383 v's 350
Thread Starter
Melting Slicks
Joined: Oct 2012
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From: Dunedin NZ.
I am not sure why your C6Z06 gets 22.5 mpg @ 70-80 MPH but I can share that I have easily achieved 27-28 MPG with my 10 Z06 at those speeds. As stated previously, all things being relatively equal, the reason that the C5Z06 achieves better MPG than the 7.0 L Z06 is primarily that the smaller displacement Z06 has 100 less HP than the C6Z06's 505 HP, not because of the the smaller Cubes essentially. Pump up that LS6 to 550 Net HP and I assure that it will get less MPG than the LS7.
Here is another way to look at this issue. A 500 HP 4, 6, and 8 cylinder engine with the SAME HP will ALL essentially get the same MPG with all things being equal again, with a very slight nod to the lesser cylinder engines due to less rotational frictional loses versus the 8 cylinder engine but the differences are small-these differences are almost non existent in a discussion of a 350 versus 383. So why does my 2012 Lexus IS 350 F sport with 306 net HP from its 3.5L V6 not get much better MPG than my C6Z06 @ a steady 80 MPH despite ,much smaller displacement, less cylinders? Simplstically, it turns about 600 RPM higher at that speed than the C6Z06. Why does a 500 HP 6 cylinder twin turbo Nissan GTR get the same MPG at 80 MPH as the 505 HP 7L LS7 at the same speed? Simple and Physics: It requires a certain amount of energy (gas) regardless of how the motor produces said HP to generate a specified HP-there is no getting around that fact and no free ride.
Take a 4 cylinder turbo engine and pump it to 500 HP and it will most likely get LESS MPG than a bigger displacement normally aspirated V8 simply because the smaller displacement 4 cylinder will be so highly stressed to achieve that level of HP.
So, back to this discussion: The difference in MPG between a a 350 versus a 383 that produce roughly the same HP is going to be negligible, if noticeable even at all, all things being equal.
Here is another way to look at this issue. A 500 HP 4, 6, and 8 cylinder engine with the SAME HP will ALL essentially get the same MPG with all things being equal again, with a very slight nod to the lesser cylinder engines due to less rotational frictional loses versus the 8 cylinder engine but the differences are small-these differences are almost non existent in a discussion of a 350 versus 383. So why does my 2012 Lexus IS 350 F sport with 306 net HP from its 3.5L V6 not get much better MPG than my C6Z06 @ a steady 80 MPH despite ,much smaller displacement, less cylinders? Simplstically, it turns about 600 RPM higher at that speed than the C6Z06. Why does a 500 HP 6 cylinder twin turbo Nissan GTR get the same MPG at 80 MPH as the 505 HP 7L LS7 at the same speed? Simple and Physics: It requires a certain amount of energy (gas) regardless of how the motor produces said HP to generate a specified HP-there is no getting around that fact and no free ride.
Take a 4 cylinder turbo engine and pump it to 500 HP and it will most likely get LESS MPG than a bigger displacement normally aspirated V8 simply because the smaller displacement 4 cylinder will be so highly stressed to achieve that level of HP.
So, back to this discussion: The difference in MPG between a a 350 versus a 383 that produce roughly the same HP is going to be negligible, if noticeable even at all, all things being equal.
Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
Pretty much the same result that you would get from building a lesser HP, high torque 350 V8. The difference in displacement is too small between a 350-355 and a 383 to have a big difference-slight difference would be the result.
Another example: The difference between GM's 3.8L V6 (231 CI) versus the 3.1L V6 (191 CI)-Thats 40 Cubes BTW? I have owned Multiple cars with both engines! Not very much-slightly noticeable. Difference between the 3.1 and Supercharged 3.8-BIG
I am not saying there is no difference just that the difference is NOT as great as folks think. Just looking to inject a dose of reality into these discussions. Same argument about those that think putting in a 383 crate engine in a C3 rated a 425 GROSS HP is going to be even remotely in the same league as a 400 NET HP C6 in terms of speed-not even close.
Another example: The difference between GM's 3.8L V6 (231 CI) versus the 3.1L V6 (191 CI)-Thats 40 Cubes BTW? I have owned Multiple cars with both engines! Not very much-slightly noticeable. Difference between the 3.1 and Supercharged 3.8-BIG
I am not saying there is no difference just that the difference is NOT as great as folks think. Just looking to inject a dose of reality into these discussions. Same argument about those that think putting in a 383 crate engine in a C3 rated a 425 GROSS HP is going to be even remotely in the same league as a 400 NET HP C6 in terms of speed-not even close.
