GT350 Engine Mean Piston Speed (Estimated Predictions)

[Genxer]

The rev limiter won't help you when you downshift into the wrong gear. It's a question of whether the rear tires have enough traction to turn the engine at whatever speed is required by the gearing. The momentum of the car can force the engine to spin at a fast rate with no ignition or fuel present.

Correct. It's a mechanical overrev. Ask S2000 owners about that. More than a few of those guys have selected the wrong gear and trashed their $8k engine.

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[Joker]

I heard from top gear uk that the gt350r is going to have 520 horsepower, not too bad but in comparison to the stock gt, its not even 100 horsepower if they are correct. Stock gt-435, Shelby-520. Thats around 85 increase. I know the whole car is pretty much better, but I was expecting at least 100+ in terms of power. But thats just me, and I still don't know if the info from top gear is 100% spot on, if it is, to me at least, they could have done at least 100 more horses. Otherwise regular gt owners can strap a whipple super charger and have more power for under the price of a 350, which I read somewhere is around 52k... Idk if this is just me thinking this or anyone else agree?

 

[DivineStrike]

Lol, people aren't buying the 350 for having the highest hp car on the block. Just want any modern v8 with a supercharger will probably have higher power numbers than the 350r

 

[Sered]

I heard from top gear uk that the gt350r is going to have 520 horsepower, not too bad but in comparison to the stock gt, its not even 100 horsepower if they are correct. Stock gt-435, Shelby-520. Thats around 85 increase. I know the whole car is pretty much better, but I was expecting at least 100+ in terms of power. But thats just me, and I still don't know if the info from top gear is 100% spot on, if it is, to me at least, they could have done at least 100 more horses. Otherwise regular gt owners can strap a whipple super charger and have more power for under the price of a 350, which I read somewhere is around 52k... Idk if this is just me thinking this or anyone else agree?

Pretty sure TopGear is making assumptions as no one knows other than Ford engineers how much power the voodoo motor makes. I'd be surprised if it wasn't more than 520, but I wouldn't worry about it to much. At 520hp, it'd be a pretty fast mover with a very wide powerband.

Per your Whipple comment, sure GT owners can strap on a Whipple and make more power on a dyno. It still won't have the suspension to handle the power or the tires or the transmission. It also won't have anywhere near the same kind of driving experience. You're not going to win a HP/$ argument with a GT350, that's for sure. There's also no reason you can supercharge the GT350 either. MANY M3s have done it and had great success with it, even at 12:1 CR.

 

[Trackaholic]

Yeah, the whole point of the engine in the GT350 is to have low inertia. You can add a S/C to the Coyote, and it will make a crap-ton (or even a metric crap-ton) more power, but it will have a very different feel.

I think 520 HP is a definite possibility, although my guess is 535.

-T

 

[Hack]

Aren't most shifters dual gate in order to prevent or at least limit this from happening?

As far as I know "dual gate" is a term for a shifter that mounts to an automatic transmission.

And no, there's nothing in a manual transmission that prevents you from selecting the wrong gear. IMO that's a cool thing about a manual transmission. It's not dummy proof.

However, when the relative speeds of the two gears are extremely different (for instance if you are traveling 60 mph and try to select 1st gear), it does become more difficult for the parts in the transmission to synchronize gear speeds and allow those gears to engage with each other. So you are more likely to feel a block or get a grind if you try to select reverse while moving forward, for instance.

But if you are hammering out shifts as hard as you can, you may have an unfortunate accident. Even if the motor doesn't fail, you could crash the car from the rear wheels losing traction.

 

[Hack]

Now the question is, what is the computer doing to react to an over-rev? is it throwing any fuel in, or is it an empty cylinder when the spark happens? If its throwing any in at all I think that'd be a recipe for disaster. Now if there is no fuel and it's just a "dead" spark; could it be said, that as long as the engine components are being lubricated properly and the valves can handle the rpms, the engine would essentially be fine?
exceeding an RPM, and if the valvetrain can handle the energy.

My understanding is fuel and spark are shut off if the engine is beyond the RPM red-line.

Usually the failure mode at high RPM is the rods will fail at TDC on the exhaust stroke, because that's where the stretching load peaks.

Another potential failure mode is the valve springs cannot control the valves sufficiently (valve float) and one or more valves touch a piston.

