Just to verify.... regualar 87 octane right?

[Cobra4B]

Cars are tuned for regular gas correct? Just wanted to verify.

[panoz302]

I do not know but I ran 93 in the car and even ran some high octane race gas 3 -4 gallons to clean it out.

[Cobra4B]

^ Higher octane won't "clean it out".... octane is simply resistance to detonation allowing you to run more compression and/or more timing.

Higher octane fuel actually combusts slower so it's appropriate to run the correct octane for the application. I'm assuming since it's a stock 5.0 w/ a stock PCM it's tuned to run on 87.

[panoz302]

Yea, my race shop said to do it to clean the fuel system but it is probably bs, i do not know if race gas does that, my engine guy said the car should run best on midgrade fuel, and I guess running higher octane does nothing unless it is setup for it.

[btwog]

It probably depends on how they have the timing set. As I recall on the old 5.0l, you could still set the timing. I'd put a timing light on it and see. I think there is a SPOUT connector you have to remove to get the correct timing. At least thats how my '87 Mustang worked.

[hooked8]

has anyone checked this with any school guys, or PAD?

[eric1h]

anyone ever find this out?

[Panoz26]

I ran 87 this week without issues untill I hit the "fuel starvation / foam blockage or whatever this issue is"... :o(

[Gatorac]

All I've run is 87. That's what my 93 5.0 LX coupe took. I bought that car new.

It would be a good idea to check the timing. Once of the things to get a little more power out of these was to advance the timing. That would require premium fuel.

[PanozDuke]

Originally Posted by btwog

It probably depends on how they have the timing set. As I recall on the old 5.0l, you could still set the timing. I'd put a timing light on it and see. I think there is a SPOUT connector you have to remove to get the correct timing. At least thats how my '87 Mustang worked.

While an old post, I can't find a complete answer. Ford advertised the 5.0 could run on 87, but recommended 93. The initial timing was set at the distributor with the SPOUT plug pulled to take the computer out of the equation. Spec was 10 degrees. That was max for 87. With 93 you could set 12-14 initial for a low and midrange pick up. If it pings under load, back it off until it's happy. The computer compensates for lower octane by retarding the timing advance and limiting total advance, closed loop only. With higher octane, get advance sooner and I believe a degree or two more total advance at WOT, but that may come from bumping the initial up. Bottom line, it will make more power sooner on 93 with more initial advance. The stock ECM does not have enough range to adapt to higher octane than 93. While the difference is noticeable and measurable, it is not earth shaking- may be 5 hp from 1500 to 4800 rpm? Could help catching those Corollas. It was worth a tenth or so in the quarter if that helps put it into perspective.

Mike

[Panoz Paul]

Greetings ... I run 91 non-oxygenated & advanced the base timing well into 20's ; plus took my rev limiter up to 6000 ... Drove it like I stold it all summer ... Keep a ear for any pre-detination knocking ; if noted ; back down a bit on the degree's ... Paul W.

[PanozDuke]

Originally Posted by Panoz Paul

Greetings ... I run 91 non-oxygenated & advanced the base timing well into 20's ; plus took my rev limiter up to 6000 ... Drove it like I stold it all summer ... Keep a ear for any pre-detination knocking ; if noted ; back down a bit on the degree's ... Paul W.

Paul,
Did you pull the SPOUT plug out of the ignition harness before you set the timing at 20 at the distributor? If you didn't, you have got the initial timing confused with what the computer is doing. You need to set the initial timing at 10-12, then put the plug back in the harness so the computer can figure out the advance. If the plug is missing, your initial timing is also your total timing and all the computer is doing is running the injectors. You may also have an aftermarket ECU, I think I read that someone found they had an Accel box. I don't know how those work.

The ford factory ECM has the rev limiter fixed at 6150. Perhaps the use of an MSD box allows for setting the rev limit separately with the replaceable plugs. Is that what you were talking about by setting the rev limit at 6000. If so, what was it before you changed it?

Thanks,
Mike

[Panoz Paul]

Mike , A Ford Master Mechanic who grew up in a Ford racing family helped me do this ... I'm sure that we unpluged for this new base line ... The rev limiter is a MSD controller thats sits next to stock looking computer ; it was internally set to 5100 rpm for the school ... I installed / pluged in an adjustable dial stat from MSD ... No Excel components ...
Thanks / Paul W.

[PanozDuke]

Thanks, Paul. It's good to know about the MSD rev limit and how to get around it after a cam swap or other changes that would move the power band up higher than 5100.

I'm still wondering about the initial advance of 20 degrees. I know when I tried to adjust the timing on a 5.0 and forgot to pull the SPOUT plug, it showed about 20 degrees, but when I'd adjust the distributor, the computer kept trying to put it back there. It was imposible to tell what the actual initial mechanical advance was. If the Ford ECM is being used, it will electronically add a total of 26 degrees of total advance to what ever the initial, mechanical advance is. This would mean a total advance of 46 degrees. That is far in excess of what the 5.0 or any production gasoline engine I know of will tolerate. The system must be modified in some way to limit the total advance to about 38 degrees or you'd be needing a new motor. Maybe you could find out the details from him and let us know, especially if there is some more hp to be had safely from these motors. It sounds like yours is very strong.

Mike

[Panoz Paul]

Mike ... I spoke out my *%^ , i mean butt ... I called the mechanic that helped me w/ this ... He recalls that we when to 15 degrees ; which is still agressive ... Your suppose to eat eggs , not wear them on your face !!!