Last edited by jb78L-82; Jun 14, 2014 at 07:08 AM.
Melting Slicks
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From: San Diego California
Pro
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From: Monroe Washington
I'm sooo glad my PO bought the 383 crate for my 81... And the exhaust he installed... I once saw another vette, same color, style, etc with a stock 350... And I could barely hear it at an idle! At that point it's just another pretty car, instead of having the PRESENCE that mine has... I get random compliments every time I drive her ... And THAT will never get old! Lol
Safety Car
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From: anchorage ak
Le Mans Master
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
it isn't the oil companies as much as the value of the dollar dropping and the oil companies trying to make the same money. all of this because of a feckless community organizer.
i remember the oil crisis of the 70's and some actually put 4 and 6 cylinder engines in corvettes, i vote for the 383 and maybe drive it less.
i remember the oil crisis of the 70's and some actually put 4 and 6 cylinder engines in corvettes, i vote for the 383 and maybe drive it less.
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
I am not sure why your C6Z06 gets 22.5 mpg @ 70-80 MPH but I can share that I have easily achieved 27-28 MPG with my 10 Z06 at those speeds. As stated previously, all things being relatively equal, the reason that the C5Z06 achieves better MPG than the 7.0 L Z06 is primarily that the smaller displacement Z06 has 100 less HP than the C6Z06's 505 HP, not because of the the smaller Cubes essentially. Pump up that LS6 to 550 Net HP and I assure you that it will get less MPG than the LS7.
Here is another way to look at this issue. A 500 HP 4, 6, and 8 cylinder engine with the SAME HP will ALL essentially get the same MPG with all things being equal again, with a very slight nod to the lesser cylinder engines due to less rotational frictional loses versus the 8 cylinder engine but the differences are small-these differences are almost non existent in a discussion of a 350 versus 383. So why does my 2012 Lexus IS 350 F sport with 306 net HP from its 3.5L V6 not get much better MPG than my C6Z06 @ a steady 80 MPH despite ,much smaller displacement, less cylinders? Simplstically, it turns about 600 RPM higher at that speed than the C6Z06. Why does a 500 HP 6 cylinder twin turbo Nissan GTR get the same MPG at 80 MPH as the 505 HP 7L LS7 at the same speed? Simple and Physics: It requires a certain amount of energy (gas) regardless of how the motor produces said HP to generate a specified HP-there is no getting around that fact and no free ride.
Take a 4 cylinder turbo engine and pump it to 500 HP and it will most likely get LESS MPG than a bigger displacement normally aspirated V8 simply because the smaller displacement 4 cylinder will be so highly stressed to achieve that level of HP. The reason that today's smaller 4 cylinder turbo engines get better mileage than the bigger displacement 6 cylinder normally aspirated engine is they generally have less HP. BMW's new 4 cylinder turbo engine has 240 HP versus the 6 turbo 300+ HP. Well, it has 60 HP less than the latter twin turbo 6. Lastly, a 4 cylinder making 240 HP is NOT the same driving experience as a 6 cylinder making 240 HP.
So, back to this discussion: The difference in MPG between a a 350 versus a 383 that produce roughly the same HP is going to be negligible, if noticeable even at all, all things being equal. Like the discussion above, both 350/383 producing roughly the same HP, the 383 has a VERY slight nod in torque, barely noticeable, if setup/built to approximately the same specs. Comparsion to a 406 SBC/427/454/502 BB, now that is a very different story. We are splitting hairs here all the way around comparing a 350 to a 383, in reality.
Hope this helps!
Here is another way to look at this issue. A 500 HP 4, 6, and 8 cylinder engine with the SAME HP will ALL essentially get the same MPG with all things being equal again, with a very slight nod to the lesser cylinder engines due to less rotational frictional loses versus the 8 cylinder engine but the differences are small-these differences are almost non existent in a discussion of a 350 versus 383. So why does my 2012 Lexus IS 350 F sport with 306 net HP from its 3.5L V6 not get much better MPG than my C6Z06 @ a steady 80 MPH despite ,much smaller displacement, less cylinders? Simplstically, it turns about 600 RPM higher at that speed than the C6Z06. Why does a 500 HP 6 cylinder twin turbo Nissan GTR get the same MPG at 80 MPH as the 505 HP 7L LS7 at the same speed? Simple and Physics: It requires a certain amount of energy (gas) regardless of how the motor produces said HP to generate a specified HP-there is no getting around that fact and no free ride.
