According to numerous FORD technicians... - Page 2

05-22-2002, 12:31 AM

Hey UNIT....as a side job maybe u should become a Ford technician. You seem to really know your Sh*t!

Turbo99GT · 05-22-2002, 07:46 AM

Quote:

Originally posted by cobrazex
I guess FORD must of made a mistake when they stamped "premium unleaded fuel only" on the fuel gauge on my 98 COBRA...........

Your Cobra has a much higher compression ratio which creates more heat and will make lower octane fuel flash earlier or pre-ignite. I'm sure if it was 9:1 instead of 9.85:1 it would be a different story. Hell, I would have my car tuned on C-16 if I thought I wouldn't go through a 55 gal. drum every 2 weeks @ over $300 a barrel. I have seen cars tuned on pump gas make 490 rwhp and then switched to C-16 on the dynoand a new tune and make over 150 rwhp more. I guess 22-23 points makes a huge difference.

Lizard King · 05-22-2002, 12:54 PM

Unit ... question for you.

My 2000GT has seen nothing but regular gas. It was a solid car to drive always consistent.

My 2002GT seems to go on Dog days when I put lower octane. So I have started putting 90+ octane gas in the car and even 94 + octane booster when I go to the track. It seems to behave consistently well when I put the higher octane gas. Could my engine ask for this type of gas??? Is that possible? or is it more likely that it is still adjusting being relatively new ~5000miles.

bstang46 · 05-24-2002, 11:51 PM

Well, how come when I burn 87 octane my car knocks. When you give it half or more throttle it knocks so loud that is all you can hear?????

Thanks

Unit 5302 · 05-25-2002, 03:11 PM

Lizard King I have a 2002 GT as well, build date 3/2002

and it's got about 1700mi on it now. I have run 89oct in it before, and I run 87 in it right now. I haven't noticed any pinging/knocking or performance degredation in the seat of the pants. Do you always get gas at the same place? I never get gas at Holiday here because of their "Blue Earth" gas campaign. It's possible the place you get your gas from is subpar? Also, I know you have a couple mods now. Anything that plays with the timing could be effecting your car, or possibly a defective anti knock sensor is pulling timing?

Did you have your car at the track when you were running 87? I'd be curious if it traps any higher on higher octane fuel.

Also, different cars do run differently. Take the old 5.0's as an example. In proper tune, people are able to bump the timing from 13-17* on premium gas. That's a 4* difference.

The difference on the 99+ cars is going to be obscene. Tolerances in the head are TERRIBLE on the new GTs. I've never seen anything so ridiculous in my life. I don't know who the moron working on the PI head design team was, but the tolerance is +/- 1.5cc in combustion chamber size. Same as the older heads, but the problem is the overall combustion chamber size on the PI heads is a meager 44.75cc. The pistons have a 17cc dish to them, but still. Your head's could have combustion chambers anywhere from 43.25cc to 46.25cc under Ford tolerences. Now, for the sake of argument we'll say your car is running really strong and you have at least one cylinder with a 43.25cc combustion chamber. Your compression ratio on that cylinder is going to be about 9.25:1, whereas if you have at least one combustion chamber with a max tolerance of 46.25cc, the compresion ratio will be 8.75:1. That's 1/2 point of difference between minimum and maximum compression from cylinder to cylinder. It's certainly concievable to me that a few real good factory "freaks" are going to have a lot of the 9.25:1 CR's and they might favor higher octane fuel a little more. There are also the "slow" 4.6's that will be making power based on a lot of the 8.75:1 CR combustion chambers. Of course the computer is designed to make sure the engine isn't knocking, and that means a little internal timing retard and more fuel on an engine that might be doing a little pinging. Of course, this is all grasping at straws because nobody knows what your head would truely cc out at. If your car truely runs better, and traps higher in the 1/4 under higher octane fuel, then you have a sensor malfunction, or your combo really does need the higher octane fuel to keep from pinging.

bstang46, How long have you been running high octane fuel in the car? If there is carbon build up, you can certainly run into the problem you are describing, although the anti-knock sensor doesn't seem to be working super good? If you've been running high octane fuel in the car for an extended period, the computer may base it's injection and timing curves on the higher octane fuel? I'm not sure how internally adjustable the newer computers are. I know on my 87GT, driving it hard lets the computer adjust itself to a more aggressive state of tune.

bstang46 · 05-25-2002, 08:00 PM

It knocked only when I used 87 ocatane. I tried the 93 to see if it would quit. So I am not sure what the problem is. There could me many things that have caused it. I used 87 first like the manual said.

Thanks

Lizard King · 05-26-2002, 02:26 AM

Thanks Unit for the help. I think this car is running some higher compression... I really seems to like the high octane stuff.

Unit 5302 · 05-26-2002, 01:28 PM

Quote:

Originally posted by Lizard King
Thanks Unit for the help. I think this car is running some higher compression... I really seems to like the high octane stuff.

It'd certainly be nice to think you have a freak on your hands. They really are a lot of fun!

