GT350 dyno results - 98 octane versus 91 octane gas

[LS587]

Dynoed my new GT350 on the Dynojet at my son's restoration shop last Saturday. With pump gas that is supposed to be 91 octane, we got 429-434 wheel Hp (about 510 engine Hp at 85% driveline efficiency) in 3 runs with pump gas. We were down to less than 1/8 tank of gas, so we filled it with Sunoco 260 GTX 98 octane race gas, and were surprised how much the power increased. We got up to 450-456 wheel Hp, which would be about 535 engine Hp.

We were surprised at this increase, because we tried this on a completely stock 2014 Boss 302S that we dynoed a year ago. It showed essentially no change in power with 91 versus 98 octane with its street gas tune, and also no more power running its 100 octane tune on race gas (both tunes provided with the car by Ford). That engine put down about 392 wheel Hp, which would be about 460 at the engine.

My 2012 street boss that I am planning to retire as a track car, put down about 368 wheel Hp on pump gas, and the regular key versus the track key made no difference.

 

[[email protected]]

Nice find! Thanks for sharing. The stock ECU really seems to be more flexible than older NA Mustangs, as you mentioned.

 

[CSL]

It is also nice to see the ECU is that adaptable to the fuel you are using in regulating spark advance to control for detonation. Thanks for sharing. Any chance you could post the dyno charts?

 

[LS587]

I'd be glad to if I can figure out how to do it. The image that I have of the paper printout is a .pdf file (Adobe Acrobat), and photobucket won't accept that file type. Can someone tell me how to get it into an image file type, or another way to get there? I did look at the thread on posting tips, but still haven't figured out how to make it work. I follow several forums, but don't post very often.

 

[ArizonaBOSS]

I'd be glad to if I can figure out how to do it. The image that I have of the paper printout is a .pdf file (Adobe Acrobat), and photobucket won't accept that file type. Can someone tell me how to get it into an image file type, or another way to get there? I did look at the thread on posting tips, but still haven't figured out how to make it work. I follow several forums, but don't post very often.

@LS587 if you are on a windows PC, open the .PDF file and press the print screen button on your keyboard "PrtScn". This will take a screenshot that you can paste (ctrl-V) into MS paint and save, then upload.

Alternately if you are on Windows 7 or above, open the .PDF file and press the "Windows" button on your keyboard, type "snipping" to find the Snipping Tool program, then select the area of the screen you want to take a picture of. Then paste into MS Paint or directly to imgur (as shown in the FAQ) using ctrl-V command.

 

[LS587]

Here are the dyno graphs. The first 3 runs are pump gas and the last 3 are race gas (Sunoco 260GTX)

 

[Berol]

Impressive.

Dyno curves on the Voodoo have incredibly strange shapes/characteristics.

 

[krt22]

Im honestly a bit shocked how much improvement there was. Any chance you will do a mix 98/91 pull to see how it fairs around the ford recommended 93 octane?

 

[LS587]

Would be interesting to do that, but not in the near future. Its in my home garage right now to get it prepared for track events. Maybe we will run it again when it's been to some track events. It only had 310 miles on it when dynoed. Most from driving it home from an out of state dealer.

 

[VoodooBoss]

I'm not surprised by this. Max power (for pump gas that's available on the street) is with 93 octane. Ford stated it would be lower with 91 octane and up to 10 hp sounds plausible. While I wouldn't expect much upside with higher octane @Shaun@AED has had a GT350 on his dyno and thought it ran a bit lean. So a higher octane would keep the car from pinging and pulling timing which could increase the hp. From Shaun's early experience with the voodoo I plan on running 98/100 on track.

 

[krt22]

I wonder if mixing in a few gallons of E85 to boost the over-all octane rating will have a similar effect.There has to be point of diminishing returns with regardless to octane level without additional tuning

 

[cloud9]

Looking forward to your 93 octane results later today. It makes you wonder if there's even more power up to 104 octane unleaded.

 

[LS587]

Ran the GT350 in a NASA event at the National Corvette Museum track. The track had two gas pumps. One with 3 choices of VP race gas and one with 3 choices of Mobil street gas, with 93 octane being the highest. I noticed that a Shell station near the track had 93 octane, so it must be commonly available there in Kentucky, while only 91 octane is available at stations here in Central Iowa.

