Hi this is Jeff from Evans Tuning, and in
this video we’re going to talk about K-Series. Over the years I’ve had tons of emails,
phone calls, and questions about K-Series related tech, and I've decided to put a video
together. This video is going to cover non-base model RSX, so were not going to do the K20A3
motor, or the new 9th Gen K24 motors. They're kind of the odd ball in the K-series family.
So we’re going to focus on the Type-S, the TSX, the 8th Gen Civic Si’s, those engines
in swap cars. The Civics, Integras, and whatever else you can stuff a K-series in. So we’re
going to go over all of the pitfalls, and some recommendations that I have to keep your
engine reliable, whether it’s N/A, supercharged, or turbo. So over the years I get a lot of questions,
what’s the biggest bang for the buck I can do for my naturally aspirated K20, K20A2,
K20Z, Z1 etc. So the Type-S style cylinder head K20 motors. What I’ve seen RBC intake
manifolds, 3” cold air intake, a race header, and a 3” exhaust, give the best possible
power, along with a tune for that particular style motor. Now if you have a TSX, so the
K24A2 motor, doing an RBC intake manifold on that engine, actually will lose power if
you’re keeping the 25-degree variable timing gear in place. I’ve actually seen better
overall power with the stock intake manifold, keeping that stock VTC gear. Now if you're
going to upgrade the VTC gear to a 50-degree, from the K20A2 motor, then you can go ahead
and do the RBC, because then you will see the gains being able to see the full movement
of the cam angle at 50-degrees on
the TSX engine. The next question we get for the naturally
aspirated K-series is “I’ve done all the bolt-ons, I’ve gotten a tune, what do I
do next, I want to make more power?” I’ve found that most peoples’ answers and most
peoples’ perceptions is, I want to do cams and a valvetrain upgrade. Doing that will
certainly make more power. On a stock engine doing a drop in cam, you know you might get
10-15 horsepower. If you're going to do 100 percent drop in cam that’s 100 percent reliable,
doing the 2006 and newer TSX cams, give the best power. Usually it’s about 5-10 foot
pounds of torque, and about 5-10 horsepower gain, they’re a drop in cam nothing needs
to be changed. If you’re doing other aftermarket brand drop in cams, or upgrading to larger
than a drop in cam that needs a full valve train upgrade, you have to be aware that there
is a potential for the timing chain tensioner to fail. The timing chain tensioner is unfortunately
one of the pitfalls of the K-series motors, I’ll kind of touch on that a little bit
later in this video. But once you drop in a non-OEM cam in a K-series engine, you open
up a can of worms for unreliability. So my personal stand point, if you want to see 40-50
horsepower gain, without going forced induction, if you have a K20 with the Type-S head, is
to take the TSX bottom end and drop your head on that and put that in the car. If you don't
change anything else so if you keep the same intake, intake manifold, header, and exhaust,
you're going to see about a 40-50 horsepower gain, and 40-50 ft/lbs of torque. So you'll
have a broader more usable power band, typically torque is 180-200 ft/lbs, and typical horsepower
is 240-250, if everything else remains the same. But you know you can’t see that type
of gain without going forced induction, and no set of cams is going to give you that much
of a usable power, and be 100 percent reliable. You know and that’s the big factor here
is reliability, I’m not talking about making 30-40 horsepower with a cam. That’s great
that it will do that, but then the tensioner breaks a couple weeks later or a couple hundred
miles later, and you're either rebuilding the engine or putting tensioners in the engine
constantly. So we get a lot of questions about forced
induction with K-series, specifically supercharged. There’s a couple options for superchargers.
There’s the Roots style kits, Jackson racing use to make a kit with the M62 Eaton blower,
that has actually been discontinued as far as I know. Comptech sells the Roots style
blower kit, and there’s also the Rotrex style kit from Kraftwerks that’s available
as a bolt-on for the 8th Gen Civic Si, and as well as the 9th Gen. When you're going
supercharged, I get this question all the time, people want to do cams, they make whatever
power they make. “I want to do a cam that’s going to make more power.” With the Roots
style blower kit, so the CT and the Jackson kits, don’t upgrade the cams. Leave them
OEM you will lose power, if you want to upgrade put the 06 TSX cams in because they’re drop
in and they might give you a slight increase in power but for the most part, save your
money keep the stock cams. Now going with a Kraftwerks kit, you can do cams, usually
a mild NA drop in cam will work, however keep in mind that once you do a cam upgrade that’s
not OEM in the K-series motor, that you're more likely to have tensioner failure. So
if you're trying to go about this from a reliability standpoint, stick with the stock cams. Another
point I want to touch on is, I did an S2000 tech video, and the S2000’s are a little
unique where the header and exhaust design is really good from Honda. Now the K-series
isn’t like that. You need to do your normal upgrades that you would have with N/A. So
with the Roots kit the supercharger is mounted on the intake manifold side, so your intake
manifold is not going to be upgraded. On the Roots kit I find doing a cold air style intake
is beneficial, doing a larger throttle body is beneficial, doing the normal race header,
so you get rid of the CAT and a 3 inch exhaust, that combination will make the most power.
