C7 Corvette

[Gotta-Qik-C7]

The (LS3) C6 and C7 guys have been going at it for months over at the Vette Forums! They finally met up to see wich car was faster! Both are stock Automatics.
https://www.youtube.com/watch?v=ZbjxVpVvOqg&feature=player_embedded

Another view.
https://www.youtube.com/watch?v=3k8fQtOUGfU&feature=player_embedded

[GoCougs]

The C6 got a huge jump and still lost huge...

[Gotta-Qik-C7]

The C6 got a huge jump and still lost huge...

Rite!

[68_427]

Yeah the C7 just walked that thing.

[SVT666]

That C7 had about the worst start in history and killed the C6.  Damn! 

[afty]

I saw a C7 on the highway yesterday. Looks pretty awesome in person.

[MX793]

The (LS3) C6 and C7 guys have been going at it for months over at the Vette Forums! They finally met up to see wich car was faster! Both are stock Automatics.
https://www.youtube.com/watch?v=ZbjxVpVvOqg&feature=player_embedded

Another view.
https://www.youtube.com/watch?v=3k8fQtOUGfU&feature=player_embedded

Is that Supertramp playing in the background?

[MX793]

Since the dawn of the high-po factory fuel injected Chevy small block it's gone from the 245 hp L98 in '85 to the 460 hp LT-1 of today without any of those significant changes. It's all simply been a matter of bigger valves, bigger cam, higher compression ratio, more RPM, wee bit more displacement, and fine tuning. By this measure, and the fact that the LS7 hasn't been touched in 9 years, there's surely some room to grow - 10-15% should be relatively easy. However, my hunch is that now that the ZL1, CTS-V, Z06 and ZR1 are all in play it's simply more cost effective to have variants of the same engine power them all, rather than two disparate engines. 

There's been some pretty significant technological changes between the Gen I L98 and the current Gen V LT-1.  And the specific output gains have been tapering off with each new iteration of the motor.  The GenV motor adds direct injection (which in turn allows for a higher compression ratio) plus VVT (two very significant changes) for 74 hp/L, the best output yet for a production SBC (LS6 and LS7 were 71 and 72, respectively).  Is there still more there?  Sure.  I just don't see huge gains (80+ hp/L) in the near future without either compromising the driveability or going to a more sophisticated valvetrain.

[GoCougs]

There's been some pretty significant technological changes between the Gen I L98 and the current Gen V LT-1.  And the specific output gains have been tapering off with each new iteration of the motor.  The GenV motor adds direct injection (which in turn allows for a higher compression ratio) plus VVT (two very significant changes) for 74 hp/L, the best output yet for a production SBC (LS6 and LS7 were 71 and 72, respectively).  Is there still more there?  Sure.  I just don't see huge gains (80+ hp/L) in the near future without either compromising the driveability or going to a more sophisticated valvetrain.

With each iteration it's mostly all been pick-n-shovel incremental work - from the L98 to LT1 it's been the basics of fuel injection, pushrods and 2 valves/cyl. IMO Direct injection and Kmart pushrod VVT are iterations, not significant nor breakthroughs (if they were the combo would be worth a lot more than ~25 hp/~5% over the LS3).

But there's plenty more to go; just a short list off the top of my head (and pretty much all incremental):
More RPM (7,000 RPM proven with the LS7 9 years ago)
More displacement (7.0L proven with the LS7)
Improved combustion/higher CR (continued improvements in modeling/design)
Elec. accessories esp. power hogs that are water and oil pumps (others do this)
Roller rocker arms (others do this and hot rodders have been doing it for years and years)

That Chevy didn't go more than 455/460 hp was more a matter of the market probably - the C7 is notably quicker than the C6 and keeps pace with the 991.

[MX793]

With each iteration it's mostly all been pick-n-shovel incremental work - from the L98 to LT1 it's been the basics of fuel injection, pushrods and 2 valves/cyl. IMO Direct injection and Kmart pushrod VVT are iterations, not significant nor breakthroughs (if they were the combo would be worth a lot more than ~25 hp/~5% over the LS3).

