DV: Unlike many accredited experts you are no ’one–make wonder’. You have built motors as diverse as your mid ten–second LS1 Camaro street car, a 9–second, championship–winning oval–track Pontiac, off–shore powerboat motors, and even a 6.7-second 209–mph turbo car. I think even a couple of V12 Lamborghini race motors have gone through your shop. Do you have any favorites?

JM: On any given day, yes, but I think overall there is a healthy competition between the big three to produce good, cost effective, performance stuff. All of them are building performance parts that I like to introduce my students to. Of course Chrysler’s foray into Winston Cup racing may well set a new pace and if it does we will all be winners, even the GM crowd.

Here is a segment of our industry full of complexity, myths, and technological nightmares. When I started building high output race motors there were very few people you could get real answers from. Tracking them down was almost impossible so like a few other successful engine builders I learned the hard way. It involved a lot trial and error to build experience. Here we are 25 or more years down the road, I’ve learned a lot and I am still learning. Unfortunately, within the industry as a whole, there is still an astounding lack of expertise in this area. I estimate 90 percent of the cams sold fall at least 10 percent short of their full potential and maybe 50 percent fall short by 30 percent. That means every second cam sold missed the mark by 30 percent. If the particular intake duration of the cam could produce a 70–hp increase, the spec is far enough off to only make 50 hp. If you want a quote here, the effect of duration is a popular fixation. Anyone who talks about cams solely in terms of duration is out of touch with the real technology involved. Getting the lobe centerlines, overlap and lift optimized are by far the most useful tools toward power production. Try finding someone who can tell you about it and back it up with dyno tests. Oh sure there are a lot that talk "the talk" but there are also a lot that are nothing more than posers. The reason I have got as far along with cams as I have is access to the few that do know and a driving need to learn anything related to producing more hp.

What I will say here is–other than getting the valve events right–opening the exhaust valve fast is almost always a waste of time. I have never seen an increase in exhaust valve acceleration produce more power but I have seen the reverse more times then I can recall. My basic philosophy here is fast in, slow out, as far as profiles are concerned.

DV: I know you have some hot opinions on strokers, and since big–inch motors are the subject of this issue, would you like to relate how these apply to what we have discussed so far?

JM: In the last 15 years the potential of a stroker motor had changed almost beyond recognition. 20 years ago even the best heads fell short of the airflow needs of a stock displacement engine. These days all that has changed. The advent of the commonly available flow bench–thanks to Superflow–and superior factory performance and aftermarket heads has meant that the airflow needs of the extra cubes can largely be met. Apart from that, we can stuff more cubes into the chamber so a given compression ratio can be achieved with a flat–top or smaller dome. This leads to a better combustion chamber and combustion process. Assuming a given maximum piston speed, the valvetrain of a stroker does not have to endure such high rpm so has an edge on reliability.

Scat has a semi–indestructible 3.75–stroke small–block Chevy crank for less than about $250. There is no way I would build a 350 when I can get a new crank plus 383 inches. Getting power cost effectively is a skill that is almost as important as getting the power in the first place.

DV: Your students get a considerable amount of time on the dyno and anyone with dyno experience knows that one of the big headaches is getting the exhaust system optimized. It’s hard to do on the dyno let alone in the car so how about your thoughts on the subject.

JM: Assuming you have the cam right, the exhaust is a major factor toward making all the super head work pay off. With a race motor the power brought about by the exhaust is due to its action on the intake during the overlap period. This is really a complex science before you add in the effect of a muffler and believe me, they are here to stay for race motors. This much I can tell you: anyone who claims to know all about exhaust systems is lying through their teeth. I have access to some of the world’s top brains in this department and they will tell you what they don’t know would probably fill a book. Like cams, it is a deeply mathematical subject. This much I can say. Pipe diameter is the first factor to concern yourself with and slightly too small beats slightly too big every day. Equal length is nice but not essential if all else is right. Also let me throw this one in–past a certain point the longer the duration of the exhaust cam the smaller the optimal pipe diameter becomes. Any pushrod two–valve motor that is making 2 to 2.2 hp per cube is living on the exhaust. You had better believe it’s important. And one last point–anybody that tells you an engine requires backpressure from the muffler to make power is probably trying to pedal an inefficient muffler. There is no such thing as too much muffler flow but there sure is a problem with too little.