Also on the Roots style kit, because they're non-intercooled, there are kits available
that add an aftercooler, that is an inline heat exchanger, that goes between the blower
and the intake manifold, and has a water pump and it circulates water, with the heat exchanger
up front like a radiator, that is typically good for 20-30 horsepower, and that keeps
the power consistently at the same level where if you didn't have that, it would get a ton
of heat soak. Then it would lose power, so if you get on it a couple of times. So that’s
a thing to keep in mind with the roots. With a Kraftwerks rotrex style kit, doing the typical
bolt-on that you would have N/A would apply to that kit because the supercharger is mounted
on the side of the motor, and has traditional piping like a turbocharger would, but you
have your header and exhaust in place. So if you're going to do an upgrade for the intake
manifold doing an RBC, if you're a swapped car that’s not an 8th Gen Civic Si, doing
an RBC intake manifold is worthwhile. If you're an 8th Gen you already have the intake manifold,
and doing the normal race header and exhaust is all you would need because the kit comes
with everything else. So if you're thinking about going a turbocharged
route with your K-series there are a whole bunch of things that I want to cover and you
will need to know. First, the K-series motor is like the S2000, it’s also like the other
Honda motors that it’s sensitive to exhaust back pressure. Putting a log style manifold
on a K-series, is going to kill power, just like it would on an S2000 or a B-series motor.
Doing a tubular style manifold, will make substantial increase in power over a log.
You're looking at 50-150 or possibly more horsepower gain, from going from a log to
a tubular style, as well as decreasing the knock sensitivity with the engine. So allowing
the engine to breath, you'll be able to make more power on the same octane, and the engine
will be able to run much safer with the additional power. Now doing a tubular style manifold
on a K-series is the same kind of situation as the S2000, you run into boost creep. So
you need to make sure you're wastegate size is adequate for the turbocharger size you
are running. There’s a lot of technical stuff we could get into, but I'm trying to
keep it relatively straightforward. If you're running a GT30R or smaller sized turbo, in
general I have seen you can get away with a TiAL 44mm MVR style wastegate. That’ll
adequately bypass enough exhaust flow from the manifold to regulate the spring pressure
that you’re trying to run. So if you're trying to run an 8 pound spring in your wastegate
and not creep to say 20 pounds, you don't want anything less than a 44mm. If you're
running something larger than that, you're either going to need two wastegates, so either
two 44’s, or one large 60mm. From a packaging standpoint, it’s a little bit of a pain
in the butt, but you don't want to get into the situation where you get massive boost
creep, you can’t control the boost, per gear, or you literally can’t control the
boost on pump gas, and you won’t be able to rev past 7,000 RPM because you'll boost
creep to 30 pounds, or something ridiculous that'll blow the engine. So you have to keep
that in mind when you turbo it, but I always recommend doing a tubular style manifold,
there a bunch of great manifolds out on the market. You want to avoid the cheap eBay brands
like, SS AutoChrome if they're even around, or a thin walled crappy welded manifold, that’s
going to crack and create problems. You want to stick to the quality brands
like Full Race, Sheepey, there’s probably many more out there that have warranty that
are thick walled, that are meant to last and not fall apart. So you’re going to want
to look into something quality from a reliability standpoint. So I want to talk about the strengths of the
K-series motor with forced induction. The cam profile design OEM is really good. A lot
of people always want to upgrade. Coming from other engines doing cam upgrades gives a lot
of power, and K-series can certainly benefit from a larger cam, but you have to keep in
mind from a reliability standpoint of having tensioner failures. Keeping stock cams can
meet power goals that people probably don't realize you can meet with a stock cam. I’ve
made into the 900 horsepower range with stock cams, and it probably can make more. The cam
really isn't a limiting factor. Can you make more with a larger cam at less boost? Yes,
you can, but you're opening a can of worms again with having the timing chain tensioners
fail and having an unreliable motor in that sense, so you’ve got to keep in mind. Another
strength of the K-series, unlike D, B, and H Series, is the factory sleeve design is
very thick. I’ve made into the 900 horsepower range with the stock sleeves. Doing sleeving
if you can afford it is always a good idea to do it, so if you have the extra cash to
spend and you want to make it ultra reliable, doing sleeves is always going to be stronger
than the stock sleeves. However the K-series sleeve, is much thicker with a much better
designed block than the B-series, for example because everyone is familiar with the B-series.
