 octane would be sufficent to put in without pinging or knock. I know 93 is better, but do you think I would have any problems with 92. Just thought I would ask before putting it in. Sometimes living way up in the mountains has its drawbacks...Thanks ....WW
Be even better if it is non-oxygenated gasoline. No corn alcohol.
Dont know what these gas stations sell anymore.
You are great at tuning. Follwed you in scan an tune.
May have to retune slightly for that 92 gas.
Let us know.
BR
Thread Starter
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
Thanks for the replys. The only gas we have here is the 10% junk. 87 vette, you have me mixed up with someone else, I don't go to scan and tune except to read, (mseven) does all my tuning....
I guess I'll just have to put some 92 in and see how it goes..Thanks again...
....WW
I guess I'll just have to put some 92 in and see how it goes..Thanks again.......WW
Last edited by WW7; Feb 14, 2011 at 08:41 AM.
Race Director
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
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Assuming Pete set you up with a good quench chamber, I don't think you'd have problems running 89 octane.
Like the guys said, the KS is there to adjust.
BTW: We have the same SCR (though my DCR is probably higher). I was hoping I could run mid-grade if I ever had to. (It's why I lowered my initial compression from 10.75:1 to 10.25.)
Like the guys said, the KS is there to adjust.
BTW: We have the same SCR (though my DCR is probably higher). I was hoping I could run mid-grade if I ever had to. (It's why I lowered my initial compression from 10.75:1 to 10.25.)
Advanced
Joined: Mar 2006
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From: Lawrence- Rock Chalk, Jayhawk. KS
IMHO, Static compression is only part of the story. What is your dynamic compression? http://www.wallaceracing.com/dynamic-cr.php
If you are able to keep your temps way down and keep you air fuel ratio at a nice safe area (mid to high 12s), I would feel ok with as much as 8.5:1 dcr. Personally 8:1 dcr for a street car is more desirable.
My current set up is 8.32:1 dcr and I have to be careful. That is why I am investigating a switch to e85.
I would talk to Pete and see what he recommends.
If you are able to keep your temps way down and keep you air fuel ratio at a nice safe area (mid to high 12s), I would feel ok with as much as 8.5:1 dcr. Personally 8:1 dcr for a street car is more desirable.
My current set up is 8.32:1 dcr and I have to be careful. That is why I am investigating a switch to e85.
I would talk to Pete and see what he recommends.
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Safety Car
Joined: Oct 2008
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From: Los Angeles CA
you can run regular if you tune it for that, I run 10.7, with aluminum heads it should handle the compression.
timing and fueling for knock events.
your tune is off.
I can tune for regular, mid and super....
you are talking about pinging right?
timing and fueling for knock events.
your tune is off.
I can tune for regular, mid and super....
you are talking about pinging right?
Last edited by slickfx3; Feb 14, 2011 at 12:47 PM.
Thread Starter
Le Mans Master
Joined: Aug 2007
Posts: 8,735
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From: WV
..Im at around 2000 ft above sea level..I would have asked Pete K this question but the guy works 80 hours a week and isn't home to much , I really hate to bother him if I can bother someone else. I figured you guys would know this, and I was correct .Im still in the process of tuning so I guess Mick (mseven) can compensate for any differences the lower octane might create..Thanks for all the info, it sounds like 92 oct will work for me...WW
Last edited by WW7; Feb 14, 2011 at 03:40 PM.
Race Director
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
IMHO, Static compression is only part of the story. What is your dynamic compression? If you are able to keep your temps way down and keep you air fuel ratio at a nice safe area (mid to high 12s), I would feel ok with as much as 8.5:1 dcr. Personally 8:1 dcr for a street car is more desirable.
My current set up is 8.32:1 dcr and I have to be careful. That is why I am investigating a switch to e85.
My current set up is 8.32:1 dcr and I have to be careful. That is why I am investigating a switch to e85.
Chad, I agree dynamic compression is important, but there are many additional factors to detonation, like:
1) DCR (some people refer to SCR and cam size on this one)
2) Outside Temps
3) CC shape and quench size (also remove sharp edges)
4) Engine Temps
5) Engine Load
6) Timing curves
7) ESC circuit condition (and ignition condition)
8) Knock sensor sensitity (for example, how tight installed)
9) Accuracy of octane rating
10) Level of additives/quality of fuel
11) Exhaust configuration/condition
These are only the items I know of. That's why it can vary so much from motor to motor.
Race Director
Joined: Nov 2003
Posts: 12,221
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Originally Posted by WW7
When I say "way up there" Im refering to living off the beaten path. The closest Civilization is 10 miles down the mountain and that place isn't to civilized, (have you seen the movie "Deliverance")..
