Page 1 of 2 12 LastLast
Results 1 to 20 of 39

Thread: Cam Gear Tuning and Theory

  1. #1

    Cam Gear Tuning and Theory

    Can anyone do a write up about cam gear settings? Thanks.
    www.muellerized.com<br />www.roadraceengineering.com

  2. #2

    Re: Cam gears

    A multi-volume library could be written about cam timing, and several are available if you would like to purchase some...

    Without getting into extremely boring engineering equations, which have limited practicality anyway, here are the basics as they apply to the 4G63 DOHC setup and the commonly used types of cams:

    There are basically 2 reasons to mess with cam timing, one being to move the powerband around to match the mods in an effort to maximize the usable powerband, and the other is to "fix" cams that are a poor match for the mods in the first place.

    Next, there are 2 basic concepts related to cam timing, which are the relationship of the cam to the crank, and the relationship of the cams to each other since we have a twin cam motor.

    The relationship of the cams to each other are commonly referred to as "overlap", and the relationship of the cam timing to the crank timing is referred to as "lobe center".

    Here is an excellent write-up, which I won't bother to recreate since it covers what is important: http://www.starracing.com/Cam%20Lobe...0Explained.htm

    So, back to EVO specific stuff...

    Do you have crappy cams, or do you have good cams? If you have crappy cams, cam timing will be very important since you need to correct for a poor cam design. If you have good cams, you can use the stock cam gears...

    If you have good cams but want to move the powerband around a bit, here are some rules of thumb.

    -Retarding both cams will move the powerband up a few hundred RPM. On the EVO with the HKS 272 cams, a popular setup is to use 2 degrees retarded for both cams. Since both cams are moved evenly, the overlap doesn't change, only the lobe centers change, causing the valves to open and close later. In this case, the cams spin half as fast as the crank, so 2 degrees at the cam is 4 degrees at the crank. The crank will be an additional 4 degrees through its rotation before the valves open/close.

    -Advancing the Intake cam, and Retarding the Exhaust cam will open up the overlap a bit. This allows the cylinder to fill sooner due to the intake valve opening sooner, which can sometimes be advantageous in a turbocharged engine.Or, the exhaust cam can be retarded more than the intake cam, as in a -1 -4 setup. Both cams are retarded in this situation, but the exhaust cam is moved more, increasing the overlap. Advancing the intake cam helps to improve the idle quality since the Intake cam has a larger impact on the idle than the Exhaust cam does. If you leave the Intake cam straight up, and retard the exhaust cam a lot, the idle will be lopier, but still much better than if you left the exhaust cam straight up and retarded just the intake cam.

    Ultimately this is one of those cases where a dyno comes in real handy. You move the cams around until you find the right combination. Unfortunately theory only gets you so far, and practice makes perfect...
    All da cars are Nekkid!Â*&nbsp; www.dsmporn.com<br /><br /><br />www.roadraceengineering.com

  3. #3

    Re: Cam gears

    when you say crappy cams do you mean brand or degree? ie HKS vs. someone else or 264 vs. 272 (+)

    i assume you mean cams that dont match the engine application very well, but clarification would be nice
    People do not care how much you know until they know how much you care<br /><br /><br />[quote author=evomrguy link=topic=34096.msg6904129#msg6904129 date=1166072308]<br />Jeezus, this is the kinda thing best left to try on $500 1g t/e/l.&nbsp; If your board pick one up and let the ghetto bull shit mods fly.&nbsp; [/quote]<br /><br />forza ferrari

  4. #4

    Re: Cam gears

    Ultimately the cam profile needs to be appropriate for the setup. If you have to tweak the cam timing just to make it run right, perhaps another cam profile would have been a better choice.
    All da cars are Nekkid!Â*&nbsp; www.dsmporn.com<br /><br /><br />www.roadraceengineering.com

  5. #5
    Community Manager GokuSSJ4's Avatar
    Join Date
    Dec 2003
    Location
    West SIDE
    Posts
    30,682
    Cars
    WW X 11 "RRE special", C6 z06, 2013 outlander sport

    Re: Cam gears

    hmmmm ... would you consider the pipers a poor desing?? Since they do require for you to purchase cam gears and to adjust them in order to get the best results out of the cams.
    ''Yo, a$$G@@! This motherfucka's dead! Ain't no Chris Angel Mind freak, David Blaine trapdoor horseshit jumpin' off here!''

