{"id":6432,"date":"2014-06-24T15:56:22","date_gmt":"2014-06-24T22:56:22","guid":{"rendered":"http:\/\/www.racingjunk.com\/news\/?p=6432"},"modified":"2016-11-30T17:14:22","modified_gmt":"2016-12-01T01:14:22","slug":"drag-race-101-building-an-ls-bracket-motor-from-scratch-part-i","status":"publish","type":"post","link":"https:\/\/www.racingjunk.com\/news\/drag-race-101-building-an-ls-bracket-motor-from-scratch-part-i\/","title":{"rendered":"Building an LS Bracket Motor from Scratch Part I"},"content":{"rendered":"

\"Parts<\/a><\/p>\n

Part I: Picking the Power Parts<\/strong><\/p>\n

When you\u2019re building an engine from scratch, there are any numbers of ways to begin the selection process.\u00a0 You can build the short block and go from there (and that seems to be the most common method). But there is another way, and I think it\u2019s a wee bit better:\u00a0 Start with the induction system (heads, intake, carb and cam) and build the rest to match. Dumb idea?\u00a0 Maybe, but today you\u2019ll find that the top end of the engine is where you\u2019ll find the power.\u00a0 The rest of the pieces pretty much contain the combustion carnage.<\/p>\n

For our hypothetical LS motor, we\u2019ll start with the heads.\u00a0 Here, we use a set of Brodix BR7 STS jobs.\u00a0 These are readily available, high quality LS7 style heads.\u00a0 Even in CNC ported form, they have a relatively small port volume (264 cc) and have a 2.204-inch intake valve (yes, that\u2019s big block territory). The Brodix BR 7 head series has an intake port volume that is closer to an oval port rat motor than a small block. There\u2019s a wee hitch in the comparison though:\u00a0 The big block has a long intake tract with a couple of convoluted ports. The LS motor is a symmetrical port arrangement (with all ports being equal).\u00a0 They have direct paths right into the combustion chamber.\u00a0 As a result, the ports tend to be shorter than their big block ancestors.<\/p>\n

So far so good, but just how much \u201cair\u201d do these cylinder heads move in the intake port?\u00a0 What follows is flow data in cubic feet per minute (CFM) collected from Brodix, using a baseline figure of 28-inches for comparison purposes.<\/p>\n

STS BR 7 Intake Flow<\/b><\/p>\n\n\n\n\n
\n

Valve Lift (inch)<\/strong><\/p>\n<\/td>\n

\n

.200<\/p>\n<\/td>\n

\n

.300<\/p>\n<\/td>\n

\n

.400<\/p>\n<\/td>\n

\n

.500<\/p>\n<\/td>\n

\n

.600<\/p>\n<\/td>\n

\n

.650<\/p>\n<\/td>\n<\/tr>\n

\n

Intake Flow<\/strong><\/p>\n<\/td>\n

\n

159<\/p>\n<\/td>\n

\n

240<\/p>\n<\/td>\n

\n

303<\/p>\n<\/td>\n

\n

343<\/p>\n<\/td>\n

\n

369<\/p>\n<\/td>\n

\n

376<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

These things flow serious air and according to folks in the know, the air speed is high.\u00a0 Translated, a properly setup engine with this head arrangement will produce some serious steam.<\/p>\n

On the exhaust side, the head has a 1.614-inch valve.\u00a0 Here are the flow figures:<\/p>\n

STS BR 7 Exhaust Flow<\/b><\/p>\n\n\n\n\n
Valve Lift (inch)<\/strong><\/td>\n\n

.200<\/p>\n<\/td>\n

\n

.300<\/p>\n<\/td>\n

\n

.400<\/p>\n<\/td>\n

\n

.500<\/p>\n<\/td>\n

\n

.600<\/p>\n<\/td>\n

\n

.650<\/p>\n<\/td>\n<\/tr>\n

Exhaust Flow\u00a0\u00a0<\/strong><\/td>\n\n

116<\/p>\n<\/td>\n

\n

169<\/p>\n<\/td>\n

\n

208<\/p>\n<\/td>\n

\n

224<\/p>\n<\/td>\n

\n

233<\/p>\n<\/td>\n

\n

235<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The combustion chamber is a 12-degree setup. Essentially, that straightens the valve up, unshrouds the sides of the valves within the combustion chamber and provides the basis for a small, efficient chamber.\u00a0 That translates into a situation where you can move air at a faster pace (increase velocity), and that\u2019s really good news when it comes to cylinder heads.<\/p>\n

