Details on likely C8 engine
04-09-2018, 01:16 PM
#61
Le Mans Master
You don't know!? ;)
720S!!! E_DIFF at the Ring
Do they have to have AFM on the 5.5L Bigdog engine ?? They wouldn't really sell enough of them to impact the fleet CAFE statistics much and I don't think a gas guzzler tax on the Bigdog Corvette would make any difference to a dude who wants to rev his engine to 8000 rpm.
On the other hand, if you can generate 750 ft-lb of torque from 1500 rpm up with the turbos, why do you care if the engine only revs to 6500 rpm ? Ever watch those Audi R10 turbodiesel monsters dominate LeMans and prototype endurance racing a few year back ? High rpm capability is almost always trumped by massive torque !!
On the other hand, if you can generate 750 ft-lb of torque from 1500 rpm up with the turbos, why do you care if the engine only revs to 6500 rpm ? Ever watch those Audi R10 turbodiesel monsters dominate LeMans and prototype endurance racing a few year back ? High rpm capability is almost always trumped by massive torque !!
04-09-2018, 05:38 PM
#62
Safety Car
The one item that is restricting both the LT1/LT4/LT5 and the new 4.2L V8 to 6,500 RPM is the heavy valve lifters for the AFM. My long stroke, 7,100 RPM LS7 does not have that limitation. In order to get the LT series to rev to 6,500, GM had to implement a cam with softer ramps for the four cylinders with the heavy lifters. The 4.2L makes maximum horsepower at 5,700 RPM. My LS7 make it at 6,300 RPM.
If GM wants to rev the hell out of a 4.2L V8 or a 5.3L V10, they will have to rethink their position on AFM.
If GM wants to rev the hell out of a 4.2L V8 or a 5.3L V10, they will have to rethink their position on AFM.
On the other hand, if you can generate 750 ft-lb of torque from 1500 rpm up with the turbos, why do you care if the engine only revs to 6500 rpm ? Ever watch those Audi R10 turbodiesel monsters dominate LeMans and prototype endurance racing a few year back ? High rpm capability is almost always trumped by massive torque !!
Maybe GM's job for the C8 Z06 is easy. Make a V10 using existing DOHC architecture from the Caddy engine, no AFM, no variable valve lift, and a decent 8,000 rpm redline. It will be cheap, capable, entertaining, desirable, and reliable. A budget Lambo V10.
04-09-2018, 05:57 PM
#63
Le Mans Master
The V10 is a compromise all around. I hope GM is not foolish to entertain that option.
04-09-2018, 06:17 PM
#64
Safety Car
No compromise in sound, in throttle response, in reliability at ~600hp. Compare that to the LT4 which I found to be perfect on paper but in reality while it did sound good, it was terribly unreliable, and had only average throttle response. I would take the 50hp deficit to not have to do with the inertia in the TVS system, inertia in the bottom end, not deal with the intercooler cooling problems, and most importantly to finish a session every time.
04-09-2018, 06:39 PM
#65
Le Mans Master
Stock F1 Supercars on a little C5 ZO6! ;)
I knew I didn't need displacement and/or low end power. I have NT05's on now, and a 3-way micro switch on my shifter, but, in first gear with Z51 gears I always just run the power at 440rwhp. Half way through an intersection I had them roasting today with a light squeeze.
Anyway, 750rwtq at 1500rpm on the street is all wheel spin and TC, like some have said.
Happy to say the 720s is proving that almost daily! Saw the BMW 1100 lose a couple of roll races today on youtube, Done.
Also, the expensive DCTs are only necessary for fast passing downshifts.
Track times perfectly driven NSM, an A10 with smooth driving, and save your money! Let it slow you down and save your brakes!
I'm liking the ME LT1 A10 PTM small Wing combo objective.
Last edited by johnglenntwo; 04-09-2018 at 06:58 PM.
04-09-2018, 06:44 PM
#66
No compromise in sound, in throttle response, in reliability at ~600hp. Compare that to the LT4 which I found to be perfect on paper but in reality while it did sound good, it was terribly unreliable, and had only average throttle response. I would take the 50hp deficit to not have to do with the inertia in the TVS system, inertia in the bottom end, not deal with the intercooler cooling problems, and most importantly to finish a session every time.