  6. #6

    Re: Cam gears

    Moving the cam timing around to extract that last 5-10HP, and moving the cam timing around to make the low end throttle response not suck so bad are two different things.

    I figure if the manufacturer knows you need to move the cams X amount of degrees to make it run right, they should have just put that into the cam profile from the beginning.
    All da cars are Nekkid!Â*&nbsp; www.dsmporn.com<br /><br /><br />www.roadraceengineering.com

  7. #7

    Re: Cam gears

    this is a hairy subject that i wasn't gonna tackle for some time... but since it's here i'll start compiling info. i'll sort through this crap later i have something to do atm.

    Quote Originally Posted by Ted B
    My 280s set at +2/0 (don't try this without expert tuning) spool as quickly as my 272s did at -3/-3, both configurations reaching full boost by 3500rpm with a TME 16G Ti/Al turbo.

    - However -

    With the 280s I made 30 ft/lbs greater torque than with the 272s, reached peak torque ~200rpm quicker, with no change in boost pressure. This is probably more reflective of the cam timing than the cams, but the point is I definitely didn't lose any torque by going to the 280s, so the notion that one loses torque with the 280s is baseless and is dependent upon tuning accuracy and other factors.

    Despite the advanced cam timing with the 280s, I reached peak power at 6400 rpm, just as I did with the 272s set at -3/-3. The difference is I made 16whp more with the 280s, again with no change in boost pressure.

    Note: This was all done with a Dyno Dynamics dyno, so tack on another 12-15% to those differences for Dynojet numbers.

    I did however install a new IC at the same time as the HKS 280s, so maybe there is some difference there, but from what I've seen, most of the observed difference is due to the cams, the timing thereof, the capability of the tuning hardware, and the skill of the tuner.
    Quote Originally Posted by Ted B
    HKS 272s, set at -3/-3, stock IC and 93 oct (black) vs. -4/-1 setting (red):




    Quote Originally Posted by Ted B
    HKS 280s set at +2/0 with Nisei IC and 93 oct:






    Quote Originally Posted by Ted B
    HKS 280s set at +2/0 with Nisei IC and 93oct + 100% METHANOL






    Quote Originally Posted by Ted B
    The Cossie M2s give a 110 deg LSA, like the HKS cams. However, the LCs for the Cossie cams show that if installed straight up, the Cossies are like HKS cams installed at +1.5 Int / +1.5 Exh. So, if one wanted to run the equivalent of HKS 280s at +2/0, he'd install the Cossie cams at +0.5 / -1.5. If he wanted to run the Cossies at the equivalent of HKS at -3/-1 (more top end), he'd set the Cossies at -4.5/-2.5.

    The nice graph you pointed to at norcalevo.net shows what one gets with the HKS 272s, when set to +1/-1, which is a setting that I always recommend for the HKS 272s for best all-around street performance.Â* In that graph, the longer valve timing of the HKS 272s is what gives the broader hp/tq bands vs. the factory cams.Â* Where cam timing is concerned, the tighter LSA of the +1/-1 setting he used for the HKS 272s vs. the factory cams at 0/0 (106 deg vs. 110) is why the larger HKS cams spooled ~250rpm quicker than the factory cams.

    More hp, more tq, larger power bands and faster spool.Â* It's definitely like having your cake and eating it too.
    Quote Originally Posted by Ted B
    If it were up to me, I would probably (at least initially) set the Cossies to the equivalent of the HKS 272s at +1/-1.Â* For the Cossies, this would be a setting of -0.5/-2.5.

    Quote Originally Posted by Ted B
    For autocross, if the revs will drop to less than 4000rpm anywhere on the course, I wouldn't touch a retarded timing configuration, such as -2/-2.Â* That improves peak power slightly, but at the expense of midrange torque and spool time.

