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Old 02-01-2003, 11:05 PM   #1 (permalink)
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Originally Posted by Originally posted by acatak
Hey Mike,
I just put in my ITR cams and skunk 2 cam gears. I was gonna tune them on my own for now becasue im not goning to go dyno my car until im done modding it. What id a good way to tune them myself? Also, should i advance intake and retard exhaust? I want to knock off the most time on my 1/4 mile so im sure top end is better.
Also, I have I/H/E also right now. What do you think would be a good next performance mod. I dont want to do any more internal work. SO i was thinking car, FPR, or VAFC. Thanks for your help






preliminary readings:

"What is a powerband?" thread












To shift or move the powerband up higher along the rpm range (for 1/4 mile et. improvement), you need to increase the overlap.

You do this by tightening the lobe separation angle (LSA) between the intake cam's and exhaust cam's lobe centers with your aftermarket adjustable cam gears . When you tighten the LSA, you increase cam overlap duration.




If you want a higher powerband location, you tighten the LSA by rotating the intake and exhaust cam gears in opposite directions from one another in steady precise increments. The trick is to find the best overlap for your particular engine's package of parts and unique way of breathing compared to everyone else's.







EFFECT OF TIGHTENING THE LSA WITH ADJUSTABLE CAM GEARS






Quote:
FIGURE LEGEND

Hp and Torque Curves with

Dots = Tighter LSA

Without Dots = Wider LSA













Wider lobe separation angle (no dots) produces more midrange torque but with a loss of upper rpm and peak torque.

Narrower lobe separation angle (with dots) produces more high rpm range and peak torque but with a loss of midrange.

Less LSA increases intake and exhaust valve opening overlap which creates more scavenging and a stronger upper rpm powerband.

Less LSA [or more intake and exhaust cams overlap] is better for a racing engine than a high performance street engine. The idle suffers as you add more overlap since there's not enough vacuum at idle rpm.




SUMMARY OF THE EFFECTS OF TIGHTENING LSA



1. Moves Peak Torque to Higher RPM

2. Increases Maximum Torque

3. Narrows Powerband

4. Builds Higher Cylinder Pressure

5. Increase Chance of Engine Knock

6. Increase Cranking Compression and Effective Compression

7. Idle Vacuum is Reduced and Idle Quality Suffers

8. Open Valve-Overlap Increases

9. Closed Valve-Overlap Increases

10. Decreases Piston-to-Valve Clearance



Obviously, widening the LSA (decreasing overlap) does the opposite to these.


Aftermarket Cam Gears: What To Look For When You Shop

Stock cam gears cannot be adjusted. You must purchase aftermarket adjustable cam gears. Good ones are:

1. light so that they don't add valvetrain mass (anodized billet aluminum)

2. have good cam gear bolts to hold down the cam gears to prevent them from slipping after you've torqued them down (usually these have more than 3 bolts but there's a balance between having too many bolts so that it becomes an inconvenience during tuning and not enough to prevent slipping. I'll put up with inconvenience since slip prevention is a priority.). The cam gear should be rigid or surface-hardened enough to prevent the bolt from sinking into the cam gear surface.

3. have etched-on, clearly readable, easy to understand, highly accurate markings. Painted on markings are easily worn off. if the 0 degree mark is not TDC what good is the cam gear? Some cam gears makers have not double-checked (quality control) their TDC markings against the stock TDC marks and degree the cams after their cam gears have been installed to see if the 0 mark is truly TDC, so be cautious on install and check.





Have you checked to make sure that INTAKE 0 degree and EXHAUST 0 degree markings on those cam gears were indeed set at TDC?


on a tuning session on the street or at the strip, I suggest that you do the cam gear tuning by going with a friend in the passenger seat with a stopwatch, if you don't have a datalogger that records speed and elapsed time. Do some wide open throttle acceleration runs at the 1/4 mile strip on a test & tune day.

