INSIDE OF K20- cam gear,cam shaft,retainers,valves/springs,rocker arm (Merged)

[skittleslegend]

Just some things I've found out about the Si's engine compared to other Hondas/Acuras.

From k20a.org:

"The head is 100% TSX
the block is a tsx 2.0L version with dual oil balance shafts and oil jets with a type s oil pan.
oil jets, and the little oil pump cover signifies the dual shafts..
The oil pan is not from the K20a2 though. It uses a different casting so that the rear motor mount can attach to it.

The type s style single pump has a longer cover

see the tsx water oulet on the right side

looks like stock k20a2 clutch


As far as the cams, they have different part numbers so we are not going to know till we test them

'06 Si Cams
Intake 14110-RRB-A00
Exhaust 14120-PRB-A01

'05 Type S Cams
Intake 14110-PRC-030
Exhaust 14120-PRC-030"

All of this is actually pretty surprising since the engine designation is K20z3 and the 06 RSX-S engine designation is K20z1. Although the Si shares some similarities, it seems to actually be closer to that of a TSX, including the Drive-By-Wire throttle. Another example, is the transmission. The Si tranny uses 1st-5th gears from the RSX, but the 6th gear is from a TSX. The LSD is from a JDM DC5R. The syncros on gears 4-5 are carbon, not brass like the 02-04 RSXs. This should reduce the problems that tranny had with gear grinding.

The Si uses the RBC Intake Manifold from the JDM Accord Euro R. The TSX uses an RBB Intake Manifold. The difference between the two is the RBC uses shorter fatter runners optimized for high rpm breathing and the RBB uses a long narrow runner which is good for torque. This is part of the reason the Si loves to rev, because it was given the intake manifold do so. It's trade-off is torque. We all know the Si's torque is low compared to it's competitors. Theoretically, you could swap the RBB Manifold onto the Si and pick up better torque, at the slight sacrifice of top-end. How much sacrifice and how much gain is unclear. The RBB Manifold is also used on the 2.4L 160hp Accord.

The Si uses raised dome pistons.


picture of the balance shafts and oil pan


The balance shaft smooths out the engine, reducing vibration, which is why there's a difference in horsepower rating between the RSX-S and the Si. These are the reason for the 4 horsepower difference after the new SAE ratings.

Air Intake

Notice the MAF sensor on top of the Air Filter. For those that don't know the MAF (Mass Airflow) sensor converts the amount of air drawn into the engine into a voltage signal. The ECM needs intake volume to calculate engine load. This is necessary to determine how much fuel to inject and when to ignite the cylinder.



Honda advertises the Si as having a cold air intake. The snorkel runs under the battery tray to another box and from that box another snorkel runs to the fender. With it's length and all the bends it probably does drawn in cooler air but at the expense of throttle response.



Here's the Head, from Fgcoupe.com




Opening the block, from Fgcoupe.com:





I woulda just posted links but I figured it made more sense to paraphrase some of the people and post pics. Knowledge is free anyway.

Most of this info is on point, but I'm still trying to iron out some of the details. I'll keep this thread updated as I find more information. Still working on you R18 guys and gals but info is pretty scarce. I can tell you, though, it has the potential to be one helluvan engine.

[skittleslegend]

from fgcoupe.com:

LSD and Tranny




Please note Speed Sensor in a different position than other Hondas
The 05-06 RSX-S and 06 Si transmissions run a countershaft driven speed sensor vs. a ring gear.

[Optimus Prime]

So what tuning issues arise do to the car having a MAF? Obviously there are less engine management choices as compared to MAP based Hondas. Also turbo kit development is more difficult with a MAF.

[boostedg35]

i am also down for a manifold.. what company would make one? we should contact someone.. i know a guy who makes plenum spacers for the g35/350 if you guys want ill ask him to look into it..

[Janizary]

Someone crawl under the car and get a pic of the oil filter location...

I just went under there this weekend, and what a PITA to get to the filter. Cripes, you almost could not put it in a harder to get to location. Dammit, I am not a gecko, monkey, rubber squid with 5 arm joints...and that's just about what you need to be to get to that damn filter. rrr.

[skittleslegend]

Originally Posted by Optimus Prime

So what tuning issues arise do to the car having a MAF? Obviously there are less engine management choices as compared to MAP based Hondas. Also turbo kit development is more difficult with a MAF.

The MAF actually works better with more air coming into it. Basically, it reads more accurately than other sensors, by sending air flow data to the engine so it can use a more balanced A/F ratio for combustion. To my understanding, the biggest problem with tuning won't be the MAF. It'll be the DBW throttle.

