VTEC vs. VTC in the 1.5L Turbo engine: GenX

SoSublime

Senior Member
Joined
Apr 1, 2017
Threads
14
Messages
135
Reaction score
99
Location
United States, California
Vehicle(s)
2017 Civic EX-T
Vehicle Showcase
1
Country flag
There seems to be some confusion, compounded by Honda as well, on whether the 1.5L is VTEC or not.

Short answer: No, it is not VTEC.

Long answer: The 1.5L Turbo engine features dual VTC on both the Intake and Exaust camshaft. This affects Valve timing only. In essence it does what VTEC does in that it is variable valve timing, minus the lift.
In laymans terms, think of lift as how far the valves open. Without VTEC they open only to a certain set height on a smaller lobe, with VTEC engaged the valve is opened by a larger lobe, resulting in a valve that is opened wider for longer.

VTC does change how long the valve stays open affecting valve timing and overlap, with the focus done on scavenging, but it does not affect lift at all. The valves always open to a certain set height due to only one size lobe being present. This helps by increasing turbo response at lower rpms and also lowering combustion chamber temperatures.

So no, even though Honda refers to the engines as "VTEC turbos" they are not because, well, they are not VTEC, they simply use VTC technology based on VTEC technology. Accurately they are simply VTC turbos.

In a real life scenario? You will probably recieve more benefit from the continuous VTC over the situational VTEC due to increased scavenging, lower combustion chamber temperatures, and increased turbo response.
Sponsored

 
OP
OP

SoSublime

Senior Member
Joined
Apr 1, 2017
Threads
14
Messages
135
Reaction score
99
Location
United States, California
Vehicle(s)
2017 Civic EX-T
Vehicle Showcase
1
Country flag
There seems to be some confusion, compounded by Honda as well, on whether the 1.5L is VTEC or not.

Short answer: No, it is not VTEC.

Long answer: The 1.5L Turbo engine features dual VTC on both the Intake and Exaust camshaft. This affects Valve timing only. In essence it does what VTEC does in that it is variable valve timing, minus the lift.
In laymans terms, think of lift as how far the valves open. Without VTEC they open only to a certain set height on a smaller lobe, with VTEC engaged the valve is opened by a larger lobe, resulting in a valve that is opened wider for longer.

VTC does change how long the valve stays open affecting valve timing and overlap, with the focus done on scavenging, but it does not affect lift at all. The valves always open to a certain set height due to only one size lobe being present. This helps by increasing turbo response at lower rpms and also lowering combustion chamber temperatures.

So no, even though Honda refers to the engines as "VTEC turbos" they are not because, well, they are not VTEC, they simply use VTC technology based on VTEC technology. Accurately they are simply VTC turbos.

In a real life scenario? You will probably recieve more benefit from the continuous VTC over the situational VTEC due to increased scavenging, lower combustion chamber temperatures, and increased turbo response.
One thing I should probably add to this, is that traditional VTEC may not be seen the same as "Turbo VTEC" by Honda. VTECs main gain would be in a NA engine, allowing more air to enter the cylinder during the intake stroke. However, as the engine is turbocharged, the air is already being forced into the cylinder by a turbine, meaning that regardless of the lift, considering VTC handles how long it stays open, under boost, you probably couldnt get more air in the cylinder if you tried unless you put it under even more boost.
So Honda may consider "Turbo VTEC" a new technology which replaces a higher lift with turbo compression to achieve the same goal and and then use VTC for the timing. Its may be VTEC reimagined. So who knows, until further notice, it is not VTEC as we know it, but it may be a new front for the VTEC platform.
 

18k

Senior Member
Joined
Aug 10, 2016
Threads
3
Messages
69
Reaction score
21
Location
Washington
Vehicle(s)
2016 civic coupe lx
Vehicle Showcase
1
The 2.0L has dual vtc as well as vtec on the intake cam, correct?
 

zroger73

Senior Member
Joined
Apr 15, 2017
Threads
56
Messages
2,477
Reaction score
4,544
Location
United States
Vehicle(s)
2019 MX-5 Miata GT-S, 2021 Ridgeline RTL-E
Country flag
I've always found VTEC to be ever-so-slightly annoying, actually. I prefer a more linear power delivery myself.
 

