Reliable Top Speed Info: Whipple S550 GT

[MisterScobbles]

I apologise in advance for what is most likely one of the most irritating discussion points for anyone who‘s spent time on this planet.

I’ve searched the forum, the rest of the internet, youtube, and even tried to imagine an answer, but there is a surprisingly no amount of information on this.

I have a son who is a bit of a car fanatic. And I own a 2016 GT with a 2.9l Whipple on it. I live at around 1,700m altitude and the last dyno recorded 420kW (~565hp) at the wheels. At zero altitude, I’d expect about 610-620whp.

My kid has asked me a few times what I’d expect the car to top out at, and I could only offer a guess, which I would expect to be around 320km/h.

Has anyone actually managed to do an instrumented top speed run on a similar car?

Thanks in advance. A lot.

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[sms2022]

I ran my E85 GT making 451whp to 170mph several times with a lot more in it so I’d say you’ll be close to 200mph. Maybe low 190s. Will take a while to get there though.

 

[SheepDog]

I apologise in advance for what is most likely one of the most irritating discussion points for anyone who‘s spent time on this planet.

I’ve searched the forum, the rest of the internet, youtube, and even tried to imagine an answer, but there is a surprisingly no amount of information on this.

I have a son who is a bit of a car fanatic. And I own a 2016 GT with a 2.9l Whipple on it. I live at around 1,700m altitude and the last dyno recorded 420kW (~565hp) at the wheels. At zero altitude, I’d expect about 610-620whp.

My kid has asked me a few times what I’d expect the car to top out at, and I could only offer a guess, which I would expect to be around 320km/h.

Has anyone actually managed to do an instrumented top speed run on a similar car?

Thanks in advance. A lot.

Auto or manual?

What rear end gearing?

What size rear tire?

 

[MisterScobbles]

I ran my E85 GT making 451whp to 170mph several times with a lot more in it so I’d say you’ll be close to 200mph. Maybe low 190s. Will take a while to get there though.

Thank you.

Why does it run out of top end so easily though? That’s a lot of power, and in the midrange at least is definitely quicker than my F10 M5 was.

I’ve not had the opportunity to rack them up on a safe road to test the top end, but going purely by what the midrange feels like, I’d expect the Mustang to take the M5 out on top, and there are plenty of indications that a stock F10 M5 would do 195mph fairly easily, 200 not a stretch from that.

I know aerodynamics play a big role, and Ford doesn’t disclose the S550’s Cd, but the Mustang is reliably making 150-180hp more.

Ah well. It’s purely academic anyway. Won’t ever have to prove to my son that it’s not the 200 I claimed it was.

 

[MisterScobbles]

Auto or manual?

What rear end gearing?

What size rear tire?

Auto, 6 speed, PP, so 3.73 diff, stock 19” wheels with 275 tyres.

 

[sms2022]

Thank you.

Why does it run out of top end so easily though? That’s a lot of power, and in the midrange at least is definitely quicker than my F10 M5 was.

I’ve not had the opportunity to rack them up on a safe road to test the top end, but going purely by what the midrange feels like, I’d expect the Mustang to take the M5 out on top, and there are plenty of indications that a stock F10 M5 would do 195mph fairly easily, 200 not a stretch from that.

I know aerodynamics play a big role, and Ford doesn’t disclose the S550’s Cd, but the Mustang is reliably making 150-180hp more.

Ah well. It’s purely academic anyway. Won’t ever have to prove to my son that it’s not the 200 I claimed it was.

Could be faster, it’s really just a guess until someone that’s really run out the top end comes along and chimes in

 

[SheepDog]

AI says 239.5 MPH. You would obviously need a very long stretch of road to achieve this.

 

[MisterScobbles]

Could be faster, it’s really just a guess until someone that’s really run out the top end comes along and chimes in

Yeah.

It will be interesting to hear if anyone has done it.