Originally Posted by WW7
Im still in the process of tuning so I guess Mick (mseven) can compensate for any differences the lower octane might create..
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Here's the table for max timing retard on an 89 bin (while in PE). Think of this as at or near WOT runs.
RPMS..Degrees
6400 --- 8°
5600 --- 8°
4800 --- 8°
4000 --- 12°
3200 --- 15°
2400 --- 11°
1600 --- 9°
0800 --- 8°
Here's the table for non-PE...
LV8..Degrees
256 --- 20°
224 --- 20°
192 --- 20°
160 --- 20°
128 --- 6°
094 --- 6°
064 --- 6°
032 --- 6°
LV8 is it's name for how much load the engine is under. Consider the measurements noted as 1/8th increments from idle to WOT (though it's a hair more complicated).
Notice, there is quite a bit of headroom here. Still, most tuners wouldn't want you pulling timing all day long. Theoretically, you'd have to drop quite a bit more than one octane point to cause major issues though.
Advanced
Joined: Mar 2006
Posts: 85
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From: Lawrence- Rock Chalk, Jayhawk. KS
Hey Chad. Seems like I remember your UserID but not that you lived in #1 College BBall land! (Look me up if you're even in KC).
Chad, I agree dynamic compression is important, but there are many additional factors to detonation, like:
1) DCR (some people refer to SCR and cam size on this one)
2) Outside Temps
3) CC shape and quench size (also remove sharp edges)
4) Engine Temps
5) Engine Load
6) Timing curves
7) ESC circuit condition (and ignition condition)
8) Knock sensor sensitity (for example, how tight installed)
9) Accuracy of octane rating
10) Level of additives/quality of fuel
11) Exhaust configuration/condition
These are only the items I know of. That's why it can vary so much from motor to motor.
Chad, I agree dynamic compression is important, but there are many additional factors to detonation, like:
1) DCR (some people refer to SCR and cam size on this one)
2) Outside Temps
3) CC shape and quench size (also remove sharp edges)
4) Engine Temps
5) Engine Load
6) Timing curves
7) ESC circuit condition (and ignition condition)
8) Knock sensor sensitity (for example, how tight installed)
9) Accuracy of octane rating
10) Level of additives/quality of fuel
11) Exhaust configuration/condition
These are only the items I know of. That's why it can vary so much from motor to motor.
Gregg,
Totally agree. DCR is not the only consideration, just a rule of thumb and more pertinent than static comp.
Ya, your just a jaunt down K-10 from me
. I need to make it up to KCIR this spring for some TT on Wed. nights.
Safety Car
Joined: Oct 2008
Posts: 4,022
Likes: 30
From: Los Angeles CA
Not sure where you got that. Plus, Mick may do it his own way.
Here's the table for max timing retard on an 89 bin (while in PE). Think of this as at or near WOT runs.
RPMS..Degrees
6400 --- 8°
5600 --- 8°
4800 --- 8°
4000 --- 12°
3200 --- 15°
2400 --- 11°
1600 --- 9°
0800 --- 8°
Here's the table for non-PE...
LV8..Degrees
256 --- 20°
224 --- 20°
192 --- 20°
160 --- 20°
128 --- 6°
094 --- 6°
064 --- 6°
032 --- 6°
LV8 is it's name for how much load the engine is under. Consider the measurements noted as 1/8th increments from idle to WOT (though it's a hair more complicated).
Notice, there is quite a bit of headroom here. Still, most tuners wouldn't want you pulling timing all day long. Theoretically, you'd have to drop quite a bit more than one octane point to cause major issues though.
Here's the table for max timing retard on an 89 bin (while in PE). Think of this as at or near WOT runs.
RPMS..Degrees
6400 --- 8°
5600 --- 8°
4800 --- 8°
4000 --- 12°
3200 --- 15°
2400 --- 11°
1600 --- 9°
0800 --- 8°
Here's the table for non-PE...
LV8..Degrees
256 --- 20°
224 --- 20°
192 --- 20°
160 --- 20°
128 --- 6°
094 --- 6°
064 --- 6°
032 --- 6°
LV8 is it's name for how much load the engine is under. Consider the measurements noted as 1/8th increments from idle to WOT (though it's a hair more complicated).
Notice, there is quite a bit of headroom here. Still, most tuners wouldn't want you pulling timing all day long. Theoretically, you'd have to drop quite a bit more than one octane point to cause major issues though.
I have been experimenting with all 3 grades of gas on m y last 3 tankfuls, I am back to 91, and pulled a little timing in some areas and hit maf 4,5,6, again.
you can get a bad tank of gas it is possible and that where the knock sensor comes into play to save you $10k motor
besides it's got forged piston and quality AFR heads, it will take a few knocks.
email me your bin file lets see what you got in there...