Speculation & Theory: Will a 45 VTC advance with short header make gains?
#1
Speculation & Theory: Will a 45 VTC advance with short header make gains?
I've been contemplating this for some time now. While it's well-known that a modded VTC with a race header will make unbelievable gains as proved by Shaang's dyno tests at Church, what about a VTC + short header?
Due to my "career needs" to keep my car stock-sounding/looking as possible, I'm not willing to have a loud exhaust note. I'm sure I'm not alone on this dillema. Therefore, my compromise to my never-ending quest of adding more power to the k24 has two options:
1. Keep shorty header
2. Change to Toda or Hytech header with added resonators
Option #2 will still cost over $2500 untuned. So, I'm wondering if I could "hypothetically" tune my setup with:
1. Comptech short header
2. Injen CAI
3. 45 VTC
For those who aren't familiar with the subject of cam advance, here's a little blurb from Hondata's website:
So, do you guys think 45 degrees will make significant gains over the stock 25 degrees? Keep in mind that the stock RSX-S already comes with a VTC that can advance to 50.
rmpage usually has the most elaborate posts on the subject of cam advance.
Due to my "career needs" to keep my car stock-sounding/looking as possible, I'm not willing to have a loud exhaust note. I'm sure I'm not alone on this dillema. Therefore, my compromise to my never-ending quest of adding more power to the k24 has two options:
1. Keep shorty header
2. Change to Toda or Hytech header with added resonators
Option #2 will still cost over $2500 untuned. So, I'm wondering if I could "hypothetically" tune my setup with:
1. Comptech short header
2. Injen CAI
3. 45 VTC
For those who aren't familiar with the subject of cam advance, here's a little blurb from Hondata's website:
The biggest gift Honda has given to tuners of the K series engine is the VTC mechanism. Located on the end of the intake camshaft the VTC mechanism, via hydraulics allows 25 [crank] degrees of continuous movement on the TSX and 50 degrees on the RSX. For all you old school tuners lurking out there still changing the jets on your carburetors, who think you have to junk the VTC mechanism and go with a good old fashioned cam timing wheel, think again. In every naturally aspirated engine K20a and K24 engine we have tuned, the intake cam needs to be rotated through 25-30 degrees between peak torque and peak power. For emissions, the ability for Honda to rotate the cam to zero at idle to dial out all overlap makes for a very clean engine with no need for EGR. EGR porting is on place on the head but is blocked off.
25 degrees of cam movement is fine for a stock TSX engine but completely inadequate for modified engine with as little as race headers and intake. A stock engine needs no more than 20 degrees of cam moment on the high cam. A well modified setup needs no less than 25 degrees on the high cam. Take a good look at the modifications we made to the VTC mechanism. If you have a TSX you are going to need these changes. Although you could probably purchase and bolt on an RSX VTC mechanism for 50 degrees travel, there is less valve to piston clearance on the TSX pistons. Our measurements suggest 45 degrees maximum cam movement is much safer. Allowing the full 50 degrees movement leads to a greater risk of valve to piston contact should you accidentally mis-shift and over-rev.
25 degrees of cam movement is fine for a stock TSX engine but completely inadequate for modified engine with as little as race headers and intake. A stock engine needs no more than 20 degrees of cam moment on the high cam. A well modified setup needs no less than 25 degrees on the high cam. Take a good look at the modifications we made to the VTC mechanism. If you have a TSX you are going to need these changes. Although you could probably purchase and bolt on an RSX VTC mechanism for 50 degrees travel, there is less valve to piston clearance on the TSX pistons. Our measurements suggest 45 degrees maximum cam movement is much safer. Allowing the full 50 degrees movement leads to a greater risk of valve to piston contact should you accidentally mis-shift and over-rev.
So, do you guys think 45 degrees will make significant gains over the stock 25 degrees? Keep in mind that the stock RSX-S already comes with a VTC that can advance to 50.
rmpage usually has the most elaborate posts on the subject of cam advance.
#2
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That's a good question... In my opinion, gains will be very minimal without longer runners on the header. Run it by Doug @ Hondata and he'll definately have an answer for you.
#3
Drives With Hands
![Agree](https://acurazine.com/forums/images/smilies/agree.gif)
LT headers and valve overlap are like peas and carrots.
Good question though. Doug is defintely equipped to answer regarding the specifics, since he wrote the reflash program to work with a shorty. You could also sniff around the RSX forums and see if anybody ran a shorty with a Kpro'd K24 and screwed around with a tune, then get their cam advance table and see where the advance is needed. That is if you haven't done so already.
#5
Drives With Hands
Anyone who is curious about how scavenging works with overlap and a long tube header may find this article interesting:
http://compcams.com/Community/Articl...?ID=1726205736
The blurb on scavenging is on page three. Also, this article caters to GM LS series V8s but it may give a newfound appreciation for how cool VTC is for somebody tuning a K series engine.
http://compcams.com/Community/Articl...?ID=1726205736
The blurb on scavenging is on page three. Also, this article caters to GM LS series V8s but it may give a newfound appreciation for how cool VTC is for somebody tuning a K series engine.