I visited the USA earlier this year and didn’t see as many Mustangs as I thought I would. Even managed to get to a Cars and Coffee in Miami.

Where do all the Mustangs live?

Glad I got it in before yesterday though. Don’t want to risk being turned away at the airport.

 

[MisterScobbles]

AI says 239.5 MPH. You would obviously need a very long stretch of road to achieve this.

This I can’t afford to purchase. Great story for my kid though!

 

[SheepDog]

This I can’t afford to purchase. Great story for my kid though!

The basic version is free. This calculation is only as good as the details you give it. For example, we don't know what the frontal area of the car is (somewhere around 23 sq/ft) but the more details you can give it, the more accurate it will be.

It'll do 200 for sure, if you have the road, the tires don't blow up, and you have the stones to keep pushing it

 

[Idaho2018GTPremium]

I’d say you have the power to go about 200 mph but the hood would rip off and the car would be really unstable overall. The regular mustang GTs don’t have any aero or downforce so it would be floaty and extremely unstable due to the lift. I’ve seen hoods bowing out at half that speed, so there’s likely no way it could hold on at 200 mph. Remember even with a huge hood vent the GT500 has hood pins and a limited top speed of 180 mph, despite having the power to exceed 200 mph. Ford didn’t design the Mustang with a high top speed in mind. Then you might have tire limitations. And on an extended pull like it would take to get to 200 mph you’d probably grenade your supercharged engine due to insufficient ring gap. The stock rings aren’t set up for supercharging so long pulls which cause extended heat and pressure in the combustion chamber, the rings expand, the ends touch, and bam, bye bye engine. Don’t do it (an extended pull).

A stock 6th Gen Camaro ZL1 which make ~560 rwhp officially hit a two way average in GM’s testing of 198 mph. 202 in one direction, 194 against the wind.

 

[K4fxd]

Don’t want to risk being turned away at the airport.

Why would you be turned away? If you go through the proper channels and have a valid VIsa = no worries.

 

[MisterScobbles]

I’d say you have the power to go about 200 mph but the hood would rip off and the car would be really unstable overall. The regular mustang GTs don’t have any aero or downforce so it would be floaty and extremely unstable due to the lift. I’ve seen hoods bowing out at half that speed, so there’s likely no way it could hold on at 200 mph. Remember even with a huge hood vent the GT500 has hood pins and a limited top speed of 180 mph, despite having the power to exceed 200 mph. Ford didn’t design the Mustang with a high top speed in mind. Then you might have tire limitations. And on an extended pull like it would take to get to 200 mph you’d probably grenade your supercharged engine due to insufficient ring gap. The stock rings aren’t set up for supercharging so long pulls which cause extended heat and pressure in the combustion chamber, the rings expand, the ends touch, and bam, bye bye engine. Don’t do it (an extended pull).

A stock 6th Gen Camaro ZL1 which make ~560 rwhp officially hit a two way average in GM’s testing of 198 mph. 202 in one direction, 194 against the wind.

Ok! I like breathing and I avoid scary movies and my mother-in-law because I can’t handle the anticipation anxiety, so no, definitely not testing its capabilities, also because it’ll be only once, because one of us will die.

As an FYI though, not worried about the hood. Have an aftermarket CF item with pins. I’m gonna have to die some other way.

 

[HKusp]

You wouldn't get turned away at the airport if you went through customs with a valid passport. Why the hell would you think otherwise? Oh, wait..."media"...just dumb.

 

[MisterScobbles]

You wouldn't get turned away at the airport if you went through customs with a valid passport. Why the hell would you think otherwise? Oh, wait..."media"...just dumb.

EXTREMELY dumb, kinda like trying to apply some cynical sarcasm in a post relating to the top speed of a car that we all like and is the common interest we have, assuming that’s enough for us to have a conversation without insulting people.

That really was dumb of me.

PS: hope you have better luck with your 2018 GT. Totalling two cars will start looking like a habit, or worse. Happy to help with some tips if you want, as a friend.

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