Fuel grade required for the 2nd gen

Truckzor said:

Not really sure what you're specifically worried about. Obviously, his rear end didn't break. It's also highly unlikely that it got any hotter in a Raptor than it would have in a regular F150, so it won't wear out any faster. The softer, longer travel suspension is the reason for the change in tow ratings.

None of this is rocket science.

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It actually is aerospace science. In the 1980s, engineers didn't understand metal fatigue and is why the roofs of airplanes were blowing off. Micro cracks form in metal at loads under failure/deformation levels. Depending on the number of cycles, some steel will fail at 50% of its design strength. Aluminum has no fatigue limit and will fail even at light loads if cycled enough.

So yes, even if the gears survived this trip, the next trip, and the one after that, if he is exceeding the fatigue limits for the drivetrain, eventually it will fail due to these micro cracks.

jaz13 said:

I don't know what was the limiting factor when Ford rated the Raptor for a different towing capacity, but the more powerful engine and not the suspension could actually be the problem.

The guys at Raptor Assault said the rear end of the drivetrain was maxed out in this design and Ford cannot upgrade the engine without redesigning the rear of the truck. Slapping a more powerful engine on the truck at the same towing capacity could easily put the drivetrain beyond its design limits if the driver puts his foot into it. Ford could have lowered the towing limits on the Raptor to keep the more powerful engine from breaking the drivetrain.

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I don't know if I'd trust everything the guys at Raptor Assault say unless it came specifically from an engineer responsible for that part of the truck.

The Raptor has the 9.75" differential, same one as used in the max-tow F-150 rated at 13,200lbs. Additionally, it has 35 spline upgraded axles, likely to withstand the nominally 35" tires.

I completely disagree with the rear end being the limiting factor on engine output...considering the Shelby Raptor uses a stock drivetrain with a tuned engine good for 525HP and 610lb-ft; the Hennesey VelociRaptor puts out 605hp and 622lb-ft on a stock drivetrain as well. Those guys at RA are saying things that aren't true...

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jaz13 said:

It actually is aerospace science. In the 1980s, engineers didn't understand metal fatigue and is why the roofs of airplanes were blowing off. Micro cracks form in metal at loads under failure/deformation levels. Depending on the number of cycles, some steel will fail at 50% of its design strength. Aluminum has no fatigue limit and will fail even at light loads if cycled enough.

So yes, even if the gears survived this trip, the next trip, and the one after that, if he is exceeding the fatigue limits for the drivetrain, eventually it will fail due to these micro cracks.

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The Raptor is not an airplane, which is why your analogy is not accurate here. Aircraft suffer stresses in probably hundreds of ways vehicles do not. Additionally, aircraft are primarily aluminum. The rear axle and differential assembly is all steel, including hardened steel gears.

I keep stating the obvious - this same diff is used in the max-tow 2018 F-150 rated at 13,200lbs. Since I'm well below that, I have not one concern in the world for axle / diff failure.

Let me give you another example: for many years, I wheeled a 1992 Range Rover. It's stock tire size was a 205x80x16 which is about 29" tall and 8" wide. That vehicle had a pretty deep low range (3.32:1) and used relatively weak 10-spline axles and small differentials. I installed a rear ARB locker *and* 285x75x16 (about 33" tall and 11.5" wide) mud tires and drove it on the road, seriously off-road, and even towed some light loads with it for many years and the vehicle had almost 200k when I sold it. The axles and diffs were all original, no failure...despite repeated shock loads from a wheel suddenly finding traction or a locker engaging even while in low. The Raptor weighs maybe 1000lbs more...yes it has a much more powerful engine...but it the axle is massively stronger.

I was under the impression that the C range tires were a primary driver in the limitation on payload and towing.

R/A were saying that the reason we don’t have e-locker in 2h is that they were seeing increased failure rate in the rear end due to some questionable use cases. Namely, big smokey burnouts on pavement.

smurfslayer said:

I was under the impression that the C range tires were a primary driver in the limitation on payload and towing.

R/A were saying that the reason we don’t have e-locker in 2h is that they were seeing increased failure rate in the rear end due to some questionable use cases. Namely, big smokey burnouts on pavement.

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The tires on the Raptor are rated for 2535lbs each. A load range E tire on an F-250 is rated for about 3200lbs in the 17" size. The Raptor GVWR is 7050lbs. With all of its 4 tires fully loaded, they would support over 10k GVW. So while we don't want to overload the rear tires...I think there is safely room for more payload with the C-rated KO2's.

I was surprised about the lack of a locker in 2HI. Once again, I have a hard time believing the RA guys because a 2018 F-150 with the 3.5L EB...has 375HP and 470lb-ft...has a locker which can be used in 2HI...and the same rear end but lighter-duty axle half-shafts.

troverman said:

I don't know if I'd trust everything the guys at Raptor Assault say unless it came specifically from an engineer responsible for that part of the truck.

The Raptor has the 9.75" differential, same one as used in the max-tow F-150 rated at 13,200lbs. Additionally, it has 35 spline upgraded axles, likely to withstand the nominally 35" tires.

I completely disagree with the rear end being the limiting factor on engine output...considering the Shelby Raptor uses a stock drivetrain with a tuned engine good for 525HP and 610lb-ft; the Hennesey VelociRaptor puts out 605hp and 622lb-ft on a stock drivetrain as well. Those guys at RA are saying things that aren't true...