04-09-2018, 06:51 PM
#67
Team Owner
How did you get to that number? Fine either way, that's not a huge amount. The way accessories are routed will likely make a difference. How it protrudes will likely make a difference too. We might not care if the heads stick out a bit in an ME but maybe there is little space for a long crank.
High revving engines are to me, pure voodoo. First, it's about piston speeds if you have to use one metric. Why can Honda make high F1 piston speeds in production engines while other engines fall apart? I don't know, seems like engineering know-how is precious here. There is no high revving small blocks given their piston speeds unless you look at the 9,000 rpm NASCAR versions.
Not quite, they could also rethink how to implement AFM. Different manufacturers have wildly different tech for doing the same thing, some can take high revvs some can't. Same for variable valve lift. Most only work to 7,000 rpm or so but Honda's from the early 2000s works at 9,000 rpm just fine.
What if you can generate 750 ft-lb and equal HP from a 2.0 turbo 4 but it sounds like a diesel and has the throttle response of an 80's turbo? V10 does everything well if built right. Lambo has quite possibly the most entertaining and the most desirable engine on the market while being competitive in all performance metrics.
Maybe GM's job for the C8 Z06 is easy. Make a V10 using existing DOHC architecture from the Caddy engine, no AFM, no variable valve lift, and a decent 8,000 rpm redline. It will be cheap, capable, entertaining, desirable, and reliable. A budget Lambo V10.
High revving engines are to me, pure voodoo. First, it's about piston speeds if you have to use one metric. Why can Honda make high F1 piston speeds in production engines while other engines fall apart? I don't know, seems like engineering know-how is precious here. There is no high revving small blocks given their piston speeds unless you look at the 9,000 rpm NASCAR versions.
Not quite, they could also rethink how to implement AFM. Different manufacturers have wildly different tech for doing the same thing, some can take high revvs some can't. Same for variable valve lift. Most only work to 7,000 rpm or so but Honda's from the early 2000s works at 9,000 rpm just fine.
What if you can generate 750 ft-lb and equal HP from a 2.0 turbo 4 but it sounds like a diesel and has the throttle response of an 80's turbo? V10 does everything well if built right. Lambo has quite possibly the most entertaining and the most desirable engine on the market while being competitive in all performance metrics.
Maybe GM's job for the C8 Z06 is easy. Make a V10 using existing DOHC architecture from the Caddy engine, no AFM, no variable valve lift, and a decent 8,000 rpm redline. It will be cheap, capable, entertaining, desirable, and reliable. A budget Lambo V10.
Bore center X 3 + bore diameter of the V8 LT1 engine.
Simple math.
The NASCAR engines are not stock small blocks. Instead of stock 4.4" bore centers, they have 4.5" bore enters(and the block is longer than a small block Chevy). On top of that, they are made of CGI which is very strong so they can even run thinner cylinder walls and maintain it's strength,
Add that together and you have a large bore(with heads that have huge valves) and a much shorter stoke than your stock small block, and still have a 358 cubic inch max displacement. The heads, intake manifold and the fuel injector move tremendous amount of air and fuel, along with very stout valve springs(that only have to last one race) so they can hit 9,500 RPM while producing over 850 HP. I ran my 283 SBC bored to 301 using the stock 3" stroke crank and stock rods to 8,500 RPM back in the early 1960's. I knew a guy that was running a destroked SBC(I think it was around 2.625" stroke) in his slingshot dragster and he was running 12,500 RPM, but not with stock rods or pistons(but with a 6-71 GMC blower).
On the Honda engine used in the S2000, Honda increased the stroke from 3.323" to 3.571" and kept the same bore diameter. This resulted in the 2L engines 8,800 RPM redline(9,000 fuel cutoff) being reduced to 8,000 RPM(8,200 fuel cutoff) for the longer stroke 2.2L engines. Horse power remained the same at 237 but the torque went up by a whopping 9 lb-ft with the longer stroke.