B-series sleeves can handle 5, 6, 700 horsepower. They’re hit or miss, I’ve seen them last
and I’ve seen them not last. The K-series typically you don't see the sleeves crack,
you’ll see the piston crack the ringlands before you'll actually see the sleeve fail.
So if you're looking to do a 6, 7, 800 horsepower build, from my point of view if it was my
personal car, I probably wouldn't sleeve it I would just do pistons and rods, and keep
it simple. If you really want to push the envelope down the road, sleeve it so you don't
have to think about it, or if you have the extra cash and you don't care and don't want
to do it twice, then cool sleeve it. But you don't absolutely need to like a B-series or
some of the older Honda motors. One of the most common issues on a K-series
motor, is the timing chain tensioners or the TCT. I’ve talked about it a whole bunch
in this video already, now I'm going to walk you through why you might not want to upgrade
your cam and have any issues. Upgrading cams, makes the engine more unreliable because the
TCT is more prone to fail. Putting a larger cam in the engine is going to make more power
in general, because you're letting more air into the engine. In the camshaft profile design,
there’s a thing called ramp rate, so it controls how quickly a valve opens, how long
it stays open, and then how quickly it closes. In that design there’s an engineering term
called Jerk, which is the relationship of what’s going on there. To keep it simple,
every camshaft design, even OEM has this term called Jerk, it has a measurable amount. That
is what causes the TCT failure. Some camshaft profile designs have it much worse than others,
but in general sticking any aftermarket cam in a K-series motor, is going to make the
TCT more prone to fail. There are some solutions to this, there are several different aftermarket
options available for upgraded TCTs, however they can and potentially will still fail.
The best option I've found from all aftermarket TCTs is from InlinePRO, they make a modified
OEM. They change some of the internals out and that seems to hold up the best that I
have found building K-series, and tuning K-series over the years compared to the other options.
But still be aware that doing cams can and will make the engine less reliable, and if
we’re talking about reliability here you know making power is great, but being able
to turn your car on everyday and drive it without having to worry, you need to keep
that in mind with putting a large aftermarket cam inside your engine. So I just touched on the TCT failure, and
all the ins and outs of that, there’s a lot of issues that I see tuning and building
K-series engines that I want to touch on to make everyone aware of. Throttle Position Sensor or the TPS sensor,
is another known failure point on a K-series, when you do a swap or if you put in stiffer
aftermarket engine mounts you're going to get a lot more vibration in the chassis and
also into the engine. The design of the factory TPS sensor can’t handle that vibration so
the sensors fail, which causes the deceleration fuel cut to turn on while you're driving,
and it makes the car really jerky, you're going to get a lot of stuttering, bucking,
whatever you want to call it. You're going to have to replace the TPS sensor. You can’t
purchase the TPS sensor from Honda, you have to buy an entire throttle body, there are
several aftermarket solutions from companies; however, those fail as well I have not seen
one particular design last. The best solution that I have come up with, K-Tuned and I think
there might be another company makes a B-series TPS adapter, so you can take a B, D, or H
series TPS sensor and bolt it on with this adapter to the K-series throttle body. The
B, D, H- series TPS sensors are not sensitive to engine vibration as badly as a K-series.