#6
Originally Posted by chuson
My question is, will the 45 degree VTC work wihtout a K-Pro? If the answer is YES, then we should able to use aftermarket intake/exhaust cam, as long as the size fit ?
rmpage - Thanks for the article.
![Thumbs Up](https://acurazine.com/forums/images/smilies/thumbsup.gif)
#7
Originally Posted by rmpage
You could also sniff around the RSX forums and see if anybody ran a shorty with a Kpro'd K24 and screwed around with a tune, then get their cam advance table and see where the advance is needed. That is if you haven't done so already.
Not really sure what header he was running.
![Shrug](https://acurazine.com/forums/images/smilies/shrug.gif)
Here's the thread:
http://www.k20a.org/forum/showthread.php?t=24586
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#8
T.DoT P.I.M.P. lol
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I've just read the whole thread on the K20a forum, there's a lot of argument in between but this is what I gather...
Hotwheelz... thread starter.... mentioned..
In order for the TSX motor to run the K20 VTC... we need...
1) Aftermarket cams... since the OEM don't like high rpm above 6K+
2) Dual Valve spring... since it will help to avoid piston collison
3) K-Pro? I'm assuming this guy has his car tuned on that dyno.
If the final product we need is K-Pro, and we still don't have it, then it means we won't be able to take advantage of the K20 VTC then??
Hotwheelz... thread starter.... mentioned..
In order for the TSX motor to run the K20 VTC... we need...
1) Aftermarket cams... since the OEM don't like high rpm above 6K+
2) Dual Valve spring... since it will help to avoid piston collison
3) K-Pro? I'm assuming this guy has his car tuned on that dyno.
If the final product we need is K-Pro, and we still don't have it, then it means we won't be able to take advantage of the K20 VTC then??
#9
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Originally Posted by Black_6spd
So far, this was the closest thing I could find to a stock K24A2 changing nothing except swapping a type-S VTC:
![](http://personal.nbnet.nb.ca/tuned/vtctunning.JPG)
Not really sure what header he was running.
When he say "custom 4-2-1," I assume it's a race header.
Here's the thread:
http://www.k20a.org/forum/showthread.php?t=24586
Not really sure what header he was running.
![Shrug](https://acurazine.com/forums/images/smilies/shrug.gif)
Here's the thread:
http://www.k20a.org/forum/showthread.php?t=24586
#12
T.DoT P.I.M.P. lol
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^^^
If that so then you are right... you got me confused too. But how can the K20 VTC has produce less power than the our stock VTC? Since they have K-Pro, they should be benefit from the additional VTC angle? No?
If that so then you are right... you got me confused too. But how can the K20 VTC has produce less power than the our stock VTC? Since they have K-Pro, they should be benefit from the additional VTC angle? No?
#13
Drives With Hands
Better yet, why is he showing off a power loss on a public forum? Yeah, it is confusing.
Also the only things we need for a 45 degree VTC are a new intake cam mechanism and a Kpro. The other valvetrain upgrades are good for when you are running a more aggressive cam profile or raising the rev limit, but I can't see them being necessary just to advance/retard the cam. Maybe he wanted stiffer springs to close the valves faster so they don't kiss a piston at redline with a huge overlap.
Also the only things we need for a 45 degree VTC are a new intake cam mechanism and a Kpro. The other valvetrain upgrades are good for when you are running a more aggressive cam profile or raising the rev limit, but I can't see them being necessary just to advance/retard the cam. Maybe he wanted stiffer springs to close the valves faster so they don't kiss a piston at redline with a huge overlap.
#14
T.DoT P.I.M.P. lol
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^^
That guy is a bit too cocky on the other site, so none of us can get more info from him.
NOOB Question: I know someone might have thought of already, but will it be possible to run a TSX ECU for whatever control we need, and also run a RSX ECU for our engine w/ K-Pro. That way we might not lose the VSA/AC/ABS blah blah blah function????
That guy is a bit too cocky on the other site, so none of us can get more info from him.
NOOB Question: I know someone might have thought of already, but will it be possible to run a TSX ECU for whatever control we need, and also run a RSX ECU for our engine w/ K-Pro. That way we might not lose the VSA/AC/ABS blah blah blah function????
![Roll Eyes](https://acurazine.com/forums/images/smilies/rolleyes.gif)
#15
Originally Posted by chuson
^^^
If that so then you are right... you got me confused too. But how can the K20 VTC has produce less power than the our stock VTC? Since they have K-Pro, they should be benefit from the additional VTC angle? No?
