Octane and detonation

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Apr 13, 2001 | 12:40 PM
  #1  
What octane do you L03 guys usually run? I regularly use the mid-grade, but lately I've been noticing bad detonation accelerating from a standstill in first.
I have a 160 degree F stat, so my car usually doesn't get much over 100 degrees C.
I check the timing fairly regularly. It's steady at 0* with EST disconnected.
Is this a computer problem? Should I go with higher octane gas?

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No guts, no glory.
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Apr 13, 2001 | 05:39 PM
  #2  
If you don't have a stock chip I would go with a 180 thermo. Run a tank of higher octane and advance the base timing to 4 or 6. Is your EGR working? After running with the high octane, notice any ping, if so then either your timing is off/inaccurate or you have some other problems that I'm not familiar with.

------------------
, Jon (350 TBI! getting 23mpg highway)
91 Red RS w/grey int, sq stereo (Alpine v12, kicker solo, MB quart premium etc)AIM: JPrevost
  • Holley 670 TB unit w/ 1/2" spacer/adapter
  • Edelbrock RPM vortec intake
  • 350ho 330hp vortec crate motor
  • 8" harm. balancer
  • Stewart stage 2 water pump w/160 thermo
  • SLP tri-y headers to full 3"
  • Rebuilt trans w/ SLP shift kit
  • Centerline 16x8's all around
  • 36/24 mm sway bars
  • Full poly bushings, even motor mounts
  • SLP LCA and panhard
  • Alston SFCs
  • Edelbrock 3 point STB
  • Global west steering brace aka wonderbar
  • Eibach pro kit springs
  • Bilstien high perf. struts and shocks
  • All this and I still have AC
My websiteAny questions?
Reply 0
Apr 13, 2001 | 06:02 PM
  #3  
I just run 87 octane most of the time when I have my stock chip installed with 2 Deg. advanced base timing. I tried 4 Deg. but that caused pinging under heavy throttle when the engine was cold. When I have my Hyperchip installed I run 92 octane with 4 Deg. timing and never have any pinging, but with the price of gas these days I keep the stock chip in unless I plan on racing it. If you have pinging with a stock chip and 0 base timing you might have lots of carbon built up in your combustion chamber, that will raise the compression ratio and or cause a piece of carbon to glow red hot and cause pinging or preignition.

------------------
92 Camaro RS 5.0 5-Speed
14" Open Air Cleaner
3.08 Posi-trac
Edelbrock TBI Intake
Crane cam
Ported & polished stock heads 3 angle valve job
HyperTech Chip
SLP Headers (Ceramic Coated)
UltraFlo cat-back exhaust

74 Dodge Dart Sport 360 (11.2 1/4 mile)

2000 Dodge 1500 Ram Sport

[This message has been edited by DartByU (edited April 13, 2001).]
Reply 0
Apr 13, 2001 | 08:56 PM
  #4  
I run 93 octane. Never had a problem with detonation.
Reply 0
Apr 13, 2001 | 10:57 PM
  #5  
Quote:
<font face="Verdana, Arial" size="2">Originally posted by JPrevost:
If you don't have a stock chip I would go with a 180 thermo.
</font>
Wouldn't running a 180 stat make it more likely to detonate? Yes, I do have the stock chip.
What's a good combustion chamber cleaner? Any preferences?
Thanks.


------------------
No guts, no glory.
Reply 0
Apr 14, 2001 | 06:44 AM
  #6  
NT, you got mail.
Reply 0
Apr 14, 2001 | 11:44 PM
  #7  
Water is my favorite combustion chamber cleaner
Reply 0
Apr 14, 2001 | 11:53 PM
  #8  
Quote:
<font face="Verdana, Arial" size="2">Originally posted by DartByU:
I just run 87 octane most of the time when I have my stock chip installed with 2 Deg. advanced base timing. I tried 4 Deg. but that caused pinging under heavy throttle when the engine was cold. When I have my Hyperchip installed I run 92 octane with 4 Deg. timing and never have any pinging, but with the price of gas these days I keep the stock chip in unless I plan on racing it. If you have pinging with a stock chip and 0 base timing you might have lots of carbon built up in your combustion chamber, that will raise the compression ratio and or cause a piece of carbon to glow red hot and cause pinging or preignition.

</font>
You can run 87 oct.with a Hyperjunk chip.I use the cheapest and do not any problems of any kind.Might be the brand of gas.
Reply 0
Apr 15, 2001 | 01:21 AM
  #9  
Quote:
<font face="Verdana, Arial" size="2">Originally posted by Zac's92:
Water is my favorite combustion chamber cleaner</font>
Okay, I'll try that. Do I just grab the garden hose, and let it fly down the throttle body? Or should I fill the gas tank with water?
If, by chance, anybody else has an idea, post it.
Thanks.

------------------
No guts, no glory.
Reply 0
Apr 15, 2001 | 07:42 AM
  #10  
Put some water in a pop bottle.with the motor running grab the throtle linkage and hold it open enough to reach 3000-4000 rpms and pour the water into the TBI as fast as the motor will take it.Make sure you get some in each side of the dual plane manifold.I have done this before with no bad side effects, but am just alittle leary of it.I guess the theory is that the water turns to steam and losens the crud out of the chamber and valves.good luck.
Dave
Reply 0
Apr 15, 2001 | 04:08 PM
  #11  
Thanks for the help. I warmed up the car, and was about to try the water thing, while I was poking around underhood. I realized that the car was warm enough to have the thermo open, but the fan wasn't turning. Last winter it was making a dead bearing squeak noise, so I figure it was old age that killed the fan. I'm going to look for a parts store replacement, but I'm wondering about the fan temperature switch. I think I've heard about guys that put a lower temp stat (like I've got) into their car, compliment it with a lower temp fan switch. Is this true?

