NASCAR V8 vs Formula 1 V8

[SubLGT]

Here is an interesting (and technical) article comparing these two V8s from the 2006 racing season. Surprised to see that the 2.4L F1 engine made around 755 HP, but only around 214 lb-ft of torque.

http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm

 

[tdi-rick]

Good article, thanks.

 

[d00df00d]

Wow. Excellent article -- at least as far as I can tell without the knowledge to evaluate the methods and data.

Thanks for posting!

 

[Shannow]

Quote:
BMEP and MPS

Two of the most accepted performance-comparison yardsticks are Brake Mean Effective Pressure (BMEP, explained HERE) and Mean Piston Speed (MPS, explained HERE).

The BMEP of the Formula One engine at peak torque (table line 13) is 15.17 bar while the Cup engine produces a peak torque BMEP of 15.12 bar (0.3 % less).

At peak power, the Formula One BMEP value (table line 22) is 14.6 bar while the Cup figure is 14.0 bar (4.1% less).

It is evident that producing 15.17 bar BMEP at 17,000 RPM and 14.6 bar at 19,250 RPM are remarkable achievements, given that the ratio between Friction Mean Effective Pressure (FMEP) and BMEP is much higher at Formula One than it is at Cup RPM.

However, it is astonishing that the Cup BMEP (remember, flat-tappet cam, pushrod / rocker arm, two-valves-per-cylinder, single carburetor) is only 0.3% less than the Formula One figure at peak torque, and only 4.1 % less than Formula One at peak power.

Even more revealing, at peak power RPM (table line 19) the Formula One engine MPS (table line 23) is 25.5 m/s (5025 ft/min), while that of the Cup engine is less than 3% lower at 24.8 m/s (4875 ft/min). At redline, the Formula One MPS is 26.5 m/sec, while the Cup MPS is a stunning 27.5 m/sec. To put those numbers in perspective, Professor Gordon Blair wrote (Race Engine Technology, issue 27) that 26.5 m/sec was the highest he had seen.

While being cautious with empiricisms, it is interesting to compare the nondimensional values of BMEP x MPS (bar x m/sec) at peak power (table line 24) and at peak torque (table line 15).

At peak power, the Cup engine value is only 7% less than the Formula One engine, again showing the remarkable performance extracted from this production-based V8. There is a bigger disparity at peak torque (nearly 9%), largely due to the greater spread between peak power and peak torque in the Cup engine (15% of redline versus 11% of redline for the Formula One engine).


Basically demonstrates that the laws of physics and material sciences remarkably apply to both engines.

This was the basic reasoning for the "rated" horsepower that they used to tax vehicles on in Britain, that lead to longer strokes as materials got better.

It's not (truly) surprising that the dimensionless comparisons of the two pinnacle engines are so similar.

 

[Steve S]

torque X rpm = HP. Then figure out the displacement difference.

 

[SteveSRT8]

It's freaking amazing that a pushrod two valve motor can be so close to the output of a Formula One engine!!!!

 

[OVERKILL]

Originally Posted By: SteveSRT8
It's freaking amazing that a pushrod two valve motor can be so close to the output of a Formula One engine!!!!


They've had some pretty wild pushrod stuff for a long time though

My cam grinder's latest project:

 

[G-MAN]

Originally Posted By: SteveSRT8
It's freaking amazing that a pushrod two valve motor can be so close to the output of a Formula One engine!!!!


Not really. For example, look at the 1994 Indy 500 where Mercedes entered the race with a purpose-built pushrod V8 that took advantage of the same rules that Buick had used for years with its V6 at Indy. Because the engine was "handicapped" with pushrods, the rules allowed more boost on the turbos and bigger throttle bodies. Mercedes kicked everyone's butt with that engine. The two Benz cars were so far out in front most of the race it wasn't even interesting.

 

[sprintman]

Bit of a capacity difference too.

 

[d00df00d]

Originally Posted By: sprintman
Bit of a capacity difference too.

Just a little.

But then, there's also a bit of a redline difference the other way...

 

[sprintman]

Of course.

 

[Shannow]

It's not that surprising when the respective engines are compared using "dimensionless numbers", which is a standard engineering practice for designing things that you haven't made before.

e.g. Reynolds number (densityxvelocityxdiameter/kinematic viscosity) tells you a lot about how a 1/2" tube and a 2' tube are related regardless of what liquids are pumped through them, and how fast.

Dimensionless numbers have been used to build scale ships, floating in (IIRC) acetone to simulate a full size vessel in salt water.

While not dimensionless, the parameters that they use demonstrate that engines are "scalable", and that materials science is the limit.

Mean Piston speed is similar...one short stroke high revs, one long stroke low revs...Con-rod materials and designs are the limit of mean piston speed.

Brake Mean Effective Pressure is an average of the usefulness of the pressure above the piston for a cycle...limited by fuels, ambient pressure and temperature.

The small engine does it twice as often as the large (broadly), giving similar power results, and lower torque (power/RPM).

The large capacity of the NASCAR engine allows/requires it to run in a range where pushrods work.

 

[Bror Jace]

"It's freaking amazing that a pushrod two-valve motor can be so close to the output of a Formula One engine!"

There's a saying:

"There's no replacement for displacement."

But it's not true. It's just that the 'replacement' comes in the form of tens (hundreds?) of millions of dollars in materials and engine development.

Another aspect not to be forgotten in the comparison is the weight of both motors: 209 lbs. versus 575 lbs. (almost 3:1)

 

[wannafbody]

Since HP and Torgue always are the same at 5250RPM the engine that makes the best low RPM power is the better engine.

 

[d00df00d]

Originally Posted By: wannafbody
Since HP and Torgue always are the same at 5250RPM the engine that makes the best low RPM power is the better engine.

I don't have the slightest idea what you mean by this, but I'm pretty sure it's not correct...

 

[OVERKILL]

Originally Posted By: d00df00d
Originally Posted By: wannafbody
Since HP and Torgue always are the same at 5250RPM the engine that makes the best low RPM power is the better engine.

I don't have the slightest idea what you mean by this, but I'm pretty sure it's not correct...


HP and torque cross at 5250RPM. Other than that being factual, I cannot see how somebody can draw any conclusions from it.

 

[Shannow]

The only cross in ftlb and horsepower world.

the crossover point in artificial units of measurement means absolutely nothing.

 

[Blokey]

Originally Posted By: d00df00d
Originally Posted By: wannafbody
...HP and Torgue always are the same at 5250RPM...

I don't have the slightest idea what you mean by this, but I'm pretty sure it's not correct...


True, but only when power is measured in horsepower and torque is measured in ft-lbs.

 

[Blokey]

Sorry Shannow, I ended up reiterating what you said. Guess I should read the replies more carefully before I hit the keyboard!

 

[Steve S]

OHC engines have the potential of much higher rpm potential because of the lighter valve train. That is not necessarily better ,I like ohv for passenger car use as it makes a more compact package.