Which Camshaft For Responsive 2.9L Bc Stroker?

[XKLABA]

Yeah all stock, car only has HG, full exhaust, cam gears boost controller and ECU

My other car is the oppersite, full built 3.0ltr with HKS GTRSs 250 poncams BC springs and made 623hp and all 4

[cobrAA]

Like anything in the car world, theres always pro and cons. So what's the cons of using procam 260 10.8mm Vs. poncam 260 9.15mm ?? I believe OP and I want quicker spool so we should both go for 260 and higher lift possible for best gain.

Since both OP and I have to rebuild the head, I guess the difference in fitting these procam Vs poncam is negligible no ?

[r32-25t]

Lift=power, duration=when

[XKLABA]

Poncam is suppose to boltin with no mods, suppose to lol

The procam will require new buckets - shims and the head to be "relieved" for lobe clearance

Look at contacting Unigroup Engineering for their 260 x 10.8, as much as their the same specs the UE ones open a lot faster therefore are peak open longer, will require new shims and head to be "relieved" for the lobes

I went from 260 to 250 poncams and would never use 260s again, 250s spool the turbos so much sooner and give more "drive" everywhere

[GTSBoy]

CobrAA, you've been given the answer to this question many times before.

[cobrAA]

CobrAA, you've been given the answer to this question many times before.

Regarding the PROS, yes. regarding the CONS, not that i recall, but now I got my answer

[GTR_JOEY]

For the love of god... Just buy the UE cams.. They are going to be better then any of the other stuff you will buy off the shelf

[Piggaz]

Cons are they will wear faster due to the aggressive profile/the need for a firmer spring. How fast is anyone's guess. Who cares though.

[levinboy]

My 272 10.8 cams go alright hahaha

Still very responsive with my baby -9s

[XKLABA]

Should add anything with more then 9.2mm lift will require better springs too

My 272 10.8 cams go alright hahaha

Still very responsive with my baby -9s

I would really like to see what happens if you where ever to put the UE 260 x 10.8mm cams in, those poor -9s would drop their bearings

[bigmikespec]

Lift=power, duration=when

Please don't spread that... the reason for longer duration is not 'when', it just happens to be a consequence of longer duration.

[levinboy]

Should add anything with more then 9.2mm lift will require better springs too

I would really like to see what happens if you where ever to put the UE 260 x 10.8mm cams in, those poor -9s would drop their bearings

Haha I know was considering it

But might be too aggressive for them

Going to bump the compression up when I get around to fixing my car

[r32-25t]

Please don't spread that... the reason for longer duration is not 'when', it just happens to be a consequence of longer duration.

so in other words it's decides when it going to make the power

[bigmikespec]

so in other words it's decides when it going to make the power

What I meant by my comment was the reason why people choose camshafts with longer duration is not because they want to make power later in the rpm range, that is just a consequence of a multiple of engine changes. As I said before, if you have low exhaust manifold back pressure relative to boost pressure (and this is usually in a high rpm engine ith big turbo that won't make a lot of power below 4000rpm... as an example), then you can choose longer duration camshafts to take advantage of scavenging effects during camshaft overlap.

XKALABA's result with going from 260 to 250 is not an accident, it makes total sense as he has factory mounted twin turbochargers that have high back pressure relative to boost pressure.

[R31Nismoid]

One example is on post #19 of this thread: http://www.sau.com.au/forums/topic/93880-rb26-turbo-upgrade-all-dyno-results/

He makes 17 more KW and greater power everywhere in the curve from just changing cam timing...seems like a lot of power increase from rotating cams and from what I read most people don't move them more than a few degrees apart.

In the list of durations of "bolt in" cams there is clearly more than just 4 degrees of cam timing changes going on and it's leading me to believe that there should be more room in there even on the smaller turbos that I will be running to gain some response from changing out the factory cams and likely even more response when I get them timed right on the dyno.

Yeah but who is to say the cam timing was 100% set-up in the first place? If it was out, then very easy to get a gain like that

Really as the other guys have said - you are putting -7s on a 2.9ltr. Putting cams in, is a waste of time.

Your power band will be from 3000rpm-6500rpm regardless of what you do because the turbos will run out of airflow, as they run out around 7000rpm on a 2.6ltr. Hell it might even come on before 3000rpm... Not too many have gone and put such small turbos on a 2.9ltr, in fact I don't think anyone has.

[bigmikespec]

Yeah but who is to say the cam timing was 100% set-up in the first place? If it was out, then very easy to get a gain like that

Really as the other guys have said - you are putting -7s on a 2.9ltr. Putting cams in, is a waste of time.

Your power band will be from 3000rpm-6500rpm regardless of what you do because the turbos will run out of airflow, as they run out around 7000rpm on a 2.6ltr. Hell it might even come on before 3000rpm... Not too many have gone and put such small turbos on a 2.9ltr, in fact I don't think anyone has.

...and you will choke the restrictive exhaust side.

[djvoodoo]

Poncam is suppose to boltin with no mods, suppose to lol

The procam will require new buckets - shims and the head to be "relieved" for lobe clearance

Look at contacting Unigroup Engineering for their 260 x 10.8, as much as their the same specs the UE ones open a lot faster therefore are peak open longer, will require new shims and head to be "relieved" for the lobes

I went from 260 to 250 poncams and would never use 260s again, 250s spool the turbos so much sooner and give more "drive" everywhere

hmmm, ok so taking all comments in this thread on board. I have -7's on stock RB26. Suprisingly the boost curve is quite laggy compared to stock (which is the opposite of what people say about -7's). Makes positive pressure below 3000, but I dont get full boost - 18psi until 4750-5000rpm ish. I was thinking Poncam 260 9.15mm lift to help bring on boost quicker and extract more torque early in the rev range.

I am now tossing up between Type R 250 9.15 due to some of the comments above.

Which makes more sense for my needs?

[r32-25t]

The type r

But before looking at cams, what dumps are you using? What's the exhaust sizing?

[XKLABA]

Stock cams on a 2.6 with -7s is best by far, i got my car with 260s and went back to 250s cause i couldnt find the stock cams , you need to get it on the dyno and dial the cam timing to get response, advance intake and retard exhaust

The result I got from the two cams where in my 34 when it was still a 2.6 with -7s, there is a dyno sheet here somewhere when it was last tuned with that setup and it would make positive pressure below 2k and usable boost in the mid 2k range ( in 5th cause 1:1 ratio ) and run 19psi to the 8200redline

What is your setup/mods and who tunes it ?

hmmm, ok so taking all comments in this thread on board. I have -7's on stock RB26. Suprisingly the boost curve is quite laggy compared to stock (which is the opposite of what people say about -7's). Makes positive pressure below 3000, but I dont get full boost - 18psi until 4750-5000rpm ish. I was thinking Poncam 260 9.15mm lift to help bring on boost quicker and extract more torque early in the rev range.

I am now tossing up between Type R 250 9.15 due to some of the comments above.

Which makes more sense for my needs?

[XKLABA]

The type r

But before looking at cams, what dumps are you using? What's the exhaust sizing?

His portal says R34 GTR so I'm guessing his stock dumps should be fine

But yeah what's the rest of the exhaust made up of ?