------------------
No guts, no glory.
Reply 0
Apr 15, 2001 | 04:40 PM
  #12  
Yes, get an adjustable on/off fan switch. I don't even have my stock fan switch wired up. For right now I just have the fan come on with ignition. This is not the best way to do it since at 75mph my fan is on....which is dumb.

------------------
, Jon (350 TBI! getting 23mpg highway)
91 Red RS w/grey int, sq stereo (Alpine v12, kicker solo, MB quart premium etc)AIM: JPrevost
  • Holley 670 TB unit w/ 1/2" spacer/adapter
  • Edelbrock RPM vortec intake
  • 350ho 330hp vortec crate motor
  • 8" harm. balancer
  • Stewart stage 2 water pump w/160 thermo
  • SLP tri-y headers to full 3"
  • Rebuilt trans w/ SLP shift kit
  • Centerline 16x8's all around
  • 36/24 mm sway bars
  • Full poly bushings, even motor mounts
  • SLP LCA and panhard
  • Alston SFCs
  • Edelbrock 3 point STB
  • Global west steering brace aka wonderbar
  • Eibach pro kit springs
  • Bilstien high perf. struts and shocks
  • All this and I still have AC
My websiteAny questions?
Reply 0
Apr 16, 2001 | 08:14 PM
  #13  
Quote:
<font face="Verdana, Arial" size="2">Originally posted by jase:
</font>
You can run 87 oct.with a Hyperjunk chip.I use the cheapest and do not any problems of any kind.Might be the brand of gas.[/b][/QUOTE]

If you don't have any pinging on cheap 87 octane you might need to check YOUR timing, and I'll admit the hypertech chip does not give a big boost to the horsepower but on my car it picked up .2 at the 1/8 mile track, and brand of gas does make a difference, I like Texaco the best.

------------------
92 Camaro RS 5.0 5-Speed
14" Open Air Cleaner
3.08 Posi-trac
Edelbrock TBI Intake
Crane cam
Ported & polished stock heads 3 angle valve job
HyperTech Chip
SLP Headers (Ceramic Coated)
UltraFlo cat-back exhaust

74 Dodge Dart Sport 360 (11.2 1/4 mile)

2000 Dodge 1500 Ram Sport
Reply 0
Apr 16, 2001 | 10:12 PM
  #14  
Quote:
<font face="Verdana, Arial" size="2">Originally posted by DartByU:
If you don't have any pinging on cheap 87 octane you might need to check YOUR timing, and I'll admit the hypertech chip does not give a big boost to the horsepower but on my car it picked up .2 at the 1/8 mile track, and brand of gas does make a difference, I like Texaco the best.

</font>
I ran the same thermomaster chip with a 160 thermo and 87 octane with no ping. I had my timing set at stock, 0 base. If you advance it like the old school trick then you'll need to run higher octane just because the chip will set it at say 40 but you changed the base to 6 or 8 and now it's 48...PING PING PING. .2 in the 1/8...you must be kidding!! I'm positive the chip isn't the reason, must have been really cold and you must have done something different. About the gas being different. It's all pretty much the same. Most of the stations get there gas from the same refinery. Gas is gas, there was something about BP gas and it's high sulfuric amount that was destroying GM SFI injectors after about 30K miles. That was with very tight toleranced injectors so don't think if you get gas from Texico that it'll perform better than Sunoco.

------------------
, Jon (350 TBI! getting 23mpg highway)
91 Red RS w/grey int, sq stereo (Alpine v12, kicker solo, MB quart premium etc)AIM: JPrevost
  • Holley 670 TB unit w/ 1/2" spacer/adapter
  • Edelbrock RPM vortec intake
  • 350ho 330hp vortec crate motor
  • 8" harm. balancer
  • Stewart stage 2 water pump w/160 thermo
  • SLP tri-y headers to full 3"
  • Rebuilt trans w/ SLP shift kit
  • Centerline 16x8's all around
  • 36/24 mm sway bars
  • Full poly bushings, even motor mounts
  • SLP LCA and panhard
  • Alston SFCs
  • Edelbrock 3 point STB
  • Global west steering brace aka wonderbar
  • Eibach pro kit springs
  • Bilstien high perf. struts and shocks
  • All this and I still have AC
My websiteAny questions?
Reply 0
Apr 16, 2001 | 10:41 PM
  #15  
Quote:
<font face="Verdana, Arial" size="2">Originally posted by JPrevost:
.2 in the 1/8...you must be kidding!! I'm positive the chip isn't the reason, must have been really cold and you must have done something different.
</font>
I'm positive the chip did gain .2 in the 1/8, I had run 4 passes with the stock chip then switched chips at the track and ran 4 more passes and gained .15 to .2 sec. after the chip change, this was about 8 years ago with the first Hypertech chip, I don't know if the chips are different now or not. And as Ripley would say Believe It Or Not!!

------------------
92 Camaro RS 5.0 5-Speed
14" Open Air Cleaner
3.08 Posi-trac
Edelbrock TBI Intake
Crane cam
Ported & polished stock heads 3 angle valve job
HyperTech Chip
SLP Headers (Ceramic Coated)
UltraFlo cat-back exhaust

74 Dodge Dart Sport 360 (11.2 1/4 mile)

2000 Dodge 1500 Ram Sport
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