new (2005-2007) mustangs - regular fuel?

I have a 2005 GT and burn only regular in it. I get right at 23.3 mpg in mostly highway driving. I know the car will go 110 in 3rd gear. That's plenty fast enough for me.

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John

Premium fuel doesn't improve performance, Period. You will see zero benefit over regular fuel in all cases, except where your compression ratio is high enough to cause pre-ignition (pinging) on regular fuel.

Engines are designed (compression ratio/timing) for a specific octane rating - it is typically a HUGE waste of money to use a higher than recommended octane rated fuel. Therefore, always use fuel with an octane rating as close as possible to what the manufacturer suggests for the engine. This mindset assumes you have not made major modifications to the engine (compression ratio/timing).

Mmm, I think the above is a true statement, or at least was, until the

John

Owners manual for that car specifies 87 octane. Recommends *against* using premium.

Yep, I have seen the Spanish Oak in action... it will dynamically add spark if it thinks the car is "under-sparked"... You can watch the knock senors add and subtract timing... What I don't know is if they can add enough spark to take advantage of higher octane... but I have seen knock sensors add like 2 degrees... So in fact John (the other one) is right...

I'll have to double check on what the manual says... LOL

The 5.0 mag dynoed the car on 87 and again on 93; they got a few more hp with the 93. I'm going to rifle around and see if I can find that issue, and I'll post a quote from the article.

John

ditto for the 2006 GT (even the 110 in 3rd gear) and the average city for me ~19

no mods :)

I'm using 87 octane in my '06 GT and it seems "peppy" enough, lol. but I am amused whenever I read a new article by an "expert" saying to use the lowest grade gas that doesn't ping. all cars have had computer controls for years and if you can make a modern car ping, you've really got problems!

have a 2002 Chrysler 300 (that's with the V6)......the owners manual recommends mid-grade, and tells you how much horsepower it develops with different octances: 215 on regular, 235 with plus. the performance isn't much different in normal driving - but is in the mountains. there is a BIG difference in miles-per-gallon: if gets 21 mpg (highway) on regular, 24 on mid and 28 with premium. most times it pays to use higher octane (on this particular car).

once my Mustang in broken-in, I'll do some comparisons with it, too.

Not really. The older 4.6's GT's (pre 2005) did not have knock sensors so there was no way for the engine management to know if there was pinging.

RT:

gees, had no idea that FoMoCo was so behind-the-times. I've got 5 cars and the only one I've ever heard ping is the '57. ('57 Packard.....only

Why did Ford stop using knock sensors?

Stop ? The 5.0 and pre-2005 4.6 never had knock sensors (The cobra's did I think). If nothing is wrong with the engine there was no need for it on these engines.

If something is wrong the car can ping. Carbon deposits inside the combustion chamber for instance can increase your compression and cause pinging. There's probably a million other reasons why it could ping.

Cobra 4.6 has had them since 1996. Actually they have two of them. They work best at detecting heavy ping and knock. Basically the stuff that could potentially be damaging. They don't work very well at detecting a mild ping at higher RPMs. The 99's received a revised sensor, that I believe was termed "dual differential". From what I understand they are a little better at detecting low level ping/knock.

Too much information. Sorry. Trying to take my mind off work on this late Friday.

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yup......289 Stude......115,000 mile California car....no rust but had to redo interior, paint, chrome, etc. blower was gone when I bought it.....found the right bits and took to Myer Studebaker in Zanesville OH. Didn't know if the old engine would take the boost.....but checked-out OK......put in new valve seals, adjusted valves & turned it and runs sweet. Too bad they used a 2 barrel to supercharge in '57/8.....think it was a space issue. The later R2/3 engines had more power, but the neat thing about the '57/8 setup is the wild, variable ratio pulley that the later ones don't have.

HaHa.....just sold my Avant II ('79 with 19000 miles)....Course, had the Chev 350.....but even so, had the usual steering box leakage, grease falling off all the fittings, little differential drip, overflow from the overflow when it gets really hot, etc. Bought by a non-Stude guy and he can't understand why "everything seems to leak".

Missed a chance to buy an R-2, 4 speed '64 Avanti years ago.......it was a wild ride (bet it's worth plenty now);

On the ''57/8 supercharger set-up......I think they determined it had to be mounted on top of the engine, and with the variable-ratio pulley it was so long that they only had room for a 2 barrel.....the output hose is only about 2 inches long when you eliminate the overlap. By not using the variable-ratio pulley on later ones, they shortened the set-up by several inches and had room for a 4 barrel. (at least that's my guess - probably as accurate as my conjectures about 2nd gear starts).

No space issues on the few '54 Packards with the same 'charger, so they blew thru a pressurized 4 barrel. Gees, flathead 359 S8 with a blower - bet they got good mileage, specially with Ultramatic).

Sorry, Ford Guys......that's why we're called StudeNuts.