If that so then you are right... you got me confused too. But how can the K20 VTC has produce less power than the our stock VTC? Since they have K-Pro, they should be benefit from the additional VTC angle? No?
the map that was posted used stock TSX basemap, in some area's it wants 30VTC where the machanical limits of the TSX VTC varies 1-2degree's i've seen the actuall TSX cam, go to 28degree on one datalog mostly would stick around 27 degree, your asking about stuff in 2004 I have the old dynochart from 2004, but the motor was new, and the TSX map didn't exist then. a different header was also used. so it's safe to assume pull away a couple hp, where the 30degree angles are, from the additional difference from the documented27 degree to 30 and it's pretty accurate, If you guys really wanted to know I could have locked it at 27 degree's instead of 30. But i wanted to show you guys the difference... so actually if you think about it... the TSX map, would have still been better than stock, because the stock VTC would have locked it sooner, so the results in difference would be greater. for the added 2-3 degrees only on the low cam.
#16
Originally Posted by chuson
NOOB Question: I know someone might have thought of already, but will it be possible to run a TSX ECU for whatever control we need, and also run a RSX ECU for our engine w/ K-Pro. That way we might not lose the VSA/AC/ABS blah blah blah function???? ![Roll Eyes](https://acurazine.com/forums/images/smilies/rolleyes.gif)
![Roll Eyes](https://acurazine.com/forums/images/smilies/rolleyes.gif)
The possible bad news for all the DBW models is the snag Hondata ran into while releasing the S2000 Kpro. The production date was supposed to be this month and has gotten bumped back into July or later.
#17
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^ I am fully prepared to test this if people think it would work (if its compatible with my automatic tranny). If you buy a tsx ECU, KPRO it, and lose the AC, Gauges, and VSA, and then buy another stock ECU to run those functions, do you guys think this would work? If you are pretty sure, then im willing to be the test subject for it.
#19
Drives With Hands
Originally Posted by TodaSi
Hondata Doug has been running that way for a while. He made a harness to work with two ecus....he doesn't offer it to the public though ![ugh](https://acurazine.com/forums/images/smilies/ugh.gif)
![ugh](https://acurazine.com/forums/images/smilies/ugh.gif)
Originally Posted by crazybaboon6000
^ I am fully prepared to test this if people think it would work (if its compatible with my automatic tranny). If you buy a tsx ECU, KPRO it, and lose the AC, Gauges, and VSA, and then buy another stock ECU to run those functions, do you guys think this would work? If you are pretty sure, then im willing to be the test subject for it.
#24
^^ While I don't understand it, it looks like you can maintain some of the immobilizer functionality:
http://www.hondata.com/immobilizer.html
As far as additional/replacement parts goes, be prepared for a laundry list of other items such as speedo sensor and O2 sensor that will have to be swapped out for our version.
http://www.hondata.com/immobilizer.html
As far as additional/replacement parts goes, be prepared for a laundry list of other items such as speedo sensor and O2 sensor that will have to be swapped out for our version.
#25
For starters:
In addition to these, I wonder if our VSA system would be dumped due to no feedback from the RSX-S ecu. Throttle input doesn't care if it thinks your wheels are slipping or not.
I guess the possible good news for me is that I already have the RSX-S tranny and the speedo gear will spin at the same speed.
The primary oxygen sensor from the 02-04 RSX or 02-05 Civic Si part number 36531-PRB-A01 must be used. The 03-06 Element O2 sensor will not work.
OBD2 must be disabled to eliminate errors generated by the ECU looking for emissions items that the 03-06 Element does not have.
The speed sensor spins about 100 times faster on the Element MT gearbox as compared to the 02-04 RSX. Above 65-70 MPH cruise control may not function smoothly and may cancel from time to time. Also see Tech - K20 Transmissions
Hondata makes hardware modifications to a donor 2002-2004 K series ECU (see below) to enable it to work with the different sensors and actuators found on the 2003-2006 Element. After these modifications the ECU will not function correctly on a 2002-2004 RSX.
OBD2 must be disabled to eliminate errors generated by the ECU looking for emissions items that the 03-06 Element does not have.
The speed sensor spins about 100 times faster on the Element MT gearbox as compared to the 02-04 RSX. Above 65-70 MPH cruise control may not function smoothly and may cancel from time to time. Also see Tech - K20 Transmissions
Hondata makes hardware modifications to a donor 2002-2004 K series ECU (see below) to enable it to work with the different sensors and actuators found on the 2003-2006 Element. After these modifications the ECU will not function correctly on a 2002-2004 RSX.
I guess the possible good news for me is that I already have the RSX-S tranny and the speedo gear will spin at the same speed.
#26
Senior Moderator
iTrader: (2)
Originally Posted by Black_6spd
^^ While I don't understand it, it looks like you can maintain some of the immobilizer functionality:
http://www.hondata.com/immobilizer.html
http://www.hondata.com/immobilizer.html
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