Which car manufacturers have a AFM that revs to 8,000 RPM? I haven't paid any attention to those engines.
Last edited by JoesC5; 04-09-2018 at 07:24 PM.
04-09-2018, 07:09 PM
#68
Le Mans Master
A NA burns fuel!
Bore center X 4 + bore diameter for the V10 using the 4.2L V8 block stretched to a V10 configuration.
Bore center X 3 + bore diameter of the V 8LT1 engine.
Simple math.
The NASCAR engines are not stock small blocks. Instead of stock 4.4" bore centers, they have 4.5" bore enters)and the block is longer than a small block Chevy). On top of that, they are made of CGI which is very strong so they can even run thinner cylinder walls and maintain it's strength,
Add that together and you have a large bore(with heads that have huge valves) and a much shorter stoke than your stock small block, and still have a 358 cubic inch max displacement. The heads, intake manifold and the fuel injector move tremendous amount of air, along with very stout valve springs(that only have to last one race) so they can hit 9,500 RPM while producing over 850 HP.
Bore center X 3 + bore diameter of the V 8LT1 engine.
Simple math.
The NASCAR engines are not stock small blocks. Instead of stock 4.4" bore centers, they have 4.5" bore enters)and the block is longer than a small block Chevy). On top of that, they are made of CGI which is very strong so they can even run thinner cylinder walls and maintain it's strength,
Add that together and you have a large bore(with heads that have huge valves) and a much shorter stoke than your stock small block, and still have a 358 cubic inch max displacement. The heads, intake manifold and the fuel injector move tremendous amount of air, along with very stout valve springs(that only have to last one race) so they can hit 9,500 RPM while producing over 850 HP.
Anymore outlandish posts, Jeeze!
Last edited by johnglenntwo; 04-09-2018 at 07:12 PM.
04-09-2018, 08:29 PM
#69
Safety Car
Bore center X 4 + bore diameter for the V10 using the 4.2L V8 block stretched to a V10 configuration.
Bore center X 3 + bore diameter of the V8 LT1 engine.
Simple math.
The NASCAR engines are not stock small blocks. Instead of stock 4.4" bore centers, they have 4.5" bore enters(and the block is longer than a small block Chevy). On top of that, they are made of CGI which is very strong so they can even run thinner cylinder walls and maintain it's strength,
Add that together and you have a large bore(with heads that have huge valves) and a much shorter stoke than your stock small block, and still have a 358 cubic inch max displacement. The heads, intake manifold and the fuel injector move tremendous amount of air and fuel, along with very stout valve springs(that only have to last one race) so they can hit 9,500 RPM while producing over 850 HP. I ran my 283 SBC bored to 301 using the stock 3" stroke crank and stock rods to 8,500 RPM back in the early 1960's. I knew a guy that was running a destroked SBC(I think it was around 2.625" stroke) in his slingshot dragster and he was running 12,500 RPM, but not with stock rods or pistons(but with a 6-71 GMC blower).
On the Honda engine used in the S2000, Honda increased the stroke from 3.323" to 3.571" and kept the same bore diameter. This resulted in the 2L engines 8,800 RPM redline(9,000 fuel cutoff) being reduced to 8,000 RPM(8,200 fuel cutoff) for the longer stroke 2.2L engines. Horse power remained the same at 237 but the torque went up by a whopping 9 lb-ft with the longer stroke.
Which car manufacturers have a AFM that revs to 8,000 RPM? I haven't paid any attention to those engines.
Bore center X 3 + bore diameter of the V8 LT1 engine.
Simple math.