So, I let the GT350 use up most of its 98 octane gas on Saturday, and filled it with 93 at the track. Then filled it with 93 again after the Sunday sessions. My son dynoed it yesterday on his Dynojet, and the highest power runs with 91 and 98 octane gas that I showed before, are plotted with the highest power run with 93 octane gas below. In all cases, the highest power run was neither the first or last dyno pull, but somewhere in the middle. The 98 octane gas that we ran before came out of a barrel, as we buy race gas from a local distributor for our 302S.

Keep in mind that these dyno runs are shown with SAE correction, as required for NASA classing. Shops who give you STP Power or Racer Corrected Power, will give you power numbers about 4.8% higher, because they are correcting the power to more favorable atmospheric conditions (lower air temperature and higher barometric pressure). I figured this out when I was dealing with a race engine builder whose engine dyno reported in STP power, and I had to tell him what I was looking for in STP Power, which was more than I needed in SAE Hp. Per some information that I found on Ford Racing's site where they showed dyno data for their sealed 374 circle track crate engine, SAE Hp means corrected per SAE standard J1349, while STP or Racer Corrected Power means corrected per an older standard, SAE J607. The later standard corrects to more realistic average atmospheric temperature and pressure.

To me, the most significant thing about running 98 octane gas is the increase in torque in the 3500-6000 RPM range. That's a higher percent increase than the increase in maximum Hp.

 

[Black Boss]

Very interesting, thanks for sharing -- looks like my Track gas costs just increased

 

[VoodooBoss]

That's impressive. How did you like your GT350 on track?

 

[cloud9]

I really appreciate you doing this for us. This is a big help (but not to my wallet). One of the best power mods looks like simply running race fuel. These gains look to be at least equivalent to what has been seen with long tube headers and offroad exhaust. Of course running those with race fuel may provide even more gains. I'm looking forward to getting on track with you guys soon, but still waiting for a wheel option to materialize.

 

[LS587]

I was anxious to get out and try it, but we wouldn't have driven 11+ hours at this time of year in the Midwest if there weren't some other attractions, like the Corvette Museum and touring the Corvette plant. Never had a Corvette, but still find anything related to performance cars interesting. The NCM even had a couple Shelbys on display, a 427 Cobra and a 67 or 68 GT500, along with one Hemi Mopar, in a side room with several other non-Corvette cars.

The full NCM track is real challenging to learn, with something like 23 total turns and about 12 that I would call real turns, not just kinks in a generally straight portion. It was cold, in the lower 50's, and its still on street tires. I was just getting to the point that I could remember the whole track after the last session on Saturday, and was looking forward to learning how to drive the car better on Sunday, when rain set in overnight. So, I really didn't get a good test of what I can do in it yet.

I did learn that since I've never learned to do a good throttle blip downshifting while braking, that I have to be really careful to let the clutch out gently on this car, since the clutch grabs so hard. I did a 180 on dry track downshifting to 2nd going into the turn that is really tight on that track. Also got a little squirrely doing a 4-3 downshift on a very slight curve. I need to get an AutoBlip for this car.

Here's s a couple of photos from the track photographer. One dry, one wet.

 

[302 Hi Pro]

I don't run a Voodoo FPC engine, but I too found your Dyno results very interesting.

As I thought about this it occurred to me that Ford programmed the FPC PCM with a great deal of care regarding knock sensor sensitivity. To me this makes sense given the attention required in the control of engine vibration of the 5.2L FPC engine. In other words, the 2 seem to go hand in hand.

Just a thought, and if the above is related, it certainly would help to explain why the 5.0L Coyote did not show similar Dyno gains with the use of improved fuel quality/octane.

Good topic here, and thank you for sharing, and good luck with your new car on the Track this season.

Regards,
302 Hi Pro

 

[ArizonaBOSS]

Killer pics, @LS587

 

[302 Hi Pro]

Yep, looks like the Bar in the TT2 class, just went up a few clicks!

Great Pics!
302 Hi Pro