glrbird (10/12/2010)
Ted .... What are the chances that this combination might make it into a street car to see what real world situation would be like with an engine making that kind to torque and HP.Not talking this particular engine but the combination in general, the chances are actually pretty good but the billet crankshaft does run the cost up in a hurry. If the pocket book isn’t an issue, then ‘yes’, the same engine could be done for the street and live for awhile. Getting the cubic inches beyond the ~345 mark in a Y tends to get expensive. The EMC Y entry was not built on the ragged edge and as a result, there is some durability built into it. I’ll add that this engine ran well on the same fuel that the other competitors were having difficulty with but there was considerable work up front to insure that the static compression ratio and dynamic compression ratios were happy with each other.
The 4” stroke combination is pretty figured out so there’s nothing fancy there other than the Honda rod journals and using an aftermarket rod for the Honda journal. Very little block work was needed in which to accommodate the longer arm on the crankshaft. The pistons are obviously custom and I broke away from the ‘D’ shaped inverted dome on this engine and went with a full conical inverted dome so that the combusion pressures would be more centered in the piston rather than on one side. Not much quench with this design but that doesn’t seem to be a deterrent at this point. The rings are 1.0mm, 1.2mm, with a 3.0mm 10lb drag oil ring and this ring package is probably marginal for a 100K mile engine but the rings are holding up just fine after 160+ hard dyno pulls. The rods in the EMC combo are 6.750” long and these are expensive to say the least but obtainable. Using a 6.300” connecting rod instead lowers the cost significantly with peak horsepower numbers only dropping a small amount. In fact, low end torque numbers could show an improvement with the shorter rods.
The EMC engine in its current format is going back on the dyno to answer some questions that the team came up with at the Challenge. After this, the engine does get tore down so that a mold of the combustion chamber and part of the cylinder can be made to facilitate making domed pistons specific to the aluminum heads. When this engine goes back together, it does so with 13-13½:1cr along with a larger camshaft. After testing, the new combination goes into the racecar to see what it can really do.
But on a less expensive note, I’m currently working on an aluminum headed 318” Y that gets there with an offset ground 292 crankshaft (3.48” stroke) and is using a 1.5mm, 1.5mm, and 3.0mm ring package. This engine will have a lower static compression ratio than the EMC engine but simply due to it also having a slightly smaller camshaft to assist in keeping the dynamic compression ratio from being excessive. It’s hard to guesstimate what the peak horsepower is going to be but all indications point it to being in excess of 450HP in a usable street rpm range. Both time and testing will tell on this.
Lorena, Texas (South of Waco)