Seriously though, you'd have to run back to back at the track. With 87, and then a higher octane to see if it's true that your car does better on high octane. If you don't trap any higher, you're not making any more power. It's still not a guarantee that you have a freak composition of small cc combustion chambers, the only way you can find that out for sure is to take the heads off and have them cc'd. Who knows?

05-22-2002, 12:54 PM	#23
Lizard King midnightruns.com Join Date: Dec 2000 Location: Ottawa, Ontario, Canada Posts: 584	Unit ... question for you. My 2000GT has seen nothing but regular gas. It was a solid car to drive always consistent. My 2002GT seems to go on Dog days when I put lower octane. So I have started putting 90+ octane gas in the car and even 94 + octane booster when I go to the track. It seems to behave consistently well when I put the higher octane gas. Could my engine ask for this type of gas??? Is that possible? or is it more likely that it is still adjusting being relatively new ~5000miles. __________________ NEW CAR! - 2002 GT TrueBlue - Best Stock ET - 13.77 Old Lizard - 2000GT Electric Green - Best ET STOCK: 13.662 @ 100.2MPH

05-24-2002, 11:51 PM	#24
bstang46 Registered Member Join Date: Sep 2001 Location: GA Posts: 84	Well, how come when I burn 87 octane my car knocks. When you give it half or more throttle it knocks so loud that is all you can hear????? Thanks __________________ 2001 Yellow GT Mods: A little of this, and a little of that.

05-25-2002, 08:00 PM	#26
bstang46 Registered Member Join Date: Sep 2001 Location: GA Posts: 84	It knocked only when I used 87 ocatane. I tried the 93 to see if it would quit. So I am not sure what the problem is. There could me many things that have caused it. I used 87 first like the manual said. Thanks __________________ 2001 Yellow GT Mods: A little of this, and a little of that.

05-26-2002, 02:26 AM	#27
Lizard King midnightruns.com Join Date: Dec 2000 Location: Ottawa, Ontario, Canada Posts: 584	Thanks Unit for the help. I think this car is running some higher compression... I really seems to like the high octane stuff. __________________ NEW CAR! - 2002 GT TrueBlue - Best Stock ET - 13.77 Old Lizard - 2000GT Electric Green - Best ET STOCK: 13.662 @ 100.2MPH

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05-22-2002, 12:31 AM	#21
StangGT2002 Guest Posts: n/a	Hey UNIT....as a side job maybe u should become a Ford technician. You seem to really know your Sh*t!

05-25-2002, 03:11 PM	#25
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Lizard King I have a 2002 GT as well, build date 3/2002 and it's got about 1700mi on it now. I have run 89oct in it before, and I run 87 in it right now. I haven't noticed any pinging/knocking or performance degredation in the seat of the pants. Do you always get gas at the same place? I never get gas at Holiday here because of their "Blue Earth" gas campaign. It's possible the place you get your gas from is subpar? Also, I know you have a couple mods now. Anything that plays with the timing could be effecting your car, or possibly a defective anti knock sensor is pulling timing? Did you have your car at the track when you were running 87? I'd be curious if it traps any higher on higher octane fuel. Also, different cars do run differently. Take the old 5.0's as an example. In proper tune, people are able to bump the timing from 13-17* on premium gas. That's a 4* difference. The difference on the 99+ cars is going to be obscene. Tolerances in the head are TERRIBLE on the new GTs. I've never seen anything so ridiculous in my life. I don't know who the moron working on the PI head design team was, but the tolerance is +/- 1.5cc in combustion chamber size. Same as the older heads, but the problem is the overall combustion chamber size on the PI heads is a meager 44.75cc. The pistons have a 17cc dish to them, but still. Your head's could have combustion chambers anywhere from 43.25cc to 46.25cc under Ford tolerences. Now, for the sake of argument we'll say your car is running really strong and you have at least one cylinder with a 43.25cc combustion chamber. Your compression ratio on that cylinder is going to be about 9.25:1, whereas if you have at least one combustion chamber with a max tolerance of 46.25cc, the compresion ratio will be 8.75:1. That's 1/2 point of difference between minimum and maximum compression from cylinder to cylinder. It's certainly concievable to me that a few real good factory "freaks" are going to have a lot of the 9.25:1 CR's and they might favor higher octane fuel a little more. There are also the "slow" 4.6's that will be making power based on a lot of the 8.75:1 CR combustion chambers. Of course the computer is designed to make sure the engine isn't knocking, and that means a little internal timing retard and more fuel on an engine that might be doing a little pinging. Of course, this is all grasping at straws because nobody knows what your head would truely cc out at. If your car truely runs better, and traps higher in the 1/4 under higher octane fuel, then you have a sensor malfunction, or your combo really does need the higher octane fuel to keep from pinging. bstang46, How long have you been running high octane fuel in the car? If there is carbon build up, you can certainly run into the problem you are describing, although the anti-knock sensor doesn't seem to be working super good? If you've been running high octane fuel in the car for an extended period, the computer may base it's injection and timing curves on the higher octane fuel? I'm not sure how internally adjustable the newer computers are. I know on my 87GT, driving it hard lets the computer adjust itself to a more aggressive state of tune.