After endless hours of dyno...
After endless hours of dyno time (thanks Westech, and especially TomHabryzk), our 410ci Engine Masters Challenge entry was ready forcompetition. With a precompetition test score of 1,038 points, we hadconfidence it would perform well against the heavy hitters in theindustry.
If you take a look at many of our tech articles for MM&FF, it should beapparent that we're big fans of horsepower graphs. We should probablyrephrase that statement by saying we're not so much fans of graphs aswe are fans of the big picture.
By this, we mean the entire power curve.In our recent comparison between the four different forms of forcedinduction ("Boost Bash, Part 1," Dec. '04, p. 125), we made sure tostart the power pulls as low as possible (in this case, 2,500 rpm) inorder to fully demonstrate the power potential offered by each form fromas low as possible all the way out to our self-imposed redline of 6,600rpm.
Running such a long sweep on the SuperFlow engine dyno was no easytask, but only by showing the power production offered throughout theentire rev range can the merits (and limitations) properly be addressed.The importance of the overall power curve was instilled in parts 1 and 2of the "Ultimate Guide to Cylinder Heads" (Aug. and Sept. '03) as well,where we compared the many 5-liter heads to the stock E7TE castings onthe airflow bench and on the dyno. Only by running them down to 2,500rpm would we know what kind of power gain (or loss) was availablethroughout the rev range.
The buildup began with a solid...
The buildup began with a solid foundation that included a Dart Windsorblock. The block featured four-bolt mains (for all five--not just thecenter three) and plenty of additional strength in all the criticalplaces. This one featured 4.125 bores, something that enhanced thebreathing capabilities of the AFR 225 heads we chose to run.
Why is it so important to know the powerproduction throughout the rev range? The shape (or change) of the powercurve determines not only the accelerative capa-bility, but also theoverall character of the motor. The often-quoted peak power numbers tellas much about the motor as a single snapshot in your photo album does ofyour personality. Imagine the opinion someone might get having only seenthat photo of you dressed up as Elvira for Halloween.
Just as yourMistress of the Darkness costume might not tell the whole story (thoughit tells us more than we wanted to know), the peak power rating providesonly a glimpse into the character of the motor. Think about it--will a400hp 5.0 offer the same performance or manners as a 400hp 408? Nothardly, as despite the similar peak power numbers, the larger 408 willalways offer much more low-speed torque--something that will make yourstreet Stang much more fun to drive and likely out-accelerate thelike-powered 5-liter version.
Thanks to Coast High Performance,...
Thanks to Coast High Performance, Scat supplied the 4340 forged-steelcrank. The Dart 4.125-bore block all but dictated the stroke length of3.825 inches. The experts at Castillo Crankshaft Specialists were calledin to knife-edge and lighten the crank.
With such an affinity for average powerproduction (especially for street buildups), is it any wonder we wereexcited when sister publication Popular Hot Rodding introduced theEngine Masters Challenge? The EMC is a unique engine-buildingcompetition that helps stress the importance of the overall power curvefor street motors by rewarding the builder who produces not the mostpeak horsepower (or torque), but the highest average power and torqueover a specific range. In this, its third year, the EMC pitted the top50 engine builders from across the country to put together small-blockstroker motors displacing no more than 410 ci.
The previous two yearsincluded 366-inch small-blocks and 470-inch big-block buildups. (Checkout enginemaster.com for full details on the rules). But, racers beingracers, it was necessary to spell out the rules in black and white, lestsome savvy individuals find those all-important gray areas that lead toimproved performance. Case in point: The rules stated that anyone usingCleveland blocks must run a 9.2-inch deck height and not the 9.5-inchheight of the Windsor. Jon Kaase read the rules that stated head gasketswere unlimited, so he built a set of 0.300-inch-thick copper headgaskets to effectively produce a 9.5-inch deck height on his 9.2 deckCleveland. Pretty trick stuff, Jon!
Coast High Performance supplied...
Coast High Performance supplied the forged-steel connecting rods andforged-aluminum pistons for the EMC project. The piston dish was chosenafter selecting the AFR 225 cylinder heads (and attending 57ccchambers). To produce the desired (92-octane friendly) staticcompression ratio, the custom pis- tons were initially machined toproduce a -6cc dish but eventually remachined down to -12 cc to furtherreduce the final com-pression to 11.82:1.
Basically, the rules limitedcylinder head, intake, and header choices to as-cast, street-orientedpieces. The motors were required to run from 2,500 rpm to 6,500 rpm on92-octane pump gas. The winner was declared by the combination of theaverage horsepower and average torque produced throughout this revrange. Each contestant was required to make three consecutive runs, theaverage of which would be their final score.
Having spent every wakinghour on the dyno in an attempt to stress the importance of the averagepower production for the past 10 years or so, it was only fitting thatMM&FF throw its hat into the ring. While we in no way consideredourselves the engine-building equal of guys with names such as Shaver,Sherma or Kaase, we were hoping to find out if all those years spent onthe dyno have actually paid off. The EMC was interesting in that, forthe first time, we were never really con-cerned about the peak poweroutput of the motor. In fact, during testing, we even reduced the peakpower by nearly 50 hp in our quest for the all-important average powernumber. Were we building the same combination for a drag racer, we wouldnot have replaced the single-plane intake with the dual-plane. But weweren't interested in the power production from 4,000 rpm to 6,500 rpm.We were interested in the power production from 2,500 rpm to 6,500rpm--and the Performer RPM Air Gap produced the highest average power inthat range.
While suspecting we were no match for the big guns in thecontest, we had at least one ace up our proverbial sleeves. Even if wecouldn't hit the combination on the head on the first try, we certainlyhad the ability to find it with testing. The Westech boys were kindenough to offer some much-needed dyno time after hours and--believeus--we put it to good use.