The point here is that , for each cam gear setting, do your timing over the exact same stretch of road and over the same exact distance. Have your friend time how long it takes you to go from say 30 mph to 90 mph. Do 2 runs for every setting. You want an objective measure ,like an acceleration time, to tell you if the setting is good for your particular engine. Acceration is the change in speed over the change in time. You want a higher number if the cam gear setting is good. A change of 1 tenth of a second or more consistently is good.

Don't rely on the butt dyno. It's only sensitive to changes in the early part of the rpm range.

DO NOT COPYCAT SOMEoNE ELSE'S CAM GEAR SETTING

Each person's engine will have a different optimal cam gear setting for it. Just because someone has the exact same model Integra and parts as you, does not necessarily mean that their engine and yours behave identically. Variations in performance can occur simply from minor differences in assembly at the factory, engine break-in procedures (if any) by the owner, and owner maintenance.


I would go 2 camshaft degrees at a time starting with the intake cam, since it also determines the reference baseline ignition timing as well (connected to the distributor) . Do 2 runs per setting over the same track distance.

When you stop seeing an improvement in the elapsed time in between your 2 set mph points, then go back to the best setting.


As for the "next best part" for your engine, I really don't think along those lines. I choose my powerband location and power goals first, and get parts that have designs or specs that will fascilitate getting those 2 goals.

Sometimes you have to do some math to get the exact specs for these but in general, high powerbands like single stage IM's and 4-1 headers with big diameter primaries & collector , for instance.

If you don't have a VTEC controller, you'll definitely need one, since the ITR cams will want a higher VTEC point, higher VTEC fuel table starting point, and different fuel tables than your stock GSR VTEC point and fuel tables.

I think we've covered quite a bit about FPR's before and when to get them and so, those threads can be easily found on a search. You can't richen the fuel delivery using a VTEC controller at full throttle and so, you'll need an FPR to richen and use the controller to lean down in the rpms that become overly rich after the FPR has been set.


DoN'T FORGET TO RESET YOUR IGNITIoN TIMING BACK TO YOUR INITIAL SETTING USING AN IGNITIoN TIMING LIGHT AFTER THE INTAKE CAM GEAR HAS BEEN CHANGED AND YOU ARE DoNE CAM GEAR TUNING.


WARNING: If you advance the intake cam gear and retard the exhaust cam gear too far, you risk piston to valve contact. Remember 1 cam gear degree = 2 crankshaft degrees and so you exceed 8-10 cam gear degree change at your own peril, unless you have precisely degreed your cams and know exactly how many degrees max. advance/retard you have to play with.

good luck with your modding.

cheers


related readings:

Dyno Tuning Basics Article
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Old 08-22-2004, 11:58 PM   #2 (permalink)
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HOW TO ADJUST 2 PIECE CAM GEARS WITH VERNIER TYPE DEGREE MARKINGS (EG. TODA, SPOoN)

Some cam gears use the Vernier scale system instead of the usual markings.

Quote:
Originally Posted by from Toda Racing
Since vernier type graduations are used, adjustment can be carried to 1 deg of the crank angle (0.5 deg of the cam angle) in order to achieve maximum results with super accuracy.














Cam gears with Vernier Scale at TDC



A closer look at TDC marks lined up (confirm & check by degreeing the cams). :



It's a good thing to degree your cams anyway to determine how much advance you have exactly before it gets "close" to piston to valve contact. Leave room or a margin for error due to heat expansion with metals.
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Old 06-03-2007, 09:24 AM   #3 (permalink)
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I got Skumk2. I haven't installed yet . Did you guys know the degree that I need to gain some hp. My car is non-vetc.
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Old 08-01-2007, 07:12 AM   #4 (permalink)
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Damn i was about to ask that too lol. But i'm wondering if i should actually widen my LSA a little since my b18b is does not have anything bolt on yet. And i'm just getting my cam gears for turbo in the future.

