Cam Shafts/cam Gears.

[joeleo87]

hey all

im very interested in knowing more about Cam shafts and Cam gears. I know you can some what move the power band in the RPMs by adjusting the Cam gears??? but i got no idea about Cam shafts, What do they do? and how do they befefit your engine? if you buy cam shafts you need to also buy ......

cheers

[r33cruiser]

google man.. basically there are 2 things u need to know (anyone else feel free to chime in i only know enough for my plans).

1st camshaft duration

2nd camshaft lift.

duration depending on its size basically moves the power band further towards the redline.

and lift is important, because the more lift=more air and fuel can get in...this is what gives people a lumpy idle,...hi lift

for u. u can fit 256d, 8.50mm lift (i think off top of head) without ANY mod's they drop in.

but after 8.5mm lift it is recommended to go better springs and a solid lifter conversion.

also u may have to get the head regrinded=clearance issues.

[SLED]

google man.. basically there are 2 things u need to know (anyone else feel free to chime in i only know enough for my plans).

1st camshaft duration

2nd camshaft lift.

duration depending on its size basically moves the power band further towards the redline.

and lift is important, because the more lift=more air and fuel can get in...this is what gives people a lumpy idle,...hi lift

for u. u can fit 256d, 8.50mm lift (i think off top of head) without ANY mod's they drop in.

but after 8.5mm lift it is recommended to go better springs and a solid lifter conversion.

also u may have to get the head regrinded=clearance issues.

Little bit too simplistic of an answer champ, there are many variables when it comes to cam lift & profile.

Other things that play a big role are overlap and ramp speed.

You can have a STD lift cam with a very lump idle if you have a big overlap.

You can even dial some compression out of your cylinders with the right profile.

Joel you would probably find that the STD cams for street use would be fine unless you're spending a few $$$ on other mods.

We need to know what you've done to your motor and what your aiming for to advise correctly.

[tridentt150v]

Cruiser and Sled are right, if you want to understand them a bit better try doing a google/yahoo search on 'What is a camshaft', you should be able to get a better idea.

Cams are a waste of $$$ unless you have the mods to take advantage of them. Have a look at the threads in All duno results RB20 and see who has camshafts and the other mods they list that make the camshafts able to be used. Camshafts on their own will do nothing [and could even make your motor perform worse].

[PSI Parts]

http://auto.howstuffworks.com/camshaft.htm

This is a great explanation for you.

[joeleo87]

Thanks for the feedback guys and the link

[rev210]

The benifits of well matched aftermarket cams and aftermarket ecu are ;

For an old motor:

* Make the same power with : less boost / less timing / less aggressive fuel map / less rpm

For a motor aimed at better performance:

* More power through the entire rpm of the power band

* Extended length of power band, earlier power and power into higher rpm.

You can gain lots out of mild cams on an RB, particularly for a street/response motor.

Any suggestion that they are a waste of money on an RB comes from a lack of experience.

Even on a stocker motor ,you may have stock turbo imposed limits to the 'peak' power number but, the bottom end and mid range gains from cams make the motor night and day different if setup correctly. In most cases 20rwhp or more can be had on all the RB series, through the whole power band.

Cams are very good in terms of an upgrade when done right end of story.

[SLED]

The benifits of well matched aftermarket cams and aftermarket ecu are ;

For an old motor:

* Make the same power with : less boost / less timing / less aggressive fuel map / less rpm

For a motor aimed at better performance:

* More power through the entire rpm of the power band

* Extended length of power band, earlier power and power into higher rpm.

You can gain lots out of mild cams on an RB, particularly for a street/response motor.

Any suggestion that they are a waste of money on an RB comes from a lack of experience.

Even on a stocker motor ,you may have stock turbo imposed limits to the 'peak' power number but, the bottom end and mid range gains from cams make the motor night and day different if setup correctly. In most cases 20rwhp or more can be had on all the RB series, through the whole power band.

Cams are very good in terms of an upgrade when done right end of story.

????? Any lobe profile that holds the valve open longer than a STD lobe will move the power curve further into the rpm and can even narrow the power band which results in less flexibility & response on the street unless you have supporting mods.......not to mention that you take a hit with slightly less compression due to increased overlap.

