Danny Lawrence Engine Builder
for #3 Monte Carlo - Engine differences are many
August 11, 1999 - By Mary DellaValle, Professional
While the ultimate goal in NASCAR
racing is winning, reaching the 750-horsepower level is a victory in itself. The
accomplishment is attained through the skills and acumen of engine builders who thrive on
continually finding ways to produce more speed.
their ingenuity makes them victims of their own success.
Danny Lawrence - Head Engine Builder for the
Dale Earnhardt #3 Monte Carlo
A case in point is when NASCAR
mandated a lower engine compression ratio beginning in 1998. The ratio, which measures the
pressure created in the cylinder by the upward movement of the piston, was reduced from
14.0:1 to 12.0:1. The goal in slowing speeds, according to NASCAR, is to cut horsepower
and enhance competition.
Danny Lawrence, Head Engine Builder (for the No. 3 Monte Carlo, Goodwrench Service Plus
NASCAR Winston Cup Series car), Richard Childress Racing, recalls it wasn't very long ago
that there were no compression limits.
"A couple of years ago (five to be exact), we had no compression ratios,"
Lawrence recounts. "They (NASCAR) would let you run whatever compression ratio you
wanted to run, but the octane in the fuel determined a lot of the compression ratio you
got. You get into detonation and all kinds of other variances when you run unlimited
He explains the 12.0:1 compression ratio limit may continue to drop, and that the reason
for further reductions involves emissions issues.
"They've started dropping the compression ratio because NASCAR is leaning toward
unleaded fuel. From what we understand, they are going to start going lower, so that we
can start running unleaded fuel. We should know toward the end of this year - NASCAR might
even go to 11:1 or 10:1 next year. The reason they're doing that is so that we can start
running unleaded fuel for the emissions."
When NASCAR institutes a rule change, such as with the engine compression ratio limit, the
teams have to go back to the drawing board with different strategies. Said Lawrence:
"Whenever they make a rule, everybody works really, really hard to get back to where
they were or even better. We're still searching for what is the best."
The compression ratio is achieved in different ways by the various teams. Lawrence
explained: "When they dropped it, everyone had to go back to work. Some teams use
what is called a 'reverse dome' where you don't have a pop-up piston or a flat-top piston
- it means you have a dome in your piston."
Pistons are custom made, and most NASCAR Winston Cup teams have their own piston design.
It's an evolutionary, detail-oriented process to achieve the best formulations, says
"We're going through different combinations right now to see what we need with
different types of cylinder heads," added Lawrence. "You can't just say, a
reverse dome works really good with this type of cylinder head and this cam. You have to
keep going back through it every time you make a change, as one phase of the engine
affects another phase.
"We revisit that stuff all the time. You never give up on it. Just because it didn't
work then, doesn't mean it's not going to work now. If somebody finds a little something
here, and you're not looking in all those areas, you could get behind really, really
Beyond meeting the challenge of staying within the engine compression ratio limit, NASCAR
Winston Cup Series teams still manage to eke out a few more horsepower, here and there.
After all, the race car engine is where races are won or lost, and any advantage gained
can make all the difference in giving a team a competitive edge.
Yet the more compression you put into an engine, the stronger you have to make the
components to withstand the stress. Preventing engine failure, therefore, is a primary
consideration and goal in building a NASCAR Winston Cup Series engine.
Lawrence knows that well.
"With more compression, you have to have stronger rods and stronger pistons - the
beefier all those parts have to be," he explained. "We're pretty much on the
cutting edge on the strength of the pieces. We try to run the lightest components that we
can, which will actually turn the engine up quicker, yet they are durable enough to finish
the race. So you don't want a real heavy piston, or a real heavy rod in that thing, that
you don't really need."
Achieving the right compromise requires intensive testing, and extensive research and
"We stress test the rods and the pistons, and we use the lightest components that
will not fail," said Lawrence. "You can build that thing where it will never
break, and you wouldn't ever have any trouble with it, but it won't turn up the RPMs. It
is sort of like walking on thin ice - you want it (components) as light as possible, but
where it won't break."
Post-race analysis and testing are big factors in component development and refinement, as
they reveal key information on the level of stress that engine components undergo.
"We are constantly changing our pieces to try to make them better. When we
disassemble an engine, we inspect it just like we do when we put it together to look for
stress, and we have a process to tell how much torture the pistons and the rods have
taken," explained Lawrence.
"We also send stuff out to metallurgists who do stress tests. You can tell by looking
at the bearings and looking at the pistons, how hot it's been and how much torture it's
Engine component stress comes in varying degrees of intensity as dictated by track
variances, according to Lawrence.
"Different race tracks put different kinds of loads on the engine." He gave the
example of equipping a race car bound for Atlanta Motor Speedway with stronger components
because the RPMs don't fall down as much on that track, compared to running at Bristol
Motor Speedway, where there isn't near as much of a load put on everything.
Lawrence compared the component configurations of a race engine and a qualifying engine
and the horsepower differences therein.
"Generally a lot of the teams' qualifying engines will be 20-25 horsepower more than
what their race engines are because of the lightness of the pieces that are inside
He explains that a qualifying engine can have a little rougher cam, and lighter weight
pistons, crank and rods, but those things would never last in a race. Everyone knows that.
Input from a NASCAR Winston Cup Series driver is critical to a team's research and
development processes, so much so that in-the-field comments are analyzed at weekly team
meetings. Detailed information about a car's performance are factored into strategies for
future races at the same track.