Take a 4 cylinder turbo engine and pump it to 500 HP and it will most likely get LESS MPG than a bigger displacement normally aspirated V8 simply because the smaller displacement 4 cylinder will be so highly stressed to achieve that level of HP. The reason that today's smaller 4 cylinder turbo engines get better mileage than the bigger displacement 6 cylinder normally aspirated engine is they generally have less HP. BMW's new 4 cylinder turbo engine has 240 HP versus the 6 turbo 300+ HP. Well, it has 60 HP less than the latter twin turbo 6. Lastly, a 4 cylinder making 240 HP is NOT the same driving experience as a 6 cylinder making 240 HP.
So, back to this discussion: The difference in MPG between a a 350 versus a 383 that produce roughly the same HP is going to be negligible, if noticeable even at all, all things being equal. Like the discussion above, both 350/383 producing roughly the same HP, the 383 has a VERY slight nod in torque, barely noticeable, if setup/built to approximately the same specs. Comparsion to a 406 SBC/427/454/502 BB, now that is a very different story. We are splitting hairs here all the way around comparing a 350 to a 383, in reality.
Hope this helps!
Of course my ZO6 will easily return low 30s mpg crushing at ~75 mph. But the point is the smaller engines use less fuel on average than a larger one.
350/355 vs. 383 isn't a big difference in displacement. If I were building a Gen1 small block today, I wouldn't think twice about it, 383 of course.
Pete
Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
I know you like to dissect other posts and explain how your way is the only true way. However, if you carefully read my post again, you will see I was describing a comparison of AVERAGE mpg between two engines displacements; 346 vs 427 over a similar thousand mile trip.
Of course my ZO6 will easily return low 30s mpg crushing at ~75 mph. But the point is the smaller engines use less fuel on average than a larger one.
350/355 vs. 383 isn't a big difference in displacement. If I were building a Gen1 small block today, I wouldn't think twice about it, 383 of course.
Pete
Of course my ZO6 will easily return low 30s mpg crushing at ~75 mph. But the point is the smaller engines use less fuel on average than a larger one.
350/355 vs. 383 isn't a big difference in displacement. If I were building a Gen1 small block today, I wouldn't think twice about it, 383 of course.
Pete
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Verdad Gallardo
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not to hijack this thread, but a question: what is the difference in potential top speed of a 383 vs 350? i'm just sort of curious (as a newbie to all this....)
i know in a lot of what i read, most say that the 350 of the 70s vettes feels underpowered...and from the 2 corvettes i've test driven (endless search)...an '80 had the standard 350 in it, and it drove/sounded fine (maybe sounded a bit souped up vs. my normal driving car), but when i drove a '78 w/ a 383, wow, that thing just roared...althought i didn't get to drive it very fast for the in town test, it just seemed like it WANTED TO GO WAY FASTER!!!!
just curious if folks knew approximent "how much faster a 383" would be....not that i'll ever get to drive it that fast.....of course...
i know in a lot of what i read, most say that the 350 of the 70s vettes feels underpowered...and from the 2 corvettes i've test driven (endless search)...an '80 had the standard 350 in it, and it drove/sounded fine (maybe sounded a bit souped up vs. my normal driving car), but when i drove a '78 w/ a 383, wow, that thing just roared...althought i didn't get to drive it very fast for the in town test, it just seemed like it WANTED TO GO WAY FASTER!!!!
just curious if folks knew approximent "how much faster a 383" would be....not that i'll ever get to drive it that fast.....of course...
Burning Brakes
Joined: Oct 2011
Posts: 956
Likes: 86
From: McDonough Georgia
not to hijack this thread, but a question: what is the difference in potential top speed of a 383 vs 350? i'm just sort of curious (as a newbie to all this....)
i know in a lot of what i read, most say that the 350 of the 70s vettes feels underpowered...and from the 2 corvettes i've test driven (endless search)...an '80 had the standard 350 in it, and it drove/sounded fine (maybe sounded a bit souped up vs. my normal driving car), but when i drove a '78 w/ a 383, wow, that thing just roared...althought i didn't get to drive it very fast for the in town test, it just seemed like it WANTED TO GO WAY FASTER!!!!
just curious if folks knew approximent "how much faster a 383" would be....not that i'll ever get to drive it that fast.....of course...
i know in a lot of what i read, most say that the 350 of the 70s vettes feels underpowered...and from the 2 corvettes i've test driven (endless search)...an '80 had the standard 350 in it, and it drove/sounded fine (maybe sounded a bit souped up vs. my normal driving car), but when i drove a '78 w/ a 383, wow, that thing just roared...althought i didn't get to drive it very fast for the in town test, it just seemed like it WANTED TO GO WAY FASTER!!!!
just curious if folks knew approximent "how much faster a 383" would be....not that i'll ever get to drive it that fast.....of course...