 

[matrix243]

I agree. Ford wants to distance themselves from dodge and the hellcat design for the gt-350. They want it to be the more technical road car, especially for the racing history. There's a point when more power on a FR car will be diminishing returns, and will only give you more rubber smoke, over worked traction control, and top speed. Plus thats where the gt-500 comes in.

 

[FPCV8YO]

As far as I know "dual gate" is a term for a shifter that mounts to an automatic transmission.

And no, there's nothing in a manual transmission that prevents you from selecting the wrong gear. IMO that's a cool thing about a manual transmission. It's not dummy proof.

However, when the relative speeds of the two gears are extremely different (for instance if you are traveling 60 mph and try to select 1st gear), it does become more difficult for the parts in the transmission to synchronize gear speeds and allow those gears to engage with each other. So you are more likely to feel a block or get a grind if you try to select reverse while moving forward, for instance.

But if you are hammering out shifts as hard as you can, you may have an unfortunate accident. Even if the motor doesn't fail, you could crash the car from the rear wheels losing traction.

As I've stated previously, I've never not owned a stick shift car in 37 years of driving experience. I believe that spring loaded gates are a part of the shifter mechanism that enhance proper shifting. Perhaps not eliminating a catastrophic miss shift but, making one much more difficult.

 

[cush]

With the lack of new information circulating, I decided to do some calculations based on the little information we have. Mean piston speed (MPS) can be an interesting way to compare engines. It tells us a little bit more about the stresses put on the internals at high rpm. We were told at the initial reveal that the 5.2L's increase in displacement over the 5.0 is "all bore," so we can deduce that they share the same 92.7mm stroke. Several shots of the cars show that the redline on the tach to be at 8,200 rpm. I compiled the bore/stroke for several modern, high revving, naturally aspirated performance engines of various configurations and calculated the piston speeds. I have them listed in order from highest MPS to lowest. Bore is not used to calculate piston speed, but I included it on the list anyway, just for comparison sake.

Engine / Bore x Stroke / Mean piston speed in feet per second @ redline


Audi 5.2L V10 / 84.5x92.8mm / 88.294 fps @ 8,700 rpm
Honda S2000 2.0L I-4 / 87x84mm / 84.514 fps @ 9,200 rpm
Audi 4.2L V8 / 84x92.8mm / 83.727 fps @ 8,250 rpm
Ford 5.2L Voodoo V8 / 94.5(est)x92.7mm / 83.13 fps @ 8,200 rpm [engine photos]
Honda S2000 2.2L I-4 / 87x90.7mm / 81.336 fps @ 8,200 rpm
Ford 5.8L Trinity V8 / 93.5x105.8mm / 80.993 fps @ 7,000 rpm
Ferrari 4.5L V8 / 94x81mm / 79.724 fps @ 9,000 rpm
GM 7.0L LS7 V8 / 104.775x101.6mm / 77.778 fps @ 7,000 rpm
Porsche 911 GT3 3.8L flat 6 / 102x77.5mm / 76.28 fps @ 9,000 rpm
Ferrari 6.3L V12 / 94x75.2mm / 71.549 fps @ 8,700 rpm
Lamborghini Aventador 6.5L V12 / 95x76.5mm / 71.112 fps @ 8,500 rpm
Ford 5.0L Coyote V8 / 92.2x92.7mm / 70.965 fps @ 7,000 rpm
BMW E90 M3 4.0L V8 / 92x75.2mm / 69.081 fps @ 8,400 rpm
GM 6.2L LT1 V8 / 103.25x92mm / 66.404 fps @ 6,600 rpm


There are a few things I would like to point out. The 5.8 Trinity is obviously not N/A, but with it's very long stroke (the longest on the list) and the over-rev function that will allow short runs up to 7,000 rpm in certain conditions, I knew it would have a high mean piston speed. Despite all of that, the Voodoo piston speeds are even higher.

Notice how much lower the piston speeds are on the standard Coyote, the GM LT1, and even the highly regarded BMW 4.0L V8. The very short stroke on the BMW gives it a much lower average piston speed, despite the slightly higher redline when compared to the Voodoo.

Also, notice that most of the engines are oversquare in design. The Audi engines are an interesting exception. I guess the engineers at Audi forgot that an engine has to be oversquare to turn high rpm. ;)

To me, this is one illustration of the level of engineering that likely went into the 5.2 for it to reliably achieve those piston speeds. Ford openly admits that they had to overcome several hurdles during development and that this was one of their most ambitious powertrain programs. There are some pretty exotic engines on that list.