    For 264s and even 272s, I would opt for +1/-1, or possibly even +2/0.Â* The result is quicker spool, fast transient response, and a significant bump in the midrange torque peak.Â* If getting in and out of corners is what you're after, this is what you want.

    this thread is just an exercise to see if you can do the math and visualization. it's got some pretty good info in it.

    http://forums.evolutionm.net/showthr...highlight=cams

    http://forums.evolutionm.net/showthr...highlight=cams


    this is ams's test of the juns vs the hks cams. beware of the aggressive ramp characteristics of such cams.

    http://forums.evolutionm.net/showthr...highlight=cams


    this is a long winded debate about long durations cams

    http://forums.evolutionm.net/showthr...highlight=cams


    here's a way to lose a lot of low end power to gain top end power.

    http://forums.evolutionm.net/showthr...highlight=cams

  8. #8

    Re: Cam gears

    Quote Originally Posted by Ludikraut
    And last, but certainly not least ... cam timing.

    When I first got the car to break it in, the HKS 280 cams were installed straight up (0/0) and spool up was ... well ... less than optimal.Â* The turbo would begin spooling around 3800 rpms, with full boost by maybe 4100, if not later.Â* Needless to say, I wasn't very enthused or amused.

    At this point a HUGE THANKS goes out to AMS, because they spent an inordinate amount of time troubleshooting the slow spool issue and were more than fair in what they charged me for labor.

    Ultimately we finally got a decent baseline tune on the car, which would be Run 038.Â* We did not adjust boost at all between runs, only timing.Â* So, to summarize the runs (SAE correction):

    Run 038: 344 whp, 300 tq - 0/0 - Baseline tune, 2nd worst spoolup, worst topend
    Run 042: 358 whp, 303 tq - -2/-2 - didn't lose spoolup, much better topend
    Run 043: 361 whp, 302 tq - -4/-4 - worst spoolup by far, best topend
    Run 048: 356 whp, 314 tq - +2/+2 - slightly better spoolup, good topend, good torque
    Run 054: 360 whp, 317 tq - +2/0 - Best spoolup, Best Torque, Best topend (just look at the curve)

    I've also attached a second graph, comparing just the torque curves (uncorrected) ... IMO it's easier to see the differences.

    So it looks like Ted B was 100% on the money when he decided on the +2/0 settings for his HKS 280s (running a TME turbo).Â* Even with a bigger turbo (GT3071), there is no appreciable topend to be gained by retarding the HKS 280 cams.Â* The gain in spoolup was significant, to the point where the car now spools up at 3500 rpms and hits full boost before 4000rpms.

    l8r)





    [/img]
    Quote Originally Posted by Ted B
    Good job!

    The cam timing results are interesting, but expected.Â* Given the similarity of results posted sometime previously by another individual, I too am sold on the +2/0 arrangement for the HKS 280s, which seems to work in good harmony with the engine's flow characteristics.

    Those who've been led to believe that cam gears aren't worth the trouble should take note of the extra 16whp, 17 ft lbs, and quicker spool time.

  9. #9

    Re: Cam gears

    Quote Originally Posted by earlyapex

    I don't have comparison charts for the different types of aftermarket cams but I do have this for the difference between stock cams/gears and HKS 272/272 with HKS cam gears and properly tuned for it, no loss anywhere, gains everywhere.

    Look at the curves not the numbers since the ECU+ dyno is 10 HP off the mustang dyno I was on when I made this log

  10. #10

  11. #11

    Re: Cam gears

    where are the pics of the 272 dyno graph -2/0 vs -3-3?

  12. #12
    Community Manager GokuSSJ4's Avatar
    Join Date
    Dec 2003
    Location
    West SIDE
    Posts
    30,682
    Cars
    WW X 11 "RRE special", C6 z06, 2013 outlander sport

    Re: Cam gears

    Quote Originally Posted by leaveit2bevo
    where are the pics of the 272 dyno graph -2/0 vs -3-3?
    search is your friend... wish i could of done a back to back of 272/280 +2 - 2 vs -2 -2 ...
    i want to try +4-2 on what i have or perhaps 280/280
    ''Yo, a$$G@@! This motherfucka's dead! Ain't no Chris Angel Mind freak, David Blaine trapdoor horseshit jumpin' off here!''

