JerriVette

What does it cost to maintain and repair a c4 ZR1 engine?

I don't see the dohc designs extra weight, extra cost, extra width , extra height a benefit to corvettes..

Who cares about small displacement engines that are larger ,weigh more and are more complicated to fix that produce less power and torque...

The gt350r I ran into the other day on the highway sounded bad *** but other than the sound...what is the reason that much more expensive engine is better than an LT1 or LT4?

Hell I personally think the LS3 is a better engine than the hoodoo voodoo..

I do dig the carbon fiber wheels of the gt350r and the sound of the voodoo but other than that? I think it's overhyped....

I'd rather have my corvette engine sharing its parts with the pickup truck lineup of GM....lol

Torque everywhere....a few hot rod parts from the factory and these low cost motors from GM kick butt on the dohc competition...

BMW? Mercedes, Maserati? McLaren? Lexus, Ferrari? ALFa Romeo?
LAmborghini?

Which ones out perform the corvette z06. ?The camaro ZL1 ? Cts v? And just as an added bonus what is the cost comparisons? Running cost comparisons? Who here is afraid to own any of those other brands mentioned outside of warranty and why?

Ask yourself these questions as you marvel at dohc engines...

Anybody in the used car market want a north star Cadillac these days or are they
Leapors....?

G fix needy

That would also give it a really mean, distinctive sound.

johnglenntwo

Why Not?

NemesisC5

Cadillac Northstar has been out of production 6-7 years??
The most relevant comparisons are the LGX and LF4 Cadillac DOHC V6 engines which are current. I'm not knocking pushrod V8's, I purchased a 2017 1500 Z71 2 days ago with a 6.2L pushrod V8 and love it, but lets face reality. DOHC engines are more fuel efficient and make more power per liter. Weight...really? The C7 weighs more than a C6 or C5, are you complaining about that as well? The GEN V LT4 has 200 lbs of added weight in the top mounted supercharger and supporting hardware that has a number of well documented overheating issues with 2015 & 2016 models on tracks in summer weather. Who said anything of small displacement? This thread is about rumored LT5 6.2L V8, the same displacement in all current C7's. That's fine you love pushrod V8's, so do I but when you start throwing around a mixed bag of facts and mis-applying them you might as well jump on a horse so you don't break your internal combustion engine parts. In closing, "lepers" is the correct spelling so your intended joke lost as much humor as your post lost credibility.

CFHay

"With headers, open exhaust and engine controls calibration revised for racing gasoline, horsepower was 400-410. "

http://www.zr1netregistry.com/Inform...ldRecords.aspx

Ford had balancing problems at a much smaller displacement so you can only imagine how much harder it would be to solve at this size. I wouldn't hold my breath.

Bill Dearborn

So if GM would have done some tuning to move the peak HP back to 6100 rpm instead of its current 6400 rpm you would think the engine is better because it has a broader power band? I think it has a phenomenal power band that just happens to have its peak point a hair below the red line. Since a hell of a lot of people run to the 6500 rpm red line to shift why not let peak HP reside at that point Vs at a lower point? That way the engine keeps pulling almost right up to the point the shift occurs.

Bill

NemesisC5

Yep, I totally forgot about that. If it were that easy Ford would have made the Voodoo at least 6.2L.

sunsalem

MB had a 6.2L DOHC producing over 600hp for many years until recently.


Also, Ford prefers smaller displacement performance motors than Chevy seems to.


OTOH, Dodge has a 6.4L NA in some of their SRT cars.

tbrenny33

There's some misconception here that DOHC weighs more which isn't necessarily true. They are larger in dimension, but not always in physical weight. MB's old 6.2 engine which made over 600 hp but weighs the same as the old LS3!!

Bill Dearborn

Supposedly, due to cost, fuel economy and emissions requirements most manufacturers are moving to what is called a single cylinder design. That means they maximize power and economy while minimizing emissions in the base cylinder design and then build engines based on the cylinder design. That way all 4, 6 and 8 engines use the same exact cylinder design just more of them. If desired cylinder displacement may be varied but in most cases the engine cylinder architecture and parts are common. That means there is a great potential for cost savings across multiple product lines for a company as large as GM. Take a look at new GM V6 engines to maybe get a look at what is coming in other variations. The XT5 V6 is a DOHC, DI, VVT engine that produces 51.6 HP per cylinder and each cylinder is .6 liter.

