New GT Owner Hennessey 850 Fuel?

[hotrodgrrrl]

Hello! I've lurked for some time but finally took delivery of my 2005 Ford GT last week! So now I'm an official Forum Member LOL! I am beyond thrilled, and put a little over 100 miles on her. Of course, now she needs fuel. Reccomendations are all over the board. The Hennessey tune calls for 91 octane. Others have recommended 100 low lead avgas (Which I happen to have a 500ga tank of). I presume the avgas would require a different tune? Planning to fuel up with 91 octane non-ethanol, but wondering if I should have re-tuned for other fuel (pros and cons?) or just leave as-is. Ashamed to say, but I've only had the car for a few days and have not had up in the air. If catalytic converter is still installed...no leaded fuel...right? Apologies in advance for my newbie ignorance. I spent my life savings (and then some) on this car so I don't want to do anything to jeopardize its performance or longevity. Any input is appreciated!

 

[extrap]

Congrats!! And welcome! You have questions that I 'suspect' I know the answers to but not expert enough so I'll defer to others here.

WRONG! I suspect you're Mustang Mandy on Bring a Trailer? and if so this is prob yours https://bringatrailer.com/listing/2006-ford-gt-160/

 

[hotrodgrrrl]

Thanks extrap, appreciate the sentiment! But alas, I am not Mustang Mandy, and my GT was alot higher mileage...which is fine since it will be driven. Hope I haven't disappointed you! This is my "win": https://bringatrailer.com/listing/2005-ford-gt-163/
Good day and thanks again!

 

[extrap]

Thanks extrap, appreciate the sentiment! But alas, I am not Mustang Mandy, and my GT was alot higher mileage...which is fine since it will be driven. Hope I haven't disappointed you! This is my "win": https://bringatrailer.com/listing/2005-ford-gt-163/
Good day and thanks again!

Oh, sorry! And here I was so certain! Congrats and welcome nonetheless! I should've known by your Hennessey mention! Not to mention your BaT and forum names are the same! Oh, geez and your title is Hennessey 850! Man, I'm a dunce!

 

[hotrodgrrrl]

LOL! No worries!

 

[nota4re]

From the BaT pictures, your car does indeed have the OEM Cats. Stay away from AV Gas and use the best fuel octane you can reasonably find. 91 is likely OK, 93 would be better if available in your area. The Whipple SC's were available with different size pulleys - the smaller the pulley the more boost. Most common was the pulley that would produce 18-19 psi.

Enjoy driving her and welcome to the family!

 

[hotrodgrrrl]

Thank you nota4re ! That is what I also gathered from the photos. I just neded confirmation. Looks like we'll be making the 40 mile drive to where I *know* can get good fuel. It has just under 1/4 of tank now so fingers crossed I can make it lol! (I'll make it).

 

[69b302]

It is generally best to go with the fuel/octane in which the tune was intended. A little extra octane will provide some insurance against knock(no knock sensors on our GTs), but will leave a little power on the table.

 

[hotrodgrrrl]

It is generally best to go with the fuel/octane in which the tune was intended. A little extra octane will provide some insurance against knock(no knock sensors on our GTs), but will leave a little power on the table.

Thank you!!

 

[nota4re]

Try not to run the GT too low on fuel. If you run it completely out of fuel, it's likely that you will kill one or both fuel pumps and this is NOT an inexpensive repair. You can drive it until the light comes on, but I wouldn't advise going much past that. Note that you will not get a "Low Fuel" light but rather a "Check Gauges" light when the GT is low on fuel. Have fun!

 

[hotrodgrrrl]

Understood and appreciated. I promise not to do anything silly

 

[fjpikul]

You need to have your status on this Forum changed to "Owner." Only the moderators may do that and you might consider a paying membership. It might be nice to know what part of the USA you are in.

 

[hotrodgrrrl]

Thanks fj! And FYI, I’m in Montana (like, really here

 

[extrap]

Thanks fj! And FYI, I’m in Montana (like, really here

Ha! I didn't think that was really a place!

 

[DakotaGT]

Congratulations on a tremendous purchase! This forum is one of the best things about the whole FGT ownership experience, and an invaluable resource. Welcome!

 

[PeteK]

Welcome to the Forum, and yes, you got a good deal. The Hennessy mods are icing on the cake. It's good to hear that you plan to drive it, because these cars are so rewarding to drive.

WARNING: These cars have almost instant torque, but don't have traction control nannies. That means the traction control is on you. Do NOT stomp on the loud pedal unless you have the car pointed straight ahead and plenty of room, otherwise you will spin it. Many of us here have done that. If you want to learn how to handle that torque, go somewhere with plenty of room, like a large empty parking lot, a closed airstrip, or someplace like that.

The Forum search doesn't work very well, so use your favorite browser search or one of the AI bots to find threads in the Forum that you want. Bookmark this link. Tech Threads/FAQ

One of the long term guys here (Roketman?) put together a list of good accessories and modifications. I didn't find it in a quick search, so I hope he chimes in with the link.

 

[extrap]

Welcome ...

One of the long term guys here (Roketman?) put together a list of good accessories and modifications. I didn't find it in a quick search, so I hope he chimes in with the link.

Here 'tis https://www.fordgtforum.com/forums/threads/for-you-new-05-06-gt-owners.37761/

 

[hotrodgrrrl]

Thanks Pete, Dakota and ext! Appreciate the input and suggestions. I've already had the car pretty deep into triple digits, and also through a canyon I like to run by my place. TOTALLY different than mid engine Corvette or Porsche that I'm used to. Those cars drive themselves. Not so here. But I love it! I definitely see how these get wrapped around telephone poles so quickly lol. I like the suggestion about messing around on a closed airstrip. I think I may do just that. So far I've been careful NOT to get too sideways, but it might be worth doing on purpose, just to see where that limit is. And now I'm rambling so...Cheers!

 

[GT@50]

Hennessey Performance - Making Fast Cars Faster Since 1991

Hennessey Performance is home to the largest lineup of late-model high-performance sports cars, muscle cars, supercars, trucks & SUVs.

www.hennesseyperformance.com

 

[white out]

Congrats on the new car! Given that it has a 91 tune, you should be good with 91+ unleaded pump as its likely a safe tune for 50 states.
In other aspects, definitely check on age of oil pump belt and make sure axle bolts have been replaced (likely with Hennessey, but it never hurts to know).