Engine Specification Comparison Chart

[dcbingaman]

Gents, since there seems to be a big discussion on that other forum on engine selection for the new C8 variants, I went browsing the Internet to compile some spec.s for comparison between our old gen. 5 small block friends and the latest DOHC V-8 and V-10 sports car engines in production, as well as the small block derived Mercury Racing SB4. Take a look and see if I missed anything.

There are a lot of TBD's on this chart because engine dry weights are hard to find. Also what is engine, and what is radiator gets more complicated for forced induction engines, so to some extent we are comparing apples, oranges and pomegranates ! Anyway, some interesting data - tell me what you think.

[John]

Thank you very much Binger! Going to spent some to time going over this screen printed chart of the above pdf. Initially, as is obvious, the Corvette once again is at the largest engine size of these. Going to a 4.2L at some point will put us roughly mid pack — quite a change from historical patterns.

clearly, I have discounted the Mercy Racing motor from my comparisons.

[SheepDog]

Engine Quesiton.
Is there an I.C. Engine engineer out there who knows about this kind of thing? LT6 is probably cross-plane? LT6 likely capable of 9000 RPMs? & what Torque based on the above?

The GM LT6 has a 81mm stroke which is the sane as the Ferrari F136. Has A bigger 103mm bore than the Ferrari 136's 94mm.Both normally aspirated. No torque given. Both have about the same HP 600 v. 597. The Ferrari 458 is a known flat-plane crank. Does that tend to indicate that the LT6 is cross-plane? The LT6 has bigger displacemen and that might indicate more HP. . Flat-plane crank tends to produce more HP than cross plane.[?] Is that a wash and gives them about the same HP.

The ferarri engine has Compression ratio of 12.5/1 and the LT6 is not stated.

Is the LT6 more likely a cross plane?
With the 81mm bore should the LT6 be capable of 9000 RPMs just like the Ferrari F136 engine, which is from the 458 naturally aspirated. Both are 81mm stroke, short stroke. And the LT6 is severely over-square.



The McLaren M838T has a 70mm bore. It tops out at about 8500 RPM with the T.Turbos on it, how many RPM would it likely attain as a naturally aspirated engine.. Since TT tends to cause restricted RPMs.

If the C8 gets the LT6 then what are we looking at? What will that alone say about the character of the C8.

What if the LT6 gets Turbos? What HP. what kind of RPMs? and torque? Educated guess please , then. What will that alone say about the character of the C8.

[dcbingaman]

Engine Quesiton.
Is there an I.C. Engine engineer out there who knows about this kind of thing? LT6 is probably cross-plane? LT6 likely capable of 9000 RPMs? & what Torque based on the above?

All great questions Sheepdog. GM hasn't actually announced the LT6 yet, so the numbers in my chart are either educated guesses or rumors from here and CF. Displacement for the bigger GM DOHC V-8 motor has been rumored to be 5.5L based on the engine forecast from about a year ago. Farmington, (the crank / camshaft subcontractor dude), says he saw a fully dressed LT6 and said the bores were 103mm which is the same as the LT1-5 6.2L engines.

If you use the same bore as the LT1 with a 5.5L displacement, then the engine must get more over-square and the stroke shortened to 81mm, (Coincidently, just like the C7.R engine !). That should allow it to rev higher and take advantage of the faster DOHC valvetrain. In that case, the rumored 600 HP is likely a conservative number. If they can get the same HP per liter as the Lambo / Audi FSI V-10, then they should be good for around 650 HP. If they only match the Mercury Racing SB4 numbers, then the horsepower is more likely around 600 HP normally aspirated. My guess is they will get a something over 650 HP, but honestly who knows.

For durability and production reasons, I think it is unlikely GM will produce a 9000 rpm wailer like the Ferrari 458 F136, but you never know. The big Ferrari V-12s remain normally aspirated and make big HP via large displacement and high rpm capability and sing like Luciano Pavarotti !! They are ungodly expensive though and reportedly require a lot of scheduled maintenance.

[dcbingaman]

BTW, the largest displacement gas piston engine ever made in the USA was the Pratt & Whitney R-4360 Major Wasp radial aircraft engine. It had 28 cylinders for a total displacement of 71.5 L and made over 3500 HP. HP / liter was only about 50, but HP / Wt. was over 1.1 / lbm. Not too shabby for an OHV engine from nearly 70 years ago.

[John]

Thanks Binger for your ideas and giving us some “likelies” about what is next for our ME’s motors.

I also love your knowledge of airplanes. Thanks greatly for adding it into our mix.

[Milliwatt Rob]

BTW, the largest displacement gas piston engine ever made in the USA was the Pratt & Whitney R-4360 Major Wasp radial aircraft engine. It had 28 cylinders for a total displacement of 71.5 L and made over 3500 HP. HP / liter was only about 50, but HP / Wt. was over 1.1 / lbm. Not too shabby for an OHV engine from nearly 70 years ago.

Actually. this Lycoming engine was larger, at 127 liters, but it never went into mass production. It was too powerful for conventional propellers.

https://en.wikipedia.org/wiki/Lycoming_XR-7755

[dcbingaman]

Thanks, Milliwatt ! I had no idea Lycoming built such a beast.

The Major Wasp went into limited production, but was quickly made obsolete by turbine engines (both turbojets and turboprops) which could produce the same HP at 1/4 the weight.

[conmax]

More trivia. Mercury Racing’s 400 Verado is a 2.6l in-line 6 with a small Whipple SC on the side of block. This gives 153hp/L and comes with a 3 yr warranty. These engines can run all day @ 7000rpm. I have 2 on my Eliminator 28 Speedster.

[SheepDog]

The CT6 V-Series with the Blackwing engine is about 38K$ more than the standard CT6's. $88,790 v $50,495. There are other differences than the engine.

Here's a Closer Look at the 550-Horsepower Blackwing V-8 from the 2019Cadillac CT6 V-Series ... Top Speed

While the Cadillac CT-6 V-Series is the first to receive this new engine, it’s also quite possible we’ll see the 4.2-liter make its way into the mid-engine Corvette C8 later this year.

If you’re interested in picking up a CT6 V-Series for yourself, you’re too late, as all 275 units are already out the door. Pricing for those lucky few who managed to snag one starts at $88,790, which is quite a bit more than the standard CT6’s MSRP of $50,495. However, for the money, CT6 V-Series owners also get a two-day experience at the Cadillac V-Performance Academy in Nevada, plus accommodations.

[John]

Thank you Sheep Dog for adding into our discussions some very cogent information. I saw your comment that the roughly $38K more was for more than the Blackwing motor. At the same time, DOHC, TT, 32V motors cost a heck of a lot more than the LT2 will. That major price difference fits in with whisperings I have been hearing, that the C8 Z06 version (whatever it will be called), is going to be a good amount more than the entry version — probably a BIGGER price difference than there was/is between the SR and Z06 now, and that the C8 Z06 will include additional components to further differentiate it from the base ME (even more differentiation than between the C7 SR and C7 Z06).

Could therefore the C8 Z06 start at around the $90K+ level? I think that that is possible.

[SheepDog]

65K$ for a base C8 + 40K$ for the DOHC = 115K$ ??

Well I like $50K + $40K.

Afraid. Of the dark-side of $100K

But , get what ya pay for.

Then what if it has a flat-plane crankshaft? ?$?$

If it sounds like the prototype C8 R that's appeared on Tube, that is the sound of $$$$$$. That will have a different look too. Render that.