I think we're in for a real treat.

Doc, please tell me the definition of the term "Mean" that you are using.
It doesn't seem to fit here, if you are measuring the speed of the piston at the engine's maximum RPM.... Just curious.

 

[Merle]

My understanding is fuel and spark are shut off if the engine is beyond the RPM red-line.

Usually the failure mode at high RPM is the rods will fail at TDC on the exhaust stroke, because that's where the stretching load peaks.

Another potential failure mode is the valve springs cannot control the valves sufficiently (valve float) and one or more valves touch a piston.

I got out of the Army in 1964 and Ordered (NOT A MUSTANG) A Galaxie
500 Fastback with the 390 ci NOT the 427 because it had only a 90 day
Warranty, the 390 had 12 Months and it was a Cruise-O-Matic, a 3 speed
Auto. Well I would run it to 60MPH in LOW Gear and the Valves would
"float". The Police Interceptor had 330 HP 30 MORE than the Normal 390.
The difference was Headers and STIFFER Valve Springs and A Holley
Carb instead of the Ford Carb. I was 21 and I drove the s#@t out of it.
I never had any problems. IT WAS BUILT FORD TOUGH!

Now to get back to the present, I had a 2013 V6 and now have a 2014 V6
and it will run to near 7000 and the Rev Limiter kicks in (thank god).

After reading all this ENGINE TECH, I AM NEVER GOING OVER 5K.
THIS HAS PUT THE FEAR OF THE LORD IN ME!

 

[DivineStrike]

My understanding is fuel and spark are shut off if the engine is beyond the RPM red-line.

Usually the failure mode at high RPM is the rods will fail at TDC on the exhaust stroke, because that's where the stretching load peaks.

Another potential failure mode is the valve springs cannot control the valves sufficiently (valve float) and one or more valves touch a piston.

ok, then it seems like with this engine there shouldn't be too much of a concern if you mechanically overrev the engine, as long as ya don't get to close to 8000rpms and the oil pump is still working.

 

[Doc Holliday]

Doc, please tell me the definition of the term "Mean" that you are using.
It doesn't seem to fit here, if you are measuring the speed of the piston at the engine's maximum RPM.... Just curious.

I am measuring average piston speed at redline. A piston's speed varies significantly throughout the course of a revolution. Mean speed is easily calculated. Maximum speed is influenced by other factors, such as rod ratio, as mentioned earlier in the thread. Did you find an error in the calculations?

The formula for MPS is (2 x stroke x RPM)/60. Or you can use this convenient online calculator http://www.csgnetwork.com/pistonspeedcalc.html

 

[Doc Holliday]

NASCAR was running 9.000 to 10.000 RPM the last few years, at some tracks. It seems that most of the failures were due to breaking Valve Springs, at least where the engine RPM varied little.

Other failures seemed to come from Belts Flying off, but that was mostly after hitting debris.

HUGE difference in valvetrain dynamics between a pushrod setup and an OHC one.....

Both are true statements I'm sure there was some extra work done on the valvetrain to guarantee OEM reliability. Time will tell.

I heard from top gear uk that the gt350r is going to have 520 horsepower, not too bad but in comparison to the stock gt, its not even 100 horsepower if they are correct. Stock gt-435, Shelby-520. Thats around 85 increase. I know the whole car is pretty much better, but I was expecting at least 100+ in terms of power. But thats just me, and I still don't know if the info from top gear is 100% spot on, if it is, to me at least, they could have done at least 100 more horses. Otherwise regular gt owners can strap a whipple super charger and have more power for under the price of a 350, which I read somewhere is around 52k... Idk if this is just me thinking this or anyone else agree?

I'm guessing 520 is probably not too far off the mark, and yes you're correct that strapping a blower to a 5.0 will net you more power than that. However, that's not the point of the GT350. This is supposed to be more of a handling, road course car, rather than a straight-line performance power monster for the drag strip. If/when Ford builds a successor to the GT500, that will most likely be the powerhouse you're looking for.

 

[Sered]

And no, there's nothing in a manual transmission that prevents you from selecting the wrong gear. IMO that's a cool thing about a manual transmission. It's not dummy proof.

Allow me to introduce you to the Skip-Shift 'feature' present in the T56 transmission. Specifically the V8 FBodies circa 1998-2002. ;)

Definitely a way to block out the gears. I doubt this will be done though. Skip-shift was put in place for emissions reasons.

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