But there's plenty more to go; just a short list off the top of my head (and pretty much all incremental):
More RPM (7,000 RPM proven with the LS7 9 years ago)
More displacement (7.0L proven with the LS7)
Improved combustion/higher CR (continued improvements in modeling/design)
Elec. accessories esp. power hogs that are water and oil pumps (others do this)
Roller rocker arms (others do this and hot rodders have been doing it for years and years)

That Chevy didn't go more than 455/460 hp was more a matter of the market probably - the C7 is notably quicker than the C6 and keeps pace with the 991.

I didn't say the SBC was tapped for power, I said that specific output is not going to see huge gains.

More RPM is useless if you can't breath at that RPM.
More displacement gets more power, but does nothing for specific output
The compression ratio is already at 11.5:1 (a CR that is impossible on pump gas unless you have DI, hence the significance of DI).  There's only so high you can go before you can't run pump gas anymore.

[GoCougs]

I didn't say the SBC was tapped for power, I said that specific output is not going to see huge gains.

More RPM is useless if you can't breath at that RPM.
More displacement gets more power, but does nothing for specific output
The compression ratio is already at 11.5:1 (a CR that is impossible on pump gas unless you have DI, hence the significance of DI).  There's only so high you can go before you can't run pump gas anymore.

Chevy has proven that it can do a (breathing, streetable) 7,000 RPM pushrod and that was 9 years ago, and there are cars today have a CR notably higher than 11.5:1.

[MX793]

The LS7 revved to 7k, but did not make peak power at that rpm.  Peak was hundreds of rpm below that.  Peak in the new motor occurs only 300 rpm shy of the LS7's peak.

With DI, higher CRs are still possible, but I still don't see this motor going above 80 HP/l in streetable form without the previously mentioned valve train tech.

[FlatBlackCaddy]

Really starting to like the new C7, even in "lowly" base trim.

I hope I don't do anything foolish.

[SVT666]

Really starting to like the new C7, even in "lowly" base trim.

I hope I don't do anything foolish.

I hope you do.

[FlatBlackCaddy]

I hope you do.

Probably will, I'm not a very responsible person.

[MrH]

Probably will, I'm not a very responsible person.

Already thought about what trim and options?  If you have suspension questions about it, I can help you out.

[FlatBlackCaddy]

Already thought about what trim and options?  If you have suspension questions about it, I can help you out.

2lt Z51
7 speed
competition seats

[MrH]

2lt Z51
7 speed
competition seats

  That's probably what I'd go for too.

[GoCougs]

The LS7 revved to 7k, but did not make peak power at that rpm.  Peak was hundreds of rpm below that.  Peak in the new motor occurs only 300 rpm shy of the LS7's peak.

With DI, higher CRs are still possible, but I still don't see this motor going above 80 HP/l in streetable form without the previously mentioned valve train tech.

The key is being able to spin 7,000 rpm in a streetable pushrod motor. VE% has its limits (and today's hi-po N/A motors are approaching it) so at some point the only answer is more RPM.

Hot rodders for years have been getting an additional streetable smog legal ~50-75 hp over stock on each iteration of the GM small block (and new Hemi and Viper V10 too) simply with mild cam and mild head work (which drives the HP improvement with each engine iteration by the factory).

[MX793]

The key is being able to spin 7,000 rpm in a streetable pushrod motor. VE% has its limits (and today's hi-po N/A motors are approaching it) so at some point the only answer is more RPM.

Again, higher RPM is worthless if you can't breath at that RPM.  The LS7 could spin to 7100 RPM without self destructing, but its peak power was down at 6300 RPM.  Above that peak power RPM, its ability to breath, aka its volumetric efficiency, fell off and with it, the engine's power output.  If Chevy had set the rev limiter to 6500 RPM in that motor, it would still be making the same power.  It gains no additional power by being able to rev beyond its peak power RPM.  If GM raised the redline of the LT-1 to 7000 RPM (which I'm sure it could safely rev to anyway), it's not going to make any more power than it does now, given that its power peak is at 6000 RPM.  It's VE falls off too much beyond that point for the power to continue to climb.  Of course, a cam with more lift, more duration, more intake/exhaust overlap will bring high RPM VE up and get you power for those extra revs, but that will come at the expense of performance at lower RPMs.

