Torque plate for honing?

[Phred]

I have worked for three nationally recognized racing engine shops. At shop #1 we built Trans-Am (and many other series) Chev engines. We had a specially built torque plate that allowed both boring, and honing through the same plate. The final results of this method was simply quicker than boring without a torque plate, then honing with a plate. This is because you could bore closer to your final size, and therefore have less material to hone to final size. There is always a minimum amount that needs to be honed, as the boring process (even with a finishing tool bit and a .003 finish cut) microscopicly tears the metal. Honing to a selected finish depends on the rings to be used, and the material being honed. After torquing on the plate of a small block chev,the surface of the bore will be displaced from the previous "round" bore, in an area next to the bolt (or stud). This displacement, is a small area about the size of a nickel, about an inch below the deck. This happens to be right where the rings are at their most important point, attempting to seal all the compression just before and during ignition. If a torque plate is not used, upon compression, a very small amount of compressed mixture will sneak by the five "windows" around the top of the cyl. With plate honing, the bore is true whith no windows to leak compression. Similarly, the main bolts/studs are also torqued before honing as they also distort the bottom of the cyl's., But this distorsion has more to do with lower bore integrity. During this time I used the same process to build all sizes of Datsun L engines with sucess. Although these blocks were not as adversly affected because the head bolt holes are further from the bore, and distorted the cylinders less.

The 2nd and 3rd engine shops I worked at, were involved with professional formula car engines. These were Cosworth, Lotus, English Ford, and Toyota as used in Formula Atlantic. These shops, in addition to torque plates, used hot water pumped through the blocks. The hot water has as big an effect as the plate, as the entire block will distort as heat expansion and distorsion varies depending on the thickness of the cyl wall. It is also much more precise in setting the clearance between piston and cyl.

Now, weather you want to avail yourself of these extream methods is up to you and your needs, and wallet. But, there is no dought these methods are measurable, and do increase the power potential of the engines discussed here. The increases were repeatable, and noteable on a first person basis, as I did the machine work, assembly, and at times the dyno work.

Phred

[woldson]

Cool nice wright up;)