In general you can go purchase a used D-series throttle body for $20 eBay, take the TPS sensor
off, buy this adapter, bolt that on and that will solve all of your issues. So if you have a swapped car, or if you have
an 8th Gen or 9th Gen Civic, that has a returnless style fuel system, a lot of people incorrectly
route the fuel pressure regulator lines going in their car. They try to use a pass through
style with a regulator, where the feed line passes through the regulator and then it goes
into the fuel rail, but there’s no return, there’s only a feed. Let’s call that “dead
heading” into the fuel rail. That’s the way it would be stock on a returnless style
system because there is no return line. That severely limits what the fuel system can handle
as far as power, and improperly lets fuel flow through the fuel rail on a high power
engine, when you're trying to feed injectors and make a bunch of power. The other issue
I see is a lot of people do not run a vacuum line from the regulator to the intake manifold
for vacuum reference. This is super critical on a forced induction application, turbo or
supercharged. You need to have a 1:1 reference for the fuel pressure needs to rise 1 pound
to overcome the pressure in the intake manifold that’s rising 1 pound. So if you don’t
do that, you will make substantially less than you would doing a 1:1 reference with
the vacuum line. So if you're going to do your fuel system, do it the traditional style,
where you're going to have a feed coming into the fuel rail, you're going to have your return
leaving the fuel rail, into the regulator, and then out of the regulator and back down
into the tank. You don't want to dead head, you don’t want to come from the fuel tank,
up in the regulator, from the regulator to the fuel rail, and then not have a return
line out of the rail. I see people do this all the time, it is incorrect, and it will
limit what kind of power you can make on a given fuel injector size. The Variable Cam Timing Solenoid, that’s
on the K-series motor is prone to have issues with higher mileage. I’ve seen now within
the last year, maybe a dozen K-series cars that I’ve been tuning that have 100,000
miles or more have bad variable cam solenoid. So that’s what controls your variable cam timing
gear movement. I’ve had issues where the solenoid itself is bad and needs to be replaced,
or I've also had issues where the solenoid screen up on the cylinder head, if you're
standing in front of the engine it’s off to the left it’s a little plate that has
two bolts holding it, it’s a little mesh screen that can be serviced and cleaned or
replaced. If that solenoid screen gets dirty it’s just like a VTEC solenoid screen, it
limits the amount of oil pressure going to your solenoid, which then limits the amount
of control the variable cam has. First before you replace the variable cam solenoid, you
want to check the screen and make sure it’s clean. If it’s clean, then the next thing
would be to replace your variable cam solenoid. You’re going to know it’s a problem if
you're looking at let’s say you're running K-Pro, if you’re looking at your cam command
of say 30 degrees, and you're only achieving 10 or 20 or you’re getting unstable cam
timing, where you cam timing is constantly moving around when you have a constant target,
say if you're steady state driving. As soon as you see that you have something going on
with the solenoid or the screen being dirty, so keep that in mind. So another area of concern on a K-Series specifically
for the 8th Gen Civic Si, is they have an oil pump with balancer shafts in them. That
oil pump design can’t handle high RPM. So if you're going to rev that engine much over
8600 RPM, you're going to need to replace the oil pump. The RSX Type-S oil pump from
an 02-04 RSX Type-S, which is the K20A2 engine, that oil pump is a drop in fitment and won’t
have the issues of revving up to 10,000 RPM. That leads me into another topic here, the
other upgrade for a K-Series engine is the S2000 oil pump with some machining options,
I think ERL sells it, along with other people that have it on the market. The S2000 oil
pump moves a little more, it’s a higher flowing oil pump. It is an option to upgrade,
if you're building the engine you're going to see a super high RPM, if you're building
a race engine that’s going to see 10,000 RPM, or a road race car, that oil pump does
put out more and it is OEM, so it is an option to upgrade, it may or may not need it, it’s
just up to what you're doing with the car. Over the years of building and tuning K-Series
engines, I've seen several different failures. The one that is not most common but I've seen
it maybe 20-30 times. The factory OEM rocker assembly, is a roller style rocker. For whatever
reason I see them get hairline cracks, or they crack and break. So it can be avoided
if you do regular inspections, you know maybe every thousand or 2 thousand miles, if you
have a larger aftermarket CAM in. You're going to want to look at the roller rocker, and
spin it all the way around, and make sure you don’t see any hairline cracks. If they
are cracking you're going to want to replace them, if they break it ends up being a mess,
it can jam a rocker up, it can drop a valve, it can break a retainer. So you want to keep
an eye on that, if you have an aftermarket cam it is more critical to keep an eye on
