GT44 performance specs

[Knighton]

Just thumbed through a car magazine - motortrend I think - and Ford is claiming:

0-60 in 3.7
1/4 mile 11.9 @122mph

I find it hard to believe 500hp and 500tq can propel a 3400lb car to these numbers, especially the 1/4 mile. Is this marketing and hype? Magical supercharger? Magical tires?

Perhaps the 44 pumps out over 600hp?

And I have a question regarding the delivery of power. Does a supercharged or turbocharged engine provide more acceleration than a normal aspirated engine with the same hp output?

In other words, if three identical cars, each producing 500hp and 500 tq but use different engines - car A has 351 stroked to 408 and car B has a twin turbo 306 and car C has supercharged 331, which car would accelerate better?

 

[ QUOTE ]
In other words, if three identical cars, each producing 500hp and 500 tq but use different engines - car A has 351 stroked to 408 and car B has a twin turbo 306 and car C has supercharged 331, which car would accelerate better?

[/ QUOTE ]

The one with the best combination of weight, weight distribution, tires and SUSPENSION SETUP.

 

[Brett James-McCall]

Wouldn't it also depend on the gearing? Have they released the ratios?

Brett

 

[Paul Thompson 'Hooligan']

Hi all -

IMHO - An experienced right foot will often help achieve low figures. The more power available, the more it helps to have the additional experience.

 

[James]

[ QUOTE ]
Hi all -

IMHO - An experienced right foot will often help achieve low figures. The more power available, the more it helps to have the additional experience.

[/ QUOTE ]

Paul,

Are you saying that you require that "additional experience" to crack the 12 sec barrier? /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

Regards,

J.P

P.S I reckon Ford must have had a 40 mile an hour tail wind to come up with those bloody figures! My calcs make it 12.5 over the 1/4.

 

[Ron Earp]

I do not find the figures unbelievable at all based on experience with 34-3800lb Mustang coupes. 500hp will get those cars into the 11s all day.

But it does require good driving and careful attention to traction, suspension, etc. And, these cars have solid rear axles and trannys that shift reasonably well and fast.

From what I've read and what the UK folks have told me it appears to me most of you have the power to get into the 11s. But, either the traction isn't there or the tranny doesn't want to play the 1/4 mile game. Maybe the new GTs tranny is a sweet shifting unit that makes it possible to bang off the shifts necessary for sub 12s and the suspension weight transfers better.

I dunno, when I see (actually at Rockingham) 2003 Cobra Mustangs at 3700lbs running 11.7s with a blower pulley swap and around 500 hp I figure the new GT ought to be in the hunt.

R

 

[Paul Thompson 'Hooligan']

HI James -

IF EXPERIENCE was ALL that was required - Roy Smart would have been into the low 10s by now
/ubbthreads/images/graemlins/cool.gif
- and when you get to drive your MDA, it would put you in the high 18s - (with a bit of practice!) - /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

Ho Ho Ho.............

 

[Knighton]

And I have a question regarding the delivery of power. Does a supercharged or turbocharged engine provide more acceleration than a normal aspirated engine with the same hp output?

In other words, if three identical cars, each producing 500hp and 500 tq but use different engines - car A has 351 stroked to 408 and car B has a twin turbo 306 and car C has supercharged 331, which car would accelerate better?



[/ QUOTE ]

??? /ubbthreads/images/graemlins/blush.gif

 

[Steve Toner]

I don't think it's a matter of the peak hp & torque numbers in a case like this, but the area under the curve.

 

[Paul Thompson 'Hooligan']

In my experience, Turbocharged and Supercharged engines generally develop more torque lower down the rev range than their normally aspirated equivalents.

I believe the increased torque will accellerate the car quicker than the n/a engine but have no logged data to prove the point. I do know that Tony Marsh's Twin Turbo GTD40 is seriously quick providing it doesn't wheelspin too much and Roy's 40 is definately quicker out of slow corners than it used to be, it now also having more low down torque.
(it is still n/a too)

All the power and torque in the world is of little use if the tyres/chassis/shocks cannot transfer it effectively.