The NASCAR engines are not stock small blocks. Instead of stock 4.4" bore centers, they have 4.5" bore enters(and the block is longer than a small block Chevy). On top of that, they are made of CGI which is very strong so they can even run thinner cylinder walls and maintain it's strength,
Add that together and you have a large bore(with heads that have huge valves) and a much shorter stoke than your stock small block, and still have a 358 cubic inch max displacement. The heads, intake manifold and the fuel injector move tremendous amount of air and fuel, along with very stout valve springs(that only have to last one race) so they can hit 9,500 RPM while producing over 850 HP. I ran my 283 SBC bored to 301 using the stock 3" stroke crank and stock rods to 8,500 RPM back in the early 1960's. I knew a guy that was running a destroked SBC(I think it was around 2.625" stroke) in his slingshot dragster and he was running 12,500 RPM, but not with stock rods or pistons(but with a 6-71 GMC blower).
On the Honda engine used in the S2000, Honda increased the stroke from 3.323" to 3.571" and kept the same bore diameter. This resulted in the 2L engines 8,800 RPM redline(9,000 fuel cutoff) being reduced to 8,000 RPM(8,200 fuel cutoff) for the longer stroke 2.2L engines. Horse power remained the same at 237 but the torque went up by a whopping 9 lb-ft with the longer stroke.
Which car manufacturers have a AFM that revs to 8,000 RPM? I haven't paid any attention to those engines.
04-09-2018, 08:47 PM
#70
Team Owner
All those extra parts just run up the cost of the engine, and what have you gained? More parts to fail? The LT5 already has 755 horsepower. Is a 5.3L Cadillac engine going to gain another 205 horsepower by adding more parts? My calculations show it would increase to 688 horsepower, just by only adding two additional cylinders. Short by 67 horses.
And, if you don't go with larger turbo's for the additional 1.1 liter displacement, you might even end up more than 67 horses shy of the LT-5's 755.
Last edited by JoesC5; 04-09-2018 at 09:44 PM.
04-09-2018, 10:17 PM
#71
Safety Car
The additional 2 rods and bearings, 2 pistons, 8 valves, 8 valve springs, 8 retainer's, 8 locks, eight cam followers etc are not worth it for me to drop from 6.2 liters(or from 7 liters in my Z06) down to 5.3 liters just to gain 1.25" of length in the V10 engine.
All those extra parts just run up the cost of the engine, and what have you gained? More parts to fail? The LT5 already has 755 horsepower. Is a 5.3L Cadillac engine going to gain another 205 horsepower by adding more parts? My calculations show it would increase to 688 horsepower, just by only adding two additional cylinders. Short by 67 horses.
And, if you don't go with larger turbo's for the additional 1.1 liter displacement, you might even end up more than 67 horses shy of the LT-5's 755.
All those extra parts just run up the cost of the engine, and what have you gained? More parts to fail? The LT5 already has 755 horsepower. Is a 5.3L Cadillac engine going to gain another 205 horsepower by adding more parts? My calculations show it would increase to 688 horsepower, just by only adding two additional cylinders. Short by 67 horses.
And, if you don't go with larger turbo's for the additional 1.1 liter displacement, you might even end up more than 67 horses shy of the LT-5's 755.
Yes, what you refer to here is a dogma of sorts that I bought into as well. The small block's greatest trick is its simplicity right?
What truly matters at the end of the day are specifics, details, and proprietary data we can never get our hands on. You can sit me down and yell into my ear all you want about small part count but that's just correlation and what holds an engine together at the end of the day is technology, part quality, and quality control not low part count.
You and me as enthusiasts have one way to test an OEM's engine, and that is to work it hard and see what fails. My experience is that well built high revving DOHC production engines can be more reliable and durable than Chevy's OHVs. My hope is that in the move to DOHC GM will increase it's reliability so that when the engine dies it will be a 200 track hours and due to low compression and general wear not by throwing a rod or dropping a valve at less than 30.
Leave the part counting to bean counters since that's their mo and don't let them trick you into thinking that's something you want!
04-10-2018, 04:15 AM
#72
Banned Scam/Spammer
This has nothing to do with what is being discussed. You talk about outlandish posts yet you post dyno graphs with nothing related to the discussion and toss out random phrases full of incomplete 3rd grade thoughts. Keep up the good work, Johnny.
04-10-2018, 07:13 AM
#73
Le Mans Master
Dude! Thanks for the help. ;)
Last edited by johnglenntwo; 04-10-2018 at 07:19 AM.