There are many different combinations to build your motor that can affect how "fast" it is.
Basic rule of thumb, a stroker does not technically make your motor have more cubic inches. What it does is increase the length of distance your piston travels, thereby increasing the size of the combustion chamber on power stroke.
Typically, a short stroke motor has a lot of speed, but little torque, and vice versa. This principal is not dependent on piston size, but rather how fast it goes up and down.
You can see the idea in action on motorcycles really easy. A big V twin Harley Davidson has a long slow stroke that is very powerful, but not very fast. So it acts tractor like and has the torque to pull stumps from your front yard.
The Ring Ding bikes that turn many thousands of RPM but are only 600 cc are tremendously fast, but not powerful.
The same is true with a 350 vs 383 stroker. A stroker will tend to pull off the line faster in a drag race simply because it has the added torque to get the car moving.
Theoretically, and with all things equal, a 350 might be a little slower off the line and turn a few more rpm.
All this is dependent on your cam, pistons, fuel system and a multitude of other things.
Top end is also affected. Theoretically, a stroker shouldn't have as high end speed as a non stroker, but again, many variables affect this.
That feeling you had with the 383 is what performance guys like.
My 383 is a world apart from my stock 190 hp motor. The 383 always wants to go, pulls like freight train.
Step on the gas and your head is laid into the seat. Makes my grandchildren squeal in delight.
I will tell you that I do not think my fuel economy has been degraded that much. I do have to use premium, and at todays prices its costly, but that has to do with the price of the gas, not the motor.
My lazy, pathetic 190 hp used low grade gas and just didn't hack it. But I did get good gas mileage. But so does a Kia.
Le Mans Master
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From: Oxford MA-----You just lost the game!!!!
Scott
Le Mans Master
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From: RI, Now Franklin/Nashville TN
Actually, Commander 47, a very nice explanation of the difference between a 350 versus a 383, and as you noted, in theory. All things being exactly equal, the 383 has the nod on power and MPG, as I have noted earlier, is much more a direct function of the HP each motor makes, NOT the additional 23 cubes over a 350 or 18 cubes in my case over my just built 355.
With all that said, many folks buy turn key crate 383's and these motors offer very respectable high performance but the more I drive my just rebuilt L-82, now a 355, the more I am convinced that a 350 built to maximize mid range torque with the proper roller cam and really high flowing heads like the AFR's to maximize high RPM HP, gives up nothing to a crate 383. As a direct comparison, I took out my 10 Z06 for a long ride today and came back to take the "new" L-82 out for a spin. Keep in mind I am still breaking in the 355, but moderate acceleration (2,000-4,500 RPM) of the 355 is pretty darn impressive compared to the 427 LS7-within reason, of course, but the L-82 can hold its own NOW and will be really impressive once broken in. Basic Specs of my 355 are:
JE Forged Pistons 9:1
Howards Roller cam-.525/.525, LSA 110, Duration 219/225
AFR 180 65 CC heads
Compression about 10-10.2:1 with .015 head gasket.
The point is that for most CRATE 383's, not someone who builds a 383 to the max, a properly built 355 can easily match the performance, gas mileage the same…..
With all that said, many folks buy turn key crate 383's and these motors offer very respectable high performance but the more I drive my just rebuilt L-82, now a 355, the more I am convinced that a 350 built to maximize mid range torque with the proper roller cam and really high flowing heads like the AFR's to maximize high RPM HP, gives up nothing to a crate 383. As a direct comparison, I took out my 10 Z06 for a long ride today and came back to take the "new" L-82 out for a spin. Keep in mind I am still breaking in the 355, but moderate acceleration (2,000-4,500 RPM) of the 355 is pretty darn impressive compared to the 427 LS7-within reason, of course, but the L-82 can hold its own NOW and will be really impressive once broken in. Basic Specs of my 355 are:
JE Forged Pistons 9:1
Howards Roller cam-.525/.525, LSA 110, Duration 219/225
AFR 180 65 CC heads
Compression about 10-10.2:1 with .015 head gasket.