Finally, this head accepts primarily OEM components. That means you can use conventional LS7 headers, any number of OEM or replacement rocker arms and so on.<\/p>\n

For an intake, we\u2019d go straight to Chevrolet Performance for one of their # 1924403 single plane LS7\/LSX intakes. It\u2019s designed for a 4150 series Holley carb and is a direct fit to the Brodix heads.\u00a0 We\u2019d port match the intake to the cylinder heads and call it done. The carb of choice?\u00a0 We\u2019d start with an 850 CFM Holley Ultra Billet job.\u00a0 This is Holley\u2019s latest aluminum piece with four corner idle, provision for a throttle stop, a choice of 1:1 or progressive linkage (the secondary link is adjustable), plus it\u2019s fully adjustable with emulsion tube bleeds, power valve channel restrictors & idle feed restrictors. Power valve channel restrictors are also machined lower in metering block for improved fuel delivery to power valve circuit.\u00a0 Bottom line?\u00a0 This is a serious race carb that is pretty much perfect for bracket racing.<\/p>\n

Upstairs, a set of Crower stainless steel shaft rockers (# 74107F) will fit the bill. You\u2019ll have to have the heads machined to accept the Crower shaft arrangement, but the folks from Brodix can help you out with the machining when you order the heads.<\/p>\n

For a camshaft, we\u2019d straight to Lunati and order one of their VooDoo 286\/298 hydraulic roller cam & lifter kits. This is a very serious, but actually streetable cam, and requires engine and computer modifications (Bonus for us \u2013 we\u2019re using a carb). And yes, it has a rough idle and the converter we use will have to be matched. Here are the specs:<\/p>\n\n\n\n\n\n\n\n\n
Advertised Duration (Int\/Exh)<\/b><\/td>\n\u00a0286\/298<\/td>\n<\/tr>\n
Duration @ .050 (Int\/Exh)<\/b><\/td>\n\u00a0235\/247<\/td>\n<\/tr>\n
Gross Valve Lift (Int\/Exh)<\/b><\/td>\n\u00a0.651\/.651<\/td>\n<\/tr>\n
LSA\/ICL<\/b><\/td>\n\u00a0112\/108<\/td>\n<\/tr>\n
Valve Lash (Int\/Exh)<\/b><\/td>\n\u00a0Hyd\/Hyd<\/td>\n<\/tr>\n
RPM Range<\/b><\/td>\n\u00a02400-7000<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Why pick a hydraulic cam?\u00a0 Simple.\u00a0 We\u2019re looking for no-fuss, no muss in a bracket buildup. The cam we picked matches the heads nicely.\u00a0 It has a good power range and trackside maintenance is minimal (actually zero).\u00a0 That\u2019s a big bonus for a bracket car.\u00a0 It allows you concentrate on going rounds instead of fixing.<\/p>\n

Next time around, we\u2019ll go downstairs and \u201cbuild\u201d the shortblock.\u00a0 You might be surprised at some of the parts we pick.<\/p>\n

 <\/p>\n

\"The<\/a>
The intake port measures 2.350 X 1.350-inches. It\u2019s designed to accept all stock Chevrolet (and of course, aftermarket) LS7 intake manifolds. Peer inside the port and you can see that the head makes use of bronze guides. Intake valves have a stem diameter of 8-mm. The stem is 5.20-inches in length.<\/figcaption><\/figure>\n

 <\/p>\n

\"The<\/a>
The intake valve measures 2.204-inches in diameter. Figure that Chevy\u2019s Special High Performance and Heavy Duty rat motors came with 2.19-inch intake valves, and you\u2019ll get the idea this head was designed to move big air.<\/figcaption><\/figure>\n

