Rumorpile: What Will Corvette Stingray Z06 Produce Power Wise?

This is my prediction:-

ZR-1 goes on a hiatus and will not return until 3~4 years into the C7's life cycle. When it does, it gets a supercharged version of the LT1 6.2 -- let's call it an LT9 -- making about 700 bhp.

Z-06 goes on a hiatus until the 2nd model year, returning with a stroked version of the LT1 -- let's call it the LT5 -- displacing 6.8 liters and making about 550 hp naturally aspirated. The reason I believe that it'll be 6.8 liters in particular is because this is what you get from using the LT1 bore with the LS7 stroke. This allows them to not have to redesign the piston or remodel the combustion chamber; shorter rods will allow the chamber geometry to be identical to the LT1 at top-dead-center while increasing compression ratio to 12.7:1 (right about where it needs to be and where it can be tolerated with 91 octane). Getting to 550 hp isn't hard. The displacement increase alone gets you from 450 to about 493 lb-ft, a 1.2 point bump in compression alone is worth about 30~35 lb-ft for a total of about 525. If that torque peaks at about 4800 rpm and with the same fall off as a the LS7 you get about 550 bhp. Bump the torque peak slightly to ~5200 rpm and you actually get closer to 575 bhp. Not bad for an engine that's 485 lbs dressed and wet.

Problem starts to become how do you put all that power to the ground on a rear drive car that isn't very heavy and it still has leaf springs too doesn't it? Unless you have all wheel drive.

Dwight, we are assuming all the lt1's "bells and whistles"? maybe not AFM?

Dwight, we are assuming all the lt1's "bells and whistles"? maybe not AFM?

The LT1 doesn't really have a lot of bells and whistles. They decided against cam-in-cam independent VVT. They decided against a variable valve lift system (which would have displaced AFM).

So, yes, I expect any of the LT1's derivatives to have DI and synchronous VVT. AFM is a maybe. AFM limits revs because of the mass it adds to the actuated valve train. Eliminating AFM gets you the ability to go maybe 500~600 rpm higher on the redline. But, you don't need that to make 550 or 575 bhp out of 6.8 liters. In fact, if you look at the LS7 (which revs to 7100 rpm) most of the upper rev range doesn't contribute to a faster car -- power peaks at 6300 rpm and falls off quite rapidly after that. Short shifting that engine probably get to better acceleration.

This car will be very soon and the ZR1 will not be far behind.

The is also some speaking of a base sub Stingray Corvette that may have a 5.3 in the low 400 HP range. This car would have a fixed roof and not be loaded up. The intent of this car is one to give the club racers and modifiers a cheaper car to base a race car or play car on. The second intent is to attract younger buyers that they sorely lack.

The Corvette is much like Cadillac and needs to attract new and non traditional buyers that will lower the average age of the buyer.

The future lies in the hands of those now buying these cars now.

Also the HP on these cars is expected to be spaced out once the ZR1 is locked in. GM intends to make the 700 HP mark and if so insiders expect the Z06 to fall in the 600 ranger and the ZL1 and CTS V to slot in near 600 HP also.

Getting the power to the ground is not an issues with electronic controls. The present ZR1 engine can do all of GM's Warranty test and emissions test up to 725 now so a DI version should have no problem. The simple fact is there is no need for this much power as few will ever come near to using it all. Even the race cars from Pratt and Miller are not even this high but it sells cars to have large magic numbers. The Vette team wishes the automakers would come to a limit on power and work in other areas to increase performance but they know that is not going to happen.

This is my prediction:-

ZR-1 goes on a hiatus and will not return until 3~4 years into the C7's life cycle. When it does, it gets a supercharged version of the LT1 6.2 -- let's call it an LT9 -- making about 700 bhp.

Z-06 goes on a hiatus until the 2nd model year, returning with a stroked version of the LT1 -- let's call it the LT5 -- displacing 6.8 liters and making about 550 hp naturally aspirated. The reason I believe that it'll be 6.8 liters in particular is because this is what you get from using the LT1 bore with the LS7 stroke. This allows them to not have to redesign the piston or remodel the combustion chamber; shorter rods will allow the chamber geometry to be identical to the LT1 at top-dead-center while increasing compression ratio to 12.7:1 (right about where it needs to be and where it can be tolerated with 91 octane). Getting to 550 hp isn't hard. The displacement increase alone gets you from 450 to about 493 lb-ft, a 1.2 point bump in compression alone is worth about 30~35 lb-ft for a total of about 525. If that torque peaks at about 4800 rpm and with the same fall off as a the LS7 you get about 550 bhp. Bump the torque peak slightly to ~5200 rpm and you actually get closer to 575 bhp. Not bad for an engine that's 485 lbs dressed and wet.

Thanks for this very cool insight.

Question for you and everyone else. If the 6.8 can get you 550HP and about 525Lbs of torque, why not use it to supercharge rather than the 6.2? Seems you can get allot more out of this 6.8 than the 6.2 based on what I have been reading?

Second question, what about reliability and long life using 6.8 versus the 6.2?

This is my prediction:-

ZR-1 goes on a hiatus and will not return until 3~4 years into the C7's life cycle. When it does, it gets a supercharged version of the LT1 6.2 -- let's call it an LT9 -- making about 700 bhp.

Z-06 goes on a hiatus until the 2nd model year, returning with a stroked version of the LT1 -- let's call it the LT5 -- displacing 6.8 liters and making about 550 hp naturally aspirated. The reason I believe that it'll be 6.8 liters in particular is because this is what you get from using the LT1 bore with the LS7 stroke. This allows them to not have to redesign the piston or remodel the combustion chamber; shorter rods will allow the chamber geometry to be identical to the LT1 at top-dead-center while increasing compression ratio to 12.7:1 (right about where it needs to be and where it can be tolerated with 91 octane). Getting to 550 hp isn't hard. The displacement increase alone gets you from 450 to about 493 lb-ft, a 1.2 point bump in compression alone is worth about 30~35 lb-ft for a total of about 525. If that torque peaks at about 4800 rpm and with the same fall off as a the LS7 you get about 550 bhp. Bump the torque peak slightly to ~5200 rpm and you actually get closer to 575 bhp. Not bad for an engine that's 485 lbs dressed and wet.

Thanks for this very cool insight.

Question for you and everyone else. If the 6.8 can get you 550HP and about 525Lbs of torque, why not use it to supercharge rather than the 6.2? Seems you can get allot more out of this 6.8 than the 6.2 based on what I have been reading?

Second question, what about reliability and long life using 6.8 versus the 6.2?

Lengthening the stroke while shortening the rods increases the piston side loads. You can avoid that by raising the deck, but that'll be a new block architecture and basically uneconomical. You can also raise or lower the crank height which creates and offset at TDC and accomplishes the same goal, but again that's a new block design. The 101.6mm stroke is tolerable up to 7100 rpm as shown in the LS7 so I guess that have "proven" that they can get away with it.

Traditionally, they used the 6.2 instead of the 7.0 because of the thicker cylinder walls which are more tolerant of forced induction's extra heat and pressures. With the 6.8 having exactly the same wall thickness (in fact it can be the same exact block) they can supercharge the 6.8 instead of the 6.2. The reason I don't think they will is because of the presumption of a 700 hp target -- there is no need to increase the displacement. Besides, with forced induction -- within reasonable limits -- increasing displacement and running lower boost has the same power result as not increasing displacement, running higher boost with lower compression. With turbocharged engine the latter produces more lag. With superchargers there is zero lag so it really doesn't matter except that higher displacement with higher static compression and lower supercharger pulley ratios is probably slightly more fuel efficient at cruise.