The point is that for most CRATE 383's, not someone who builds a 383 to the max, a properly built 355 can easily match the performance, gas mileage the same…..
Last edited by jb78L-82; Jun 15, 2014 at 06:50 PM.
Le Mans Master
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
i have to ask, if stroke doesn't "technically" increase displacement, what does? that makes no sense maybe you worded it improperly.
Burning Brakes
Joined: Apr 2013
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From: Las Vegas NV
Not disagreeing with your point at all, but couldn't you easily mitigate the narrow power curve by installing a higher stall converter...assuming of course the transmission is an auto...
Safety Car
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From: anchorage ak
not to hijack this thread, but a question: what is the difference in potential top speed of a 383 vs 350? i'm just sort of curious (as a newbie to all this....)
i know in a lot of what i read, most say that the 350 of the 70s vettes feels underpowered...and from the 2 corvettes i've test driven (endless search)...an '80 had the standard 350 in it, and it drove/sounded fine (maybe sounded a bit souped up vs. my normal driving car), but when i drove a '78 w/ a 383, wow, that thing just roared...althought i didn't get to drive it very fast for the in town test, it just seemed like it WANTED TO GO WAY FASTER!!!!
just curious if folks knew approximent "how much faster a 383" would be....not that i'll ever get to drive it that fast.....of course...
i know in a lot of what i read, most say that the 350 of the 70s vettes feels underpowered...and from the 2 corvettes i've test driven (endless search)...an '80 had the standard 350 in it, and it drove/sounded fine (maybe sounded a bit souped up vs. my normal driving car), but when i drove a '78 w/ a 383, wow, that thing just roared...althought i didn't get to drive it very fast for the in town test, it just seemed like it WANTED TO GO WAY FASTER!!!!
just curious if folks knew approximent "how much faster a 383" would be....not that i'll ever get to drive it that fast.....of course...
Race Director
Joined: Aug 2004
Posts: 10,628
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From: Duvall, WA
Thank you for saving me from typing pretty much the same thing you said.
Le Mans Master
Joined: Aug 2008
Posts: 5,578
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From: Austin TX
Actually, Commander 47, a very nice explanation of the difference between a 350 versus a 383, and as you noted, in theory. All things being exactly equal, the 383 has the nod on power and MPG, as I have noted earlier, is much more a direct function of the HP each motor makes, NOT the additional 23 cubes over a 350 or 18 cubes in my case over my just built 355.
With all that said, many folks buy turn key crate 383's and these motors offer very respectable high performance but the more I drive my just rebuilt L-82, now a 355, the more I am convinced that a 350 built to maximize mid range torque with the proper roller cam and really high flowing heads like the AFR's to maximize high RPM HP, gives up nothing to a crate 383. As a direct comparison, I took out my 10 Z06 for a long ride today and came back to take the "new" L-82 out for a spin. Keep in mind I am still breaking in the 355, but moderate acceleration (2,000-4,500 RPM) of the 355 is pretty darn impressive compared to the 427 LS7-within reason, of course, but the L-82 can hold its own NOW and will be really impressive once broken in. Basic Specs of my 355 are:
JE Forged Pistons 9:1
Howards Roller cam-.525/.525, LSA 110, Duration 219/225
AFR 180 65 CC heads
Compression about 10-10.2:1 with .015 head gasket.
The point is that for most CRATE 383's, not someone who builds a 383 to the max, a properly built 355 can easily match the performance, gas mileage the same…..
With all that said, many folks buy turn key crate 383's and these motors offer very respectable high performance but the more I drive my just rebuilt L-82, now a 355, the more I am convinced that a 350 built to maximize mid range torque with the proper roller cam and really high flowing heads like the AFR's to maximize high RPM HP, gives up nothing to a crate 383. As a direct comparison, I took out my 10 Z06 for a long ride today and came back to take the "new" L-82 out for a spin. Keep in mind I am still breaking in the 355, but moderate acceleration (2,000-4,500 RPM) of the 355 is pretty darn impressive compared to the 427 LS7-within reason, of course, but the L-82 can hold its own NOW and will be really impressive once broken in. Basic Specs of my 355 are:
JE Forged Pistons 9:1
Howards Roller cam-.525/.525, LSA 110, Duration 219/225
AFR 180 65 CC heads
Compression about 10-10.2:1 with .015 head gasket.
The point is that for most CRATE 383's, not someone who builds a 383 to the max, a properly built 355 can easily match the performance, gas mileage the same…..
383-355= 28
Le Mans Master
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From: Austin TX