roro40p

Senior Member
Joined
Apr 17, 2016
Threads
16
Messages
252
Reaction score
354
Location
dallas
Vehicle(s)
2018 TYPE R-11883
Vehicle Showcase
1
Country flag
my question is why do international model civics have VTEC on them and is even advertised ? is it a different engine or is it what you are referring in VTC and they say is VTEC ?
 


ikbenben

Belgium spec
Joined
Apr 2, 2017
Threads
12
Messages
435
Reaction score
271
Location
Belgium, Europe
Vehicle(s)
'17 Civic 1.5T Sport Plus HB
Vehicle Showcase
1
Country flag
my question is why do international model civics have VTEC on them and is even advertised ? is it a different engine or is it what you are referring in VTC and they say is VTEC ?
They don't, even when it's advertised. It's indeed VTC and not VTEC.
 

FK7Hatch

Senior Member
Joined
Jan 4, 2017
Threads
7
Messages
332
Reaction score
162
Location
MD
Vehicle(s)
17' Civic Hatchback Sport
Country flag
I believe the type r has VTEC on the exhaust cam
 

roro40p

Senior Member
Joined
Apr 17, 2016
Threads
16
Messages
252
Reaction score
354
Location
dallas
Vehicle(s)
2018 TYPE R-11883
Vehicle Showcase
1
Country flag
They don't, even when it's advertised. It's indeed VTC and not VTEC.
thats crazy , i was down in Mexico and saw all these cars that said VTEC turbo t the dealer ... and i was like what ????
 

ikbenben

Belgium spec
Joined
Apr 2, 2017
Threads
12
Messages
435
Reaction score
271
Location
Belgium, Europe
Vehicle(s)
'17 Civic 1.5T Sport Plus HB
Vehicle Showcase
1
Country flag
Took a picture of my valve cover.

Honda Civic 10th gen VTEC vs. VTC in the 1.5L Turbo engine: GenX TQeLyZV
 


Shankmeyster

Senior Member
Joined
Mar 15, 2017
Threads
46
Messages
3,660
Reaction score
1,847
Location
AZ
Vehicle(s)
23 Si
Vehicle Showcase
1
Country flag
VTEC is old tech though. I would rather they keep innovating and making the variable timing better with more power/mpg. Used to be you got 7 more hp out of a 2.0l NA motor on the Si than the Sport's 190hp 1.5l. Even the 2.4l only had 201 hp and both got worse gas mileage. What does it really matter as most people really have no idea what VTEC actually does?
 

typemismatch

Senior Member
First Name
Russell
Joined
Jun 15, 2017
Threads
8
Messages
974
Reaction score
945
Location
Fargo, ND
Vehicle(s)
A whole farm of Hondas
Country flag
There seems to be some confusion, compounded by Honda as well, on whether the 1.5L is VTEC or not.
Short answer: No, it is not VTEC.
True

Long answer: The 1.5L Turbo engine features dual VTC on both the Intake and Exaust camshaft. This affects Valve timing only. In essence it does what VTEC does in that it is variable valve timing, minus the lift.
False, VTEC is VTEC, VTC was added to i-VTEC motors, they perform completely different functions

In laymans terms, think of lift as how far the valves open. Without VTEC they open only to a certain set height on a smaller lobe, with VTEC engaged the valve is opened by a larger lobe, resulting in a valve that is opened wider for longer.
True

VTC does change how long the valve stays open affecting valve timing and overlap, with the focus done on scavenging, but it does not affect lift at all. The valves always open to a certain set height due to only one size lobe being present. This helps by increasing turbo response at lower rpms and also lowering combustion chamber temperatures.
Somewhat true, VTC doesn't change the duration (how long the valves stay open) of the cams, just adjusts the LSA (overlap) which improves the efficiency of the motor over a broad rpm range.

Yes, varying the overlap improves turbo response.

So no, even though Honda refers to the engines as "VTEC turbos" they are not because, well, they are not VTEC, they simply use VTC technology based on VTEC technology. Accurately they are simply VTC turbos.

In a real life scenario? You will probably recieve more benefit from the continuous VTC over the situational VTEC due to increased scavenging, lower combustion chamber temperatures, and increased turbo response.
True

I've always found VTEC to be ever-so-slightly annoying, actually. I prefer a more linear power delivery myself.
Properly tuned VTEC motors don't have "cross-over", which makes the power much more linear.

I believe the type r has VTEC on the exhaust cam
True
Sponsored

 


 


Top