[Optimus Prime]

Originally Posted by skittleslegend

The MAF actually works better with more air coming into it. Basically, it reads more accurately than other sensors, by sending air flow data to the engine so it can use a more balanced A/F ratio for combustion. To my understanding, the biggest problem with tuning won't be the MAF. It'll be the DBW throttle.

No, DBW throttle isn't that much of an issue. Most tuners will allow the stock ECU to control the DBW cable, and interface it with another engine management, although with cars like the Subaru STi, that has DBW, they have chip systems, like Hondata, that will adjust all the necessary settings on the stock ecu (products like EcuTek and Cobb AccessPort).

MAF is a big problem because (well this is more pronounced in a turbo car) if the air turbulence is greater than stock, you will get incorrect readings. This is why on an STi, only two aftermarket intakes work. The AEM and others tend to create turbulence around the MAF and it gets incorrect readings. The big problem will be when turboing the car. The distance between the MAF and the throttle body will matter, then if you need bigger injectors, you will need to scale them in the ECU, or get a larger diameter MAF housing to adjust for the bigger injectors. Also with turbos, you now can't have a Blow Off Valve that vents to the atmosphere as you will cause the car to run rich by blowing out air that has already been metered. Of course then you can try and design a blow through MAF setup, but that takes some time and a good engine management setup.

The thing in the past that made tuning a Honda so fun was the lack of the MAF, now things will be difficult, unless Hondata comes out with something real slick.

[skittleslegend]

Originally Posted by Optimus Prime

No, DBW throttle isn't that much of an issue. Most tuners will allow the stock ECU to control the DBW cable, and interface it with another engine management, although with cars like the Subaru STi, that has DBW, they have chip systems, like Hondata, that will adjust all the necessary settings on the stock ecu (products like EcuTek and Cobb AccessPort).

MAF is a big problem because (well this is more pronounced in a turbo car) if the air turbulence is greater than stock, you will get incorrect readings. This is why on an STi, only two aftermarket intakes work. The AEM and others tend to create turbulence around the MAF and it gets incorrect readings. The big problem will be when turboing the car. The distance between the MAF and the throttle body will matter, then if you need bigger injectors, you will need to scale them in the ECU, or get a larger diameter MAF housing to adjust for the bigger injectors. Also with turbos, you now can't have a Blow Off Valve that vents to the atmosphere as you will cause the car to run rich by blowing out air that has already been metered. Of course then you can try and design a blow through MAF setup, but that takes some time and a good engine management setup.

The thing in the past that made tuning a Honda so fun was the lack of the MAF, now things will be difficult, unless Hondata comes out with something real slick.

Ah, thanks. It was kinda of confusing. It seems less so of a problem for S/C the car than it is for turboing. But most of the turbo/S/C kits I've seen for different cars with MAF sensors, like VR6's, come with larger MAF housings. I've seen the design of a MAF plug. It's interesting how they divert airflow over the sensor. But it makes sense that a BOV (that releases to the atmosphere not back into the system) would cause the MAF to run rich.

So with the DBW on the STi's and BMW's does the chip actually increase throttle sensitivity? That seems to be a problem with the Si, is it's lack of sensitivity during spirited driving. I know the lag was a tad annoying. I've heard people getting annoyed about the artifical way the revs hang but I thought it was a good thing. It allowed me to enter a corner at a high rev and maintain VTEC all the way through so I could exit faster.

[Optimus Prime]

Originally Posted by skittleslegend

Ah, thanks. It was kinda of confusing. It seems less so of a problem for S/C the car than it is for turboing. But most of the turbo/S/C kits I've seen for different cars with MAF sensors, like VR6's, come with larger MAF housings. I've seen the design of a MAF plug. It's interesting how they divert airflow over the sensor. But it makes sense that a BOV (that releases to the atmosphere not back into the system) would cause the MAF to run rich.

So with the DBW on the STi's and BMW's does the chip actually increase throttle sensitivity? That seems to be a problem with the Si, is it's lack of sensitivity during spirited driving. I know the lag was a tad annoying. I've heard people getting annoyed about the artifical way the revs hang but I thought it was a good thing. It allowed me to enter a corner at a high rev and maintain VTEC all the way through so I could exit faster.

I've seen people on here ask about the DBW lag, and to be honest, it is no issue with the STi and most likely you are feeling turbo lag. What the DBW program on the STI does is tend to make the pedal more sensitive, meeting if you stab it at half throttle, the car thinks you were going for full and pulls the cable more than you expected, so it is actually overly sensitive. Some after market ECUs for the STi (the Hydra) have a DBW function that is more linear...kind of making your pedal feel analog, like it should.