"A lot of times we'll go to the race track with different combinations.....like the
No. 31 car had this kind of engine, and the No. 3 car had this kind of engine, so we get
the driver input," explained Lawrence. For example, "Dale Earnhardt says the
engine ran really good from the flag stand on, and then Mike Skinner says my engine ran
really good from the center of the corner to the flag stand. So, we come back and put the
car on the chassis dyno or the engine back on the race dyno and we'll run those engines
against each other. We try to figure out what would be best for that race track when we go
back. It's a never-ending thing. You never stop tweaking and you never stop trying to find
that horsepower or that torque . It's a continuous thing and you never give up on it. You
can always get better."
Perfection doesn't come overnight, nor without keeping your eyes and ears open, alluded
"We're looking down the road. We're always planning for the next three months. All of
this stuff is custom made, so when you decide that you're going to run a different type of
piston, you just don't decide today that you can do it tomorrow because this stuff has to
be built, and it takes time.
"We're always looking at what everybody else does. Someone will call and say I've got
the latest carburetor. We get it in here and you have to look at that kind of stuff. You
can't give up on anything; there is no end."
All of the expertise, hard work, and research and development that goes into preparing a
NASCAR Winston Cup Series car for race day must pass one final test - that of the NASCAR
Officials who give the engines a final "thumbs up."
Starting with the carburetor, then working down through the manifold, NASCAR Officials end
up by verifying that the vehicle's engine compression ratio is within the legal limit -
12.0:1. They use a "P&G pump" to check the engine displacement, then they
feed that information into the "whistler" which measures the engine compression.
It actually measures the volume of the combustion chamber by sound waves. A thermometer is
also used to check the engine, providing yet another number that is added to the whistler
as a pre-race check.
All teams' race and qualifying engines are whistled and P&Gd on race day, before any
of the race cars are allowed on the track. The entire inspection, which Lawrence says
takes under 10 minutes if the team is prepared when the NASCAR Officials get there, is
Lawrence runs through a typical engine compression inspection. First, NASCAR Officials
appoint a cylinder that will be checked. There is a board on the NASCAR Winston Cup
Officials trailer that says, for example, 'P&G second cylinder on the right side,' he
explains. For the NASCAR Officials to check engine displacement, "What you have to do
is pull all of the spark plugs out of the engine, pull the valve covers off and take the
two rocker arms off of the cylinder that they designate," explained Lawrence.
"They (NASCAR Officials) have a gauge that they screw into a spark plug hole. They
then put a hose to that gauge and spin the engine over, and what it does is it reads how
much velocity of air comes out of that cylinder. If you have a really big engine and it
pumps more velocity of air out, they can pretty much tell. That's what they call P&G,
which stands for pump and gauge."
This data is then fed into the whistler to determine the engine compression, says
"What you do is you pull your engine up to top dead center (TDC), and usually you'll
put your engine a couple degrees before TDC. The whistler goes in that same hole
(mentioned above) and, with the valves closed, it reads how much area you have with the
piston at TDC. It pumps air into the cylinder and pulls air back out of the cylinder, and
it tells how much area is in there."
Lawrence adds that the NASCAR Officials take the P&G number (i.e. the motor is 356
cubic inches), and the formula they get from the whistler, and they put that in the
whistler (356 and the temperature, and how much air flows in and out of the engine with
the piston at TDC), and it roughly tells them the engine compression ratio.
The readings obtained from this inspection are close, but not totally accurate, says
Lawrence, because the process is affected by carbon and the outside temperature.
"But, it gives them a really close reading without tearing the engine apart."
An engine tear down is not improbable, however, even though an engine builder signs off on
the engine, indicating it is legal, says Lawrence.
"If they see something that is out of the norm, for example, after qualifying or
after the race, everyone's engine whistles 11:4 or 11:5 and mine whistles 12:1, they'll
make me tear that engine down after I use it and then they'll check to see why it's
different. They don't just let you off the hook."
There's no comparison between the power and efficiency of a NASCAR Winston Cup Series
engine and a factory production engine, not to mention that NASCAR Winston Cup cars still
use carburetors, and today's new cars are fuel-injected. But some similarities do exist.
For example, NASCAR Winston Cup Series cars' engine specs mirror those of a factory
engine, including the number and angle of the cylinders, the location of the camshaft, the
number of valves per cylinder, the number of intake and exhaust ports, and the location of
the spark plugs.
And while they are miles apart in terms of horsepower and performance, when you consider a
NASCAR Winston Cup engine produces more than 700 horsepower, compared to a typical street
vehicle that runs in the 200-horsepower range, the principles governing their upkeep and
maintenance should run parallel. Even though your customers' engines won't be pushed to
achieve designated horsepower goals, they still need to run efficiently and perform at
their peak. Meeting your challenge of keeping them well-tuned and in top-running condition
will hit your goals of satisfied customers and no repair comebacks.
Blk3GM's Dale Earnhardt Site was born on
July 26, 1998 and is owned and maintained by Gary Harris. This site is a
tribute to "NASCAR's Greatest Driver" and his up and coming son. We are
not affiliated with any official Team, Sponsors, Media Group or NASCAR. This site is
solely for entertainment purposes. Information and statistic's on this site have
been collected from various NASCAR related sites on the internet, from Winston Cup Scene,
Newspapers, Television and our personal experience at Winston Cup and Busch Grand National
races. All statistics are believed to be accurate at the time they are updated but
cannot be guaranteed.