  13. #13

    Re: Cam gears

    Whats the advantage of running -3-3? I know a lot of people like them there so there must be some reason.

  14. #14
    Community Manager GokuSSJ4's Avatar
    Join Date
    Dec 2003
    Location
    West SIDE
    Posts
    30,682
    Cars
    WW X 11 "RRE special", C6 z06, 2013 outlander sport

    Re: Cam gears

    Quote Originally Posted by leaveit2bevo
    Whats the advantage of running -3-3? I know a lot of people like them there so there must be some reason.
    your mainly aiming for top end ... while advancing the intake by +2 or +4 will get you bottom end results....
    ''Yo, a$$G@@! This motherfucka's dead! Ain't no Chris Angel Mind freak, David Blaine trapdoor horseshit jumpin' off here!''

  15. #15

    Re: Cam gears

    +4 -2 on 280s is almost a two stroke engine... why do you want your intake valves to make out with your exhaust valves. it also won't idle unless you somehow attatch some cylinder extensions to make it 5 liters.

  16. #16
    Community Manager GokuSSJ4's Avatar
    Join Date
    Dec 2003
    Location
    West SIDE
    Posts
    30,682
    Cars
    WW X 11 "RRE special", C6 z06, 2013 outlander sport

    Re: Cam gears

    Quote Originally Posted by trinyDeX
    +4 -2 on 280s is almost a two stroke engine... why do you want your intake valves to make out with your exhaust valves. it also won't idle unless you somehow attatch some cylinder extensions to make it 5 liters.
    had that set up on the cosworth (i do realize is a different camshafts set up) but a +4 -2 worked wonders ... spool up and tq was beautiful... i also believe others have use a +2 -2 set up on the 280s HKS cams in order not to sacrifice all the midrange on the camshaft set up and not gain just top end
    ''Yo, a$$G@@! This motherfucka's dead! Ain't no Chris Angel Mind freak, David Blaine trapdoor horseshit jumpin' off here!''

  17. #17

    Re: Cam gears

    cams

  18. #18
    Evo Guru
    Join Date
    Jul 2004
    Posts
    6,209
    Cars
    Formely '04 Evo 8 & '10 OBP Evo X - Currently 14 WW MR

    Re: Cam gears

    I'm running (I think -3/-3) right now on my stock turbo with 280 cams and its doing shit for me ... I wish I knew what TTP did with that Evo they tuned so I could try some new cam gear settings .. but it looks like I will try +2/0 at my next oppourtunity + a retune ... and if yields me yet even more shittier results I'll just flash back to my current tune and go back to the recommended -3/-3 ...

    I'm having a ridiculously hard time making good power (numbers and powerband) even after 2 retunes ...
    2014 WW Evo MR ~ Derick 3.0

  19. #19
    Evo Guru
    Join Date
    Jul 2004
    Posts
    6,209
    Cars
    Formely '04 Evo 8 & '10 OBP Evo X - Currently 14 WW MR

    Re: Cam Gear Tuning and Theory

    Its a Stg 1+ with 280 cams instead of 264 or 272's .. Should be knocking on 300whp with a comparable curve ... and its been tuned ... twice ... I really gotta crack my cam gear cover off and see if its slipped a tooth or something- that or try new cam gear settings ... 264whp is just pathetic where as other evo's on that same dyno and similar mods were in the 300+whp range w/ comparable torque ...
    2014 WW Evo MR ~ Derick 3.0

  20. #20
    Canyon Racer
    Join Date
    Apr 2006
    Location
    La Jolla, California, United States
    Posts
    2,173

    Re: Cam Gear Tuning and Theory

    Would it be safe to try the +2/0 cam gear setting on a set of 272i/264e setup? Also how is the idle with this setting??? i currently have mine set at -3/-3 from the Vishnu site (what they recommend on the Stage 1+) and the cams lump pretty good...just wondering...dont get me wrong...i would perfer performance over sound anyday...

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •