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This flat-plane-crank Z06 will have you spinning to 8250 rpm


#1

Big, rumbling V-8s have been a Corvette staple since the introduction of Chevrolet’s small-block in 1955. However, this particular Vette is singing a different tune. Currently listed for sale on eBay is a 2006 Chevrolet Corvette Z06 with a high revving, flat-plane-crank engine. And no, it’s not a Ferrari swap.


This is a companion discussion topic for the original entry at https://www.hagerty.com/articles-videos/articles/2018/09/27/ebay-flat-plane-crank-corvette-z06

#2

I would give anything to hear the dyno pull:sunglasses:


#3

Gosh, back in the 80s, the bottom end on a small block Chevy was good to 9000 rpm - reference Smokey Yunick’s “Power Secrets”. It’s the valvetrain that needed enhancement to survive up there - and aftermarket parts were/are available to do that if that’s your goal (see picture). The valvetrain in this picture was good to 8000. A shaft mounted rocker arm system (also available) would have been even better. High torque is what you need on the street for acceleration and that’s what you get with long strokes. It was a mistake to remove a 4" stroke crank and replace it with a 3" for a street car.


#4

You’re absolutely right to point out that usually, it’s the valvetrain that limits rpm, but I think the author was simply pointing out that a flatplane crank is unbalanced and can cause excessive NHV- thus the shorter stroke. After spending a small fortune to build this engine, I doubt the owner was unaware of the trade-offs! He wasn’t looking for torque…


#5

here’s the street video on the car: https://www.youtube.com/watch?v=Hgi7gW_QyOA


#6

Listening and watching the video of the LS7 Z06 with a $20K flat plane crank system I can say I love the exotic sound of the high revving engine. But only gaining 50hp and losing torque and a few pounds of nose weight does not seem worth the dollars. For the same money I would add a twin turbo system making 200-300 additional HP.


#7

Different strokes for different folks, folks. Just because it’s a street car doesn’t mean there weren’t other considerations at play. If the builder was a semi-serious autocrosser or racer, then there could be class limitations to displacement, weight, power, etc. that caused him to make this choice. Could also be the oringinal C6Z LS7’s notorious propensity for dropping valves that caused him to do a unique engine build. Personally I like it, LS7, LS3 heads, flat plane crank, decent cam, awesome.


#8

@kkmiller - So this is more your speed? I was not a fan until I heard a destroked LS at work like this.


#9

@dkinev - I agree. For the amount of work it really didn’t seem worth it. Rear mounted turbo(s) would go a long way, but I guess depending on the end goal for the car it might have made sense.


#10

Yes! Exactly! I used to work for a corvette restoration and performance shop and we were big fans of destroking the LS to make it fit in any situation that we needed. 1400 race motor? Start with an LS376 crate motor, good heads, GREAT block, destroke it, procharger. Need a 600 naturally aspirated autorcross car? Similar start, still destroke it, but then enhance the valve train to rev as high as you can so you can stay in your chosen gear for longer time. Often times the difference between the top step on the podium and not getting a trophy at a national autocross event can be as simple as not having to shift as frequently, and the extra rpm can make that difference!


#11

Ugh, rear mounts are so laggy. Really only something that you want on a dedicated race car that you can stage and build the boost. TONS of intake volume to fill. A friend had a 4th gen WS6 with a rear-mount setup, made 550 whp at peak, but it took so long to come on that on the road course my 350 whp 1993 RX7 (factory 2 rotor wankel, factory turbos with increased boost pressure and supporting modifications built for SCCA Solo II SM class) was able to pull away enough just by being able to get on it earlier that he never could close the gap on the long straights, and I had so much power coming out of the corner and he had to wait so long I kept getting further and further in front of him. He’d freight train me at the drag strip though.

For a street driven LS, I think the best all around setup is a centrifugal (I’m a big ProCharger fan) blower on an LS3 or new LT1. 625-650 reliable, all day horsepower. Plus blower noises and no extra heat between the VCs like you get with a roots. Meth injection can really keep those intake charges down too and net you an extra 25-50 hp depending on tuning and blend.


#12

Yes! Love it. All depends on what your purpose oriented goals are but this is an awesome way to go. Thank you for the eye opening options.