The big thing that concerns me about MAF based setups is passing OBDII emissions. Without the MAF, you could throw anything at the car and as long as it passed the sniffer test, you were fine. Now if you remove your MAF and go for OBDII, you will fail. Although, many companies have made some strides in Engine Management to address this.

On thing though, who ever makes the first turbo kit needs to make it use a blow-through MAF (MAF sensor on the pipe between the intercooler and the throttle body).

[Dale_K]

Why do they use an aluminum intake manifold? Seems like it would be lighter and cheaper to go with plastic. I mean it's not like it's under pressure or anything.

[skittleslegend]

Someone needs to sticky this thread.

I found this video on fgcoupe of the head teardown and port/polish prep. Right click and save.

http://www.fgcoupe.com/video/diy/2006Head.zip

For custom work check out Jpax @ JP Tuning Parts. You can find him at ephatch.com

[FigiSi06]

very interesting stuff. Thanks

[skittleslegend]

Originally Posted by Dale_K

Why do they use an aluminum intake manifold? Seems like it would be lighter and cheaper to go with plastic. I mean it's not like it's under pressure or anything.

higher underhood temps could melt the plastic. I'm guessing they went aluminum because it's lighter than steel and more durable than cast iron.

[Gone]

From what I understand, the MAF sensor is not much of a problem, its the MAP sensor (Manifold Absolute Pressure). The MAF has beek cracked, but the MAP hasn't and without both, fuel curves can't be adjusted much, if at all. I'm sure Hondata will have this figured out in a week or two.

[Optimus Prime]

Originally Posted by Gone

From what I understand, the MAF sensor is not much of a problem, its the MAP sensor (Manifold Absolute Pressure). The MAF has beek cracked, but the MAP hasn't and without both, fuel curves can't be adjusted much, if at all. I'm sure Hondata will have this figured out in a week or two.

I'm not saying you're wrong, but Honda's have always had MAP sensors, I think the new Civic is the first Honda to use MAF, so I could see that being an issue.

[Gone]

Originally Posted by Optimus Prime

I'm not saying you're wrong, but Honda's have always had MAP sensors, I think the new Civic is the first Honda to use MAF, so I could see that being an issue.

The 2006 Si is the first Honda to have a MAF and Acura used MAP's on the RSX's in the past. I don't think that the MAP and MAF sensors were integrated into the ECU programming together before though. This use of both together supposedly gives a more accurate reading of air flow and engine load.

Even so, that doesn't mean that the MAP and MAF use the same control schemes as previous K20 engines. Generally, it can be said that the K20Z3 is just a derivative of the K20A's in the RSX's, but when you get down into them, they are pretty damn different. The '06 Si doesn't just reuse a reflashed version of the RSX Type-S ECU. This is a brand new unit, probably to keep a tighter leash on emissions.

Edit: S2K's use MAF sensors (MAF's are more accurate than MAP's)

[leviathan18]

everyone is doing R&D for the k20z3 but not for the r18

[skittleslegend]

Originally Posted by leviathan18

everyone is doing R&D for the k20z3 but not for the r18

I'm trying to find information for you guys that have the R18, but it's scarce at best. I haven't found any pictures or anybody who's actually torn into the block yet, mostly because of its header design (or lack thereof) and the presence of the K20z3. It's going to take time, IF that. People may not even delve into that block, at least not until the K20z3 hype dies down. You may find one or two companies willing to make products for it, but the demand for it won't be high, that much I can guarantee.

As far as MAF sensors go, whenever I've seen a turbo kit for GTI's and such, the kit came with a MAF tunnel that was wider to accomodate the increased airflow. The MAF itself adjusts to the increase in air to determine the A/F, but like Gone said, I believe it's a combination of the MAF and MAP that seems to be the problem. Hondata is trying to crack it, and for the most part they have, but the Si's ECU is completely different from any of the other K-series ECU's. As I've shown the engine is not exactly the same as the RSX-S's. I think it's a bit of a compromise between the RSX-S and the TSX's. It uses a K24a2 head with the water port. There are some similarities, like cams and such and those are inter-swappable, but other things, like the clutch are slightly different.

[leviathan18]

we have to motivate the companies to research on the R18 if you have the luck to talk with any company tell them there is base of ppl wanting partos for their ex coupes not everybody has an si

[CameronJr9]

Originally Posted by leviathan18

we have to motivate the companies to research on the R18 if you have the luck to talk with any company tell them there is base of ppl wanting partos for their ex coupes not everybody has an si

As far as the Civics are concerned, aren't there MORE r18s than k20z3s? All models except the Si use the same engine. Surely there's someone out there trying to create something. Maybe we should write a letter to our congress person.