I have a 1966 Chevy II with a 327 and a four-speed. It’s a great car because it’s light and kinda nimble for a ‘60s car. I’m considering an LS engine swap rather than building another small-block Chevy. I know it will cost more to do the conversion, but I really like the idea of an all-aluminum LS7 with its stock 505 hp rating. My goal is 400 rear-wheel horsepower but to use a carbureted style intake and my throttle body EFI so I can keep the traditional look. The problem is that engine is guaranteed to exceed my budget. I’d like to hear your thoughts. – K.S.
Jeff Smith: Everybody says that there’s no such thing as too much power. But with a little Chevy II with fairly narrow back tires, I think it’s fair to say that this would represent an aggressive amount of power for your car.
We’re making several assumptions here, but let’s run with this. Let’s assume a stock rear leaf spring suspension with a 245/60R15 tire which is probably close to the biggest tire you can stuff under the stock wheel wells. Those are somewhat short and not very wide tires which lays down a relatively small footprint on the pavement.
The GM LS7 is a stout engine rated at 505 hp at 6,300 rpm and 470 lb-ft of torque at 4,800. Besides the power, this all-aluminum engine will remove roughly 100 pounds from the front of the car, which will help reduce the car’s nose-heavy weight distribution.
All of this is achievable, but also a bit pricey. Summit sells the LS7 crate engine for a little over $12,000. GM offers a warranty and the engine has a great reputation. But consider that you will also need new headers, motor mounts, an oil pan, and a complete accessory drive. This engine also uses drive-by-wire throttle which will require the pedal and controller kit. That’s another $1,300.
While researching, we looked for other long blocks that might be a little less expensive. One package that caught our eye was the BluePrint Engines‘ iron block 6.0L version (BPLS364OC). This started life as an iron block LQ4 engine from an early 2000’s truck. Bored an additional 0.030-inch, the block is fitted with forged pistons, 6.135-inch I-beam rods, and a cast 6.0L, 24x crankshaft that displaces 369 cubic inches.
BluePrint fits the block with its own hydraulic roller with specs of 223/223 degrees at 0.050 with a 114 degree lobe separation angle and 0.556-inch valve lift for both intake and exhaust. The short block is topped with a pair of factory rectangle port heads with 2.165/1.60-inch valves. The BluePrint website says that with an LS3 intake (and presumably headers) that this engine will make 470-plus horsepower and 455 lb-ft of torque.
[Note: To learn about effectively upgrading the LQ4 engine, read: LQ4/LQ9 Engine Upgrade Guide: Expert Advice for LQ4 & LQ9 Mods to Maximize Performance.]
Taking this a little further, I’ve always felt that LS street engines that aren’t aimed directly at all-out peak horsepower can benefit from cathedral port cylinder heads.
I recently tested an LQ4 iron 6.0L engine that had roughly 150,000 miles on the rotating assembly, which included the original pistons and ring. We added a very mild 219/227 degrees at 0.050 COMP Cams hydraulic roller cam with 0.607/0.614-inch lift and a pair of mildly ported 5.3L heads.
I used the 5.3L heads because the smaller chamber creates around 10.4:1 compression with the stock, dished LQ4 pistons. Then we added a stock Trailblazer SS intake to this package which is a tall, EFI truck manifold. The advantage is this manifold makes excellent torque and is also very affordable. We also used a large 102mm throttle body although a 90mm version would have made the same power.
This package made 496 hp at 5,600 rpm with peak torque at 495 lb-ft at 4,800 and even managed 410 lb-ft of torque at 3,000 rpm.
This is nearly the same peak horsepower as the much larger LS7 and our engine makes more torque! That Trailblazer SS intake may not fit under the stock hood of a Chevy II and it would not fit into your carbureted look. But substitute a dual-plane intake and carburetor and it would still make 475 hp.
This is great power and you could build it for much less than a brand new crate engine although it will be roughly 100 pounds heavier since it’s an iron block.
Either way, you will have plenty of power. All of this is easy. The hard part with any near-500 hp engine in this Chevy II will be hooking it up. Traction can be achieved, but will require some sticky tires and plenty of suspension tuning to make it all work.
These ideas offer a wealth of opportunities to choose from across a broad spectrum of cost, power, and displacement. It’s a great time to be adding horsepower!