Ron has experience of both n/a and force fed power I believe - what do you think Ron? /ubbthreads/images/graemlins/confused.gif

 

[Ron Earp]

I agree with Steve on this one, area under the curve is what is important.

And, since I believe that I also agree with Paul - the force fed motors, at least the ones I've built and run, always develop more low end power (I don't use centrifugal blowers if possible but positive displacement or turbos) and thus accelerate harder in the lower RPM band. But, the traction problem can become a serious issue.

So, the motor in the new GT is rated at 500 hp but its torque curve will be the same as the new Ford Lightnings and Cobras - very, very, very flat from 2000-6000 RPM. Check the link which shows rear wheel torque and horsepower from a modified 2003 Cobra motor.

Link to a Typical Modded 2003 Cobra

There is a lot of area under this motor. And, they seem to take punishment unlike the eariler build Cobra motors. These have Manley rods and forged cranks, supposedly good for around 700hp according to Ford engineers.

So, if the new GT motor produces figures like these or anywhere close the car will be fast.

R

 

I agree a fat curve and traction are very important.

As far as the where a SC or turbo car will produce torque (ie. high , mid, or low in the rev range) is highly dependant on the the way the system is set up and what type of SC is used.

Positive displacment Superchargers like a roots or a 'screw' type SC will produce boost pretty much right off idle and continue to produce it right through the rev range and have a less peaky curve. Though some older roots designs, in general, can have efficiency problems as SC revs increase so you may be producing boost but the density of the air is reduced as it is also producing more heat. Being belt driven you have all the problems associated with sapping power away from the engine to drive the SC. More boost the more power is required again.

A belt driven SC is genearlly geared to produce a peak boost level at a particuar engine RPM. Unlike Positive displacement they will build boost gradually as the compressor speed increases. Very generally, if you double the speed of the compressor you will increase boost by a factor of 4. You get this 'pulled along feeling' as boost builds. Centifugal SC's will have a more 'peaky' curve than positive displacment.

Turbos are centrifugal supercharges driven by the exhaust heat so it works similar to a belt drive centrifugal as far as how it produces boost. However the speed of the turbo charger is not directly linked to engine speed. For this reason the Turbo will be more 'peaky' in its curve than a belt drive centrifugal but can be setup to produce peak boost and maintain it along a broader engine rev range. For this reason traction can be a problem because a turbo will in general build boost more quickly (car feels like is being launched by a catapult). Turbo systems can be designed to produce boost in different areas of the rev range. So a turbo system can be set up for low rev boost but this will probably restrict top end performance. Vise versa a turbo that works well up the top will generally be lethargic at the bottom. Turbo systems are a lot harder to design and tune then belt drive SC's as sizing of the compressor and exhaust wheels, Turbo housing, Cams (especially the exhaust), manafolds are all so important for drivability and output. There is no point in putting on a moster turbo on a car that won't produce boost until after 4,000rpm if your engine only revs to 6,000!!

Centrifugal SC's including Turbos are in general more efficient than a roots and about on par with a 'screw' type. All have advanatages and limitations and this will effect how the engine performs.

BTW I am no expert but have done a bit of reading on SC's and turbos. Correct me if I am wrong!!

Cheers,

Danny

 

[ChrisL]

The greatest advantage of a turbo charged engine is that the compressor is powered by an energy source that is mostly discarded (ie the exhaust), whereas a supercharged engine "steals" power directly from the engine. So in theory all else being equal, a turbo engine should have more horsepower at the rear wheels for a given boost. Having said that, the greatest disadvantage of the turbo is that acceleration levels do not accurately follow throttle movement (turbo lag) so finessing the accelerator to minimise wheel-spin is more difficult. So in the case of the turbo engine, the horsepower may well be less useable in some cases.

In the case of a normally aspirated engine, more sacrifices are usually needed in order to get the high HP figures so the torque curve will usually be more peaky. However, because power will generally be more user-friendly, you may be able to compensate with some clever gearing. My observations have lead me to the conclusion that a same horsepower NA car is far quicker around a race track simply because it is easier to drive. This is particularly important for a mid-engined car where balance is everything.