Bill

chuntington101

Bill, that's reallly interesting and yo can see this in he likes of BMW and Mercedes. It would make sense as well as you only spend the development costs once wit much lower to production costs.

What people fail to understand is GM could make as much power as they wanted from the current platform. They could make it incredibly fuel efficient as well. Or they could make it very low emissions. Unfortunately you have to have a balance of all 3!

Also a large NA V8 seems a little backward from what everyone else is doing.

dar02081961

While I understand your point and generally in the past you may have been correct.

However your hypothesis doesn't apply to the LT4.
As Bill said when you shift an LT4 with Z06 gearing at peak power the engine never "falls off" as drastically as you state.

Looking at the power curve for the LT4 you can see even with the M7 transmission shifting at 6500 rpm the engine never dips below 600hp and lands above 600 ft lbs of tq when the shift is made. At which point the LT4 is still making more power than many comparable engines at their peak which is often 1k-2k rpm higher.

This fact takes some adjustment in your driving style. I have told a few friends about this fact over the years. There is very little (or a lot less) penalty for short shifting an LT4. Simply because even if you do you end up higher on the torque curve with over 600 ft lbs tq. Levels few other engines ever reach. Try shifting most DOHC engines anywhere less than the power peak and then as you say you will see what "falling on its face" really means. The LT4 not so much

SBC_and_a_stick

I see both your guys' points being correct. glass sliper is thinking in absolute terms, while you are thinking in relative terms. His point may be stated as follows: if you had an LT4 with the same power/torque rating, even the same curves, but had a higher redline, you could extract more performance out of the vehicle. It does matter where you land upon shifting, and therefore a higher redline would allow the driver to use higher average power, although the max power at any instant in time is the same.

Your point is also true, in that I see the power drop at the start of the higher gear is rather small in terms of % power loss. It is in fact a small amount relative to peak power.

As far as I can tell, keeping the fuel cut low at 6,600 prevents two types of stress on the engine. First, the TVS rotor speed is limited, and therefore the chance of bearing failure is low. Second, pushrod actuated valves have more play given the distance from the in block cam to the valves. A lower redline reduces mechanical stress in OHV designs far more than in SOHC/DOHC configuration. Overall, GM is probably smart to give up a tad bit of performance, especially since few enthusiasts understand the benefits of revving higher with the same torque curve.

johnglenntwo

Road Tracking not so much!

dar02081961

Great comments. It is my opinion GM doesn't give up anything (much)by not revving the LT4 higher. The reason is the engines torque output at its weakest point during performance shifting is still close to 600ftlbs. So staying right at peak hp or having a peak hp that's flat for 1k rpm isn't critical. Simply because there is enough torque awaiting after the shift to achieve the same goal.

Your points are well taken and valued, however may comments were directed at the comment "the LT4 falls on its face" and power "dropping to 500 hp" when you shift.

Which isn't completely true. To the contrary there is so much torque available to aid in acceleration that if you don't have the nannies engaged and are not on your P&Q's when you shift you will likely end up counter steering or in a ditch.

Point is even with the M7 shifting at 6500 rpm the LT4 only drops you about 60hp when you go to the next gear, not 150hp as suggested. But that 60hp drop is countered and you are rewarded with an additional 100 ftlb of tq when you arrive in the next gear. A reward that isn't there for most NA DOHC engines if you look at their power curves. This makes it paramount they stay on the HP curve or they "fall on their face". The LT4 has you covered in this instance because it has the luxury of plenty of torque to keep you accelerating.

johnglenntwo

Again, this sucker should hopefully be going with the 10-Speed!

dar02081961

That would be nice. Hopefully they can get the 10 speed packaged for the Vette. Even though I think a revised geared A8 would be pretty effective at keeping it on the "boil" as well.

Interesting times and I cant wait to see how this all plays out.

johnglenntwo

My information is that by 2018 all the cars would have the 10, but, with the C8 coming in 2019 all bets are off as far as the C7, I guess!
I retrospect it actually makes sense that they just option stuff that could be used universally.

MSG C5

I think the timing may be right if it does indeed fit the C7 platform. Considering the top trim Camaro ZL1 had exclusivity for the A10 for one year (2017) it would make sense that the top trim Corvette would also have this transmission as it moves into other GM vehicles for 2018. I've heard nothing but great things about the A10 so far in the Camaro test runs and with all the additional cooling vents on the test mule, hopefully it all pieces together.

Hopefully we know for sure in January at the Detroit Auto Show.

johnglenntwo