that as a maintenance item to keep an eye out for. So when you put an aftermarket clutch in any
engine, it’s going to have a higher clamping force on your pressure plate. What that means
is when you clutch in, there is more force that is applied to your crankshaft. When the
engine is cold and there isn’t oil pressure built up, there’s a thrust shim, there isn’t
adequate oil supply on that thrust shim on cold start, so every time you push your clutch
pedal in with a higher pressure plate clutch, an aftermarket clutch, you're basically putting
metal on metal contact. You're going to have obviously some oil there because of the oil
pan, but there’s not oil pressure built up on that surface. So what ends up happening over time is that you wear out the thrust shim. The higher the pressure plate clamping force on the clutch,
the quicker that can wear out the thrust shim. On any aftermarket clutch I always recommend
taking out the factory clutch switch, so you don't have to clutch in on a cold start. You
have to be mindful to keep the car out of gear, or your car will jump forward when you're
trying to start it. But eliminating the clutch switch will eliminate the potential for the
thrust shim to fail. So another weak link on the K-Series, is the
transmissions. Specifically, I've seen most failures with 2nd gear. Also with doing a
high RPM fast shifting, the shift selectors actually get bent. Unfortunately, there is
no solution for 2nd gear failure. There are some gear sets aftermarket, that seem to help
the 2nd gear be a little bit stronger, so that is an option to upgrade. There are shift
selector upgrades, I believe Speedfactory is one of the people that make the factory
shift selector upgrade, that makes it stronger. So if you end up running into those, there
are aftermarket solutions but they can and will break OEM. If you're replacing them with
OEM parts and you're not making them stronger, they are going to fail at some point again,
and have the same exact problem. So if you have an RSX or an 8th Gen Civic
Si, you have a returnless style fuel system in your car. If you're going forced induction
the limit of the returnless style fuel system with upgraded injectors and an upgraded fuel
pump in the tank is about 450 horsepower. That’s with 1000cc and a 255 in the tank.
That’s give or take, I've seen then as low as 400 and as high as 450. You don't even
want to approach 450 with the returnless style fuel system. So if you're going to make more
power than that, you'll need to do a return style fuel system. You'll need to add a return
line, a fuel pressure regulator, and an aftermarket fuel rail in order to convert from returnless
to a return style. That’ll give you much more power at least 100-150 more horsepower
on the same size fuel injector. Also, when you do it you need to make sure you run a
vacuum line from your intake manifold to your fuel pressure regulator, so it raises your
fuel pressure 1 PSI for 1 PSI of boost increase. If you don't do this you're substantially
limiting what the fuel system can support. So if you’ve done a swap in a Civic, Integra,
or something with a K-series motor, and you haven't upgraded the clutch and flywheel the
stock clutch and flywheel can technically hold what normal bolt-on modifications will
produce for power. I have seen now multiple times over the years where someone has bought
a used swap, and they haven't changed out the clutch and flywheel. They put it in the
car, they do the bolt-ons, I start getting tuning, and the clutch slips, because the
car either has a ton of miles or it was abused in the previous car it came from, which would've
been an unknown history to the person doing the swap. So if you can afford to do it, I
would upgrade the clutch and flywheel. Now if you're going forced induction, supercharged,
turbo, or nitrous, you're going to want to upgrade the clutch. The factory clutch is
not going to handle it. If you're going to swap in a K24 bottom end then you're going
to want to upgrade the clutch. You don't want to be in the position of doing all the work,
you swap all of your parts on, and you go to the dyno and your clutch slips. So if you
can afford it, do the clutch and flywheel. You'll also have to keep in mind, you'll have
to do more clutch than what you need, like a Competition Stage 2 is good for your normal
bolt-on car, a K24, or a Roots style blower car. If you're going to do a Rotrex kit, or
go turbocharged, you're going to look at a stage 4, or a 5, or a twin disk that can handle
much more torque capacity. You are going to compromise some drivability going with a higher
sprung clutch, so it’s a factor you have to keep in mind. So that’s it for our K-Series tech video,
all my opinions in this video are based on reliability, not so much making the most amount
of power. There are multiple different ways to do the swaps and to do the power upgrades.
I'm sure there are going to be people that watch this and don’t agree with what I have
said, but from a reliability standpoint and having done this the last 8-10 years, working
with K-Series motors this is what I’ve seen and what I've seen be the most reliable or
unreliable out of the K-Series. So there are a lot of things to keep in mind in general,
but if you want to have a reliable K-Series, swap, car, whatever, pay attention to everything
I said in the video and you’ll be good.
