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Discussion Starter · #1 ·
I was just thinking as I do..
Is VTC the right path for performance motors?
sure you get good power below 5000rpm, maybe its god for a daily driver but personally I believe thats where it ends. as I'm sure alot of people wonder.

Take the top B-series cams imagine having 25 degrees of adjustment avaliable on the intake cam. imagine a skunk2 stage 3 with that much adjustment. surely there is more potential in the K-series by getting rid of the VTC and having a cam with 10 degree's max adjustment or less.. isnt that where the power is. Don't most High Hp motors have a limited clearance?

Personally I think we will slowly see a range of cams developed with out VTC compatability. 25 degrees means a huge clearance range for the vavles to have. surely there is more to be gained by reducing the clearances? Maybe I'm wrong completely, everyone has an opinion.

I can say I have spent alot of time looking at Cam timing plots and even the ones companies supply with there K-Pro calibnrations. peak power is made around the cam being at 20-25VTC so thats retarded 2.5-0 degrees in real cam timing. So why have VTC? Also I have heard tht in some cases of VTC pulleys spiking, are these companies standing by there products no matter what. so if you get a spike from 45 to 50 VTC timing and you smash the vavles are they covered. I bet not.....

anyway let me know your thoughts.
 

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Gary, are you running any cam angle advance? I do not know anything about the links ecu you are running. With k-pro, you can run 0,10,20,30,40,50 degree cam angle maps. And yes, bigger cams require less cam advance. The dyno will prove this point. I think that you are better off experimenting with cam advance versus not running any at all. Of course, you need to clay for clearances. When I had my IPS K2's tuned, my tuner started from scratch. Once he tunes one particular cam angle, he is able copy and paste the parameters into the other cam angle maps. To give you an example, with the 10degree map, we made 180whp with only adjusting the a/f(13.0:1). Then he copied and pasted the values into the 20degree map and made a pull. 202whp instantly! That is in back-to-back pulls with no tuning. VTC is God's gift to tuners.
 

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Discussion Starter · #3 ·
yeah I dont run VTC. Honestly I dont have the clearance in my motor to really adjust from where I am. SO do you ever run below 20 degrees?? because if you have bigger cams then surely you woulnt be able to adjust the cam angles further foward. I know the K2's EDO recommends not advancing past 45.
I just think about the top B-series motors if you could have 20 degree of cam timing that would be insane. surely by having the clearance to run 10 degrees of actual cam advance or 45 VTC angle you will be loosing some of the potential CR if you need an extra 1-2mm of piston to vavle clearance just so at 5500rpm you can advance the cam.

Plus people are starting to question the time the VTC takes to adjust, the fact that sometimes it spikes. when your talking 0.02 clearance a VTC spike would see the vavles die. Personally I see VTC being removed from alot of top N/A motors.

I've never had VTC on my motor and honestly before I got my ITB's and when i ran an RSX header the power was still comparable to a K-pro'd DC5R
 

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I got away with 45degrees cam advance with a Toda headgasket! I agree that top N/A dragsters will not be running VTC. But it is an incredible asset for the street. Being at the strip, you're only concerned with the power about 6500rpms anyways. I know that shifting at 9k with my old Toda N2's, I would land generously in the 6700-6800rpm range. With bigger cams comes the less need for cam advance. Yes, clearances will dictate that, but you will also see that the cam will not like the advance anyways. I am really interested in your exhaust cam gear. Can you give me a little more information on it? Did it make a difference? How hard to tune?
 

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Discussion Starter · #5 ·
apart from the fact of having to lift the cover off to get to adjusting it, adjusting it was easy. Honestly mine is on the zero mark or close to it.. within 2 degrees. I think it ended up being about 2-3 degrees different from the factorty gear I cant remember which way... as for the difference I would be guessing but id say it was 10whp. I know the Hondata guys have some info on it.. if they give it to you thats another question..
I noticed you said you made 22hp by adjusting the VTC from 10 to 20..
when i installed my VTC killers the VTC had been on 0 or resting and we gained about 35-40whp at 6000rpm.
Honestly I'm just happy cause without VTC timing tuning the car is quick and easy. That and everytime my car hits the dyno it makes power..
 

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did you have to install the VTC killer to run the LINK ECU? Also, could you post a link where i can find more information about the LINK ECU. thanks.
 

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Discussion Starter · #7 ·
Info on the link ECU can be found on www.link-electro.co.nz there is a link to there USA site on there. We had the car running with out the VTC. the VTC kller gears were to make up for the software issues. But now they have proven invaluable to us in dialing such a big cam into our motor.
I beleive Link is releasing a new software system which will be along the lines of Motec, just cheaper, faster and with a few new features... it has been succesfully trialed on a couple of top cars including a 800+whp 4wd Pikes Peak styled hill climb car..
 

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Excuse my ignorance, but this talk of "real advance" brings up a simple question:
On a stock K20A2, with VTC set at 0, what is the real angle when lift starts on the inlet valve.(assuming VTC can be adjusted from 0-50deg). Also, on stock cams, when does the exhaust valve start to lift (0.050") Thanks!
 
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