[rev210]

????? Any lobe profile that holds the valve open longer than a STD lobe will move the power curve further into the rpm and can even narrow the power band which results in less flexibility & response on the street unless you have supporting mods.......not to mention that you take a hit with slightly less compression due to increased overlap.

You assume the standard cams are designed for a wide power band only? Are they optimal for the motor for power?

What about lift? What about the reduction in airflow restriction in the valve opening moment?

Re-think the possibillity of a better designed cam than stock. The only way to make a semi-accurate guess is to plug the data into a cam design program.

I can assure you an off the shelf 256 duration set will lay smack down on stock cams even on a stock turbo. It will bring the turbo on boost sooner and make more average power.

I've had the benifit or having someone run some cam ideas for an RB in the past on a cam program and it accurately predicted a result. The motor was an Rb25 with a stock turbo, it made more down low and everywhere.

I have also demonstrated a 40rwhp gain at as little as 3,000rpm on a standard gtr setup with rather big 260's.

Size the cam right and you get excellent results. On RB's the stock cams are ok but, far from great power wise.

[SLED]

You assume the standard cams are designed for a wide power band only? Are they optimal for the motor for power?

What about lift? What about the reduction in airflow restriction in the valve opening moment?

Re-think the possibillity of a better designed cam than stock. The only way to make a semi-accurate guess is to plug the data into a cam design program.

I can assure you an off the shelf 256 duration set will lay smack down on stock cams even on a stock turbo. It will bring the turbo on boost sooner and make more average power.

I've had the benifit or having someone run some cam ideas for an RB in the past on a cam program and it accurately predicted a result. The motor was an Rb25 with a stock turbo, it made more down low and everywhere.

I have also demonstrated a 40rwhp gain at as little as 3,000rpm on a standard gtr setup with rather big 260's.

Size the cam right and you get excellent results. On RB's the stock cams are ok but, far from great power wise.

If you read what I've said carefully you'll see I was referring to response and flexibility, there's no arguement that increased lift and duration will draw more air and fuel which = more power.

[SLED]

I can assure you an off the shelf 256 duration set will lay smack down on stock cams even on a stock turbo. It will bring the turbo on boost sooner INCORRECT and make more average power CORRECT.

That is assuming all things are even and you're running a stock ECU because a good Motec system can wind lag out of motors with big turbos & cams to a certain degree......but don't forget that's the ECU doing that not the cams.

[Simon-S14]

another thing to take in account of is that stock cams are always going to be sedate things, with emissions, idle quality and low down drive ability to take care of, they are never going to be mass power producers.

[rev210]

That is assuming all things are even and you're running a stock ECU because a good Motec system can wind lag out of motors with big turbos & cams to a certain degree......but don't forget that's the ECU doing that not the cams.

Motec system YO! Yep they are fully sick. They wind lag out of motors and wind up clocks too.

Strange really as I had mistakenly thought that an aftermarket ecu's abillity to add more timing brought boost on earlier and that I thought (also mistakenly) this also had the effect of advancing the intake cam timing therfore increasing the cranking compression.....

You seem to be the expert mate. I've just tuned and help tune a few cam setups in RB's that seem to be at odds with your extensive and superior knowledge.

I'll leave it to you to explain it all on this thread from here on as clearly I'm wrong.

People who would like to hear the rantings of a crazy fool like me on putting cams in an RB can PM me but, remember there is far better info in this thread.

Edited March 11, 2008 by rev210

[SLED]

another thing to take in account of is that stock cams are always going to be sedate things, with emissions, idle quality and low down drive ability to take care of, they are never going to be mass power producers.

No arguement there.....isn't that what I was saying though......have another read and you'll see I was referring to response & flexibility on an otherwise stock motor?

In my first post on this thread I asked Joel what else he's done to his motor and what his plans are b4 being able to advise further.

Why would someone change cams on a relatively stock motor.....doesn't make any sense (if that is the case).

[SLED]

Motec system YO! Yep they are fully sick. They wind lag out of motors and wind up clocks too.

Strange really as I had mistakenly thought that an aftermarket ecu's abillity to add more timing brought boost on earlier and that I thought (also mistakenly) this also had the effect of advancing the intake cam timing therfore increasing the cranking compression.....You've just agreed with my previous post that it's the ECU that does this.

You seem to be the expert mate. I've just tuned and help tune a few cam setups in RB's that seem to be at odds with your extensive and superior knowledge.

