2020 GT Supercharge or not?

[GreenS550]

I've had three supercharged coyote engines in my mustangs. Two gen three and one gen two. The one that went with only two thousand miles on it was the Gen 2 engine. It was badly tuned. Tuning is 98% of the issue with these engines. The other 2% being a bad gas. Fine supercharging it as long as you keep the boost under about 10 psi. And PD blowers are harder on the engine than Centri. As they produce almost instant torque at a lower rpm.

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[IamCDNJosh]

No problem boosting the gen 3. None at all. In fact the lower compression engines allow for more fuel/air in the combustion chamber for more power but 10psi of boost is 10psi whether the engine originally was 9:1 or 12:1. The charge volume would be greater on the lower compression engine likely making more power and more more stressed on the engine. Ford used 9.5:1 to make power at a lower boost.

I would argue that an engine originally designed to take 12:1 NA vs an engine that was designed to take 11:1 originally had better engineered and stronger parts.

Your analysis is a little flawed here, when talking about 10psi of boost this is in addition to ATM (14.7psi). When the piston is at the bottom of its stroke and the intake valve is open that the pressures will be identical if the CR is 9.5:1 or 12:1. When the piston reaches TDC with all valves closed is where the pressure differentials change. Its been a while since I did my Mechancial engineering degree, but rough calculations are below, this is not taking into account any efficiency losses due to heat etc:

(ATM + Pressure) x CR = Cylinder Pressure

9.5:1 CR @ 10psi Boost (14.7psi + 10psi) x 9.5 = 234psi @ TDC

12:1 CR @ 10psi Boost (14.7psi + 10psi) x 12 = 296psi @TDC

Increased cylinder pressure on the compression results in an increase in heat on the compression stroke (causing knock). Now with variable cam timing you can dynamically lower this ratio with some valve overlap. What I wanted to show here is that with a high compression motor and boost your simply eating into the safety factor built into the engine leaving you with less room for error and pulling timing.

The Gen3 Coyote is a fantastic N/A platform but not an ideal platform for boost especially if its going to see some abuse.

Any other engineers or physics nerds I'd love to see you chime in on this one. I've been out of the Mechanical Engineering game for years now and realize what I've posted is a little simplistic.

 

[LSchicago]

Your analysis is a little flawed here, when talking about 10psi of boost this is in addition to ATM (14.7psi). When the piston is at the bottom of its stroke and the intake valve is open that the pressures will be identical if the CR is 9.5:1 or 12:1. When the piston reaches TDC with all valves closed is where the pressure differentials change. Its been a while since I did my Mechancial engineering degree, but rough calculations are below, this is not taking into account any efficiency losses due to heat etc:

(ATM + Pressure) x CR = Cylinder Pressure

9.5:1 CR @ 10psi Boost (14.7psi + 10psi) x 9.5 = 234psi @ TDC

12:1 CR @ 10psi Boost (14.7psi + 10psi) x 12 = 296psi @TDC

Increased cylinder pressure on the compression results in an increase in heat on the compression stroke (causing knock). Now with variable cam timing you can dynamically lower this ratio with some valve overlap. What I wanted to show here is that with a high compression motor and boost your simply eating into the safety factor built into the engine leaving you with less room for error and pulling timing.

The Gen3 Coyote is a fantastic N/A platform but not an ideal platform for boost especially if its going to see some abuse.

Any other engineers or physics nerds I'd love to see you chime in on this one. I've been out of the Mechanical Engineering game for years now and realize what I've posted is a little simplistic.

Theoretically the may not be the best for boost, but in reality, they are some of the best V8's built in America for boost, if not the best. With enough octane or simply E85, they are amazing when boosted.

 

[GreenS550]

Your error is forgetting direct injection. Direct injection sprays that fuel charge right on top of the piston . Cooling the combustion chamber off . That's what allows for higher compression in the Gen 3. the Gen 3 is totally fine and just as durable boosted to the same PSI as gen 2. With the caveat, properly tuned.

 

[IamCDNJosh]

I agree with you that DI can allow for an increased compression ratio. My truck has the 3.5EB which has a 10:1 compression ratio that can run on 87 octane (per the manual, premium is recommended for towing).

I just found it interesting the design considerations that Ford took on the Predator engine.

 

[engineermike]

Gdi allows for about 1 compression number increase, but Ford already used that up on the gen3.

 

[GreenS550]

On top of that. Using e85 which burns super cool allows that gen 3 to make some serious horsepower. Even NA. The engine with its overhead cams independently variable timed camshafts and direct injection allows a tuner to make serious horsepower with 85 or a very high octane gasoline. Back tuning ability doesn't exist on the Gen 2 because it doesn't have direct injection. it's my belief that Ford set that engine up to make some serious horsepower if somebody was willing to tune it properly and use e85

 

[IamCDNJosh]

Unlikely, the Gen 3 Coyote likely was designed allowing for regular grade fuel with a power bump over the Gen 2 while meeting emission targets. Keep in mind many GT's end up in rental fleets which the user is NOT going to spring for premium fuel. Its doubtful that the end user tuning the engine to run on E85 was ever a design consideration.

 

[GreenS550]

It's a flex fuel vehicle. And can run on e85 . Why design a car that can run on e85 and call it a flex fuel vehicle if they didn't have that in mind? The other proof that Ford knows people are going to modify many mustangs is that they do not lock the computer like they do on Chrysler products. Additionally, many things Ford has incorporated in the Mustang was first done by the private sector. On the 18 and up mustangs, the fuel system will provide enough fuel flow to run e85 with just a tune. No need for an additional booster pump.

 

[IamCDNJosh]

I can't find any documentation supporting the statement that the Mustang GT is a flex fuel vehicle.

 

[GeorgeC]

You're a good man, when I divorced I gave my ex-wife more than half the assets so that she and the kids wouldn't have to move. Sometimes you find you're just an incompatible match and the best thing is for both of you to move on. I did buy my mustang after because I didn't have anyone to tell me "no" anymore......

It's so much easier to get forgivness than permission

 

[brucelinc]

The Mustang GT is not a flex fuel vehicle and requires appropriate aftermarket tuning to run E85. In stock form, it will not adjust A/F ratio rich enough for E85. With the tuning, however, E85 does improve performance, cooling and resistance to detonation.

I totally agree the Ford is supportive of modifications. Just look at their accessory website.....tunes, superchargers, suspension upgrades, etc. Performance Ford dealerships are happy to sell and install mods...even non-Ford mods. The Coyote was obviously designed with the capability of handling additional power. Of course, there is always a limit.....and some will find it.

 

[GreenS550]

My bad! You guys are right on. No not flex fuel. I mis-spoke. What I meant is the gen 3 doesn't need additional fuel upgrades to run e85. Just a tune. Before I put the ProCharger on my, 18 I had a Lund e85 tune. Very significant.
They had a "flex fuel" tune for it where the computer adjusted to the ethanol level.

Ford engineers had to know tuners would do this I would think.

 

[Jackson1320]

On top of that. Using e85 which burns super cool allows that gen 3 to make some serious horsepower. Even NA. The engine with its overhead cams independently variable timed camshafts and direct injection allows a tuner to make serious horsepower with 85 or a very high octane gasoline. Back tuning ability doesn't exist on the Gen 2 because it doesn't have direct injection. it's my belief that Ford set that engine up to make some serious horsepower if somebody was willing to tune it properly and use e85

Why is it that the stock coyote h.p record is held by the gen2?

 

[LSchicago]

Why doesn't Ford make the Mustang Flex fuel like the F150's? Too much power for their liking?

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