 <\/p>\n

\"Exhaust<\/a>
Exhaust ports on the BR 7 series cylinder heads are engineered for use with conventional Chevy LS7 components. That means headers (or manifolds) designed for those combinations are a direct fit. It\u2019s easy to see the streamlined guide (with a bronze insert) in this photo.<\/figcaption><\/figure>\n

 <\/p>\n

\"Here\u2019s<\/a>
Here\u2019s a look at the combustion chamber on the STS BR 7 head. As you can see, it\u2019s fully machined. It holds 71-cc\u2019s (1 more than specified for a stock LS7) and includes huge 2.204-inch intake valves and 1.614-inch exhausts.<\/figcaption><\/figure>\n

 <\/p>\n

\"Courtesy:<\/a>
Courtesy: Chevrolet
For an intake, we\u2019ll dig into the Chevy Performance parts bin and use one of their single plane carburetor intake manifolds. As you can see, it\u2019s setup for a single 4150 Holley carb.<\/figcaption><\/figure>\n

 <\/p>\n

\"Courtesy:<\/a>
Courtesy: Holley
For a baseline setup, we\u2019d pick a Holley 415 Ultra Series carburetor. It\u2019s loaded with bracket racer friendly features. Check out the text for more info.<\/figcaption><\/figure>\n

 <\/p>\n\n\n\n\n<\/colgroup>\n\n\n\n\n\n\n\n
Parts Used<\/strong><\/td>\n\u00a0<\/strong><\/td>\nParts #<\/strong><\/td>\n<\/tr>\n
Heads<\/td>\nBrodix BR7 STS LS7 heads<\/td>\n<\/td>\n<\/tr>\n
Intake<\/td>\nChevrolet Performance LS7\/LSX intakes<\/td>\n# 1924403<\/td>\n<\/tr>\n
Carburetor<\/td>\n850 CFM Holley Ultra Billet<\/td>\n<\/td>\n<\/tr>\n
Rockers<\/td>\nCrower stainless steel shaft rockers<\/td>\n# 74107F<\/td>\n<\/tr>\n
Camshaft<\/td>\nLunati VooDoo 286\/298 hydraulic roller cam & lifter kits<\/td>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

——————————————————————————————————————————————————————–<\/p>\n

So You Want to Be A Drag Racer: Buying, Building, Wrenching and Racing<\/strong><\/em><\/p>\n

The allure of the drag strip is easy to understand \u2013 a place where \u00a0it takes less than 10 seconds to make a stand, prove your skill, speed, and nerve.\u00a0 But the road to the races can be intimidating.\u00a0 The Burnout wants to make that road a lot smoother for aspiring racers, whether it\u2019s through building a new car, modding a used one, or taking that ride all the way up to the burnout box and beyond.\u00a0 This series is a work in progress, an ever expanding comprehensive guide to all the things that take drag racing from concept to reality.<\/em><\/p>\n

Want to chat about this on social media? Use #RJDragRace on Facebook or Twitter<\/p>\n","protected":false},"excerpt":{"rendered":"

Building your LS Bracket Motor from scratch involves learning more about the engine and considering what you ultimately want from the experience and engine. Part 1 walks you through the basics.<\/p>\n<\/div>","protected":false},"author":20,"featured_media":6440,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[3448,3465,5008,3712,11,3698,9],"tags":[965,990,989,962,961,963,14,992,991,966,321],"class_list":["post-6432","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-drag-race-101","category-drag-racing","category-engine","category-hot-rods","category-how-tos","category-tech","category-tech-tips","tag-rjdragrace","tag-big-block","tag-build-it","tag-build-it-or-buy-it","tag-drag-race-101","tag-engines","tag-hot-rods","tag-ls-engines","tag-small-block","tag-tech-tuesday","tag-wayne-scraba"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2014\/06\/Parts-7Feature.jpg","jetpack_shortlink":"https:\/\/wp.me\/p42YSK-1FK","jetpack_sharing_enabled":true,"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/6432","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/comments?post=6432"}],"version-history":[{"count":9,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/6432\/revisions"}],"predecessor-version":[{"id":33248,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/6432\/revisions\/33248"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media\/6440"}],"wp:attachment":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media?parent=6432"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/categories?post=6432"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/tags?post=6432"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}