I'll leave it to you to explain it all on this thread from here on as clearly I'm wrong.

People who would like to hear the rantings of a crazy fool like me on putting cams in an RB can PM me but, remember there is far better info in this thread.

You're way too emotional and taking this personally not to mention moving away from the specific subject in relation to the question asked by Joel.

During my 20 years at Adelaide Engine we had a cam grinder with approx 200 different masters that included profiles from everything from a 40hp 1200cc VW to Porsche.....what's your engineering background?

[rev210]

You're way too emotional and taking this personally not to mention moving away from the specific subject in relation to the question asked by Joel.

During my 20 years at Adelaide Engine we had a cam grinder with approx 200 different masters that included profiles from everything from a 40hp 1200cc VW to Porsche.....what's your engineering background?

Not emo' just sarcastic. Don't take it the wrong way...

I'm putting in my 2c of actual experience with these motors, limited as it is. I have plenty of evidence to substanciate what I am reccomending for this type of engine. I am trying to be helpfull not argumentative....ok so maybe I'm being a bit mean on the odd occasion

From my actual experience Response and flexibillty are vastly improved over stock cams. If by response you mean how quickly boost comes on and by flexibillity you mean the width of the power band or average power. The stock cams aren't optimised for either else they would lose out in emissions and to some extent fuel efficiency. If we look at the profiles they have they are really conservative.

Driving a nice set of well sorted Tomei drop in's is chalk and cheeze, the car pulls like a freight train unlike the stock cams.

I have a graph or two of dynos that demonstrate this that have been stuck up before and if you search you can find a number of other examples of what I am talking about.

You have a nice GTR I see and if you haven't considered cams before I'd be happy to show you some results specific to the RB26's.

You will also be pleased to hear I have no engineering background so any time you like you can dismiss what I say, I won't be offended.

[SLED]

Not emo' just sarcastic. Don't take it the wrong way...

I'm putting in my 2c of actual experience with these motors, limited as it is. I have plenty of evidence to substanciate what I am reccomending for this type of engine. I am trying to be helpfull not argumentative....ok so maybe I'm being a bit mean on the odd occasion

From my actual experience Response and flexibillty are vastly improved over stock cams. If by response you mean how quickly boost comes on and by flexibillity you mean the width of the power band or average power. The stock cams aren't optimised for either else they would lose out in emissions and to some extent fuel efficiency. If we look at the profiles they have they are really conservative.

Driving a nice set of well sorted Tomei drop in's is chalk and cheeze, the car pulls like a freight train unlike the stock cams.

I have a graph or two of dynos that demonstrate this that have been stuck up before and if you search you can find a number of other examples of what I am talking about.

You have a nice GTR I see and if you haven't considered cams before I'd be happy to show you some results specific to the RB26's.

You will also be pleased to hear I have no engineering background so any time you like you can dismiss what I say, I won't be offended.

Yeah no offense taken .

I always try to compare apples with apples though, ie: same valve timing on the 2 types etc because as you have already stated, response can go up and down the rpm range just with a set of adj gears.

Having said all that, my GTR does have a few mods so I would be keen to see some of your results on 26dett's.........I realize there are alot more experts out there that I could learn from as my knowlegde is not neccesarily engine specific and what works for a 6cyl boxer motor may not work on an RB26.

Here is a good post from my mate WEGS who has had responses from some of the big guns on a similar issue......I think you even had a go in there.

http://www.skylinesaustralia.com/forums/Ke...43#entry3617443

[joeleo87]

Well im aiming for about 230-240kws, i know i could do the conversion thing but i dun wanna ;p i like the RB20 if revs like a mofo.

i was thinking along the lines of mods:

-R34 GTR fuel pump (legend sled)

-444cc or 555cc injectors

-Cam Gears

-Cam shafts (been quoted $820 for a set of RB20 cam shafts 254 DURO and 8.5 lift) <- sound good??

-Bigger turbo, been looking at the hypergear turbos, i like the look of the TR43HF.

the cams part sound ok???

[rad100]

im looking at almost the same...

except i have a

gt2530

gtr injectors

pfc

gtr pump..

and was wondering how the cam/cam gears are going to help.

[Simon-S14]

what cams joel?

personally i reckon go the 25, still revs fine, but makes awesome torque