---------- Post added at 08:27 AM ---------- Previous post was at 08:18 AM ----------




The Raptor is not an airplane, which is why your analogy is not accurate here. Aircraft suffer stresses in probably hundreds of ways vehicles do not. Additionally, aircraft are primarily aluminum. The rear axle and differential assembly is all steel, including hardened steel gears.

I keep stating the obvious - this same diff is used in the max-tow 2018 F-150 rated at 13,200lbs. Since I'm well below that, I have not one concern in the world for axle / diff failure.

Let me give you another example: for many years, I wheeled a 1992 Range Rover. It's stock tire size was a 205x80x16 which is about 29" tall and 8" wide. That vehicle had a pretty deep low range (3.32:1) and used relatively weak 10-spline axles and small differentials. I installed a rear ARB locker *and* 285x75x16 (about 33" tall and 11.5" wide) mud tires and drove it on the road, seriously off-road, and even towed some light loads with it for many years and the vehicle had almost 200k when I sold it. The axles and diffs were all original, no failure...despite repeated shock loads from a wheel suddenly finding traction or a locker engaging even while in low. The Raptor weighs maybe 1000lbs more...yes it has a much more powerful engine...but it the axle is massively stronger.

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You just convinced me and I take it all back. It sounds like you know more about this truck than the engineers who designed it. What could possibly go wrong with logic like yours? I say go for it.

jaz13 said:

You just convinced me and I take it all back. It sounds like you know more about this truck than the engineers who designed it. What could possibly go wrong with logic like yours? I say go for it.

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I'm not trying to offend you, and I don't know more than the engineers who designed it...but my logic is sound.

troverman said:

I'm not trying to offend you, and I don't know more than the engineers who designed it...but my logic is sound.

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It's your truck. Drive it however you want.

smurfslayer said:

Thanks for the real world feedback, good info.

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Not directly on topic, but years ago I had an Audi A3, and its literature said flat-out it was tested with/would only hit its claimed HP numbers with premium fuel. I also had twin-turbo S4 before that, and there was a noticeable difference in it between 87 and 93. So, I know octane matters, especially in turbo-charged motors. When I get my '18, I will run mostly 93 from Costco with some 87/89 mixed in when I'm not nearby.

robbcwz said:

The Raptor supplement page 38 may be a better reference than the "general" F150 Manual:

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I'd hate to see this thread die. While it has covered fuel octane pretty well...and even tried it's hand at towing capacity and limitations of the Raptor drivetrain and suspension...this slid by un-noticed in robbcwz's post:

The Raptor supplement shows spark plugs are SP534. Those of us who have pulled our plugs know that is not true from the factory. Factory plugs are SP550.

Will your truck run with SP534's? Of course. But is that what Ford puts in the truck NO. Will it run better with SP550's? YES. And that is precisely why Ford switched to them.

Let that be a lesson to all the penny pinching, manual quoting idiots running 87 octane.

And now, let the thread continue...the year is not over yet!

PS - have you looked up what the prefix DF stands for on Urban Dictionary?

bfr said:

I'd hate to see this thread die. While it has covered fuel octane pretty well...and even tried it's hand at towing capacity and limitations of the Raptor drivetrain and suspension...this slid by un-noticed in robbcwz's post:

The Raptor supplement shows spark plugs are SP534. Those of us who have pulled our plugs know that is not true from the factory. Factory plugs are SP550.

Will your truck run with SP534's? Of course. But is that what Ford puts in the truck NO. Will it run better with SP550's? YES. And that is precisely why Ford switched to them.

Let that be a lesson to all the penny pinching, manual quoting idiots running 87 octane.

And now, let the thread continue...the year is not over yet!

PS - have you looked up what the prefix DF stands for on Urban Dictionary?

Click to expand...

My posting of the manual excerpt was in relationship to the previous comments of "only 91 OCT" when the manual was actually saying the you could go as low as the 87 and so you have taken my post somewhat out of context by using it for spark plug arguments and rather strange comments such as "Let that be a lesson to all the penny pinching, manual quoting idiots running 87 octane" which has no explanation or reference in your rambling post.

Truth is that for most, if not all parts, one should use the vehicle VIN# so that the parts tech (in theory) will look up and be referenced to the latest part. If you walk in and ask for "SP534's" there is a good chance you'll get them as opposed to giving the VIN and getting the latest SP550's.

When it becomes time to change my plugs I will go the VIN# route and not "I need SP550's gapped at .028 because FRF says so". There is some intelligence in here but also a lot of scary idiots working without skill on a $70k vehicle. I wouldn't trust half the people with the kind of changes being made when most demonstrate zero ability to even change their oil successfully. One needs to be very careful in whom they trust, I believe.

So back to the evils of 87! I've ran 87 almost exclusively for my Gen 2's 15,000 miles. To this point, the majority of its time is spent doing trips of 100 to 300 miles; very little in town traffic or red light racing, and it seems to do fine on 87 and, on the occasions a little tete-to-tete racing has been needed it has never failed to perform. Did I miss the extra 10HP from 91? I don't think so. Did I miss the 0.1second from the red light - not yet!

If my only mission was to treat every trip as a full speed, race from every light regardless of whether there was anyone to race and all at full boost, then yup I would be using the higher octane.

My truck gets used a lot in a number of driving styles with the only missing mode so far being the BAJA since the high speed desert racing is hard to find in Louisiana! It gets driven hard but not abused. But I'm feeling confident that when I change the plugs at 30k I will not be sitting there wishing I'd have run the higher octane.

And to conclude, I have neither the Sasquatch drilled hole in the intercooler, and nor do I have a catch can -and so by that I may never make the 30k mark, yes?