{"id":4004,"date":"2014-03-13T15:04:41","date_gmt":"2014-03-13T22:04:41","guid":{"rendered":"http:\/\/www.racingjunk.com\/news\/?p=4004"},"modified":"2016-11-30T15:26:27","modified_gmt":"2016-11-30T23:26:27","slug":"horsepower-in-a-box-what-to-look-for-inside-a-crate-motor-part-ii","status":"publish","type":"post","link":"https:\/\/www.racingjunk.com\/news\/horsepower-in-a-box-what-to-look-for-inside-a-crate-motor-part-ii\/","title":{"rendered":"Horsepower in a Box: What to Look for Inside a Crate Motor, Part II"},"content":{"rendered":"

\"Crate<\/a>Engine in a box?\u00a0 A few decades ago, \u201cwho da\u2019 thunk.\u201d\u00a0 It wasn\u2019t possible, but today, things are truly different.\u00a0 Last issue we took a look at cylinder blocks and reciprocating assemblies.\u00a0 They\u2019re absolutely important, but equally critical is the complete valve train and of course, the cylinder heads that support it.\u00a0 Now, we mentioned this in detail in the first segment, but it\u2019s really worth repeating again: You have to figure out the mission of the engine before you make the leap.\u00a0 The wrong valve train and\/or cylinder head choices can truly mess up a power plant.\u00a0 Remember: First and foremost, decide what the engine is going to do.\u00a0 It\u2019s the most important consideration you\u2019ll make when laying out your hard earned dollars for a new motor.<\/p>\n

Keeping that in mind, let\u2019s dig a little deeper inside the motor.<\/p>\n

Camshafts & Valve Train:<\/b>\u00a0 There’s no question that roller camshafts are the accepted norm in motorsports today, and many crate engines have these pieces as standard equipment.\u00a0 Mechanical rollers generally make the most power.\u00a0 They also mandate considerable ancillary equipment:\u00a0 Roller lifters, high-pressure valve springs, titanium retainers and so on.\u00a0 But in some cases, you might actually be dollars ahead with a good old-fashioned flat tappet cam and components.\u00a0 Why?\u00a0 Simple.\u00a0 Take a look at a low RPM, flat top piston, grunt style engine as an example.\u00a0 It might never see the high side of 6,000 RPM, and then the use of a complete roller camshaft valve train is likely overkill.\u00a0 On a similar note, if the crate engine you’re thinking of buying is destined for your tow truck or motor home, and then something like a mild RV-style hydraulic cam might be the best choice.\u00a0 We don\u2019t have room here for a complete run down on what to look for in a cam, but suffice to say the bottom line here is to match the valve train to the task at hand.<\/p>\n

One important thing we should discuss is distributor gear compatibility. When dealing with a roller cam you\u2019ll soon discover is the fact a steel cam and a cast distributor gear don\u2019t mix (at least, not for long).\u00a0 Most cam manufacturers suggest you swap the distributor gear for a bronze job, but over the long haul in something like a street driven car that\u2019s only a stopgap fix.\u00a0 One solution is to incorporate a cast cam gear on the back of the camshaft.\u00a0 This way, you don\u2019t have to concern yourself with oddball distributor gears or heavy wear patterns on the distributor gear.\u00a0 Keep this in mind when shopping for a crate motor.<\/p>\n

Cylinder Heads: <\/b>\u00a0Like many other parts of the engine, cylinder heads have become prolific.\u00a0 There are countless options out there, and in some cases, more than one perfect head exists for your engine.\u00a0 In today’s world, you can purchase cylinder heads that flow almost as well as anything used on a Pro Mod car.\u00a0 But is bigger better?\u00a0 Not necessarily.\u00a0 The cylinder heads required to feed a 9,500+ RPM, nitrous assisted big block are far different than those necessary to feed a replacement engine for your tow truck.<\/p>\n

Remember too that your crate engine can use iron heads or aluminum heads.\u00a0 Aside from the weight issues, both offer advantages and have disadvantages.\u00a0 Here are a few examples:\u00a0 Iron heads tend to make more power than their aluminum cousins (all things being equal).\u00a0 Aluminum heads are easier to repair if you have experience some engine carnage.\u00a0 Iron heads are less costly than aluminum models.\u00a0 Aluminum heads are technically easier to port.\u00a0 Aluminum heads tend to allow for more compression ratio with pump gasoline.\u00a0 And the list goes on.\u00a0 The real answer is that you match the heads to the intended application.\u00a0 Like other parts of the engine, you won’t be sorry.<\/p>\n

That\u2019s a wrap for this segment.\u00a0 In the next blog post, we\u2019ll take a look at the induction system on the motor along with the ignition system.\u00a0 But we\u2019re getting ahead of ourselves. For the time being, see the photos and captions for more insight into \u201chorsepower in a box.\u201d<\/p>\n