The length of the cylinder is important because it dictates how much piston will be pulled out of the bore at bottom dead center. In stock form, GM’s 6.0L offers 364 cid from a 4.000˝ bore and a 3.622˝ stroke crankshaft.įor example, cylinder length and how it limits stroke, is one of the factors to consider when starting a build. What does that mean for the end user – the racer (and your customer)? It means hundreds of runs without needing to pull a valve cover, much less adjust valves. All of this makes 7,800 rpm possible with a low-maintenance hydraulic lifter valvetrain. The large diameter, hydraulic roller cam and the factory production rocker arms make for a light and stable valvetrain. Even though a solid lifter camshaft will make more power, many LS builds feature a hydraulic roller design. A 55mm cam diameter makes for more gentle valve events. Many engine builders say one of the best parts of the LS engine is the valvetrain. All of this makes it easier to achieve impressive power levels, while spending less money. Even though the external dimensions are small, 454 cubic inches can be easily obtained and heads flowing close to 400 cfm are readily available through several aftermarket companies. Designers literally took the good from its predecessor and rebuilt it from the ground up using 50 years of learned technology. These engines were a 100% redesign of the Gen I and II small block. They share the same 4.400˝ bore spacing as a standard small block Chevy, but have a raised cam tunnel location, a near 1/4-inch taller deck height, and a rigid 6-bolt main cap design. With a 15-degree valve angle, intake ports that flow 300 cfm and a 55mm camshaft diameter, one can see what the engineers at GM were after when designing these engines – efficiency and performance. The amazing thing is I can get over 19 mpg cruising on the freeway with the AC on and drive it anywhere.What is so great about these LS engines? First, the LS engine has multiple design features that help it achieve near-big-block levels of horsepower. A lot of fun to drive, since it is in a grandma Nova it has surprised quite a few people. Computer estimates are around 450 hp and close to 500 lb ft of torque with a fairly flat curve. The engine is still pulling hard at 6000 rpm's but I try to keep it under 5500 most of the time. The most expensive part of the whole engine was the heads, but they sure help make the power. Runs on pump premium and with 50° of total timing there is no detonation. 010" piston heightġ0.25:1 compression ratio with a quench area of about. Speed Pro H601P pistons (These are dished)Ĥ bolt block bored. Nothing needed to be clearanced, just normal machine work. Built it for making all of the power under 6000 rpm's to save money. Here is what I did, no plans on track time, just wanted a reliable engine with plenty of power. Phil are you just wanting a street only engine? If so it can be done for low buck. Should be an easy 550 HP piece that will be anvil reliable and need nothing more than a quality synthetic oil change at regular intervals. Vic Jr intake with port matching and minor plenum blending Go for a hyd roller cam, you're specs will be fine, although I prefer a tighter lobe separation. Go with the AFR 195's, they will easily eclipse your HP target, and they have the correct springs for a hyd roller cam. (Wiseco/SRP would work as well, but Mahle's use a thin metric ring pack that eliminate needing oil ring spacer rails, plus they weight NOTHING) It's a MUCH more durable piece, will cost you nearly the same as all the fluff and buff BS to get a factory 400 block to "close" to the strength of a Dart block.īuy a Scat forged crank and Scat 6" I beam rods with the 7/16 capscrews, and top it off with Mahle dished forged pistons. Since you're starting from scratch, buy a Dart SHP block. Take it from a guy who owns a machine shop and has done one for himself (current 406) installing splayed caps in a 2 bolt block, don't waste your time. I later whittled the times down to 10.96 121.6 at a sea level track. The first time out it ran 12.1 112 at my local 2200' elevation track with 3.42 gears/5xxx stall. This combo ran with reduced timing on premium on the street, and was fed 50/50 with race gas for the track. 050 solid flat tappet cam, roller rockers Stock 350 rods, later replaced by Scat I beams (wasn't necessary)Ĭomp 259/266. GM iron Bowtie heads, copious hours of portwork, easily duplicated by buying a set of AFR 195's.įorged flat top pistons, zero deck, 11.4:1 My first 408 was very streetable, in fact it was my daily driver during the summer.
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