can anyone explain

[metcoll]

maybe some of you  expierenced engine builders can explain to me how they build them..just picked-up mopar action magazine & there is a 69 roadrunner running in c/stock class...this car is running high10s,now i realize that the car has 489 gears & probably a lot of duration on the cam profile, but its using stock valve sizes on heads, stock lift profile for the cam,stock 440 crank....i have a pretty good build ona 440 in my cahrger with 4.56 gears but no where near 10 second area, anybody have any info how they do this...ps the car weighs 3750..........thx

[Challenger340]

Far more "trick" stuff goin on there, !

and not just in the engine.

If you pay attention to the "mph" actually attached, to those ET's, you'll see the "actual"  Horsepower being produced, is not that impressive as the ET would lead you to believe.

Those guys 60ft like gangbusters, they HAVE to to get the ET, but then they just "putter" down the rest of the track @ higher rpm's, they don't PULL real hard.

Anything "gained", or "lost", in the first 60 ft., can be "doubled" off the ET at the end of the track.

If the application of soft averages for example, is applied to 2 identical cars, SAME HORSEPOWER, you'll see what I mean.

Car #1 runs an ET of 11.7 @ 114-115 mph, with a 60 ft. time of 1.71
Thats about "average", remember, for EXAMPLE only,

Now car #2 runs the 1/4 in 10.95 @ same 114-115 mph, but, with a 60 ft time of 1.33

From the above, you can see that car #2, had a quicker 60 ft time by .38, therefore, .38 X 2 = .76 quicker ET off the 11.7 - .76 = 10.95, BUT STILL @ THE 114-115 MPH.(SAME HORSEPOWER).


Not saying those guys aren't making relatively good horsepower for what they are, they do, but, it's NOT unmakeable power for what they are, with alot of work
Roughly speaking, 2 hp for every cfm of head flow utilized, with well matched Bumpstick & C.R.
What can a stock head flow ? 250 ? 260? 270?

It's enough to say, "not what they ARE telling you, it's more what they AREN'T telling you".

Here's a few engine tricks;
hour, after hour, after hour,..
-acid dipping goin on in the bowl areas of the heads,
-hours developing seat profiles & flow on low lift(area UNDER the curve),
-cheat the crank grind with a bit of offset grinding,
-ramping the lifter off the Cam

you could go on forever here,
but my point is, the CAR ,is as much responsible for those ET's, as are the engines.
'nuff said.

Bob out.

[Animal]

Great info Bob , thanks.