[GoCougs]

Again, higher RPM is worthless if you can't breath at that RPM.  The LS7 could spin to 7100 RPM without self destructing, but its peak power was down at 6300 RPM.  Above that peak power RPM, its ability to breath, aka its volumetric efficiency, fell off and with it, the engine's power output.  If Chevy had set the rev limiter to 6500 RPM in that motor, it would still be making the same power.  It gains no additional power by being able to rev beyond its peak power RPM.  If GM raised the redline of the LT-1 to 7000 RPM (which I'm sure it could safely rev to anyway), it's not going to make any more power than it does now, given that its power peak is at 6000 RPM.  It's VE falls off too much beyond that point for the power to continue to climb.  Of course, a cam with more lift, more duration, more intake/exhaust overlap will bring high RPM VE up and get you power for those extra revs, but that will come at the expense of performance at lower RPMs.

Breathing is easy, it's designing for reliable operation at higher RPM that is more work for a pushrod engine, which was/is my point.

Not necessarily on the last statement. The LS3 has WAY more cam lift and duration than the old L98 yet cleans its clock throughout the power and torque curves.

[Gotta-Qik-C7]

Really starting to like the new C7, even in "lowly" base trim.

I hope I don't do anything foolish.

Go for it! I wish I could pull the trigger rite now........

2lt Z51
7 speed
competition seats

I'd rather have the NPP Exhaust than the Comp Seats as I would rarely track my car.

[MrH]

I just priced one out.  $64,000.  2lt Z51, 7-speed, competition seats, black wheels, stripes, and navigation.  That's a ton of money, but you get a lot of car.  I'd get the seats over the performance exhaust.  I'd probably do an aftermarket exhaust at some point anyways.

[CALL_911]

For all that, that is not a ton of money

[Gotta-Qik-C7]

This is how I'd order mine.
http://www.chevrolet.com/corvette-stingray/build-your-own.html?x-zipcode=44117#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@

[CALL_911]

Same

[MX793]

Breathing is easy, it's designing for reliable operation at higher RPM that is more work for a pushrod engine, which was/is my point.

Not necessarily on the last statement. The LS3 has WAY more cam lift and duration than the old L98 yet cleans its clock throughout the power and torque curves.

If breathing is easy, then why do 2-valve motors still lag behind most multi valves in specific output?  Even those that make peak power at OHC-like RPMs like the LS7 are still well off the mark.

The differences between the L98 and LS3 go way beyond the cam profile.  Throw an LS3 cam in an L98 and you're not going to get anything remotely close to an LS3 power curve.

[FlatBlackCaddy]

Here's my build

http://www.chevrolet.com/corvette-stingray/build-your-own.html?x-zipcode=44117#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@

Frankly, for the money, you can't beat it. In the next few months I was looking at spending 15K(ish) on upgrades to the Evo and Z. Upgrades that are specifically oriented to track usage.

It really is never ending. Lately I have less and less time to work on cars. It's taking away from seat time(on track or just on the street). As odd as it sounds, buying the car shown above would SIMPLIFY things greatly for me. I'd sell the Z and either leave the EVO be or maybe sell that too.

For a track car I don't think you could find anything better for the money that still is a fantastic street car that looks awesome.

[Rich]

Yeah, after taking the Miata on track recently, I'd have liked the piece of mind of a newer car.  A lot of people will say that a dedicated track car will be faster, blah blah blah.  But they are usually old ratty POSs that you need a trailer/hauler to get it to the track.  The fun for me is just getting out there and not having to worry about the car, just enjoy the drive.  That's something I think the Z51 offers in spades with the oil/diff cooler, great brakes, LSD, and warranty.

Unfortunately I make about 70,000 less per year than I should to be able to afford one of these hotrods.

[GoCougs]

If breathing is easy, then why do 2-valve motors still lag behind most multi valves in specific output?  Even those that make peak power at OHC-like RPMs like the LS7 are still well off the mark.

The differences between the L98 and LS3 go way beyond the cam profile.  Throw an LS3 cam in an L98 and you're not going to get anything remotely close to an LS3 power curve.

Specific power doesn't count, total power does, and GM is keeping the p00prod dream alive by keeping pace with other V8s in their respective classes.

Give the L98 the compression ratio, heads and ECU/FI system, and yeah, you'll have about LS3 power/torque curve; IOW, cam lift/duration by itself doesn't mean a whole lot.