Any recommended setting for a STOCK b18b that is suitable for daily drive?
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Old 08-01-2007, 08:52 AM   #5 (permalink)
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Thought I would add some other good reading:

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Old 08-02-2007, 02:08 AM   #6 (permalink)
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Quote:
Originally Posted by codenamezero on Aug/01/07
Damn i was about to ask that too lol. But i'm wondering if i should actually widen my LSA a little since my b18b is does not have anything bolt on yet. And i'm just getting my cam gears for turbo in the future.

Any recommended setting for a STOCK b18b that is suitable for daily drive?
Honestly...I wouldn't waste your money on cam gears if you don't have ANY mods to the engine. Cam gears are TRULY a TUNING tool. They help you dial in the powerband when tuning the car. Advancing/Retarding the cam timing helps you manipulate the cylinder pressures of the engine and thus manipulate the powerband.

For a stock engine w/ stock cams, etc.; Cam Gears = Waste of Money. That money could be better spent elsewhere.
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Old 08-02-2007, 02:32 AM   #7 (permalink)
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Talk about back from the dead. But, cam gears are not a cost effective mod for people with basic bolt ons. You dont need them unless you actually need to adjust cam timing.
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Old 08-02-2007, 07:52 AM   #8 (permalink)
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well, changing timing belt and cam seals, may as well put it on and save labor.
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Old 04-09-2009, 02:21 AM   #9 (permalink)
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Quote:
Originally Posted by C_Rock77 on Aug/02/07
Quote: codenamezero on Aug/01/07Damn i was about to ask that too lol. But i'm wondering if i should actually widen my LSA a little since my b18b is does not have anything bolt on yet. And i'm just getting my cam gears for turbo in the future.
Any recommended setting for a STOCK b18b that is suitable for daily drive?


Honestly...I wouldn't waste your money on cam gears if you don't have ANY mods to the engine. Cam gears are TRULY a TUNING tool. They help you dial in the powerband when tuning the car. Advancing/Retarding the cam timing helps you manipulate the cylinder pressures of the engine and thus manipulate the powerband.

For a stock engine w/ stock cams, etc.; Cam Gears = Waste of Money. That money could be better spent elsewhere.
While true, there are easier ponies to be found/released.....I do recall a Import Tuner or Honda Tuning or Super Street or who the fuckever article about cams and adj. cam gears w/ them stating that Skunk2 cam gears were actually lighter than the OEM's and that alone would lighten up parasitic drag.

How much lighter? How much drag reduced? Probably not enough to suffice the price Skunk2/Spoon/Toda want for the fucking things, but when you're trying to squeeze every last pony out of a motor, they're on the list.

You could chalk them up with pulleys and such.
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Old 06-08-2010, 09:29 PM   #10 (permalink)
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what this i hear about messing with the cams on doing a b20/vtec build? i hear everwhere they have timing issues?
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Old 06-13-2010, 08:53 PM   #11 (permalink)
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anybody?
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Old 07-02-2011, 12:39 PM   #12 (permalink)
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Just reading in the article that increasing the overlap gives more peak torque and puts the torque curve higher. The latter is true but in my research I find that increasing the overlap period or tightening the LSA reduces overall torque in the engine but prolongs the "level" of torque for longer in the RPM range allowing your horsepower numbers to rack up.

But I do have one question......can one have too much overlap. I am going to road tune using a NEO and have toda gears and toda spec A cams. What would be a good base to start from. Motor is a B18C1 JDM, peaks torque at 6412rpm but drops off kinda fast thereafter, BHP is a good 211
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Old 07-02-2011, 04:11 PM   #13 (permalink)
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really cam gears that are on a build engines should be set when putting the engine together and not messed with after that in less you know how much room you have with valve to piston.alot of tuners go right in there and start messing with cam gears and don't even know how far they can go.cams that are aftermarket and cam gears to go with them should be set at peak point so the top end and bottom end are doing everything at the same time to get peak HP out of the cams and overall built engine.

cam gears are a waste if your engine is stock.
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