Needless to say, all this is theory and design is very important. Use the wrong cam for example in any of the above engines, and all theory goes out the window.

As the previous contributor also mentioned, I am no expert either. I have only built the odd turbo charged and NA engine

 

[Paul Thompson 'Hooligan']

Hi Chris -
I too believe turbocharging generates more power for a specific boost level over supercharging, although temperature levels are something to consider more so with turbos i suspect.

Turbocharged engines can be torque controlled (restrained?) by modern engine management systems but traction controls on turbos, from my observation, always seem to give vicious exhaust notes - popping and banging like mad!

In addition, I'm not sure how n/a measure up against turbocharged on a track. Certainly a well set up n/a car will be easier to drive but just think of the turbochaged F1 cars of old, the big turbocharged Porsches or even the 600BHP+ Sierra Cosworths of late 80s touring car fame - Awesome!! Once mastered (if ever) a powerfull turbo car must be just a dream.... (or am I just being biased?)

If you ever get the chance of a ride in a major modified turbo car - take it - and 'feel the force Luke' - oop's, there I go again.

The thread that showed a turbocharged Chevrolet engine out of an Ultima (1300BHP!?)- now that must be a blast! /ubbthreads/images/graemlins/grin.gif

 

[Hershal Byrd]

Add some drugs (nitros)to this equation and you really
will feel the force... /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/ooo.gif

Hersh

 

Hi Chris,

Don't forget that turbos contribute additional back pressure to the engine which in a way robs the engine of power as well. A consideration in turbo design is the boost to back pressure ratio, typically race cars have low back pressure and high boost but are not really streetable... though some will try.

SC's on the other hand arn't that sensitive to header design (unlike turbos and atmo's which are).

Nothing is for Free!!! /ubbthreads/images/graemlins/frown.gif

Turbo's V's superchargers? You could argue all day (and a lot of people do) its upto the owner/builder. Top Fuelers are pretty darn powerful though don't you think? /ubbthreads/images/graemlins/wink.gif


Cheers,

Danny

 

[ChrisL]

[ QUOTE ]
but just think of the turbochaged F1 cars of old

[/ QUOTE ]

Ahhh yes, the turbocharged F1 cars of yester-year. But we get into a different discussion now. You're certainly correct about the ability to get more horsepower with a turbo'ed engine. This is why F1 went that way. But aren't we discussing same horsepower? Here's a thought. If the horsepower levels were to be controlled in F1 (which will never happen) would they choose the characteristics of a turbo or an NA engine?

I saw an awsome demonstration at the Philip Island Historics a number of years ago of an "old" turbo F1 Ferrari. It spun while travelling in a straight line under power and destroyed itself against a concrete barrier. A very sad sight. Obviously the driver (not the owner /ubbthreads/images/graemlins/shocked.gif ) had little understanding of the sling-shot effect of the turbo engine.

 

[Lynn Larsen]

I think I have to go with Danny on this one. Yes, turbos can produce more total HP, but like Ron, Danny and others have said, for 1/4 mile times, it is where it is produced and the area under the curve in the time it takes to go from 0 to the end of this short distance. Bye the way, back pressure isn't all bad. If you reduce it too much, you will loose torque. This yields a better top end, but lower power on the bottom which most will say is more important in drag racing. All that said and ALL other things being equal, I'd give the edge to supercharging barely, if at all, beating a HUGE, oversized turbo w/ a lot of RPM off the line.

 

[Howard Jones]

The reason F1 went to turbos was that the engines were limmited in displacement. The best of the F1 turbo's was the BMW the Nelson Piquet won the world championship with in the mid 80's. It was also the year that allowed the most boost pressure if I remember correctly. That motor was a 1500 cc inline 4 that was thought to make somthing like 1500hp in qualifying trim and about 1000hp+ over the race distance. Now 1000hp is a lot of power but it would not be all that difficult to achieve with say 600 cubic inches. There is, after all, no substitute for cubic inches.

Hummm.......... 1000hp ali 600 inch big block in the back of a 40. The powertrain would cost 3 times the cost of the motor!!!!! Can you say toque.