RE: [DML] "Horsepower" In The Neverending Performance Debate

["Tom Tait" <TTait@xxxxxxxxxx>]

Bill - Thank you!

 

I will also throw in that there is a mid level cost option to getting
more HP as well.

 

I have recently installed DMCC's performance cam kit.  Its not a small
job, but I had to replace the head gaskets on my car anyway so it was no
extra work in my case.  The cams are $600 for a set.  While this is not
cheap, Don Stengor has put cars on a dyno - first stock and running
well, and then a week later with his cams installed, and he has gotten
impressive results.

 

My car has not been on the Dyno, and even if it was I don't have a
baseline, so I won't quote numbers here. Don knows them and I'd rather
he make those statements if anyone is interrested.  They are very (very)
close to the numbers for the Stage II engine though.  Not bad for a job
you could do yourself if you had the gumption and $600 in performance
upgrade parts.  If you have DMCC do the install for you it is still
likely half the cost of a stage II upgrade.

 

(By the way there is a fantastic write up in the tech section or doing a
head swap - if you're a good mechanic, or budget challenged as I am it
is do-able.  Most owners however will be happier paying the pros to do
their magic - it's a do-able job but not recreational.)

 

I've just sent the car down to Don to check my valve adjustments, but
it's already running nicely.  Long term information on the upgrade will
have to come from others for now.

 

Your write up, Bill, will help readers understand that the actual
performance of the engine as compared to a stage II will obviously vary
even if the HP numbers are the same, because they will have different
torque curves.  Maybe it's better for your driving style, maybe not, but
it's worth consideration.

 

Tom

10902

________________________________

From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf
Of content22207
Sent: Thursday, October 25, 2007 10:03 PM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: [DML] "Horsepower" In The Neverending Performance Debate

 

In the current performance debate the word "horsepower" is starting to
be tossed around. A refresher primer may be necessary:

There is no such measurement as horsepower. Horsepower is a
*CALCULATION*, made from other measurements. For example, there is no
such thing as a "horsepower gauge." There are gauges that measure is
calculative components, but horsepower itself does not independently
exist.

HP = Torque x RPM / 5252

Torque and RPM are the measurable components of the HP calculation.
Gauges exist to measure each.

BTW: There's a historical explanation to that obscure formula. In the
1800's a fellow named Watt wanted to sell steam pumps to raise water
from coal mines. That job was already being performed by horse driven
pumps (horses were harnessed to big horizontal wheels, walked in
circles, and the motion was tranfered to vertical pumps). He needed a
calculation that would allow mine owners to compare his engines to the
horses they already were using. Watt measured how much weight an
average horse could raise vertically in one minute. That weight &
height translates into the 5252 (its a factor of 1, so the formula
holds for however much torque or however many RPM's are measured).

What does all this mean? First, owners need to divest themselves of
images of horses harnessed to the front of their little silver cars
like a Conestoga wagon. That's the popular image: 130 HP equals the
power of 130 pulling horses. Nothing could be further from the truth.
There are 400 HP semi tractors that pull 70,000 lbs of weight with
relative ease, and there are 400 HP sportscars that can't pull a
U-Haul. Same 400 HP rating, so obviously the horse drawn image doesn't
work.

It all boils down to torque (sometimes called "bottom end power") and
RPM's ("top end power"?). An engine that produces a tremendous amount
of rotational force, but does so at low RPM's, will have a
surprisingly low HP calculation. An engine that produces relatively
little rotational force, but spins very quickly, will have a
deceptively high HP calculation.

In our sportscar example: Hitched to a semi trailer, the little car
would either stall the engine, burn up the clutch at point of release,
or boil the transmission fluid (if it were an automatic), before it
budged the trailer. The sportscar doesn't produce any usable power
until its engine is spinning very quickly. At idle it's very weak.

By contrast, the semi tractor produces a tremendous amount of power
from idle forward. But its engine does not rev very high at all
(semi's spend most of their life in the 1,200-1,500 RPM range). Hence
its HP calculation is a fairly low number.

Of course transmissions also affect the transfer of power to driving
wheels (semi's have up to 18 gears), but the HP principle remains.

Again, what does all this mean? Second, DeLorean owners need not hang
heads in total shame over our paltry 130 HP rating. The PRV produces
more torque than many higher reving engines with corresponding higher
HP numbers. Until those engines reach their higher RPM's, we have more
usable power. If they fail to reach those RPM's (under load, going
uphill, etc), they never will match our power.

Could the PRV produce even more torque or RPM's? Of course. The
easiest way to bump up torque is higher compression or forced
induction. RPM's are harder to modify since they are largely
determined by internal engine components such as camshafts and
crankshafts. Which brings up a good point: "Red line" is not the point
at which an engine is producing its maximum power. Rather, the red
line is the point at which an engine is producing no more power.
Basically the valves are starting to float. Maximum power is actually
reached prior to the red line (ever notice how HP calculation graphs
peak, then start to drop off?). Noise level continues to increase, but
usable power is declining.

The big picture? DeLorean owners need to decide what performance
targets they are trying to reach. If they want a more powerful engine,
compression and induction are the avenues they need to explore.
Modifying ignition may help marginally, but the gains are nothing
compared to super or turbocharging. However, if "performance" means
reliability, consistent operation in a variety of atmospheric
conditions, maximum fuel burn, etc, modifying ignition *IS* a viable
avenue. I personally chase the latter targets (why in the world
otherwise would I modify ignition on humongous 7.5 liter low reving
Lincoln engines! They certainly aren't going to change into race
engines from ignition alone).

Food for thought in the neverending performance debate.

Bill Robertson
#5939

 



[Non-text portions of this message have been removed]



To address comments privately to the moderating team, please address:
moderators@xxxxxxxxxxx

For more info on the list, tech articles, cars for sale see www.dmcnews.com

To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews 
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/dmcnews/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/dmcnews/join
    (Yahoo! ID required)

<*> To change settings via email:
    mailto:dmcnews-digest@xxxxxxxxxxxxxxx 
    mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    dmcnews-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/